ant.c
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ant.c
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	#if defined(__GNUC__) && !defined(__clang__)
	#pragma GCC optimize("O3,inline")
	#endif

	#include <compat.h> // IWYU pragma: keep

	#include "ant.h"
	#include "utf8.h"
	#include "ptr.h"
	#include "debug.h"
	#include "tokens.h"
	#include "common.h"
	#include "utils.h"
	#include "sugar.h"
	#include "base64.h"
	#include "runtime.h"
	#include "internal.h"
	#include "errors.h"
	#include "descriptors.h"
	#include "shapes.h"

	#include "gc.h"
	#include "gc/objects.h"
	#include "gc/roots.h"

	#include "esm/remote.h"
	#include "esm/loader.h"
	#include "esm/exports.h"
	#include "esm/builtin_bundle.h"

	#include "silver/lexer.h"
	#include "silver/compiler.h"
	#include "silver/engine.h"

	#include <uv.h>
	#include <assert.h>
	#include <pcre2.h>
	#include <stdarg.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <time.h>
	#include <utarray.h>
	#include <uthash.h>
	#include <float.h>
	#include <tlsuv/tlsuv.h>
	#include <tlsuv/http.h>
	#include <minicoro.h>

	#ifdef _WIN32
	#include <sys/stat.h>
	#else
	#include <sys/time.h>
	#include <sys/stat.h>
	#include <sys/resource.h>
	#endif

	#include "modules/atomics.h"
	#include "modules/bigint.h"
	#include "modules/timer.h"
	#include "modules/symbol.h"
	#include "modules/ffi.h"
	#include "modules/date.h"
	#include "modules/buffer.h"
	#include "modules/blob.h"
	#include "modules/collections.h"
	#include "modules/lmdb.h"
	#include "modules/regex.h"
	#include "modules/globals.h"

	#define D(x) ((double)(x))

	_Static_assert(sizeof(double) == 8, "NaN-boxing requires 64-bit IEEE 754 doubles");
	_Static_assert(sizeof(uint64_t) == 8, "NaN-boxing requires 64-bit integers");
	_Static_assert(sizeof(double) == sizeof(uint64_t), "double and uint64_t must have same size");

	#if defined(__STDC_IEC_559__) \|\| defined(__GCC_IEC_559)
	#elif defined(__FAST_MATH__)
	#error "NaN-boxing is incompatible with -ffast-math"
	#elif DBL_MANT_DIG != 53 \|\| DBL_MAX_EXP != 1024
	#error "NaN-boxing requires IEEE 754 binary64 doubles"
	#endif

	typedef struct interned_string {
	uint64_t hash;
	char *str;
	size_t len;
	struct interned_string *next;
	} interned_string_t;

	typedef struct {
	uint32_t id;
	uint32_t flags;
	const char *key;
	uint32_t desc_len;
	char desc[];
	} ant_symbol_heap_t;

	static size_t intern_count = 0;
	static size_t intern_bytes = 0;

	static interned_string_t **intern_buckets = NULL;
	static size_t intern_bucket_count = 0;

	#define INTERN_BUCKET_MIN 1024u
	#define INTERN_LOAD_NUM 4u
	#define INTERN_LOAD_DEN 5u

	static bool intern_table_init(void) {
	if (intern_buckets) return true;
	intern_bucket_count = INTERN_BUCKET_MIN;
	intern_buckets = ant_calloc(sizeof(intern_buckets) intern_bucket_count);
	if (!intern_buckets) {
	intern_bucket_count = 0;
	return false;
	}
	return true;
	}

	static bool intern_table_rehash(size_t new_bucket_count) {
	if (!intern_buckets \|\| new_bucket_count < INTERN_BUCKET_MIN) return false;

	interned_string_t *next = ant_calloc(sizeof(next) * new_bucket_count);
	if (!next) return false;

	for (size_t i = 0; i < intern_bucket_count; i++) {
	interned_string_t *entry = intern_buckets[i];
	while (entry) {
	interned_string_t *link = entry->next;
	size_t bucket = (size_t)(entry->hash & (new_bucket_count - 1));
	entry->next = next[bucket];
	next[bucket] = entry;
	entry = link;
	}
	}

	free(intern_buckets);
	intern_buckets = next;
	intern_bucket_count = new_bucket_count;

	return true;
	}

	static const UT_icd promise_handler_icd = {
	.sz = sizeof(promise_handler_t),
	.init = NULL,
	.copy = NULL,
	.dtor = NULL,
	};

	static uint32_t next_promise_id = 1;
	static uint32_t get_promise_id(ant_t *js, ant_value_t p);

	static ant_promise_state_t get_promise_data(ant_t js, ant_value_t promise, bool create);
	static ant_proxy_state_t *get_proxy_data(ant_value_t obj);

	static inline uint32_t promise_handler_count(const ant_promise_state_t *pd) {
	return pd ? (uint32_t)pd->handler_count : 0;
	}

	static inline bool promise_has_handlers(const ant_promise_state_t *pd) {
	return promise_handler_count(pd) != 0;
	}

	static bool promise_handler_append(ant_promise_state_t pd, const promise_handler_t handler) {
	if (!pd \|\| !handler) return false;

	if (pd->handler_count == 0) {
	pd->inline_handler = *handler;
	pd->handler_count = 1;
	return true;
	}

	if (pd->handler_count == 1) {
	if (!pd->handlers) utarray_new(pd->handlers, &promise_handler_icd);
	if (!pd->handlers) return false;
	utarray_push_back(pd->handlers, &pd->inline_handler);
	utarray_push_back(pd->handlers, handler);
	pd->handler_count = 2;
	return true;
	}

	if (!pd->handlers) utarray_new(pd->handlers, &promise_handler_icd);
	if (!pd->handlers) return false;

	utarray_push_back(pd->handlers, handler);
	pd->handler_count++;

	return true;
	}

	static inline promise_handler_t promise_handler_at(ant_promise_state_t pd, uint32_t index) {
	if (!pd \|\| index >= pd->handler_count) return NULL;
	if (pd->handler_count == 1) return &pd->inline_handler;
	if (!pd->handlers) return NULL;
	return (promise_handler_t *)utarray_eltptr(pd->handlers, (unsigned int)index);
	}

	static inline void promise_handlers_clear(ant_promise_state_t *pd) {
	if (!pd) return;
	pd->handler_count = 0;
	pd->inline_handler = (promise_handler_t){ 0 };
	if (pd->handlers) utarray_clear(pd->handlers);
	}

	ant_value_t tov(double d) {
	union { double d; ant_value_t v; } u = {d};
	if (__builtin_expect(isnan(d), 0))
	return (u.v > NANBOX_PREFIX)
	? 0x7FF8000000000000ULL : u.v; // canonical NaN
	return u.v;
	}

	double tod(ant_value_t v) {
	union { ant_value_t v; double d; } u = {v}; return u.d;
	}

	static bool is_tagged(ant_value_t v) {
	return v > NANBOX_PREFIX;
	}

	size_t vdata(ant_value_t v) {
	return (size_t)(v & NANBOX_DATA_MASK);
	}

	ant_object_t *js_obj_ptr(ant_value_t v) {
	if (!is_object_type(v)) return NULL;
	ant_value_t as_obj = js_as_obj(v);
	return (ant_object_t *)(uintptr_t)vdata(as_obj);
	}

	ant_value_t js_obj_from_ptr(ant_object_t *obj) {
	if (!obj) return js_mkundef();
	return mkval(T_OBJ, (uintptr_t)obj);
	}

	void js_mark_constructor(ant_value_t value, bool is_constructor) {
	ant_object_t *obj = js_obj_ptr(value);
	if (obj) obj->is_constructor = is_constructor ? 1u : 0u;
	}

	static inline ant_extra_slot_t obj_extra_slots(ant_object_t obj) {
	return (ant_extra_slot_t *)obj->extra_slots;
	}

	static ant_value_t obj_extra_get(ant_object_t *obj, internal_slot_t slot) {
	if (!obj \|\| obj->extra_count == 0) return js_mkundef();
	ant_extra_slot_t *entries = obj_extra_slots(obj);
	for (uint8_t i = 0; i < obj->extra_count; i++) {
	if ((internal_slot_t)entries[i].slot == slot) return entries[i].value;
	}
	return js_mkundef();
	}

	static bool obj_extra_set(ant_object_t *obj, internal_slot_t slot, ant_value_t value) {
	if (!obj) return false;
	ant_extra_slot_t *entries = obj_extra_slots(obj);
	for (uint8_t i = 0; i < obj->extra_count; i++) {
	if ((internal_slot_t)entries[i].slot == slot) {
	entries[i].value = value;
	return true;
	}
	}

	if (obj->extra_count == UINT8_MAX) return false;
	uint8_t next_count = (uint8_t)(obj->extra_count + 1);
	ant_extra_slot_t next = realloc(entries, sizeof(next) * next_count);
	if (!next) return false;

	next[obj->extra_count].slot = (uint8_t)slot;
	next[obj->extra_count].value = value;
	obj->extra_slots = (ant_value_t *)next;
	obj->extra_count = next_count;
	return true;
	}

	static ant_offset_t propref_make(ant_t js, ant_object_t obj, uint32_t slot) {
	if (!js \|\| !obj) return 0;

	if (js->prop_refs_len >= js->prop_refs_cap) {
	ant_offset_t next_cap = js->prop_refs_cap ? js->prop_refs_cap * 2 : 256;
	ant_prop_ref_t next = realloc(js->prop_refs, sizeof(next) * next_cap);
	if (!next) return 0;
	js->prop_refs = next;
	js->prop_refs_cap = next_cap;
	}

	ant_offset_t handle = js->prop_refs_len + 1;
	js->prop_refs[js->prop_refs_len++] = (ant_prop_ref_t){
	.obj = obj,
	.slot = slot,
	.valid = true,
	};
	obj->propref_count++;
	return handle;
	}

	static ant_prop_ref_t propref_get(ant_t js, ant_offset_t handle) {
	if (!js \|\| handle == 0 \|\| handle > js->prop_refs_len) return NULL;
	ant_prop_ref_t *ref = &js->prop_refs[handle - 1];
	return ref->valid ? ref : NULL;
	}

	static inline ant_value_t propref_load(ant_t *js, ant_offset_t handle) {
	ant_prop_ref_t *ref = propref_get(js, handle);
	if (!ref \|\| !ref->obj \|\| ref->slot >= ref->obj->prop_count) return js_mkundef();
	return ant_object_prop_get_unchecked(ref->obj, ref->slot);
	}

	static inline bool propref_store(ant_t *js, ant_offset_t handle, ant_value_t value) {
	ant_prop_ref_t *ref = propref_get(js, handle);
	if (!ref \|\| !ref->obj \|\| ref->slot >= ref->obj->prop_count) return false;
	ant_object_prop_set_unchecked(ref->obj, ref->slot, value);
	gc_write_barrier(js, ref->obj, value);
	return true;
	}

	static void propref_adjust_after_swap_delete(ant_t js, ant_object_t obj, uint32_t deleted_slot, uint32_t swapped_from) {
	if (!js \|\| !obj \|\| obj->propref_count == 0) return;

	for (ant_offset_t i = js->prop_refs_len; i-- > 0;) {
	ant_prop_ref_t *ref = &js->prop_refs[i];
	if (!ref->valid \|\| ref->obj != obj) continue;

	if (ref->slot == deleted_slot) {
	ref->valid = false;
	obj->propref_count--;
	if (obj->propref_count == 0) return;
	} else if (ref->slot == swapped_from) ref->slot = deleted_slot;
	}
	}

	bool js_obj_ensure_prop_capacity(ant_object_t *obj, uint32_t needed) {
	if (!obj) return false;
	uint32_t inobj_limit = ant_object_inobj_limit(obj);
	uint32_t old_count = obj->prop_count;
	if (needed <= obj->prop_count) return true;

	if (needed > inobj_limit) {
	uint32_t overflow_needed = needed - inobj_limit;
	if (overflow_needed > obj->overflow_cap) {
	uint32_t new_cap = obj->overflow_cap ? (uint32_t)obj->overflow_cap * 2 : 4;
	while (new_cap < overflow_needed) new_cap *= 2;

	if (new_cap > 255) new_cap = overflow_needed;
	ant_value_t next = realloc(obj->overflow_prop, sizeof(next) * new_cap);
	if (!next) return false;

	obj->overflow_prop = next;
	obj->overflow_cap = (uint8_t)new_cap;
	}
	} else if (obj->overflow_prop) {
	free(obj->overflow_prop);
	obj->overflow_prop = NULL;
	obj->overflow_cap = 0;
	}

	obj->prop_count = needed;
	for (uint32_t i = old_count; i < needed; i++) {
	ant_object_prop_set_unchecked(obj, i, js_mkundef());
	}
	return true;
	}

	bool js_obj_ensure_unique_shape(ant_object_t *obj) {
	if (!obj \|\| !obj->shape) return false;
	if (!ant_shape_is_shared(obj->shape)) return true;

	ant_shape_t *copy = ant_shape_clone(obj->shape);
	if (!copy) return false;

	ant_shape_release(obj->shape);
	obj->shape = copy;
	return true;
	}

	static void obj_remove_prop_slot(ant_object_t *obj, uint32_t slot) {
	if (!obj \|\| slot >= obj->prop_count) return;
	uint32_t last = obj->prop_count - 1;
	if (slot != last) {
	ant_object_prop_set_unchecked(obj, slot, ant_object_prop_get_unchecked(obj, last));
	}
	obj->prop_count--;
	}

	static ant_exotic_ops_t obj_ensure_exotic_ops(ant_object_t obj) {
	if (!obj) return NULL;
	if (!obj->exotic_ops) {
	ant_exotic_ops_t ops = calloc(1, sizeof(ops));
	if (!ops) return NULL;
	obj->exotic_ops = ops;
	}
	return (ant_exotic_ops_t )(void )obj->exotic_ops;
	}

	static ant_object_t obj_alloc(ant_t js, uint8_t type_tag, uint8_t inobj_limit) {
	size_t threshold = GC_HEAP_GROWTH(js->gc_last_live);

	if (threshold < 2048) threshold = 2048;
	if (js->obj_arena.live_count >= threshold) gc_run(js);

	ant_object_t obj = (ant_object_t )fixed_arena_alloc(&js->obj_arena);
	if (!obj) return NULL;

	obj->type_tag = type_tag;
	obj->proto = js_mkundef();
	obj->shape = ant_shape_new_with_inobj_limit(inobj_limit);
	obj->overflow_prop = NULL;
	obj->overflow_cap = 0;
	obj->prop_count = 0;
	obj->inobj_limit = ant_shape_get_inobj_limit(obj->shape);
	for (uint32_t i = 0; i < ANT_INOBJ_MAX_SLOTS; i++) obj->inobj[i] = js_mkundef();
	obj->extensible = 1;
	obj->frozen = 0;
	obj->sealed = 0;
	obj->is_exotic = 0;
	obj->is_constructor = 0;
	obj->fast_array = 0;
	obj->exotic_ops = NULL;
	obj->exotic_keys = NULL;
	obj->promise_state = NULL;
	obj->proxy_state = NULL;
	obj->u.data.value = js_mkundef();
	obj->extra_slots = NULL;
	obj->extra_count = 0;
	obj->gc_pending_next = NULL;
	obj->gc_pending_rooted = false;
	obj->generation = 0;
	obj->in_remember_set = 0;

	obj->next = js->objects;
	js->objects = obj;

	return obj;
	}

	static ant_value_t get_slot(ant_value_t obj, internal_slot_t slot);
	static void set_slot(ant_value_t obj, internal_slot_t slot, ant_value_t value);

	static ant_value_t get_proto(ant_t *js, ant_value_t obj);
	static void set_proto(ant_t *js, ant_value_t obj, ant_value_t proto);

	const char *typestr(uint8_t t) {
	static const char *names[] = {
	[T_UNDEF] = "undefined", [T_NULL] = "object", [T_BOOL] = "boolean",
	[T_NUM] = "number", [T_BIGINT] = "bigint", [T_STR] = "string",
	[T_SYMBOL] = "symbol", [T_OBJ] = "object", [T_ARR] = "object",
	[T_FUNC] = "function", [T_CFUNC] = "function", [T_CLOSURE] = "closure",
	[T_PROMISE] = "object", [T_GENERATOR] = "object",
	[T_ERR] = "err", [T_TYPEDARRAY] = "typedarray",
	[T_FFI] = "ffi", [T_NTARG] = "ntarg"
	};

	return (t < sizeof(names) / sizeof(names[0])) ? names[t] : "??";
	}

	uint8_t vtype(ant_value_t v) {
	return is_tagged(v) ? ((v >> NANBOX_TYPE_SHIFT) & NANBOX_TYPE_MASK) : (uint8_t)T_NUM;
	}

	ant_value_t mkval(uint8_t type, uint64_t data) {
	return NANBOX_PREFIX
	\| ((ant_value_t)(type & NANBOX_TYPE_MASK) << NANBOX_TYPE_SHIFT)
	\| (data & NANBOX_DATA_MASK);
	}

	ant_value_t js_obj_to_func_ex(ant_value_t obj, uint8_t flags) {
	ant_t *js = rt->js;

	sv_closure_t *closure = js_closure_alloc(js);
	if (!closure) return mkval(T_ERR, 0);

	closure->func_obj = (vtype(obj) == T_OBJ) ? obj : mkval(T_OBJ, vdata(obj));
	closure->bound_this = js_mkundef();
	closure->bound_args = js_mkundef();
	closure->super_val = js_mkundef();
	closure->call_flags = flags;

	ant_object_t *func_obj = js_obj_ptr(closure->func_obj);
	if (func_obj) {
	if (flags & SV_CALL_IS_DEFAULT_CTOR) func_obj->is_constructor = 1;
	// mark native function objects as constructors when they are
	// created with an explicit .prototype own property.
	else if (
	!func_obj->is_constructor &&
	func_obj->shape &&
	js->intern.prototype &&
	vtype(obj_extra_get(func_obj, SLOT_CFUNC)) == T_CFUNC
	) if (ant_shape_lookup_interned(func_obj->shape, js->intern.prototype) >= 0
	) func_obj->is_constructor = 1;
	}

	return mkval(T_FUNC, (uintptr_t)closure);
	}

	ant_value_t js_obj_to_func(ant_value_t obj) {
	return js_obj_to_func_ex(obj, 0);
	}

	ant_value_t js_mktypedarray(void *data) {
	return mkval(T_TYPEDARRAY, (uintptr_t)data);
	}

	void *js_gettypedarray(ant_value_t val) {
	if (vtype(val) != T_TYPEDARRAY) return NULL;
	return (void *)vdata(val);
	}

	ant_value_t js_get_slot(ant_value_t obj, internal_slot_t slot) {
	return get_slot(js_as_obj(obj), slot);
	}

	ant_value_t js_mkffi(unsigned int index) {
	return mkval(T_FFI, (uint64_t)index);
	}

	int js_getffi(ant_value_t val) {
	if (vtype(val) != T_FFI) return -1;
	return (int)vdata(val);
	}

	typedef enum {
	NTARG_INVALID = 0,
	NTARG_NEW_TARGET = 1
	} ntarg_kind_t;

	static inline bool is_unboxed_obj(ant_t *js, ant_value_t val, ant_value_t expected_proto) {
	if (vtype(val) != T_OBJ) return false;
	if (vtype(get_slot(val, SLOT_PRIMITIVE)) != T_UNDEF) return false;
	ant_value_t proto = get_slot(val, SLOT_PROTO);
	return vdata(proto) == vdata(expected_proto);
	}

	uint32_t js_to_uint32(double d) {
	if (!isfinite(d) \|\| d == 0) return 0;
	double sign = (d < 0) ? -1.0 : 1.0;
	double posInt = sign * floor(fabs(d));
	double val = fmod(posInt, 4294967296.0);
	if (val < 0) val += 4294967296.0;
	return (uint32_t) val;
	}

	int32_t js_to_int32(double d) {
	uint32_t uint32 = js_to_uint32(d);
	if (uint32 >= 2147483648U) return (int32_t)(uint32 - 4294967296.0);
	return (int32_t) uint32;
	}

	static size_t strstring(ant_t js, ant_value_t value, char buf, size_t len);
	static size_t strkey(ant_t js, ant_value_t value, char buf, size_t len);

	ant_offset_t vstrlen(ant_t *js, ant_value_t v) {
	if (str_is_heap_rope(v)) {
	ant_rope_heap_t *rope = ant_str_rope_ptr(v);
	return rope ? rope->len : 0;
	}
	if (str_is_heap_builder(v)) {
	ant_string_builder_t *builder = ant_str_builder_ptr(v);
	return builder ? builder->len : 0;
	}
	ant_flat_string_t *flat = ant_str_flat_ptr(v);
	return flat ? flat->len : 0;
	}

	static ant_value_t proxy_read_target(ant_t *js, ant_value_t obj);
	static ant_offset_t proxy_aware_length(ant_t *js, ant_value_t obj);
	static ant_value_t proxy_aware_get_elem(ant_t js, ant_value_t obj, const char key, size_t key_len);

	static ant_offset_t get_dense_buf(ant_value_t arr);
	static ant_offset_t dense_capacity(ant_offset_t doff);
	static ant_offset_t get_array_length(ant_t *js, ant_value_t arr);
	static ant_value_t arr_get(ant_t *js, ant_value_t arr, ant_offset_t idx);
	static bool arr_has(ant_t *js, ant_value_t arr, ant_offset_t idx);

	static bool streq(const char buf, size_t len, const char p, size_t n);
	static bool parse_func_params(ant_t js, uint8_t flags, int *out_count);
	static bool try_dynamic_setter(ant_t js, ant_value_t obj, const char key, size_t key_len, ant_value_t value);
	static uintptr_t lkp_with_setter(ant_t js, ant_value_t obj, const char buf, size_t len, ant_value_t setter_out, bool has_setter_out);
	static ant_value_t call_proto_accessor(ant_t js, ant_value_t prim, ant_value_t accessor, bool has_accessor, ant_value_t arg, int arg_count, bool is_setter);
	static ant_value_t get_prototype_for_type(ant_t *js, uint8_t type);

	static inline ant_value_t lkp_val(ant_t js, ant_value_t obj, const char buf, size_t len);
	static inline ant_value_t lkp_sym_proto_val(ant_t *js, ant_value_t obj, ant_offset_t sym_off);
	static size_t tostr(ant_t js, ant_value_t value, char buf, size_t len);
	static size_t strpromise(ant_t js, ant_value_t value, char buf, size_t len);

	static ant_value_t js_call_valueOf(ant_t *js, ant_value_t value);
	static ant_value_t js_call_toString(ant_t *js, ant_value_t value);
	static ant_value_t js_call_method(ant_t js, ant_value_t obj, const char method, ant_value_t *args, int nargs);
	static ant_value_t builtin_object_defineProperty(ant_t js, ant_value_t args, int nargs);

	static inline bool is_slot_prop(ant_offset_t header);
	static inline ant_offset_t next_prop(ant_offset_t header);

	static ant_value_t builtin_promise_then(ant_t js, ant_value_t args, int nargs);
	static ant_value_t proxy_get(ant_t js, ant_value_t proxy, const char key, size_t key_len);
	static ant_value_t proxy_get_val(ant_t *js, ant_value_t proxy, ant_value_t key_val);
	static ant_value_t proxy_get_prototype_of(ant_t *js, ant_value_t proxy);
	static ant_value_t proxy_set(ant_t js, ant_value_t proxy, const char key, size_t key_len, ant_value_t value);
	static ant_value_t proxy_has(ant_t js, ant_value_t proxy, const char key, size_t key_len);
	static ant_value_t proxy_has_val(ant_t *js, ant_value_t proxy, ant_value_t key_val);
	static ant_value_t proxy_get_own_property_descriptor(ant_t *js, ant_value_t proxy, ant_value_t key_val);
	static ant_value_t proxy_has_own(ant_t *js, ant_value_t proxy, ant_value_t key_val);
	static ant_value_t proxy_delete(ant_t js, ant_value_t proxy, const char key, size_t key_len);
	static ant_value_t proxy_delete_val(ant_t *js, ant_value_t proxy, ant_value_t key_val);
	static ant_value_t proxy_define_property(ant_t *js, ant_value_t proxy, ant_value_t key_val, ant_value_t descriptor);

	static ant_value_t get_ctor_proto(ant_t js, const char name, size_t len);
	static inline void array_len_set(ant_t *js, ant_value_t obj, ant_offset_t new_len);

	typedef struct { ant_value_t handle; bool is_new; } ctor_t;

	static ctor_t get_constructor(ant_t js, const char name, size_t len) {
	ctor_t ctor;

	ctor.handle = get_ctor_proto(js, name, len);
	ctor.is_new = (vtype(js->new_target) != T_UNDEF);

	return ctor;
	}

	ant_value_t unwrap_primitive(ant_t *js, ant_value_t val) {
	if (__builtin_expect(vtype(val) != T_OBJ, 1)) return val;
	ant_value_t prim = get_slot(val, SLOT_PRIMITIVE);
	if (__builtin_expect(vtype(prim) == T_UNDEF, 1)) return val;
	return prim;
	}

	static ant_value_t to_string_val(ant_t *js, ant_value_t val) {
	uint8_t t = vtype(val);
	if (t == T_STR) return val;
	if (t == T_OBJ) {
	ant_value_t prim = get_slot(val, SLOT_PRIMITIVE);
	if (vtype(prim) == T_STR) return prim;
	}
	return js_call_toString(js, val);
	}

	bool js_truthy(ant_t *js, ant_value_t v) {
	static const void *dispatch[] = {
	[T_OBJ] = &&l_true,
	[T_FUNC] = &&l_true,
	[T_CFUNC] = &&l_true,
	[T_ARR] = &&l_true,
	[T_PROMISE] = &&l_true,
	[T_GENERATOR] = &&l_true,
	[T_SYMBOL] = &&l_true,
	[T_BOOL] = &&l_bool,
	[T_STR] = &&l_str,
	[T_BIGINT] = &&l_bigint,
	[T_NUM] = &&l_num,
	};

	uint8_t t = vtype(v);
	if (t < sizeof(dispatch) / sizeof(*dispatch) && dispatch[t])
	goto *dispatch[t];
	return false;

	l_true: return true;
	l_bool: return vdata(v) != 0;
	l_str: return vstrlen(js, v) > 0;
	l_bigint: return !bigint_is_zero(js, v);
	l_num: {
	double d = tod(v);
	return d != 0.0 && !isnan(d);
	}
	}

	static size_t cpy(char dst, size_t dstlen, const char src, size_t srclen) {
	if (dstlen == 0) return srclen;
	size_t len = srclen < dstlen - 1 ? srclen : dstlen - 1;
	memcpy(dst, src, len); dst[len] = '\0';
	return srclen;
	}

	size_t uint_to_str(char *buf, size_t bufsize, uint64_t val) {
	if (bufsize == 0) return 0;
	if (val == 0) {
	buf[0] = '0';
	buf[1] = '\0';
	return 1;
	}
	char temp[24];
	size_t len = 0;
	while (val > 0 && len < sizeof(temp)) {
	temp[len++] = '0' + (val % 10);
	val /= 10;
	}
	if (len >= bufsize) len = bufsize - 1;
	for (size_t i = 0; i < len; i++) {
	buf[i] = temp[len - 1 - i];
	}
	buf[len] = '\0';
	return len;
	}

	static ant_value_t stringify_stack[MAX_STRINGIFY_DEPTH];
	static int stringify_depth = 0;
	static int stringify_indent = 0;

	static ant_value_t multiref_objs[MAX_MULTIREF_OBJS];
	static int multiref_ids[MAX_MULTIREF_OBJS];
	static int multiref_count = 0;
	static int multiref_next_id = 0;

	static void scan_refs(ant_t *js, ant_value_t value);
	static ant_value_t strobj_call_custom_inspect(ant_t *js, ant_value_t obj);

	static int find_multiref(ant_value_t obj) {
	for (int i = 0; i < multiref_count; i++) {
	if (multiref_objs[i] == obj) return multiref_ids[i];
	}
	return 0;
	}

	static bool is_on_stack(ant_value_t obj) {
	for (int i = 0; i < stringify_depth; i++) {
	if (stringify_stack[i] == obj) return true;
	}
	return false;
	}

	static void mark_multiref(ant_value_t obj) {
	for (int i = 0; i < multiref_count; i++) {
	if (multiref_objs[i] == obj) {
	if (multiref_ids[i] == 0) multiref_ids[i] = ++multiref_next_id;
	return;
	}
	}
	if (multiref_count < MAX_MULTIREF_OBJS) {
	multiref_objs[multiref_count] = obj;
	multiref_ids[multiref_count] = 0;
	multiref_count++;
	}
	}

	static void scan_obj_refs(ant_t *js, ant_value_t obj) {
	if (is_on_stack(obj)) {
	mark_multiref(obj);
	return;
	}

	if (stringify_depth >= MAX_STRINGIFY_DEPTH) return;
	stringify_stack[stringify_depth++] = obj;

	ant_object_t *ptr = js_obj_ptr(obj);
	if (ptr && ptr->shape) {
	uint32_t count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < count && i < ptr->prop_count; i++) {
	scan_refs(js, ant_object_prop_get_unchecked(ptr, i));
	}
	}

	ant_value_t proto_val = get_proto(js, obj);
	if (vtype(proto_val) == T_OBJ) scan_refs(js, proto_val);

	stringify_depth--;
	}

	static void scan_arr_refs(ant_t *js, ant_value_t obj) {
	if (is_on_stack(obj)) {
	mark_multiref(obj);
	return;
	}

	if (stringify_depth >= MAX_STRINGIFY_DEPTH) return;
	stringify_stack[stringify_depth++] = obj;

	ant_object_t *ptr = js_obj_ptr(obj);
	if (ptr && ptr->shape) {
	uint32_t count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < count && i < ptr->prop_count; i++) {
	scan_refs(js, ant_object_prop_get_unchecked(ptr, i));
	}
	}

	stringify_depth--;
	}

	static void scan_func_refs(ant_t *js, ant_value_t value) {
	ant_value_t func_obj = js_func_obj(value);

	if (is_on_stack(func_obj)) {
	mark_multiref(func_obj);
	return;
	}

	if (stringify_depth >= MAX_STRINGIFY_DEPTH) return;
	stringify_stack[stringify_depth++] = func_obj;

	ant_object_t *ptr = js_obj_ptr(func_obj);
	if (ptr && ptr->shape) {
	uint32_t count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < count && i < ptr->prop_count; i++) {
	scan_refs(js, ant_object_prop_get_unchecked(ptr, i));
	}
	}

	stringify_depth--;
	}

	static void scan_refs(ant_t *js, ant_value_t value) {
	switch (vtype(value)) {
	case T_OBJ: scan_obj_refs(js, value); break;
	case T_ARR: scan_arr_refs(js, value); break;
	case T_FUNC: scan_func_refs(js, value); break;
	default: break;
	}
	}

	static int get_circular_ref(ant_value_t obj) {
	if (is_on_stack(obj)) {
	int ref = find_multiref(obj);
	return ref ? ref : -1;
	}
	return 0;
	}

	static bool is_circular(ant_value_t obj) {
	return is_on_stack(obj);
	}

	static int get_self_ref(ant_value_t obj) {
	return find_multiref(obj);
	}

	static void push_stringify(ant_value_t obj) {
	if (stringify_depth < MAX_STRINGIFY_DEPTH) {
	stringify_stack[stringify_depth++] = obj;
	}
	}

	static void pop_stringify(void) {
	if (stringify_depth > 0) stringify_depth--;
	}

	static size_t add_indent(char *buf, size_t len, int level) {
	size_t wanted = (size_t)(level * 2);
	size_t n = 0;
	for (int i = 0; i < level * 2 && n < len; i++) {
	buf[n++] = ' ';
	}
	return wanted;
	}

	const char get_str_prop(ant_t js, ant_value_t obj, const char key, ant_offset_t klen, ant_offset_t out_len) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, obj);
	ant_value_t v = lkp_val(js, obj, key, klen);

	GC_ROOT_PIN(js, v);
	if (vtype(v) != T_STR) {
	GC_ROOT_RESTORE(js, root_mark);
	return NULL;
	}

	const char str = (const char )(uintptr_t)(vstr(js, v, out_len));
	GC_ROOT_RESTORE(js, root_mark);

	return str;
	}

	static bool is_small_array(ant_t js, ant_value_t obj, int elem_count) {
	ant_offset_t length = get_array_length(js, obj);
	if (length > 64) { if (elem_count) *elem_count = (int)length; return false; }

	int count = 0; bool has_nested = false;
	for (ant_offset_t i = 0; i < length; i++) {
	ant_value_t val = arr_get(js, obj, i); uint8_t t = vtype(val);
	if (t == T_OBJ \|\| t == T_ARR \|\| t == T_FUNC) has_nested = true;
	count++;
	}

	if (elem_count) *elem_count = count;
	return count <= 4 && !has_nested;
	}

	static inline bool is_array_index(const char *key, ant_offset_t klen) {
	if (klen == 0 \|\| (klen > 1 && key[0] == '0')) return false;
	for (ant_offset_t i = 0; i < klen; i++) {
	if (key[i] < '0' \|\| key[i] > '9') return false;
	}
	return true;
	}

	static inline bool parse_array_index(const char key, size_t klen, ant_offset_t max_len, unsigned long out_idx) {
	if (klen == 0 \|\| key[0] < '0' \|\| key[0] > '9') return false;
	unsigned long parsed_idx = 0;

	for (size_t i = 0; i < klen; i++) {
	if (key[i] < '0' \|\| key[i] > '9') return false;
	parsed_idx = parsed_idx * 10 + (key[i] - '0');
	}

	if (parsed_idx >= max_len) return false;
	*out_idx = parsed_idx;
	return true;
	}

	#define ANT_ARRAY_INDEX_EXCLUSIVE ((ant_offset_t)UINT32_MAX)

	static inline ant_object_t *array_obj_ptr(ant_value_t obj) {
	if (!is_object_type(obj)) return NULL;
	ant_object_t *ptr = js_obj_ptr(obj);
	return (ptr && ptr->type_tag == T_ARR) ? ptr : NULL;
	}

	static inline void array_define_or_set_index(ant_t js, ant_value_t obj, const char key, size_t klen) {
	if (!key) return;
	if (!array_obj_ptr(obj)) return;

	unsigned long idx = 0;
	if (!parse_array_index(key, klen, ANT_ARRAY_INDEX_EXCLUSIVE, &idx)) return;

	ant_offset_t next_len = (ant_offset_t)idx + 1;
	if (next_len > get_array_length(js, obj)) {
	array_len_set(js, obj, next_len);
	}
	}

	static ant_offset_t get_array_length(ant_t *js, ant_value_t arr) {
	if (!is_object_type(arr)) return 0;

	ant_object_t *arr_ptr = array_obj_ptr(arr);
	if (arr_ptr) return (ant_offset_t)arr_ptr->u.array.len;

	ant_value_t val = lkp_interned_val(js, arr, js->intern.length);
	if (vtype(val) == T_NUM) return (ant_offset_t) tod(val);

	return 0;
	}

	static ant_value_t get_obj_ctor(ant_t *js, ant_value_t obj) {
	ant_value_t ctor = get_slot(obj, SLOT_CTOR);
	if (vtype(ctor) == T_FUNC) return ctor;
	ant_value_t proto = get_slot(obj, SLOT_PROTO);
	if (vtype(proto) != T_OBJ) return js_mkundef();
	return lkp_interned_val(js, proto, js->intern.constructor);
	}

	static const char get_func_name(ant_t js, ant_value_t func, ant_offset_t *out_len) {
	if (vtype(func) != T_FUNC) return NULL;
	ant_value_t name = lkp_val(js, js_func_obj(func), "name", 4);
	if (vtype(name) != T_STR) return NULL;
	ant_offset_t str_off = vstr(js, name, out_len);
	return (const char *)(uintptr_t)(str_off);
	}

	static const char get_class_name(ant_t js, ant_value_t obj, ant_offset_t out_len, const char skip) {
	const char *name = get_func_name(js, get_obj_ctor(js, obj), out_len);
	if (!name) return NULL;
	if (skip && out_len == (ant_offset_t)strlen(skip) && memcmp(name, skip, out_len) == 0) return NULL;
	return name;
	}

	static inline ant_offset_t dense_iterable_length(ant_t *js, ant_value_t obj) {
	ant_offset_t doff = get_dense_buf(obj);
	if (!doff) return 0;
	ant_offset_t dense_len = dense_capacity(doff);
	ant_offset_t semantic_len = get_array_length(js, obj);
	return dense_len < semantic_len ? dense_len : semantic_len;
	}

	static size_t strarr(ant_t js, ant_value_t obj, char buf, size_t len) {
	int ref = get_circular_ref(obj);
	if (ref) return ref > 0 ? (size_t) snprintf(buf, len, "[Circular *%d]", ref) : cpy(buf, len, "[Circular]", 10);

	push_stringify(obj);
	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	ant_offset_t length = get_array_length(js, obj);
	ant_offset_t d_len = dense_iterable_length(js, obj);
	ant_offset_t iter_len = (d_len >= length) ? length : d_len;

	ant_offset_t class_len = 0;
	const char *class_name = get_class_name(js, obj, &class_len, "Array");

	int elem_count = 0;
	bool inline_mode = is_small_array(js, obj, &elem_count);
	size_t n = 0;

	if (class_name) {
	n += cpy(buf + n, REMAIN(n, len), class_name, class_len);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "(%u) ", (unsigned) length);
	}

	if (length == 0) {
	n += cpy(buf + n, REMAIN(n, len), "[]", 2);
	pop_stringify();
	return n;
	}

	n += cpy(buf + n, REMAIN(n, len), inline_mode ? "[ " : "[\n", 2);
	if (!inline_mode) stringify_indent++;

	bool printed_first = false;
	for (ant_offset_t i = 0; i < iter_len; i++) {
	if (printed_first) n += cpy(buf + n, REMAIN(n, len), inline_mode ? ", " : ",\n", 2);
	if (!inline_mode) n += add_indent(buf + n, REMAIN(n, len), stringify_indent);

	ant_value_t val = arr_get(js, obj, i); bool found = arr_has(js, obj, i);
	n += found ? tostr(js, val, buf + n, REMAIN(n, len)) : cpy(buf + n, REMAIN(n, len), "undefined", 9);
	printed_first = true;
	}

	if (ptr && ptr->shape) {
	uint32_t shape_count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < shape_count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop \|\| prop->type == ANT_SHAPE_KEY_SYMBOL) continue;
	const char *key = prop->key.interned;
	ant_offset_t klen = (ant_offset_t)strlen(key);
	if (is_length_key(key, klen)) continue;

	if (printed_first) n += cpy(buf + n, REMAIN(n, len), inline_mode ? ", " : ",\n", 2);
	if (!inline_mode) n += add_indent(buf + n, REMAIN(n, len), stringify_indent);

	ant_value_t val = (i < ptr->prop_count) ? ant_object_prop_get_unchecked(ptr, i) : js_mkundef();
	if (is_array_index(key, klen)) {
	n += tostr(js, val, buf + n, REMAIN(n, len));
	} else {
	n += cpy(buf + n, REMAIN(n, len), key, klen);
	n += cpy(buf + n, REMAIN(n, len), ": ", 2);
	n += tostr(js, val, buf + n, REMAIN(n, len));
	}
	printed_first = true;
	}
	}

	if (!inline_mode) {
	stringify_indent--;
	n += cpy(buf + n, REMAIN(n, len), "\n", 1);
	n += add_indent(buf + n, REMAIN(n, len), stringify_indent);
	}

	n += cpy(buf + n, REMAIN(n, len), inline_mode ? " ]" : "]", inline_mode ? 2 : 1);
	pop_stringify();
	return n;
	}

	static size_t strdate(ant_t js, ant_value_t obj, char buf, size_t len) {
	ant_value_t time_val = js_get_slot(obj, SLOT_DATA);
	if (vtype(time_val) != T_NUM) return cpy(buf, len, "Invalid Date", 12);

	static const date_string_spec_t kSpec = {DATE_STRING_FMT_ISO, DATE_STRING_PART_ALL};
	ant_value_t iso = get_date_string(js, obj, kSpec);
	if (is_err(iso) \|\| vtype(iso) != T_STR) return cpy(buf, len, "Invalid Date", 12);

	ant_offset_t slen;
	ant_offset_t soff = vstr(js, iso, &slen);

	return cpy(buf, len, (const char *)(uintptr_t)(soff), slen);
	}

	static bool is_valid_identifier(const char *str, ant_offset_t slen) {
	if (slen == 0) return false;
	char c = str[0];
	if (!((c >= 'a' && c <= 'z') \|\| (c >= 'A' && c <= 'Z') \|\| c == '_' \|\| c == '$')) return false;
	for (ant_offset_t i = 1; i < slen; i++) {
	c = str[i];
	if (!((c >= 'a' && c <= 'z') \|\| (c >= 'A' && c <= 'Z') \|\| (c >= '0' && c <= '9') \|\| c == '_' \|\| c == '$')) return false;
	}
	return true;
	}

	static size_t strkey(ant_t js, ant_value_t value, char buf, size_t len) {
	ant_offset_t slen, off = vstr(js, value, &slen);
	const char str = (const char )(uintptr_t)(off);

	if (is_valid_identifier(str, slen)) {
	return cpy(buf, len, str, slen);
	}
	return strstring(js, value, buf, len);
	}

	static size_t strkey_interned(ant_t js, const char key, size_t klen, char *buf, size_t len) {
	if (is_valid_identifier(key, (ant_offset_t)klen)) {
	return cpy(buf, len, key, klen);
	}
	ant_value_t key_str = js_mkstr(js, key, klen);
	return strstring(js, key_str, buf, len);
	}

	static bool is_small_object(ant_t js, ant_value_t obj, int prop_count) {
	int count = 0;
	bool has_nested = false;

	ant_value_t as_obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(as_obj);
	uintptr_t obj_off = (uintptr_t)vdata(as_obj);
	if (ptr && ptr->shape) {
	uint32_t shape_count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < shape_count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop) continue;

	if (prop->type == ANT_SHAPE_KEY_SYMBOL) {
	count++;
	continue;
	}

	if ((ant_shape_get_attrs(ptr->shape, i) & ANT_PROP_ATTR_ENUMERABLE) == 0) continue;

	ant_value_t val = (i < ptr->prop_count) ? ant_object_prop_get_unchecked(ptr, i) : js_mkundef();
	uint8_t t = vtype(val);
	if (t == T_OBJ \|\| t == T_ARR \|\| t == T_FUNC) has_nested = true;
	count++;
	}
	}

	if (ptr && ptr->is_exotic) {
	descriptor_entry_t desc, tmp;
	HASH_ITER(hh, desc_registry, desc, tmp) {
	if (desc->obj_off != obj_off) continue;
	if (!desc->enumerable) continue;
	if (!desc->has_getter && !desc->has_setter) continue;
	count++;
	}
	}

	if (prop_count) *prop_count = count;
	return count <= 4 && !has_nested;
	}

	void js_inspect_builder_init_fixed(js_inspect_builder_t builder, ant_t js, char *buf, size_t len, size_t initial_n) {
	builder->js = js;
	builder->buf = buf;
	builder->len = len;
	builder->n = initial_n;
	builder->growable = false;
	builder->inline_mode = false;
	builder->first = true;
	builder->closed = false;
	builder->did_indent = false;
	}

	bool js_inspect_builder_init_dynamic(js_inspect_builder_t builder, ant_t js, size_t initial_cap) {
	size_t cap = initial_cap ? initial_cap : 128;
	char *buf = malloc(cap);
	if (!buf) return false;

	buf[0] = '\0';
	builder->js = js;
	builder->buf = buf;
	builder->len = cap;
	builder->n = 0;
	builder->growable = true;
	builder->inline_mode = false;
	builder->first = true;
	builder->closed = false;
	builder->did_indent = false;

	return true;
	}

	void js_inspect_builder_dispose(js_inspect_builder_t *builder) {
	if (builder->growable) free(builder->buf);
	builder->buf = NULL;
	builder->len = 0;
	builder->n = 0;
	}

	ant_value_t js_inspect_builder_result(js_inspect_builder_t *builder) {
	ant_value_t out = js_mkstr(builder->js, builder->buf ? builder->buf : "", builder->n);
	js_inspect_builder_dispose(builder);
	return out;
	}

	static bool js_inspect_builder_reserve(js_inspect_builder_t *builder, size_t extra) {
	if (!builder->growable) return true;

	size_t needed = builder->n + extra + 1;
	if (needed <= builder->len) return true;

	size_t new_cap = builder->len ? builder->len : 128;
	while (new_cap < needed) new_cap *= 2;

	char *new_buf = realloc(builder->buf, new_cap);
	if (!new_buf) return false;

	builder->buf = new_buf;
	builder->len = new_cap;

	return true;
	}

	static bool js_inspect_append(js_inspect_builder_t builder, const char src, size_t srclen) {
	if (builder->growable) {
	if (!js_inspect_builder_reserve(builder, srclen)) return false;
	memcpy(builder->buf + builder->n, src, srclen);
	builder->n += srclen;
	builder->buf[builder->n] = '\0';
	return true;
	}

	builder->n += cpy(builder->buf + builder->n, REMAIN(builder->n, builder->len), src, srclen);
	return true;
	}

	static bool __attribute__((format(printf, 2, 0)))
	js_inspect_vappendf(js_inspect_builder_t builder, const char fmt, va_list args) {
	if (builder->growable) {
	va_list copy;
	va_copy(copy, args);
	int needed = vsnprintf(NULL, 0, fmt, copy);
	va_end(copy);
	if (needed < 0) return false;
	if (!js_inspect_builder_reserve(builder, (size_t)needed)) return false;
	vsnprintf(builder->buf + builder->n, builder->len - builder->n, fmt, args);
	builder->n += (size_t)needed;
	return true;
	}

	int needed = vsnprintf(builder->buf + builder->n, REMAIN(builder->n, builder->len), fmt, args);
	if (needed < 0) return false;
	builder->n += (size_t)needed;

	return true;
	}

	static bool __attribute__((format(printf, 2, 3)))
	js_inspect_appendf(js_inspect_builder_t builder, const char fmt, ...) {
	va_list args;
	va_start(args, fmt);
	bool ok = js_inspect_vappendf(builder, fmt, args);
	va_end(args);
	return ok;
	}

	static bool js_inspect_append_indent(js_inspect_builder_t *builder, int indent) {
	for (int i = 0; i < indent; i++) if (!js_inspect_append(builder, " ", 2)) return false;
	return true;
	}

	static bool js_inspect_append_tostr(js_inspect_builder_t *builder, ant_value_t value) {
	if (!builder->growable) {
	builder->n += tostr(builder->js, value, builder->buf + builder->n, REMAIN(builder->n, builder->len));
	return true;
	}

	size_t cap = 128;
	char *tmp = malloc(cap);
	if (!tmp) return false;

	for (;;) {
	size_t written = tostr(builder->js, value, tmp, cap);
	if (written < cap) {
	bool ok = js_inspect_append(builder, tmp, written);
	free(tmp);
	return ok;
	}

	size_t new_cap = written + 1;
	char *new_tmp = realloc(tmp, new_cap);
	if (!new_tmp) {
	free(tmp);
	return false;
	}
	tmp = new_tmp;
	cap = new_cap;
	}
	}

	static bool js_inspect_append_key_interned(js_inspect_builder_t builder, const char key, size_t klen) {
	if (!builder->growable) {
	builder->n += strkey_interned(builder->js, key, klen, builder->buf + builder->n, REMAIN(builder->n, builder->len));
	return true;
	}

	size_t cap = klen + 16;
	char *tmp = malloc(cap);
	if (!tmp) return false;

	for (;;) {
	size_t written = strkey_interned(builder->js, key, klen, tmp, cap);
	if (written < cap) {
	bool ok = js_inspect_append(builder, tmp, written);
	free(tmp);
	return ok;
	}

	size_t new_cap = written + 1;
	char *new_tmp = realloc(tmp, new_cap);
	if (!new_tmp) {
	free(tmp);
	return false;
	}
	tmp = new_tmp;
	cap = new_cap;
	}
	}

	bool js_inspect_header(js_inspect_builder_t builder, const char fmt, ...) {
	va_list args;
	va_start(args, fmt);
	bool ok = js_inspect_vappendf(builder, fmt, args);
	va_end(args);
	if (!ok) return false;
	if (!js_inspect_append(builder, " {\n", 3)) return false;

	builder->inline_mode = false;
	builder->first = true;
	builder->closed = false;
	builder->did_indent = false;

	return true;
	}

	bool js_inspect_tagged_header(js_inspect_builder_t builder, const char tag, size_t tag_len) {
	if (!js_inspect_append(builder, "Object [", 8)) return false;
	if (!js_inspect_append(builder, tag, tag_len)) return false;
	if (!js_inspect_append(builder, "] {\n", 4)) return false;

	builder->inline_mode = false;
	builder->first = true;
	builder->closed = false;
	builder->did_indent = false;

	return true;
	}

	// TODO: modularize
	static bool js_inspect_plain_header(js_inspect_builder_t *builder, ant_value_t obj) {
	ant_t *js = builder->js;
	int prop_count = 0;
	bool inline_mode = is_small_object(js, obj, &prop_count);

	ant_value_t proto_val = js_get_proto(js, obj);
	bool is_null_proto = (vtype(proto_val) == T_NULL);
	bool proto_is_null_proto = false;
	const char *class_name = NULL;
	ant_offset_t class_name_len = 0;

	do {
	if (is_null_proto) break;
	uint8_t pt = vtype(proto_val);
	if (pt != T_OBJ && pt != T_FUNC) break;

	ant_value_t proto_proto = js_get_proto(js, proto_val);
	ant_value_t object_proto = js->sym.object_proto;
	proto_is_null_proto = (vtype(proto_proto) == T_NULL) && (vdata(proto_val) != vdata(object_proto));

	class_name = get_class_name(js, obj, &class_name_len, "Object");
	} while (0);

	if (prop_count == 0) {
	if (is_null_proto) {
	if (!js_inspect_append(builder, "[Object: null prototype] {}", 27)) return false;
	} else if (class_name && class_name_len > 0) {
	if (!js_inspect_append(builder, class_name, class_name_len)) return false;
	if (proto_is_null_proto) {
	if (!js_inspect_append(builder, " <[Object: null prototype] {}> {}", 33)) return false;
	} else if (!js_inspect_append(builder, " {}", 3)) return false;
	} else if (proto_is_null_proto) {
	if (!js_inspect_append(builder, "<[Object: null prototype] {}> {}", 32)) return false;
	} else if (!js_inspect_append(builder, "{}", 2)) return false;

	builder->closed = true;
	return true;
	}

	if (is_null_proto) {
	if (!js_inspect_append(builder, "[Object: null prototype] ", 25)) return false;
	} else if (class_name && class_name_len > 0) {
	if (!js_inspect_append(builder, class_name, class_name_len)) return false;
	if (proto_is_null_proto) {
	if (!js_inspect_append(builder, " <[Object: null prototype] {}> ", 31)) return false;
	} else if (!js_inspect_append(builder, " ", 1)) return false;
	} else if (proto_is_null_proto) {
	if (!js_inspect_append(builder, "<[Object: null prototype] {}> ", 30)) return false;
	}

	if (!js_inspect_append(builder, inline_mode ? "{ " : "{\n", 2)) return false;
	builder->inline_mode = inline_mode;
	builder->first = true;
	builder->closed = false;
	builder->did_indent = false;

	return true;
	}

	bool js_inspect_object_body(js_inspect_builder_t *builder, ant_value_t obj) {
	if (builder->closed) return true;

	if (!builder->inline_mode && !builder->did_indent) {
	stringify_indent++;
	builder->did_indent = true;
	}

	bool first = builder->first;
	ant_t *js = builder->js;
	ant_value_t tag_sym = get_toStringTag_sym();
	ant_value_t as_obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(as_obj);
	uintptr_t obj_off = (uintptr_t)vdata(as_obj);
	uint32_t shape_count = (ptr && ptr->shape) ? ant_shape_count(ptr->shape) : 0;

	for (uint32_t i = 0; i < shape_count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop) continue;
	if ((ant_shape_get_attrs(ptr->shape, i) & ANT_PROP_ATTR_ENUMERABLE) == 0) continue;
	ant_value_t val = (i < ptr->prop_count) ? ant_object_prop_get_unchecked(ptr, i) : js_mkundef();

	if (prop->type == ANT_SHAPE_KEY_SYMBOL) {
	ant_offset_t sym_off = prop->key.sym_off;
	if (vtype(tag_sym) == T_SYMBOL && sym_off == (ant_offset_t)vdata(tag_sym)) continue;

	if (ptr && ptr->is_exotic) {
	prop_meta_t meta;
	if (lookup_symbol_prop_meta(as_obj, sym_off, &meta) && !meta.enumerable) continue;
	}

	ant_value_t sym = mkval(T_SYMBOL, sym_off);

	if (!first && !js_inspect_append(builder, builder->inline_mode ? ", " : ",\n", 2)) return false;
	first = false;
	if (!builder->inline_mode && !js_inspect_append_indent(builder, stringify_indent)) return false;
	if (!js_inspect_append(builder, "[", 1)) return false;
	if (!js_inspect_append_tostr(builder, sym)) return false;
	if (!js_inspect_append(builder, "]: ", 3)) return false;
	if (!js_inspect_append_tostr(builder, val)) return false;
	continue;
	}

	const char *key = prop->key.interned;
	ant_offset_t klen = (ant_offset_t)strlen(key);
	if (ptr && ptr->is_exotic) {
	prop_meta_t meta;
	if (lookup_string_prop_meta(js, as_obj, key, (size_t)klen, &meta) && !meta.enumerable) continue;
	}

	if (prop->has_getter \|\| prop->has_setter) {
	if (!first && !js_inspect_append(builder, builder->inline_mode ? ", " : ",\n", 2)) return false;
	first = false;
	if (!builder->inline_mode && !js_inspect_append_indent(builder, stringify_indent)) return false;
	if (!js_inspect_append_key_interned(builder, key, (size_t)klen)) return false;
	if (!js_inspect_append(builder, ": ", 2)) return false;
	if (prop->has_getter && prop->has_setter) {
	if (!js_inspect_append(builder, "[Getter/Setter]", 15)) return false;
	} else if (prop->has_getter) {
	if (!js_inspect_append(builder, "[Getter]", 8)) return false;
	} else if (!js_inspect_append(builder, "[Setter]", 8)) return false;
	continue;
	}

	if (!first && !js_inspect_append(builder, builder->inline_mode ? ", " : ",\n", 2)) return false;
	first = false;
	if (!builder->inline_mode && !js_inspect_append_indent(builder, stringify_indent)) return false;

	bool is_special_global = false;
	if (vtype(val) == T_UNDEF && streq(key, klen, "undefined", 9)) {
	is_special_global = true;
	} else if (vtype(val) == T_NUM) {
	double d = tod(val);
	if (isinf(d) && d > 0 && streq(key, klen, "Infinity", 8)) {
	is_special_global = true;
	} else if (isnan(d) && streq(key, klen, "NaN", 3)) {
	is_special_global = true;
	}
	}

	if (is_special_global) {
	if (!js_inspect_append_tostr(builder, val)) return false;
	} else {
	if (!js_inspect_append_key_interned(builder, key, (size_t)klen)) return false;
	if (!js_inspect_append(builder, ": ", 2)) return false;
	if (!js_inspect_append_tostr(builder, val)) return false;
	}
	}

	if (ptr && ptr->is_exotic) {
	descriptor_entry_t desc, tmp;
	HASH_ITER(hh, desc_registry, desc, tmp) {
	if (desc->obj_off != obj_off) continue;
	if (!desc->enumerable) continue;
	if (!desc->has_getter && !desc->has_setter) continue;

	if (!first && !js_inspect_append(builder, builder->inline_mode ? ", " : ",\n", 2)) return false;
	first = false;
	if (!builder->inline_mode && !js_inspect_append_indent(builder, stringify_indent)) return false;
	if (!js_inspect_append(builder, desc->prop_name, desc->prop_len)) return false;
	if (!js_inspect_append(builder, ": ", 2)) return false;

	if (desc->has_getter && desc->has_setter) {
	if (!js_inspect_append(builder, "[Getter/Setter]", 15)) return false;
	} else if (desc->has_getter) {
	if (!js_inspect_append(builder, "[Getter]", 8)) return false;
	} else if (!js_inspect_append(builder, "[Setter]", 8)) return false;
	}
	}

	builder->first = first;
	return true;
	}

	bool js_inspect_close(js_inspect_builder_t *builder) {
	if (builder->closed) return true;

	if (builder->did_indent) {
	stringify_indent--;
	builder->did_indent = false;
	}

	if (builder->inline_mode) {
	if (!js_inspect_append(builder, " }", 2)) return false;
	} else {
	if (!builder->first && !js_inspect_append(builder, "\n", 1)) return false;
	if (!js_inspect_append_indent(builder, stringify_indent)) return false;
	if (!js_inspect_append(builder, "}", 1)) return false;
	}

	builder->closed = true;
	return true;
	}

	// todo: split into smaller functions
	static size_t strobj(ant_t js, ant_value_t obj, char buf, size_t len) {
	int ref = get_circular_ref(obj);
	if (ref) return ref > 0 ? (size_t) snprintf(buf, len, "[Circular *%d]", ref) : cpy(buf, len, "[Circular]", 10);

	push_stringify(obj);

	size_t n = 0;
	int self_ref = get_self_ref(obj);
	if (self_ref) {
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "<ref *%d> ", self_ref);
	}

	ant_value_t inspect_val = strobj_call_custom_inspect(js, obj);
	if (vtype(inspect_val) == T_STR) {
	size_t slen = 0;
	const char *s = js_getstr(js, inspect_val, &slen);
	n += cpy(buf + n, REMAIN(n, len), s ? s : "", slen);
	pop_stringify();
	return n;
	}

	if (is_date_instance(obj)) {
	n += strdate(js, obj, buf + n, REMAIN(n, len));
	pop_stringify();
	return n;
	}

	ant_value_t tag_sym = get_toStringTag_sym();
	ant_value_t tag_val = (vtype(tag_sym) == T_SYMBOL) ? lkp_sym_proto_val(js, obj, (ant_offset_t)vdata(tag_sym)) : js_mkundef();
	bool is_map = false, is_set = false, is_arraybuffer = false;
	ant_offset_t tlen = 0, toff = 0;
	const char *tag_str = NULL;

	if (vtype(tag_val) == T_STR) {
	toff = vstr(js, tag_val, &tlen);
	tag_str = (const char *)(uintptr_t)(toff);
	is_map = (tlen == 3 && memcmp(tag_str, "Map", 3) == 0);
	is_set = (tlen == 3 && memcmp(tag_str, "Set", 3) == 0);
	is_arraybuffer = (tlen >= 11 && memcmp(tag_str + tlen - 11, "ArrayBuffer", 11) == 0);

	TypedArrayData *ta = buffer_get_typedarray_data(obj);
	if (ta && ta->buffer) {
	const char *type_name = NULL;
	size_t type_len = 0;

	ant_value_t proto = js_get_proto(js, obj);
	ant_value_t buffer_proto = get_ctor_proto(js, "Buffer", 6);
	if (vtype(proto) == T_OBJ && vtype(buffer_proto) == T_OBJ && vdata(proto) == vdata(buffer_proto)) {
	type_name = "Buffer";
	type_len = 6;
	} else if (ta->type <= TYPED_ARRAY_BIGUINT64) {
	type_name = buffer_typedarray_type_name(ta->type);
	type_len = strlen(type_name);
	} else {
	type_name = "TypedArray";
	type_len = 10;
	}

	n += cpy(buf + n, REMAIN(n, len), type_name, type_len);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "(%zu) ", ta->length);
	n += cpy(buf + n, REMAIN(n, len), "[ ", 2);

	uint8_t *data = ta->buffer->data + ta->byte_offset;

	for (size_t i = 0; i < ta->length && i < 100; i++) {
	if (i > 0) n += cpy(buf + n, REMAIN(n, len), ", ", 2);

	switch (ta->type) {
	case TYPED_ARRAY_INT8:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%d", (int)((int8_t*)data)[i]);
	break;
	case TYPED_ARRAY_UINT8:
	case TYPED_ARRAY_UINT8_CLAMPED:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%u", (unsigned)data[i]);
	break;
	case TYPED_ARRAY_INT16:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%d", (int)((int16_t*)data)[i]);
	break;
	case TYPED_ARRAY_UINT16:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%u", (unsigned)((uint16_t*)data)[i]);
	break;
	case TYPED_ARRAY_INT32:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%d", ((int32_t*)data)[i]);
	break;
	case TYPED_ARRAY_UINT32:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%u", ((uint32_t*)data)[i]);
	break;
	case TYPED_ARRAY_FLOAT16:
	n += (size_t) snprintf(
	buf + n, REMAIN(n, len), "%g", half_to_double(((uint16_t*)data)[i])
	);
	break;
	case TYPED_ARRAY_FLOAT32:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%g", (double)((float*)data)[i]);
	break;
	case TYPED_ARRAY_FLOAT64:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%g", ((double*)data)[i]);
	break;
	case TYPED_ARRAY_BIGINT64:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%lldn", (long long)((int64_t*)data)[i]);
	break;
	case TYPED_ARRAY_BIGUINT64:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%llun", (unsigned long long)((uint64_t*)data)[i]);
	break;
	default:
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%u", (unsigned)data[i]);
	break;
	}
	}

	if (ta->length > 100) n += cpy(buf + n, REMAIN(n, len), ", ...", 5);
	n += cpy(buf + n, REMAIN(n, len), " ]", 2);
	pop_stringify();
	return n;
	}

	if (is_arraybuffer) {
	ArrayBufferData *ab_data = buffer_get_arraybuffer_data(obj);
	if (ab_data) {
	size_t bytelen = ab_data ? ab_data->length : 0;

	n += cpy(buf + n, REMAIN(n, len), tag_str, tlen);
	n += cpy(buf + n, REMAIN(n, len), " {\n", 3);
	n += cpy(buf + n, REMAIN(n, len), " [Uint8Contents]: <", 20);

	if (ab_data && ab_data->data && bytelen > 0) {
	for (size_t i = 0; i < bytelen; i++) {
	if (i > 0) n += cpy(buf + n, REMAIN(n, len), " ", 1);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%02x", ab_data->data[i]);
	}
	}

	n += cpy(buf + n, REMAIN(n, len), ">,\n", 3);
	n += cpy(buf + n, REMAIN(n, len), " [byteLength]: ", 16);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%zu", bytelen);
	n += cpy(buf + n, REMAIN(n, len), "\n}", 2);
	pop_stringify();
	return n;
	}
	}

	bool is_dataview = (tlen == 8 && memcmp(tag_str, "DataView", 8) == 0);
	if (is_dataview) {
	DataViewData *dv = buffer_get_dataview_data(obj);
	if (dv && dv->buffer) {
	n += cpy(buf + n, REMAIN(n, len), "DataView {\n", 11);
	n += cpy(buf + n, REMAIN(n, len), " [byteLength]: ", 16);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%zu", dv->byte_length);
	n += cpy(buf + n, REMAIN(n, len), ",\n", 2);
	n += cpy(buf + n, REMAIN(n, len), " [byteOffset]: ", 16);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%zu", dv->byte_offset);
	n += cpy(buf + n, REMAIN(n, len), ",\n", 2);
	n += cpy(buf + n, REMAIN(n, len), " [buffer]: ArrayBuffer {\n", 26);
	n += cpy(buf + n, REMAIN(n, len), " [Uint8Contents]: <", 22);

	if (dv->buffer->data && dv->buffer->length > 0) {
	for (size_t i = 0; i < dv->buffer->length; i++) {
	if (i > 0) n += cpy(buf + n, REMAIN(n, len), " ", 1);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%02x", dv->buffer->data[i]);
	}
	}

	n += cpy(buf + n, REMAIN(n, len), ">,\n", 3);
	n += cpy(buf + n, REMAIN(n, len), " [byteLength]: ", 18);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%zu", dv->buffer->length);
	n += cpy(buf + n, REMAIN(n, len), "\n }\n}", 6);
	pop_stringify();
	return n;
	}
	}

	if (is_map) {
	ant_value_t map_val = js_get_slot(obj, SLOT_MAP);
	if (vtype(map_val) != T_UNDEF) {
	map_entry_t map_ptr = (map_entry_t)(size_t)tod(map_val);
	n += cpy(buf + n, REMAIN(n, len), "Map(", 4);

	unsigned int count = 0;
	if (map_ptr && map_ptr) count = HASH_COUNT(map_ptr);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%u", count);
	n += cpy(buf + n, REMAIN(n, len), ") ", 2);

	if (count == 0) {
	n += cpy(buf + n, REMAIN(n, len), "{}", 2);
	} else {
	n += cpy(buf + n, REMAIN(n, len), "{\n", 2);
	stringify_indent++;
	bool first = true;
	if (map_ptr && *map_ptr) {
	map_entry_t entry, tmp;
	HASH_ITER(hh, *map_ptr, entry, tmp) {
	if (!first) n += cpy(buf + n, REMAIN(n, len), ",\n", 2);
	first = false;
	n += add_indent(buf + n, REMAIN(n, len), stringify_indent);
	n += tostr(js, entry->key_val, buf + n, REMAIN(n, len));
	n += cpy(buf + n, REMAIN(n, len), " => ", 4);
	n += tostr(js, entry->value, buf + n, REMAIN(n, len));
	}
	}
	stringify_indent--;
	n += cpy(buf + n, REMAIN(n, len), "\n", 1);
	n += add_indent(buf + n, REMAIN(n, len), stringify_indent);
	n += cpy(buf + n, REMAIN(n, len), "}", 1);
	}
	pop_stringify();
	return n;
	}
	}

	if (is_set) {
	ant_value_t set_val = js_get_slot(obj, SLOT_SET);
	if (vtype(set_val) != T_UNDEF) {
	set_entry_t set_ptr = (set_entry_t)(size_t)tod(set_val);
	n += cpy(buf + n, REMAIN(n, len), "Set(", 4);

	unsigned int count = 0;
	if (set_ptr && set_ptr) count = HASH_COUNT(set_ptr);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%u", count);
	n += cpy(buf + n, REMAIN(n, len), ") ", 2);

	if (count == 0) {
	n += cpy(buf + n, REMAIN(n, len), "{}", 2);
	} else {
	n += cpy(buf + n, REMAIN(n, len), "{\n", 2);
	stringify_indent++;
	bool first = true;
	if (set_ptr && *set_ptr) {
	set_entry_t entry, tmp;
	HASH_ITER(hh, *set_ptr, entry, tmp) {
	if (!first) n += cpy(buf + n, REMAIN(n, len), ",\n", 2);
	first = false;
	n += add_indent(buf + n, REMAIN(n, len), stringify_indent);
	n += tostr(js, entry->value, buf + n, REMAIN(n, len));
	}
	}
	stringify_indent--;
	n += cpy(buf + n, REMAIN(n, len), "\n", 1);
	n += add_indent(buf + n, REMAIN(n, len), stringify_indent);
	n += cpy(buf + n, REMAIN(n, len), "}", 1);
	}
	pop_stringify();
	return n;
	}
	}

	if (tag_str) {
	bool is_blob = (tlen == 4 && memcmp(tag_str, "Blob", 4) == 0);
	bool is_file = (tlen == 4 && memcmp(tag_str, "File", 4) == 0);
	if (is_blob \|\| is_file) {
	blob_data_t *bd = blob_get_data(obj);
	n += cpy(buf + n, REMAIN(n, len), is_file ? "File" : "Blob", 4);
	n += cpy(buf + n, REMAIN(n, len), " { size: ", 9);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%zu", bd ? bd->size : 0);
	n += cpy(buf + n, REMAIN(n, len), ", type: '", 9);
	if (bd && bd->type) n += cpy(buf + n, REMAIN(n, len), bd->type, strlen(bd->type));
	n += cpy(buf + n, REMAIN(n, len), "'", 1);
	if (is_file) {
	n += cpy(buf + n, REMAIN(n, len), ", name: '", 9);
	if (bd && bd->name) n += cpy(buf + n, REMAIN(n, len), bd->name, strlen(bd->name));
	n += cpy(buf + n, REMAIN(n, len), "'", 1);
	n += cpy(buf + n, REMAIN(n, len), ", lastModified: ", 16);
	n += (size_t) snprintf(buf + n, REMAIN(n, len), "%" PRId64, bd ? bd->last_modified : 0);
	}
	n += cpy(buf + n, REMAIN(n, len), " }", 2);
	pop_stringify();
	return n;
	}
	}

	js_inspect_builder_t builder;
	js_inspect_builder_init_fixed(&builder, js, buf, len, n);
	bool ok = js_inspect_tagged_header(&builder, (const char *)(uintptr_t)toff, (size_t)tlen);
	if (ok) ok = js_inspect_object_body(&builder, obj);
	if (ok) ok = js_inspect_close(&builder);
	n = builder.n;
	pop_stringify();
	return n;
	}

	js_inspect_builder_t builder;
	js_inspect_builder_init_fixed(&builder, js, buf, len, n);
	bool ok = js_inspect_plain_header(&builder, obj);
	if (ok) ok = js_inspect_object_body(&builder, obj);
	if (ok) ok = js_inspect_close(&builder);
	n = builder.n;
	pop_stringify();

	return n;
	}

	static size_t fix_exponent(char *buf, size_t n) {
	char *e = strchr(buf, 'e');
	if (!e) return n;

	char *src = e + 1;
	char *dst = src;

	if (src == '+' \|\| src == '-') {
	dst++;
	src++;
	}

	while (*src == '0' && src[1] != '\0') src++;

	if (src != dst) {
	memmove(dst, src, strlen(src) + 1);
	return strlen(buf);
	}
	return n;
	}

	static size_t strnum(ant_value_t value, char *buf, size_t len) {
	double dv = tod(value);

	if (isnan(dv)) return cpy(buf, len, "NaN", 3);
	if (isinf(dv)) return cpy(buf, len, dv > 0 ? "Infinity" : "-Infinity", dv > 0 ? 8 : 9);
	if (dv == 0.0) return cpy(buf, len, "0", 1);

	char temp[64];
	int sign = dv < 0 ? 1 : 0;
	double adv = sign ? -dv : dv;

	double iv;
	double frac = modf(adv, &iv);
	if (frac == 0.0 && adv < 9007199254740992.0) {
	int result = snprintf(temp, sizeof(temp), "%.0f", dv);
	fix_exponent(temp, (size_t)result);
	return cpy(buf, len, temp, strlen(temp));
	}

	for (int prec = 1; prec <= 17; prec++) {
	int n = snprintf(temp, sizeof(temp), "%.*g", prec, dv);
	double parsed = strtod(temp, NULL);
	if (parsed == dv) {
	fix_exponent(temp, (size_t)n);
	return cpy(buf, len, temp, strlen(temp));
	}
	(void)n;
	}

	int result = snprintf(temp, sizeof(temp), "%.17g", dv);
	fix_exponent(temp, (size_t)result);
	return cpy(buf, len, temp, strlen(temp));
	}

	static inline ant_offset_t assert_flat_string_len(ant_t js, ant_value_t value, const char *out_ptr) {
	(void)js;
	ant_flat_string_t *flat = ant_str_flat_ptr(value);
	assert(flat != NULL);
	ant_offset_t len = flat->len;
	if (out_ptr) *out_ptr = flat->bytes;
	return len;
	}

	static inline ant_rope_heap_t *assert_rope_ptr(ant_value_t value) {
	assert(vtype(value) == T_STR);
	assert(str_is_heap_rope(value));
	ant_rope_heap_t *ptr = ant_str_rope_ptr(value);
	assert(ptr != NULL);
	return ptr;
	}

	static inline ant_offset_t rope_len(ant_value_t value) {
	ant_rope_heap_t *ptr = assert_rope_ptr(value);
	return ptr->len;
	}

	static inline uint16_t rope_depth(ant_value_t value) {
	ant_rope_heap_t *ptr = assert_rope_ptr(value);
	return ptr->depth;
	}

	static inline ant_value_t rope_left(ant_value_t value) {
	ant_rope_heap_t *ptr = assert_rope_ptr(value);
	return ptr->left;
	}

	static inline ant_value_t rope_right(ant_value_t value) {
	ant_rope_heap_t *ptr = assert_rope_ptr(value);
	return ptr->right;
	}

	static inline ant_value_t rope_cached_flat(ant_value_t value) {
	ant_rope_heap_t *ptr = assert_rope_ptr(value);
	return ptr->cached;
	}

	static inline void rope_set_cached_flat(ant_value_t rope, ant_value_t flat) {
	ant_rope_heap_t *ptr = assert_rope_ptr(rope);
	ptr->cached = flat;
	}

	static inline ant_string_builder_t *assert_builder_ptr(ant_value_t value) {
	assert(vtype(value) == T_STR);
	assert(str_is_heap_builder(value));

	ant_string_builder_t *ptr = ant_str_builder_ptr(value);
	assert(ptr != NULL);

	return ptr;
	}

	static inline ant_offset_t builder_len(ant_value_t value) {
	ant_string_builder_t *ptr = assert_builder_ptr(value);
	return ptr->len;
	}

	static inline ant_value_t builder_cached_flat(ant_value_t value) {
	ant_string_builder_t *ptr = assert_builder_ptr(value);
	return ptr->cached;
	}

	static inline void builder_set_cached_flat(ant_value_t builder, ant_value_t flat) {
	ant_string_builder_t *ptr = assert_builder_ptr(builder);
	ptr->cached = flat;
	}

	static void rope_flatten_into(ant_t js, ant_value_t str, char dest, ant_offset_t *pos) {
	assert(vtype(str) == T_STR);

	if (!str_is_heap_rope(str)) {
	const char *sptr;
	ant_offset_t slen = assert_flat_string_len(js, str, &sptr);
	memcpy(dest + *pos, sptr, slen);
	*pos += slen; return;
	}

	ant_value_t cached = rope_cached_flat(str);
	if (vtype(cached) == T_STR && !str_is_heap_rope(cached)) {
	const char *cptr;
	ant_offset_t clen = assert_flat_string_len(js, cached, &cptr);
	memcpy(dest + *pos, cptr, clen);
	*pos += clen; return;
	}

	ant_value_t stack[ROPE_MAX_DEPTH + 8];
	int sp = 0; stack[sp++] = str;

	while (sp > 0) {
	ant_value_t node = stack[--sp];
	assert(vtype(node) == T_STR);

	if (!str_is_heap_rope(node)) {
	const char *sptr;
	ant_offset_t slen = assert_flat_string_len(js, node, &sptr);
	memcpy(dest + *pos, sptr, slen);
	*pos += slen; continue;
	}

	ant_value_t c = rope_cached_flat(node);
	if (vtype(c) == T_STR && !str_is_heap_rope(c)) {
	const char *cptr;
	ant_offset_t clen = assert_flat_string_len(js, c, &cptr);
	memcpy(dest + *pos, cptr, clen);
	*pos += clen; continue;
	}

	if (sp + 2 <= ROPE_MAX_DEPTH + 8) {
	stack[sp++] = rope_right(node);
	stack[sp++] = rope_left(node);
	}
	}
	}

	ant_value_t rope_flatten(ant_t *js, ant_value_t rope) {
	assert(vtype(rope) == T_STR);
	if (!str_is_heap_rope(rope)) return rope;

	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, rope);

	ant_value_t cached = rope_cached_flat(rope);
	GC_ROOT_PIN(js, cached);
	if (vtype(cached) == T_STR && !str_is_heap_rope(cached)) {
	GC_ROOT_RESTORE(js, root_mark);
	return cached;
	}

	ant_offset_t total_len = rope_len(rope);
	ant_value_t flat = js_mkstr(js, NULL, total_len);
	GC_ROOT_PIN(js, flat);

	if (is_err(flat)) {
	GC_ROOT_RESTORE(js, root_mark);
	return flat;
	}

	ant_flat_string_t flat_ptr = (ant_flat_string_t )(uintptr_t)vdata(flat);
	ant_offset_t pos = 0;

	rope_flatten_into(js, rope, flat_ptr->bytes, &pos);
	flat_ptr->bytes[pos] = '\0';
	flat_ptr->is_ascii = str_detect_ascii_bytes(flat_ptr->bytes, (size_t)pos);

	rope_set_cached_flat(rope, flat);
	GC_ROOT_RESTORE(js, root_mark);

	return flat;
	}

	static ant_value_t builder_flatten(ant_t *js, ant_value_t builder) {
	assert(vtype(builder) == T_STR);
	if (!str_is_heap_builder(builder)) return builder;

	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, builder);

	ant_value_t cached = builder_cached_flat(builder);
	GC_ROOT_PIN(js, cached);

	if (vtype(cached) == T_STR && !str_is_heap_rope(cached) && !str_is_heap_builder(cached)) {
	GC_ROOT_RESTORE(js, root_mark);
	return cached;
	}

	ant_string_builder_t *ptr = assert_builder_ptr(builder);
	ant_value_t flat = js_mkstr(js, NULL, (size_t)ptr->len);

	GC_ROOT_PIN(js, flat);
	if (is_err(flat)) {
	GC_ROOT_RESTORE(js, root_mark);
	return flat;
	}

	ant_flat_string_t flat_ptr = (ant_flat_string_t )(uintptr_t)vdata(flat);
	size_t cursor = 0;

	for (ant_builder_chunk_t *chunk = ptr->head; chunk; chunk = chunk->next) {
	ant_value_t chunk_value = chunk->value;
	if (str_is_heap_rope(chunk_value) \|\| str_is_heap_builder(chunk_value)) {
	chunk_value = str_materialize(js, chunk_value);
	if (is_err(chunk_value)) {
	GC_ROOT_RESTORE(js, root_mark);
	return chunk_value;
	}}

	ant_flat_string_t *chunk_flat = ant_str_flat_ptr(chunk_value);
	if (!chunk_flat \|\| chunk_flat->len == 0) continue;
	memcpy(flat_ptr->bytes + cursor, chunk_flat->bytes, (size_t)chunk_flat->len);
	cursor += (size_t)chunk_flat->len;
	}

	if (ptr->tail_len > 0) {
	memcpy(flat_ptr->bytes + cursor, ptr->tail, ptr->tail_len);
	cursor += ptr->tail_len;
	}

	flat_ptr->bytes[cursor] = '\0';
	flat_ptr->is_ascii = ptr->ascii_state;
	builder_set_cached_flat(builder, flat);
	GC_ROOT_RESTORE(js, root_mark);

	return flat;
	}

	ant_value_t str_materialize(ant_t *js, ant_value_t value) {
	if (vtype(value) != T_STR) return value;
	if (str_is_heap_rope(value)) return rope_flatten(js, value);
	if (str_is_heap_builder(value)) return builder_flatten(js, value);
	return value;
	}

	ant_offset_t vstr(ant_t js, ant_value_t value, ant_offset_t len) {
	if (str_is_heap_rope(value) \|\| str_is_heap_builder(value)) {
	ant_value_t flat = str_materialize(js, value);
	assert(!is_err(flat));
	value = flat;
	}

	const char *ptr = NULL;
	ant_offset_t slen = assert_flat_string_len(js, value, &ptr);
	if (len) *len = slen;
	return (ant_offset_t)(uintptr_t)ptr;
	}

	static size_t strstring(ant_t js, ant_value_t value, char buf, size_t len) {
	ant_offset_t slen, off = vstr(js, value, &slen);
	const char str = (const char )(uintptr_t)off;
	size_t n = 0;
	n += cpy(buf + n, REMAIN(n, len), "'", 1);
	for (ant_offset_t i = 0; i < slen && n < len - 1; i++) {
	char c = str[i];
	if (c == '\n') { n += cpy(buf + n, REMAIN(n, len), "\\n", 2); }
	else if (c == '\r') { n += cpy(buf + n, REMAIN(n, len), "\\r", 2); }
	else if (c == '\t') { n += cpy(buf + n, REMAIN(n, len), "\\t", 2); }
	else if (c == '\\') { n += cpy(buf + n, REMAIN(n, len), "\\\\", 2); }
	else if (c == '\'') { n += cpy(buf + n, REMAIN(n, len), "\\'", 2); }
	else { if (n < len) buf[n++] = c; }
	}
	n += cpy(buf + n, REMAIN(n, len), "'", 1);

	return n;
	}

	const char intern_string(const char str, size_t len) {
	if (!intern_table_init()) return NULL;

	if ((intern_count + 1) * INTERN_LOAD_DEN >= intern_bucket_count * INTERN_LOAD_NUM) {
	size_t next_bucket_count = intern_bucket_count << 1;
	if (next_bucket_count > intern_bucket_count) intern_table_rehash(next_bucket_count);
	}

	uint64_t h = hash_key(str, len);
	size_t bucket = (size_t)(h & (intern_bucket_count - 1));

	for (interned_string_t *e = intern_buckets[bucket]; e; e = e->next) {
	if (e->hash == h && e->len == len && memcmp(e->str, str, len) == 0) return e->str;
	}

	size_t alloc_size = sizeof(interned_string_t) + len + 1;
	interned_string_t entry = (interned_string_t )ant_calloc(alloc_size);
	if (!entry) return NULL;

	entry->str = (char *)(entry + 1);
	memcpy(entry->str, str, len);
	entry->str[len] = '\0';
	entry->len = len;
	entry->hash = h;
	entry->next = intern_buckets[bucket];
	intern_buckets[bucket] = entry;

	intern_count++;
	intern_bytes += alloc_size;

	return entry->str;
	}

	js_intern_stats_t js_intern_stats(void) {
	return (js_intern_stats_t){
	.count = intern_count,
	.bytes = intern_bytes
	};
	}

	bool is_internal_prop(const char *key, ant_offset_t klen) {
	if (klen < 2) return false;
	if (key[0] != '_' \|\| key[1] != '_') return false;
	if (klen == STR_PROTO_LEN && memcmp(key, STR_PROTO, STR_PROTO_LEN) == 0) return false;
	return true;
	}

	struct func_format {
	const char *prefix;
	size_t prefix_len;
	const char *anon;
	size_t anon_len;
	};

	static const struct func_format formats[] = {
	[0] = { "[Function: ", 11, "[Function (anonymous)]", 22 },
	[1] = { "[AsyncFunction: ", 16, "[AsyncFunction (anonymous)]", 27 },
	};

	// todo: make it work with bytecode NAME
	static size_t strfunc(ant_t js, ant_value_t value, char buf, size_t len) {
	ant_offset_t name_len = 0;
	const char *name = get_func_name(js, value, &name_len);

	ant_value_t func_obj = js_func_obj(value);
	ant_value_t code_slot = get_slot(func_obj, SLOT_CODE);
	ant_value_t builtin_slot = get_slot(func_obj, SLOT_BUILTIN);
	ant_value_t async_slot = get_slot(func_obj, SLOT_ASYNC);

	bool is_async = (async_slot == js_true);
	bool has_code = (vtype(code_slot) == T_CFUNC);

	const struct func_format *fmt = &formats[is_async];

	if (vtype(builtin_slot) == T_NUM) {
	if (name && name_len > 0) {
	size_t n = cpy(buf, len, fmt->prefix, fmt->prefix_len);
	n += cpy(buf + n, REMAIN(n, len), name, name_len);
	n += cpy(buf + n, REMAIN(n, len), "]", 1);
	return n;
	}
	return cpy(buf, len, fmt->anon, fmt->anon_len);
	}

	if (!has_code) {
	ant_value_t cfunc_slot = get_slot(func_obj, SLOT_CFUNC);
	bool is_native = (vtype(cfunc_slot) == T_CFUNC);
	size_t n;

	if (name && name_len > 0) {
	n = cpy(buf, len, fmt->prefix, fmt->prefix_len);
	n += cpy(buf + n, REMAIN(n, len), name, name_len);
	n += cpy(buf + n, REMAIN(n, len), "]", 1);
	} else {
	n = cpy(buf, len, fmt->anon, fmt->anon_len);
	}

	if (!is_native) return n;

	ant_value_t proto = get_slot(func_obj, SLOT_PROTO);
	uint8_t pt = vtype(proto);
	if (pt != T_OBJ && pt != T_FUNC) return n;

	ant_value_t ctor = lkp_val(js, proto, "constructor", 11);
	uint8_t ct = vtype(ctor);
	if (ct != T_FUNC && ct != T_CFUNC) return n;

	ant_offset_t ctor_name_len = 0;
	const char *ctor_name = get_func_name(js, ctor, &ctor_name_len);
	if (ctor_name && ctor_name_len > 0) {
	n += cpy(buf + n, REMAIN(n, len), " ", 1);
	n += cpy(buf + n, REMAIN(n, len), ctor_name, ctor_name_len);
	}
	return n;
	}

	if (name && name_len > 0) {
	size_t n = cpy(buf, len, fmt->prefix, fmt->prefix_len);
	n += cpy(buf + n, REMAIN(n, len), name, name_len);
	n += cpy(buf + n, REMAIN(n, len), "]", 1);
	return n;
	}

	return cpy(buf, len, fmt->anon, fmt->anon_len);
	}

	static size_t tostr(ant_t js, ant_value_t value, char buf, size_t len) {
	switch (vtype(value)) {
	case T_UNDEF: return ANT_COPY(buf, len, "undefined");
	case T_NULL: return ANT_COPY(buf, len, "null");

	case T_BOOL: {
	bool b = vdata(value) & 1;
	return b ? ANT_COPY(buf, len, "true") : ANT_COPY(buf, len, "false");
	}

	case T_ARR: return strarr(js, value, buf, len);
	case T_OBJ: return strobj(js, value, buf, len);
	case T_STR: return strstring(js, value, buf, len);
	case T_NUM: return strnum(value, buf, len);
	case T_BIGINT: return strbigint(js, value, buf, len);
	case T_PROMISE: return strpromise(js, value, buf, len);
	case T_FUNC: return strfunc(js, value, buf, len);

	case T_CFUNC: return ANT_COPY(buf, len, "[native code]");
	case T_FFI: return ANT_COPY(buf, len, "[native code (ffi)]");

	case T_ERR: {
	uint64_t data = vdata(value);
	if (data != 0) {
	ant_value_t obj = mkval(T_OBJ, data);
	ant_value_t stack = js_get(js, obj, "stack");
	if (vtype(stack) == T_STR) {
	ant_offset_t slen;
	ant_offset_t off = vstr(js, stack, &slen);
	return cpy(buf, len, (const char *)(uintptr_t)(off), slen);
	}
	}
	return ANT_COPY(buf, len, "Error");
	}

	case T_SYMBOL: {
	const char *desc = js_sym_desc(js, value);
	if (desc) return (size_t) snprintf(buf, len, "Symbol(%s)", desc);
	return ANT_COPY(buf, len, "Symbol()");
	}

	default: return (size_t) snprintf(buf, len, "VTYPE%d", vtype(value));
	}
	}

	static char tostr_alloc(ant_t js, ant_value_t value) {
	size_t cap = 64;
	char *buf = ant_calloc(cap);
	size_t n = tostr(js, value, buf, cap);
	if (n >= cap) {
	free(buf);
	buf = ant_calloc(n + 1);
	tostr(js, value, buf, n + 1);
	}
	return buf;
	}

	js_cstr_t js_to_cstr(ant_t js, ant_value_t value, char stack_buf, size_t stack_size) {
	js_cstr_t out = { .ptr = "", .len = 0, .needs_free = false };

	if (is_err(value)) {
	uint64_t data = vdata(value);
	if (data != 0) {
	ant_value_t obj = mkval(T_OBJ, data);
	ant_value_t stack = js_get(js, obj, "stack");
	if (vtype(stack) == T_STR) {
	ant_offset_t slen;
	ant_offset_t off = vstr(js, stack, &slen);
	out.ptr = (const char *)(uintptr_t)(off);
	out.len = slen;
	return out;
	}
	}
	out.ptr = "Error";
	out.len = 5;
	return out;
	}

	if (vtype(value) == T_STR) {
	size_t len = 0;
	char *str = js_getstr(js, value, &len);
	out.ptr = str ? str : ""; out.len = len;
	return out;
	}

	multiref_count = 0;
	multiref_next_id = 0;
	stringify_depth = 0;
	scan_refs(js, value);

	size_t capacity = stack_size;
	char *buf = stack_buf;
	out.needs_free = false;

	if (!buf \|\| capacity == 0) {
	capacity = 64;
	buf = ant_calloc(capacity);
	if (!buf) return out;
	out.needs_free = true;
	}

	for (;;) {
	stringify_depth = 0;
	stringify_indent = 0;
	size_t len = tostr(js, value, buf, capacity);

	if (len < capacity - 1) {
	out.ptr = buf;
	out.len = len;
	return out;
	}

	size_t new_capacity = capacity * 2;
	char *next = out.needs_free
	? ant_realloc(buf, new_capacity)
	: ant_calloc(new_capacity);

	if (!next) {
	if (out.needs_free) free(buf);
	out.ptr = ""; out.len = 0;
	out.needs_free = false;
	return out;
	}

	if (!out.needs_free) {
	memcpy(next, buf, capacity);
	out.needs_free = true;
	}

	buf = next;
	capacity = new_capacity;
	}
	}

	ant_value_t js_tostring_val(ant_t *js, ant_value_t value) {
	uint8_t t = vtype(value);
	char *buf; size_t len, buflen;

	static const void *jump_table[] = {
	[T_OBJ] = &&L_OBJ, [T_STR] = &&L_STR,
	[T_UNDEF] = &&L_UNDEF, [T_NULL] = &&L_NULL, [T_NUM] = &&L_NUM,
	[T_BOOL] = &&L_BOOL, [T_FUNC] = &&L_OBJ, [T_CFUNC] = &&L_DEFAULT,
	[T_ERR] = &&L_DEFAULT, [T_ARR] = &&L_OBJ,
	[T_PROMISE] = &&L_DEFAULT, [T_TYPEDARRAY] = &&L_DEFAULT,
	[T_BIGINT] = &&L_BIGINT, [T_SYMBOL] = &&L_DEFAULT,
	[T_GENERATOR] = &&L_DEFAULT, [T_FFI] = &&L_DEFAULT
	};

	if (t < sizeof(jump_table) / sizeof(jump_table[0])) goto *jump_table[t];
	goto L_DEFAULT;

	L_STR: return value;
	L_UNDEF: return js_mkstr(js, "undefined", 9);
	L_NULL: return js_mkstr(js, "null", 4);
	L_BOOL: return vdata(value) ? js_mkstr(js, "true", 4) : js_mkstr(js, "false", 5);
	L_OBJ: return js_call_toString(js, value);

	L_NUM: {
	buf = (char *)ant_calloc(32);
	len = strnum(value, buf, 32);
	ant_value_t result = js_mkstr(js, buf, len);
	free(buf); return result;
	}

	L_BIGINT: {
	buflen = bigint_digits_len(js, value);
	buf = (char *)ant_calloc(buflen + 2);
	len = strbigint(js, value, buf, buflen + 2);
	ant_value_t result = js_mkstr(js, buf, len);
	free(buf); return result;
	}

	L_DEFAULT: {
	buf = tostr_alloc(js, value);
	ant_value_t result = js_mkstr(js, buf, strlen(buf));
	free(buf); return result;
	}
	}

	const char js_str(ant_t js, ant_value_t value) {
	if (is_err(value)) {
	uint64_t data = vdata(value);
	if (data != 0) {
	ant_value_t obj = mkval(T_OBJ, data);
	ant_value_t stack = js_get(js, obj, "stack");
	if (vtype(stack) == T_STR) {
	ant_offset_t slen, off = vstr(js, stack, &slen);
	return (const char *)(uintptr_t)off;
	}
	}
	return "Error";
	}

	multiref_count = 0;
	multiref_next_id = 0;
	stringify_depth = 0;
	scan_refs(js, value);

	size_t capacity = 4096;
	char buf = (char )ant_calloc(capacity);
	if (!buf) return "";

	size_t len;
	for (;;) {
	stringify_depth = 0;
	stringify_indent = 0;
	len = tostr(js, value, buf, capacity);

	if (len < capacity - 1) break;

	capacity *= 2;
	buf = (char *)ant_realloc(buf, capacity);
	if (!buf) return "";
	}

	ant_value_t str = js_mkstr(js, buf, len);
	free(buf);

	if (is_err(str)) return "";
	ant_offset_t off = vstr(js, str, NULL);
	return (const char *)(uintptr_t)off;
	}

	static inline ant_offset_t get_dense_buf(ant_value_t arr) {
	ant_object_t *ptr = js_obj_ptr(js_as_obj(arr));
	if (!ptr \|\| !ptr->fast_array \|\| !ptr->u.array.data \|\| ptr->u.array.cap == 0) return 0;
	return (ant_offset_t)(uintptr_t)ptr;
	}

	static inline ant_object_t *dense_obj(ant_offset_t doff) {
	if (!doff) return NULL;
	ant_object_t ptr = (ant_object_t )(uintptr_t)doff;
	if (!ptr \|\| !ptr->fast_array \|\| !ptr->u.array.data \|\| ptr->u.array.cap == 0) return NULL;
	return ptr;
	}

	static inline ant_value_t *dense_data(ant_offset_t doff) {
	ant_object_t *ptr = dense_obj(doff);
	return ptr ? ptr->u.array.data : NULL;
	}

	static inline ant_offset_t dense_capacity(ant_offset_t doff) {
	ant_object_t *ptr = dense_obj(doff);
	return ptr ? (ant_offset_t)ptr->u.array.cap : 0;
	}

	static inline ant_value_t dense_get(ant_offset_t doff, ant_offset_t idx) {
	ant_object_t *ptr = dense_obj(doff);
	if (!ptr \|\| idx >= ptr->u.array.cap) return js_mkundef();
	return ptr->u.array.data[idx];
	}

	static inline void dense_set(ant_t *js, ant_offset_t doff, ant_offset_t idx, ant_value_t val) {
	ant_object_t *ptr = dense_obj(doff);
	if (!ptr \|\| idx >= ptr->u.array.cap) return;
	ptr->u.array.data[idx] = val;
	gc_write_barrier(js, ptr, val);
	}

	static ant_offset_t dense_grow(ant_t *js, ant_value_t arr, ant_offset_t needed) {
	ant_object_t *obj = js_obj_ptr(js_as_obj(arr));
	if (!obj) return 0;

	ant_offset_t old_cap = obj->u.array.cap;
	ant_offset_t new_cap = old_cap ? old_cap : MAX_DENSE_INITIAL_CAP;

	while (new_cap < needed) new_cap *= 2;
	ant_value_t next = realloc(obj->u.array.data, sizeof(next) * (size_t)new_cap);
	if (!next) return 0;

	for (ant_offset_t i = old_cap; i < new_cap; i++) next[i] = T_EMPTY;

	obj->u.array.data = next;
	obj->u.array.cap = (uint32_t)new_cap;
	if (obj->u.array.len > obj->u.array.cap) obj->u.array.len = obj->u.array.cap;
	obj->fast_array = 1;
	return (ant_offset_t)(uintptr_t)obj;
	}

	// TODO: make get and set dry
	static inline ant_value_t arr_get(ant_t *js, ant_value_t arr, ant_offset_t idx) {
	ant_offset_t semantic_len = get_array_length(js, arr);

	if (idx >= semantic_len) return js_mkundef();
	ant_offset_t doff = get_dense_buf(arr);

	if (doff) {
	ant_offset_t len = dense_iterable_length(js, arr);
	if (idx < len) {
	ant_value_t v = dense_get(doff, idx);
	if (!is_empty_slot(v)) return v;
	}
	}

	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)idx);

	return lkp_val(js, arr, idxstr, idxlen);
	}

	static inline void arr_set(ant_t *js, ant_value_t arr, ant_offset_t idx, ant_value_t val) {
	ant_offset_t doff = get_dense_buf(arr);

	if (doff) {
	ant_offset_t len = dense_iterable_length(js, arr);

	if (idx < len) {
	dense_set(js, doff, idx, val);
	return;
	}

	ant_offset_t density_limit = len > 0 ? len * 4 : 64;
	if (idx >= density_limit) goto sparse;

	ant_offset_t cap = dense_capacity(doff);
	if (idx >= cap) {
	doff = dense_grow(js, arr, idx + 1);
	if (doff == 0) goto sparse;
	}

	for (ant_offset_t i = len; i < idx; i++) {
	ant_value_t v = dense_get(doff, i);
	if (!is_empty_slot(v) && vtype(v) == T_UNDEF) dense_set(js, doff, i, T_EMPTY);
	}
	dense_set(js, doff, idx, val);
	array_len_set(js, arr, idx + 1);
	return;
	}

	sparse:;
	char idxstr[24];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (uint64_t)idx);
	ant_value_t key = js_mkstr(js, idxstr, idxlen);

	js_setprop(js, arr, key, val);
	}

	static inline bool arr_has(ant_t *js, ant_value_t arr, ant_offset_t idx) {
	ant_offset_t semantic_len = get_array_length(js, arr);
	if (idx >= semantic_len) return false;
	ant_offset_t doff = get_dense_buf(arr);

	if (doff) {
	ant_offset_t len = dense_iterable_length(js, arr);
	if (idx < len) {
	ant_value_t v = dense_get(doff, idx);
	if (!is_empty_slot(v)) return true;
	}
	}

	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)idx);

	return lkp(js, arr, idxstr, idxlen) != 0;
	}

	enum { ANT_ARGUMENTS_NATIVE_TAG = 0x41524753u }; // ARGS

	typedef struct {
	sv_vm_t *vm;
	int frame_index;
	uint32_t mapped_count;
	uint8_t in_setter;
	uint8_t deleted[];
	} ant_arguments_state_t;

	static inline ant_arguments_state_t *js_arguments_state(ant_value_t obj) {
	if (!js_check_native_tag(obj, ANT_ARGUMENTS_NATIVE_TAG)) return NULL;
	return (ant_arguments_state_t *)js_get_native_ptr(obj);
	}

	static ant_value_t js_arguments_getter(ant_t js, ant_value_t obj, const char key, size_t key_len) {
	ant_offset_t arr_len = get_array_length(js, obj);
	unsigned long idx = 0;

	if (!parse_array_index(key, key_len, arr_len, &idx)) return js_mkundef();
	if ((ant_offset_t)idx >= arr_len) return js_mkundef();

	ant_arguments_state_t *state = js_arguments_state(obj);
	if (
	state && state->frame_index >= 0 &&
	(uint32_t)idx < state->mapped_count &&
	!state->deleted[idx]
	) {
	sv_frame_t *frame = &state->vm->frames[state->frame_index];
	return frame->bp[idx];
	}

	return arr_get(js, obj, (ant_offset_t)idx);
	}

	static bool js_arguments_setter(
	ant_t js, ant_value_t obj, const char key, size_t key_len, ant_value_t value
	) {
	unsigned long idx = 0;
	if (!parse_array_index(key, key_len, (ant_offset_t)-1, &idx)) return false;

	ant_arguments_state_t *state = js_arguments_state(obj);
	if (state) state->in_setter = 1;
	arr_set(js, obj, (ant_offset_t)idx, value);

	if (state) state->in_setter = 0;
	if (
	state && state->frame_index >= 0 &&
	(uint32_t)idx < state->mapped_count &&
	!state->deleted[idx]
	) {
	sv_frame_t *frame = &state->vm->frames[state->frame_index];
	frame->bp[idx] = value;
	}

	return true;
	}

	static bool js_arguments_deleter(ant_t js, ant_value_t obj, const char key, size_t key_len) {
	unsigned long idx = 0;
	if (!parse_array_index(key, key_len, (ant_offset_t)-1, &idx)) return false;

	ant_arguments_state_t *state = js_arguments_state(obj);
	if (state && (uint32_t)idx < state->mapped_count) state->deleted[idx] = 1;
	return true;
	}

	static void js_arguments_finalizer(ant_t js, ant_object_t obj) {
	if (!obj \|\| obj->native.tag != ANT_ARGUMENTS_NATIVE_TAG) return;
	free(obj->native.ptr);
	obj->native.ptr = NULL;
	obj->native.tag = 0;
	}

	ant_value_t js_create_arguments_object(
	ant_t *js,
	ant_value_t callee,
	sv_frame_t *frame,
	int argc,
	int mapped_count,
	bool is_strict
	) {
	GC_ROOT_SAVE(root_mark, js);

	ant_value_t arr = js_mkarr(js);
	if (is_err(arr)) {
	GC_ROOT_RESTORE(js, root_mark);
	return arr;
	} GC_ROOT_PIN(js, arr);

	if (frame && frame->bp && argc > 0) {
	for (int i = 0; i < argc; i++) js_arr_push(js, arr, frame->bp[i]);
	}

	if (is_strict) js_set_slot(arr, SLOT_STRICT_ARGS, js_true);
	else if (vtype(callee) == T_FUNC) setprop_cstr(js, arr, "callee", 6, callee);
	js_set_sym(js, arr, get_toStringTag_sym(), js_mkstr(js, "Arguments", 9));

	if (is_object_type(js->sym.array_proto)) {
	ant_value_t iter_fn = js_get_sym(js, js->sym.array_proto, get_iterator_sym());
	if (vtype(iter_fn) == T_FUNC \|\| vtype(iter_fn) == T_CFUNC)
	js_set_sym(js, arr, get_iterator_sym(), iter_fn);
	}

	if (!is_strict && mapped_count > 0 && frame && js->vm) {
	ant_arguments_state_t *state = calloc(
	1, sizeof(state) + (size_t)mapped_count sizeof(state->deleted[0]));
	if (!state) {
	GC_ROOT_RESTORE(js, root_mark);
	return js_mkerr(js, "oom");
	}

	state->vm = js->vm;
	state->frame_index = (int)(frame - js->vm->frames);
	state->mapped_count = (uint32_t)mapped_count;

	js_set_native_ptr(arr, state);
	js_set_native_tag(arr, ANT_ARGUMENTS_NATIVE_TAG);
	js_set_finalizer(arr, js_arguments_finalizer);
	js_set_getter(arr, js_arguments_getter);
	js_set_setter(arr, js_arguments_setter);
	js_set_deleter(arr, js_arguments_deleter);
	}

	GC_ROOT_RESTORE(js, root_mark);
	return arr;
	}

	void js_arguments_detach(ant_t *js, ant_value_t obj) {
	ant_arguments_state_t *state = js_arguments_state(obj);
	if (!state \|\| state->frame_index < 0) return;

	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, obj);

	sv_frame_t *frame = &state->vm->frames[state->frame_index];
	ant_offset_t arr_len = get_array_length(js, obj);
	ant_offset_t limit = (ant_offset_t)state->mapped_count;
	if (arr_len < limit) limit = arr_len;

	for (ant_offset_t i = 0; i < limit; i++) {
	if (state->deleted[i]) continue;
	state->in_setter = 1;
	arr_set(js, obj, i, frame->bp[i]);
	state->in_setter = 0;
	}

	state->frame_index = -1;
	GC_ROOT_RESTORE(js, root_mark);
	}

	void js_arguments_sync_slot(ant_t *js, ant_value_t obj, uint32_t idx, ant_value_t value) {
	ant_arguments_state_t *state = js_arguments_state(obj);
	if (!state \|\| state->frame_index < 0 \|\|
	idx >= state->mapped_count \|\| state->deleted[idx]) {
	return;
	}

	state->in_setter = 1;
	arr_set(js, obj, (ant_offset_t)idx, value);
	state->in_setter = 0;
	}

	static inline void arr_del(ant_t *js, ant_value_t arr, ant_offset_t idx) {
	ant_offset_t semantic_len = get_array_length(js, arr);
	if (idx >= semantic_len) return;
	ant_offset_t doff = get_dense_buf(arr);

	if (doff) {
	ant_offset_t len = dense_iterable_length(js, arr);
	if (idx < len) dense_set(js, doff, idx, T_EMPTY);
	}

	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)idx);
	js_delete_prop(js, arr, idxstr, idxlen);
	}

	ant_value_t js_mkstr(ant_t js, const void ptr, size_t len) {
	ant_flat_string_t flat = (ant_flat_string_t )js_type_alloc(
	js, ANT_ALLOC_STRING, sizeof(*flat) + len + 1, _Alignof(ant_flat_string_t)
	);
	if (!flat) return js_mkerr(js, "oom");

	flat->len = (ant_offset_t)len;
	if (ptr && len > 0) memcpy(flat->bytes, ptr, len);

	flat->bytes[len] = '\0';
	flat->is_ascii = (ptr \|\| len == 0)
	? str_detect_ascii_bytes(flat->bytes, len)
	: STR_ASCII_UNKNOWN;

	return mkval(T_STR, (uintptr_t)flat);
	}

	ant_value_t js_mkstr_permanent(ant_t js, const void ptr, size_t len) {
	size_t size = sizeof(ant_flat_string_t) + len + 1;
	size_t align = _Alignof(ant_flat_string_t);

	if (js->pool.permanent.block_size == 0)
	js->pool.permanent.block_size = ANT_POOL_STRING_BLOCK_SIZE;
	ant_flat_string_t flat = (ant_flat_string_t )pool_alloc_chain(
	&js->pool.permanent.head, NULL, js->pool.permanent.block_size, size, align
	);
	if (!flat) return js_mkerr(js, "oom");

	flat->len = (ant_offset_t)len;
	if (ptr && len > 0) memcpy(flat->bytes, ptr, len);

	flat->bytes[len] = '\0';
	flat->is_ascii = (ptr \|\| len == 0)
	? str_detect_ascii_bytes(flat->bytes, len)
	: STR_ASCII_UNKNOWN;

	return mkval(T_STR, (uintptr_t)flat);
	}

	static ant_value_t js_mkrope(ant_t *js, ant_value_t left, ant_value_t right, ant_offset_t total_len, uint16_t depth) {
	ant_rope_heap_t rope = (ant_rope_heap_t )js_type_alloc(
	js, ANT_ALLOC_ROPE, sizeof(*rope), _Alignof(ant_rope_heap_t)
	);
	if (!rope) return js_mkerr(js, "oom");
	rope->len = total_len;
	rope->depth = depth;
	rope->left = left;
	rope->right = right;
	rope->cached = js_mkundef();
	return ant_mkrope_value(rope);
	}


	static ant_value_t mkobj_with_inobj_limit(ant_t *js, ant_offset_t parent, uint8_t inobj_limit) {
	(void)parent;
	ant_object_t *obj = obj_alloc(js, T_OBJ, inobj_limit);
	if (!obj) return js_mkerr(js, "oom");
	return mkval(T_OBJ, (uintptr_t)obj);
	}

	ant_value_t mkobj(ant_t *js, ant_offset_t parent) {
	return mkobj_with_inobj_limit(js, parent, (uint8_t)ANT_INOBJ_MAX_SLOTS);
	}

	ant_value_t js_mkobj_with_inobj_limit(ant_t *js, uint8_t inobj_limit) {
	return mkobj_with_inobj_limit(js, 0, inobj_limit);
	}

	static ant_value_t alloc_array_with_proto(ant_t *js, ant_value_t proto) {
	ant_object_t *obj = obj_alloc(js, T_ARR, (uint8_t)ANT_INOBJ_MAX_SLOTS);
	if (!obj) return js_mkerr(js, "oom");

	ant_value_t arr = mkval(T_ARR, (uintptr_t)obj);
	if (is_object_type(proto)) js_set_proto_init(arr, proto);

	obj->u.array.cap = MAX_DENSE_INITIAL_CAP;
	obj->u.array.len = 0;
	obj->u.array.data = malloc(sizeof(obj->u.array.data) (size_t)obj->u.array.cap);

	if (obj->u.array.data) {
	for (uint32_t i = 0; i < obj->u.array.cap; i++) obj->u.array.data[i] = T_EMPTY;
	obj->fast_array = 1;
	} else {
	obj->u.array.cap = 0;
	obj->u.array.len = 0;
	obj->fast_array = 0;
	}

	return arr;
	}

	static inline ant_value_t mkarr(ant_t *js) {
	return alloc_array_with_proto(js, js->sym.array_proto);
	}

	ant_value_t js_mkarr(ant_t *js) {
	return mkarr(js);
	}

	ant_value_t js_newobj(ant_t *js) {
	ant_value_t obj = mkobj(js, 0);
	ant_value_t proto = js->sym.object_proto;
	if (vtype(proto) == T_OBJ) js_set_proto_init(obj, proto);
	return obj;
	}

	ant_offset_t js_arr_len(ant_t *js, ant_value_t arr) {
	if (!array_obj_ptr(arr)) return 0;
	return get_array_length(js, arr);
	}

	ant_value_t js_arr_get(ant_t *js, ant_value_t arr, ant_offset_t idx) {
	if (vtype(arr) != T_ARR) return js_mkundef();
	return arr_get(js, arr, idx);
	}

	static inline bool is_const_prop(ant_t *js, ant_offset_t propoff) {
	ant_prop_ref_t *ref = propref_get(js, propoff);
	if (!ref) return false;
	uint8_t attrs = ant_shape_get_attrs(ref->obj->shape, ref->slot);
	return (attrs & ANT_PROP_ATTR_WRITABLE) == 0;
	}

	static inline const ant_shape_prop_t prop_shape_meta(ant_t js, ant_offset_t propoff) {
	ant_prop_ref_t *ref = propref_get(js, propoff);
	if (!ref \|\| !ref->obj \|\| !ref->obj->shape) return NULL;
	return ant_shape_prop_at(ref->obj->shape, ref->slot);
	}

	static inline bool is_nonconfig_prop(ant_t *js, ant_offset_t propoff) {
	ant_prop_ref_t *ref = propref_get(js, propoff);
	if (!ref) return false;
	uint8_t attrs = ant_shape_get_attrs(ref->obj->shape, ref->slot);
	return (attrs & ANT_PROP_ATTR_CONFIGURABLE) == 0;
	}

	static void js_init_intern_cache(ant_t *js) {
	js->intern.length = intern_string("length", 6);
	js->intern.buffer = intern_string("buffer", 6);
	js->intern.prototype = intern_string("prototype", 9);
	js->intern.constructor = intern_string("constructor", 11);
	js->intern.name = intern_string("name", 4);
	js->intern.message = intern_string("message", 7);
	js->intern.done = intern_string("done", 4);
	js->intern.value = intern_string("value", 5);
	js->intern.get = intern_string("get", 3);
	js->intern.set = intern_string("set", 3);
	js->intern.arguments = intern_string("arguments", 9);
	js->intern.callee = intern_string("callee", 6);
	js->intern.idx[0] = intern_string("0", 1);
	js->intern.idx[1] = intern_string("1", 1);
	js->intern.idx[2] = intern_string("2", 1);
	js->intern.idx[3] = intern_string("3", 1);
	js->intern.idx[4] = intern_string("4", 1);
	js->intern.idx[5] = intern_string("5", 1);
	js->intern.idx[6] = intern_string("6", 1);
	js->intern.idx[7] = intern_string("7", 1);
	js->intern.idx[8] = intern_string("8", 1);
	js->intern.idx[9] = intern_string("9", 1);
	}

	ant_value_t mkprop(ant_t *js, ant_value_t obj, ant_value_t k, ant_value_t v, uint8_t attrs) {
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);

	if (!ptr \|\| !ptr->shape) return js_mkerr(js, "invalid object");
	if (!attrs) attrs = ANT_PROP_ATTR_DEFAULT;

	uint32_t slot = 0;
	bool added = false;
	if (vtype(k) == T_SYMBOL) {
	ant_offset_t sym_off = (ant_offset_t)vdata(k);
	int32_t found = ant_shape_lookup_symbol(ptr->shape, sym_off);
	if (found >= 0) {
	slot = (uint32_t)found;
	if (!js_obj_ensure_unique_shape(ptr)) return js_mkerr(js, "oom");
	ant_shape_set_attrs_symbol(ptr->shape, sym_off, attrs);
	} else {
	if (!ant_shape_add_symbol_tr(&ptr->shape, sym_off, attrs, &slot)) {
	return js_mkerr(js, "oom");
	}
	added = true;
	}
	} else {
	ant_offset_t klen = 0;
	ant_offset_t koff = vstr(js, k, &klen);
	const char p = (const char )(uintptr_t)(koff);
	const char *interned = intern_string(p, klen);
	if (!interned) return js_mkerr(js, "oom");

	int32_t found = ant_shape_lookup_interned(ptr->shape, interned);
	if (found >= 0) {
	slot = (uint32_t)found;
	if (!js_obj_ensure_unique_shape(ptr)) return js_mkerr(js, "oom");
	ant_shape_set_attrs_interned(ptr->shape, interned, attrs);
	} else {
	if (!ant_shape_add_interned_tr(&ptr->shape, interned, attrs, &slot)) {
	return js_mkerr(js, "oom");
	}
	added = true;
	}
	}

	if (added && !js_obj_ensure_prop_capacity(ptr, ant_shape_count(ptr->shape))) {
	return js_mkerr(js, "oom");
	}

	if (slot >= ptr->prop_count && !js_obj_ensure_prop_capacity(ptr, slot + 1)) {
	return js_mkerr(js, "oom");
	}
	ant_object_prop_set_unchecked(ptr, slot, v);
	gc_write_barrier(js, ptr, v);

	return v;
	}

	ant_value_t mkprop_interned(ant_t js, ant_value_t obj, const char interned_key, ant_value_t v, uint8_t attrs) {
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| !ptr->shape \|\| !interned_key) return js_mkerr(js, "invalid object");

	if (!attrs) attrs = ANT_PROP_ATTR_DEFAULT;

	uint32_t slot = 0;
	bool added = false;
	int32_t found = ant_shape_lookup_interned(ptr->shape, interned_key);
	if (found >= 0) {
	slot = (uint32_t)found;
	if (!js_obj_ensure_unique_shape(ptr)) return js_mkerr(js, "oom");
	ant_shape_set_attrs_interned(ptr->shape, interned_key, attrs);
	} else {
	if (!ant_shape_add_interned_tr(&ptr->shape, interned_key, attrs, &slot)) {
	return js_mkerr(js, "oom");
	}
	added = true;
	}

	if (added && !js_obj_ensure_prop_capacity(ptr, ant_shape_count(ptr->shape))) {
	return js_mkerr(js, "oom");
	}
	if (slot >= ptr->prop_count && !js_obj_ensure_prop_capacity(ptr, slot + 1)) {
	return js_mkerr(js, "oom");
	}
	ant_object_prop_set_unchecked(ptr, slot, v);
	gc_write_barrier(js, ptr, v);
	return v;
	}

	ant_value_t js_mkprop_fast(ant_t js, ant_value_t obj, const char key, size_t len, ant_value_t v) {
	const char *interned = intern_string(key, len);
	if (!interned) return js_mkerr(js, "oom");
	return mkprop_interned(js, obj, interned, v, 0);
	}

	ant_offset_t js_mkprop_fast_off(ant_t js, ant_value_t obj, const char key, size_t len, ant_value_t v) {
	const char *interned = intern_string(key, len);
	if (!interned) return 0;
	ant_value_t prop = mkprop_interned(js, obj, interned, v, 0);
	if (is_err(prop)) return 0;
	return lkp_interned(js, obj, interned, len);
	}

	void js_saveval(ant_t *js, ant_offset_t off, ant_value_t v) {
	bool ok = propref_store(js, off, v);
	assert(ok && "js_saveval expects a valid property handle");
	(void)ok;
	}

	static void set_slot(ant_value_t obj, internal_slot_t slot, ant_value_t val) {
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| slot < 0 \|\| slot > SLOT_MAX) return;
	if (slot == SLOT_PROTO) {
	ptr->proto = val;
	ant_ic_epoch_bump();
	return;
	}
	if (slot == SLOT_DATA) {
	ptr->u.data.value = val;
	return;
	}
	(void)obj_extra_set(ptr, slot, val);
	}

	static void set_slot_wb(ant_t *js, ant_value_t obj, internal_slot_t slot, ant_value_t val) {
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| slot < 0 \|\| slot > SLOT_MAX) return;
	if (slot == SLOT_PROTO) {
	ptr->proto = val;
	gc_write_barrier(js, ptr, val);
	ant_ic_epoch_bump();
	return;
	}
	if (slot == SLOT_DATA) {
	ptr->u.data.value = val;
	gc_write_barrier(js, ptr, val);
	return;
	}
	(void)obj_extra_set(ptr, slot, val);
	gc_write_barrier(js, ptr, val);
	}

	void js_set_slot(ant_value_t obj, internal_slot_t slot, ant_value_t value) {
	set_slot(js_as_obj(obj), slot, value);
	}

	void js_set_slot_wb(ant_t *js, ant_value_t obj, internal_slot_t slot, ant_value_t value) {
	set_slot_wb(js, js_as_obj(obj), slot, value);
	}

	static ant_value_t get_slot(ant_value_t obj, internal_slot_t slot) {
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| slot < 0 \|\| slot > SLOT_MAX) return js_mkundef();
	if (slot == SLOT_PROTO) return ptr->proto;
	if (slot == SLOT_DATA) {
	return ptr->u.data.value;
	}
	return obj_extra_get(ptr, slot);
	}

	static void set_func_code_ptr(ant_t js, ant_value_t func_obj, const char code, size_t len) {
	set_slot(func_obj, SLOT_CODE, mkval(T_CFUNC, (size_t)code));
	set_slot(func_obj, SLOT_CODE_LEN, tov((double)len));
	}

	static void set_func_code(ant_t js, ant_value_t func_obj, const char code, size_t len) {
	const char *arena_code = code_arena_alloc(code, len);
	if (!arena_code) return;
	set_func_code_ptr(js, func_obj, arena_code, len);
	}

	static const char get_func_code(ant_t js, ant_value_t func_obj, ant_offset_t *len) {
	ant_value_t code_val = get_slot(func_obj, SLOT_CODE);
	ant_value_t len_val = get_slot(func_obj, SLOT_CODE_LEN);

	if (vtype(code_val) != T_CFUNC) {
	if (len) *len = 0;
	return NULL;
	}

	if (len) *len = (ant_offset_t)tod(len_val);
	return (const char *)vdata(code_val);
	}

	static inline bool js_is_trim_space(char ch) {
	return ch == ' ' \|\| ch == '\t' \|\| ch == '\n' \|\| ch == '\r';
	}

	static inline bool js_try_parse_ascii_decimal_fast(const char str, size_t len, double out) {
	size_t i = 0;
	int sign = 1;
	int int_digits = 0;
	int frac_digits = 0;

	double value = 0.0;
	double scale = 1.0;
	bool saw_digit = false;

	if (len == 0) return false;
	if (str[i] == '+' \|\| str[i] == '-') {
	sign = (str[i] == '-') ? -1 : 1;
	i++;
	if (i == len) return false;
	}

	while (i < len && str[i] >= '0' && str[i] <= '9') {
	if (int_digits >= 18) return false;
	value = value * 10.0 + (double)(str[i] - '0');
	saw_digit = true;
	int_digits++; i++;
	}

	if (i < len && str[i] == '.') {
	i++;
	while (i < len && str[i] >= '0' && str[i] <= '9') {
	if (frac_digits >= 18) return false;
	scale *= 0.1;
	value += (double)(str[i] - '0') * scale;
	saw_digit = true;
	frac_digits++; i++;
	}}

	if (!saw_digit \|\| i != len) return false;
	*out = (sign < 0) ? -value : value;

	return true;
	}

	double js_to_number(ant_t *js, ant_value_t arg) {
	if (vtype(arg) == T_NULL) return 0.0;
	if (vtype(arg) == T_UNDEF) return JS_NAN;

	if (vtype(arg) == T_NUM) return tod(arg);
	if (vtype(arg) == T_BOOL) return vdata(arg) ? 1.0 : 0.0;
	if (vtype(arg) == T_BIGINT) return bigint_to_double(js, arg);

	if (vtype(arg) == T_STR) {
	ant_flat_string_t *flat = ant_str_flat_ptr(arg);
	const char *base = NULL;
	const char *s = NULL;
	const char *end = NULL;

	if (flat) {
	base = flat->bytes;
	s = base;
	end = base + flat->len;
	} else {
	ant_offset_t len = 0;
	ant_offset_t off = vstr(js, arg, &len);
	base = (const char *)(uintptr_t)off;
	s = base;
	end = base + len;
	}

	while (s < end && js_is_trim_space(*s)) s++;
	if (s == end) return 0.0;

	double fast_val = 0.0;
	if (js_try_parse_ascii_decimal_fast(s, (size_t)(end - s), &fast_val))
	return fast_val;

	char *parse_end = NULL;
	double val = strtod(s, &parse_end);
	while (parse_end < end && js_is_trim_space(*parse_end)) parse_end++;

	return (parse_end == s \|\| parse_end != end) ? JS_NAN : val;
	}

	if (vtype(arg) == T_OBJ \|\| vtype(arg) == T_ARR) {
	if (vtype(arg) == T_OBJ) {
	ant_value_t prim = js_call_valueOf(js, arg);
	uint8_t pt = vtype(prim);
	if (pt != T_OBJ && pt != T_ARR && pt != T_FUNC) return js_to_number(js, prim);
	}

	ant_value_t str_val = js_tostring_val(js, arg);
	if (is_err(str_val) \|\| vtype(str_val) != T_STR) return JS_NAN;
	return js_to_number(js, str_val);
	}

	return JS_NAN;
	}

	static ant_value_t setup_func_prototype(ant_t *js, ant_value_t func) {
	ant_value_t proto_obj = mkobj(js, 0);
	if (is_err(proto_obj)) return proto_obj;

	ant_value_t object_proto = js->sym.object_proto;
	if (vtype(object_proto) == T_OBJ) {
	js_set_proto_init(proto_obj, object_proto);
	}

	ant_value_t constructor_key = js_mkstr(js, "constructor", 11);
	if (is_err(constructor_key)) return constructor_key;

	ant_value_t res = mkprop(js, proto_obj, constructor_key, func, 0);
	if (is_err(res)) return res;
	js_set_descriptor(js, proto_obj, "constructor", 11, JS_DESC_W \| JS_DESC_C);

	ant_value_t prototype_key = js_mkstr(js, "prototype", 9);
	if (is_err(prototype_key)) return prototype_key;

	res = js_setprop(js, func, prototype_key, proto_obj);
	if (is_err(res)) return res;
	js_set_descriptor(js, js_as_obj(func), "prototype", 9, JS_DESC_W);

	js_mark_constructor(func, true);

	return js_mkundef();
	}

	static inline bool same_object_identity(ant_value_t a, ant_value_t b) {
	if (!is_object_type(a) \|\| !is_object_type(b)) return false;
	return vdata(js_as_obj(a)) == vdata(js_as_obj(b));
	}

	static inline ant_value_t proto_next_obj_or_null(ant_t *js, ant_value_t cur) {
	if (!is_object_type(cur)) return js_mknull();
	ant_value_t next = get_proto(js, cur);
	return is_object_type(next) ? next : js_mknull();
	}

	typedef struct {
	int depth;
	bool overflow;
	ant_value_t fast;
	} proto_overflow_guard_t;

	static inline void proto_overflow_guard_init(proto_overflow_guard_t *g) {
	g->depth = 0;
	g->overflow = false;
	g->fast = js_mknull();
	}

	static inline bool proto_overflow_guard_hit_cycle(ant_t js, proto_overflow_guard_t g, ant_value_t cur) {
	if (!g->overflow) {
	if (++g->depth < MAX_PROTO_CHAIN_DEPTH) return false;
	g->overflow = true;
	g->fast = cur;
	}

	g->fast = proto_next_obj_or_null(js, g->fast);
	g->fast = proto_next_obj_or_null(js, g->fast);
	return same_object_identity(cur, g->fast);
	}

	static inline bool proto_walk_next(ant_t js, ant_value_t cur, uint8_t *t, uint8_t flags) {
	uint8_t ct = *t;

	if (flags & PROTO_WALK_F_OBJECT_ONLY) {
	if (!is_object_type(*cur)) return false;
	ant_value_t next = get_proto(js, *cur);
	uint8_t nt = vtype(next);
	if (nt == T_NULL \|\| nt == T_UNDEF \|\| !is_object_type(next)) return false;
	cur = next; t = nt;
	return true;
	}

	if (JS_TPFLG(ct) & T_OBJECT_MASK) {
	ant_value_t as_obj = js_as_obj(*cur);
	ant_value_t proto = get_slot(as_obj, SLOT_PROTO);

	uint8_t pt = vtype(proto);
	if (pt == T_OBJ \|\| pt == T_ARR \|\| pt == T_FUNC) {
	*cur = proto;
	*t = pt;
	return true;
	}

	if (JS_TPFLG(ct) & T_NEEDS_PROTO_FALLBACK) {
	ant_value_t fallback = get_prototype_for_type(js, ct);
	uint8_t ft = vtype(fallback);
	if (ft == T_NULL \|\| ft == T_UNDEF) return false;
	*cur = fallback;
	*t = ft;
	return true;
	}

	return false;
	}

	if (ct == T_STR \|\| ct == T_NUM \|\| ct == T_BOOL \|\| ct == T_BIGINT \|\| ct == T_SYMBOL) {
	ant_value_t proto = get_prototype_for_type(js, ct);
	uint8_t pt = vtype(proto);
	if (pt == T_NULL \|\| pt == T_UNDEF) return false;
	cur = proto; t = pt;
	return true;
	}

	return false;
	}

	typedef struct {
	int depth;
	bool overflow;
	bool fast_active;
	ant_value_t fast_cur;
	uint8_t fast_t;
	} proto_walk_overflow_guard_t;

	static inline void proto_walk_overflow_guard_init(proto_walk_overflow_guard_t *g) {
	g->depth = 0;
	g->overflow = false;
	g->fast_active = false;
	g->fast_cur = js_mknull();
	g->fast_t = T_NULL;
	}

	static inline bool proto_walk_overflow_guard_hit_cycle(
	ant_t *js,
	proto_walk_overflow_guard_t *g,
	ant_value_t cur,
	uint8_t cur_t,
	uint8_t flags
	) {
	if (!g->overflow) {
	if (++g->depth < MAX_PROTO_CHAIN_DEPTH) return false;
	g->overflow = true;
	g->fast_active = true;
	g->fast_cur = cur;
	g->fast_t = cur_t;
	}

	if (g->fast_active && !proto_walk_next(js, &g->fast_cur, &g->fast_t, flags))
	g->fast_active = false;
	if (g->fast_active && !proto_walk_next(js, &g->fast_cur, &g->fast_t, flags))
	g->fast_active = false;

	return g->fast_active && same_object_identity(cur, g->fast_cur);
	}

	ant_value_t js_instance_proto_from_new_target(ant_t *js, ant_value_t fallback_proto) {
	ant_value_t instance_proto = js_mkundef();

	if (vtype(js->new_target) == T_FUNC \|\| vtype(js->new_target) == T_CFUNC) {
	ant_value_t nt_obj = js_as_obj(js->new_target);
	ant_value_t nt_proto = lkp_interned_val(js, nt_obj, js->intern.prototype);
	if (is_object_type(nt_proto)) instance_proto = nt_proto;
	}

	if (!is_object_type(instance_proto) && is_object_type(fallback_proto))
	instance_proto = fallback_proto;

	return instance_proto;
	}

	bool proto_chain_contains(ant_t *js, ant_value_t obj, ant_value_t proto_target) {
	if (!is_object_type(obj) \|\| !is_object_type(proto_target)) return false;
	ant_value_t cur = obj;
	uint8_t t = vtype(cur);
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);

	while (true) {
	if (!proto_walk_next(js, &cur, &t, PROTO_WALK_F_OBJECT_ONLY)) break;
	if (same_object_identity(cur, proto_target)) return true;
	if (proto_overflow_guard_hit_cycle(js, &guard, cur)) break;
	}
	return false;
	}

	static inline bool is_wrapper_ctor_target(ant_t *js, ant_value_t this_val, ant_value_t expected_proto) {
	if (vtype(js->new_target) == T_UNDEF) return false;
	if (vtype(this_val) != T_OBJ) return false;
	if (vtype(get_slot(this_val, SLOT_PRIMITIVE)) != T_UNDEF) return false;
	return proto_chain_contains(js, this_val, expected_proto);
	}

	ant_value_t get_ctor_species_value(ant_t *js, ant_value_t ctor) {
	if (!is_object_type(ctor) && vtype(ctor) != T_CFUNC) return js_mkundef();
	return js_get_sym(js, ctor, get_species_sym());
	}

	bool same_ctor_identity(ant_t *js, ant_value_t a, ant_value_t b) {
	if (vtype(a) == vtype(b) && vdata(a) == vdata(b)) return true;

	if (vtype(a) == T_FUNC && vtype(b) == T_CFUNC) {
	ant_value_t c = get_slot(a, SLOT_CFUNC);
	return vtype(c) == T_CFUNC && vdata(c) == vdata(b);
	}

	if (vtype(a) == T_CFUNC && vtype(b) == T_FUNC) {
	ant_value_t c = get_slot(b, SLOT_CFUNC);
	return vtype(c) == T_CFUNC && vdata(c) == vdata(a);
	}

	if (vtype(a) == T_FUNC && vtype(b) == T_FUNC) {
	ant_value_t ca = get_slot(a, SLOT_CFUNC);
	ant_value_t cb = get_slot(b, SLOT_CFUNC);
	if (vtype(ca) == T_CFUNC && vtype(cb) == T_CFUNC && vdata(ca) == vdata(cb)) return true;
	}

	return false;
	}

	static ant_value_t array_constructor_from_receiver(ant_t *js, ant_value_t receiver) {
	if (!is_object_type(receiver)) return js_mkundef();

	ant_value_t species_source = receiver;
	if (is_proxy(species_source)) {
	species_source = proxy_read_target(js, species_source);
	}

	bool receiver_is_array = (vtype(species_source) == T_ARR);
	if (!receiver_is_array) {
	ant_value_t array_proto = get_ctor_proto(js, "Array", 5);
	if (is_object_type(array_proto) && is_object_type(species_source)) {
	receiver_is_array = proto_chain_contains(js, species_source, array_proto);
	}
	}
	if (!receiver_is_array) return js_mkundef();

	ant_value_t ctor = js_getprop_fallback(js, receiver, "constructor");
	if (is_err(ctor)) return ctor;

	ant_value_t species = get_ctor_species_value(js, ctor);
	if (is_err(species)) return species;

	if (vtype(species) == T_NULL) return js_mkundef();
	if (vtype(species) == T_FUNC \|\| vtype(species) == T_CFUNC) return species;
	if (vtype(ctor) != T_FUNC && vtype(ctor) != T_CFUNC) return js_mkundef();

	return ctor;
	}

	static ant_value_t array_alloc_from_ctor_with_length(ant_t *js, ant_value_t ctor, ant_offset_t length_hint) {
	if (vtype(ctor) != T_FUNC && vtype(ctor) != T_CFUNC) {
	return mkarr(js);
	}

	ant_value_t seed = js_mkobj(js);
	if (is_err(seed)) return seed;

	ant_value_t proto = js_get(js, ctor, "prototype");
	if (is_err(proto)) return proto;
	if (is_object_type(proto)) js_set_proto_init(seed, proto);

	ant_value_t ctor_args[1] = { tov((double)length_hint) };
	ant_value_t saved_new_target = js->new_target;
	js->new_target = ctor;
	ant_value_t constructed = sv_vm_call(js->vm, js, ctor, seed, ctor_args, 1, NULL, true);
	js->new_target = saved_new_target;
	if (is_err(constructed)) return constructed;

	ant_value_t result = is_object_type(constructed) ? constructed : seed;
	set_slot(js_as_obj(result), SLOT_CTOR, ctor);
	return result;
	}

	static inline ant_value_t array_alloc_from_ctor(ant_t *js, ant_value_t ctor) {
	return array_alloc_from_ctor_with_length(js, ctor, 0);
	}

	static inline ant_value_t array_alloc_like(ant_t *js, ant_value_t receiver) {
	ant_value_t ctor = array_constructor_from_receiver(js, receiver);
	if (is_err(ctor)) return ctor;
	return array_alloc_from_ctor(js, ctor);
	}

	static ant_value_t validate_array_length(ant_t *js, ant_value_t v) {
	if (vtype(v) != T_NUM) {
	return js_mkerr_typed(js, JS_ERR_RANGE, "Invalid array length");
	}
	double d = tod(v);
	if (d < 0 \|\| d != (uint32_t)d \|\| d >= 4294967296.0) {
	return js_mkerr_typed(js, JS_ERR_RANGE, "Invalid array length");
	}
	return js_mkundef();
	}

	static inline ant_value_t check_object_extensibility(ant_t *js, ant_value_t obj) {
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return js_mkundef();

	if (ptr->frozen) {
	return sv_is_strict_context(js)
	? js_mkerr(js, "cannot add property to frozen object")
	: js_false;
	}

	if (ptr->sealed) {
	return sv_is_strict_context(js)
	? js_mkerr(js, "cannot add property to sealed object")
	: js_false;
	}

	if (!ptr->extensible) {
	return sv_is_strict_context(js)
	? js_mkerr(js, "cannot add property to non-extensible object")
	: js_false;
	}

	return js_mkundef();
	}

	static inline void array_len_set(ant_t *js, ant_value_t obj, ant_offset_t new_len) {
	ant_object_t *arr_ptr = array_obj_ptr(obj);
	if (arr_ptr) {
	if (new_len > (ant_offset_t)UINT32_MAX) new_len = (ant_offset_t)UINT32_MAX;
	arr_ptr->u.array.len = (uint32_t)new_len;
	return;
	}

	ant_value_t new_len_val = tov((double)new_len);
	ant_offset_t len_off = lkp_interned(js, obj, js->intern.length, 6);

	if (len_off != 0) js_saveval(js, len_off, new_len_val);
	else js_mkprop_fast(js, obj, "length", 6, new_len_val);
	}

	static ant_value_t js_setprop_array_fast(ant_t js, ant_value_t obj, ant_value_t k, ant_value_t v, ant_offset_t klen, const char key) {
	unsigned long idx;
	if (!parse_array_index(key, klen, (ant_offset_t)-1, &idx)) return js_mkundef();

	ant_offset_t cur_len = get_array_length(js, obj);
	ant_offset_t doff = get_dense_buf(obj);
	if (doff) {
	ant_offset_t dense_len = dense_iterable_length(js, obj);
	if (idx < dense_len) { dense_set(js, doff, (ant_offset_t)idx, v); return v; }

	ant_offset_t density_limit = dense_len > 0 ? dense_len * 4 : 64;
	if (idx >= density_limit) goto sparse;

	ant_value_t extensibility_error = check_object_extensibility(js, obj);
	if (is_err(extensibility_error)) return extensibility_error;
	if (extensibility_error == js_false) return v;

	arr_set(js, obj, (ant_offset_t)idx, v);
	return v;
	}

	sparse:;
	if (idx < cur_len) return js_mkundef();

	ant_value_t extensibility_error = check_object_extensibility(js, obj);
	if (is_err(extensibility_error)) return extensibility_error;
	if (extensibility_error == js_false) return v;

	ant_value_t result = mkprop(js, obj, k, v, 0);
	if (is_err(result)) return result;
	array_define_or_set_index(js, obj, key, (size_t)klen);

	return v;
	}

	static inline void prop_meta_defaults(prop_meta_t *out) {
	*out = (prop_meta_t){
	.has_getter = false,
	.has_setter = false,
	.writable = true,
	.enumerable = true,
	.configurable = true,
	.getter = js_mkundef(),
	.setter = js_mkundef(),
	};
	}

	static inline void prop_meta_from_shape(prop_meta_t out, const ant_shape_prop_t prop) {
	out->has_getter = prop->has_getter != 0;
	out->has_setter = prop->has_setter != 0;
	out->writable = (prop->attrs & ANT_PROP_ATTR_WRITABLE) != 0;
	out->enumerable = (prop->attrs & ANT_PROP_ATTR_ENUMERABLE) != 0;
	out->configurable = (prop->attrs & ANT_PROP_ATTR_CONFIGURABLE) != 0;
	out->getter = prop->getter;
	out->setter = prop->setter;
	}

	static inline void prop_meta_from_desc(prop_meta_t out, const descriptor_entry_t desc) {
	out->has_getter = desc->has_getter;
	out->has_setter = desc->has_setter;
	out->writable = desc->writable;
	out->enumerable = desc->enumerable;
	out->configurable = desc->configurable;
	out->getter = desc->getter;
	out->setter = desc->setter;
	}

	bool lookup_prop_meta(
	ant_t *js,
	ant_value_t cur_obj,
	prop_meta_key_t key_kind,
	const char *key,
	size_t klen,
	ant_offset_t sym_off,
	prop_meta_t *out
	) {
	if (!out \|\| !is_object_type(cur_obj)) return false;
	if (key_kind == PROP_META_STRING && !key) return false;

	prop_meta_defaults(out);

	ant_object_t *cur_ptr = js_obj_ptr(cur_obj);
	if (!cur_ptr) return false;
	if (key_kind == PROP_META_STRING && key && is_length_key(key, klen) &&
	cur_ptr->type_tag == T_ARR) {
	out->has_getter = false;
	out->has_setter = false;
	out->writable = true;
	out->enumerable = false;
	out->configurable = false;
	out->getter = js_mkundef();
	out->setter = js_mkundef();
	return true;
	}

	if (cur_ptr->shape) {
	int32_t slot = -1;
	if (key_kind == PROP_META_SYMBOL) {
	slot = ant_shape_lookup_symbol(cur_ptr->shape, sym_off);
	} else {
	const char *interned_key = intern_string(key, klen);
	if (interned_key) slot = ant_shape_lookup_interned(cur_ptr->shape, interned_key);
	}

	if (slot >= 0) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(cur_ptr->shape, (uint32_t)slot);
	if (!prop) return false;
	prop_meta_from_shape(out, prop);
	return true;
	}
	}

	if (!cur_ptr->is_exotic) return false;

	descriptor_entry_t *desc = NULL;
	if (key_kind == PROP_META_SYMBOL) {
	desc = lookup_sym_descriptor(cur_obj, sym_off);
	} else if (js) {
	desc = lookup_descriptor(cur_obj, key, klen);
	}

	if (!desc) return false;
	prop_meta_from_desc(out, desc);
	return true;
	}

	bool js_try_get_own_data_prop(ant_t js, ant_value_t obj, const char key, size_t key_len, ant_value_t *out) {
	if (out) *out = js_mkundef();
	if (!key \|\| !out) return false;

	uint8_t t = vtype(obj);
	if (t == T_FUNC) obj = js_func_obj(obj);
	else if (t != T_OBJ && t != T_ARR) return false;

	ant_value_t as_obj = js_as_obj(obj);
	if (is_proxy(as_obj)) return false;

	prop_meta_t meta;
	bool has_meta = lookup_string_prop_meta(js, as_obj, key, key_len, &meta);
	if (has_meta && (meta.has_getter \|\| meta.has_setter)) return false;

	ant_offset_t off = lkp(js, as_obj, key, (ant_offset_t)key_len);
	if (off != 0) {
	*out = propref_load(js, off);
	return true;
	}

	if (array_obj_ptr(as_obj) && is_length_key(key, (ant_offset_t)key_len)) {
	*out = tov((double)get_array_length(js, as_obj));
	return true;
	}

	return false;
	}

	// TODO: decompose into smaller helpers
	ant_value_t js_setprop(ant_t *js, ant_value_t obj, ant_value_t k, ant_value_t v) {
	uint8_t ot = vtype(obj);

	if (ot == T_CFUNC) {
	ant_value_t promoted = js_cfunc_promote(js, obj);
	return js_setprop(js, promoted, k, v);
	}

	if (ot == T_STR \|\| ot == T_NUM \|\| ot == T_BOOL) {
	ant_offset_t klen; ant_offset_t koff = vstr(js, k, &klen);
	const char key = (char )(uintptr_t)(koff);

	ant_value_t proto = get_prototype_for_type(js, ot);
	if (is_object_type(proto)) {
	ant_value_t setter = js_mkundef();
	bool has_setter = false;

	lkp_with_setter(js, proto, key, klen, &setter, &has_setter);
	if (has_setter && (vtype(setter) == T_FUNC \|\| vtype(setter) == T_CFUNC)) {
	call_proto_accessor(js, obj, setter, true, &v, 1, true);
	return v;
	}}

	if (sv_is_strict_context(js)) return js_mkerr_typed(js, JS_ERR_TYPE,
	"Cannot create property '%.*s' on %s",
	(int)klen, key, typestr(ot)
	);

	return v;
	}

	if (vtype(obj) == T_FUNC) obj = js_func_obj(obj);
	if (vtype(k) == T_SYMBOL) {
	ant_offset_t sym_off = (ant_offset_t)vdata(k);
	ant_value_t cur = obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);

	while (is_object_type(cur)) {
	ant_value_t cur_obj = js_as_obj(cur);
	prop_meta_t meta;
	if (lookup_symbol_prop_meta(cur_obj, sym_off, &meta)) {
	if (meta.has_setter) {
	ant_value_t setter = meta.setter;
	if (vtype(setter) == T_FUNC \|\| vtype(setter) == T_CFUNC) {
	ant_value_t result = sv_vm_call(sv_vm_get_active(js), js, setter, obj, &v, 1, NULL, false);
	if (is_err(result)) return result;
	return v;
	}
	}
	if (meta.has_getter && !meta.has_setter) {
	if (sv_is_strict_context(js)) return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot set property which has only a getter");
	return v;
	}
	if (!meta.has_getter && !meta.has_setter && !meta.writable) {
	if (sv_is_strict_context(js)) return js_mkerr(js, "assignment to read-only property");
	return v;
	}
	break;
	}

	ant_value_t proto = get_proto(js, cur_obj);
	if (!is_object_type(proto)) break;
	cur = proto;
	if (proto_overflow_guard_hit_cycle(js, &guard, cur)) break;
	}

	ant_offset_t existing = lkp_sym(js, obj, sym_off);

	if (existing > 0) {
	if (is_const_prop(js, existing)) return js_mkerr(js, "assignment to constant");
	js_saveval(js, existing, v);
	return v;
	}

	{
	ant_value_t extensibility_error = check_object_extensibility(js, obj);
	if (is_err(extensibility_error)) return extensibility_error;
	if (extensibility_error == js_false) return v;
	}

	return mkprop(js, obj, k, v, 0);
	}

	ant_offset_t klen; ant_offset_t koff = vstr(js, k, &klen);
	const char key = (char )(uintptr_t)(koff);

	if (array_obj_ptr(obj) && klen > 0 && key[0] >= '0' && key[0] <= '9') {
	ant_arguments_state_t *args_state = js_arguments_state(obj);
	if (args_state && !args_state->in_setter && js_arguments_setter(js, obj, key, (size_t)klen, v)) return v;
	}

	if (array_obj_ptr(obj) && !is_proxy(obj) && klen > 0 && key[0] >= '0' && key[0] <= '9') {
	ant_value_t result = js_setprop_array_fast(js, obj, k, v, klen, key);
	if (vtype(result) != T_UNDEF) return result;
	}

	if (array_obj_ptr(obj) && is_length_key(key, klen)) {
	ant_value_t err = validate_array_length(js, v);
	if (is_err(err)) return err;
	ant_offset_t doff = get_dense_buf(obj);
	ant_offset_t new_len_val = (ant_offset_t) tod(v);
	if (doff) {
	ant_offset_t cap = dense_capacity(doff);
	ant_offset_t cur_len = get_array_length(js, obj);
	ant_offset_t clear_to = (cur_len < cap) ? cur_len : cap;
	if (new_len_val < clear_to) {
	for (ant_offset_t i = new_len_val; i < clear_to; i++)
	dense_set(js, doff, i, T_EMPTY);
	}
	}
	array_len_set(js, obj, new_len_val);
	return v;
	}

	if (is_proxy(obj)) {
	ant_value_t result = proxy_set(js, obj, key, klen, v);
	if (is_err(result)) return result;
	return v;
	}

	if (try_dynamic_setter(js, obj, key, klen, v)) return v;
	ant_offset_t existing = lkp(js, obj, key, klen);

	{
	const char *interned_key = intern_string(key, (size_t)klen);
	bool found_desc = false;
	bool desc_on_receiver = false;
	bool desc_has_getter = false;
	bool desc_has_setter = false;
	bool desc_writable = true;
	ant_value_t desc_setter = js_mkundef();

	ant_value_t cur = obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);
	bool on_receiver = true;
	while (is_object_type(cur)) {
	ant_value_t cur_obj = js_as_obj(cur);
	ant_object_t *cur_ptr = js_obj_ptr(cur_obj);
	if (!cur_ptr) break;

	bool found_here = false;
	if (cur_ptr->shape && interned_key) {
	int32_t slot = ant_shape_lookup_interned(cur_ptr->shape, interned_key);
	if (slot >= 0) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(cur_ptr->shape, (uint32_t)slot);
	if (prop) {
	found_here = true;
	desc_has_getter = prop->has_getter != 0;
	desc_has_setter = prop->has_setter != 0;
	desc_writable = (prop->attrs & ANT_PROP_ATTR_WRITABLE) != 0;
	desc_setter = prop->setter;
	}
	}
	}

	if (!found_here && cur_ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(cur_obj, key, klen);
	if (desc) {
	found_here = true;
	desc_has_getter = desc->has_getter;
	desc_has_setter = desc->has_setter;
	desc_writable = desc->writable;
	desc_setter = desc->setter;
	}
	}

	if (found_here) {
	found_desc = true;
	desc_on_receiver = on_receiver;
	break;
	}

	ant_value_t proto = get_proto(js, cur_obj);
	if (vtype(proto) != T_OBJ && vtype(proto) != T_FUNC) break;
	cur = proto;
	on_receiver = false;
	if (proto_overflow_guard_hit_cycle(js, &guard, cur)) break;
	}

	if (!found_desc) goto no_descriptor;
	if (!desc_on_receiver && !desc_has_setter && !desc_has_getter && desc_writable) goto no_descriptor;

	if (desc_has_setter) {
	ant_value_t setter = desc_setter;
	uint8_t setter_type = vtype(setter);
	if (setter_type == T_FUNC \|\| setter_type == T_CFUNC) {
	js_error_site_t saved_errsite = js->errsite;
	ant_value_t result = sv_vm_call(sv_vm_get_active(js), js, setter, obj, &v, 1, NULL, false);
	js->errsite = saved_errsite;
	if (is_err(result)) return result;
	return v;
	}
	}

	if (desc_has_getter && !desc_has_setter) {
	if (sv_is_strict_context(js)) return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot set property which has only a getter");
	return v;
	}

	if (!desc_writable) {
	if (sv_is_strict_context(js)) return js_mkerr(js, "assignment to read-only property");
	return v;
	}

	if (existing <= 0) goto no_descriptor;
	}

	no_descriptor:
	if (existing <= 0) goto create_new;
	if (is_const_prop(js, existing)) return js_mkerr(js, "assignment to constant");

	js_saveval(js, existing, v);
	array_define_or_set_index(js, obj, key, (size_t)klen);
	return v;

	create_new:
	{
	ant_value_t extensibility_error = check_object_extensibility(js, obj);
	if (is_err(extensibility_error)) return extensibility_error;
	if (extensibility_error == js_false) return v;
	}

	ant_value_t result = mkprop(js, obj, k, v, 0);
	if (is_err(result)) return result;
	array_define_or_set_index(js, obj, key, (size_t)klen);

	return v;
	}

	ant_value_t setprop_cstr(ant_t js, ant_value_t obj, const char key, size_t len, ant_value_t v) {
	obj = js_as_obj(obj);
	const char *interned = intern_string(key, len);
	if (!interned) return js_mkerr(js, "oom");
	return mkprop_interned(js, obj, interned, v, 0);
	}

	ant_value_t js_define_own_prop(ant_t js, ant_value_t obj, const char key, size_t klen, ant_value_t v) {
	obj = js_as_obj(obj);
	if (is_proxy(obj)) {
	ant_value_t result = proxy_set(js, obj, key, klen, v);
	if (is_err(result)) return result;
	return v;
	}

	if (try_dynamic_setter(js, obj, key, klen, v)) return v;
	ant_offset_t existing = lkp(js, obj, key, klen);

	{
	bool has_desc = false;
	bool desc_writable = true;
	bool desc_has_setter = false;
	ant_value_t desc_setter = js_mkundef();
	ant_value_t as_obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(as_obj);
	const char *interned_key = intern_string(key, klen);

	if (ptr && ptr->shape && interned_key) {
	int32_t slot = ant_shape_lookup_interned(ptr->shape, interned_key);
	if (slot >= 0) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, (uint32_t)slot);
	if (prop) {
	has_desc = true;
	desc_writable = (prop->attrs & ANT_PROP_ATTR_WRITABLE) != 0;
	desc_has_setter = prop->has_setter != 0;
	desc_setter = prop->setter;
	}
	}
	}

	if (!has_desc && ptr && ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(as_obj, key, klen);
	if (desc) {
	has_desc = true;
	desc_writable = desc->writable;
	desc_has_setter = desc->has_setter;
	desc_setter = desc->setter;
	}
	}

	if (has_desc) {
	if (!desc_writable && !desc_has_setter) {
	if (sv_is_strict_context(js)) return js_mkerr(js, "assignment to read-only property");
	return v;
	}
	if (desc_has_setter) {
	ant_value_t setter = desc_setter;
	uint8_t setter_type = vtype(setter);
	if (setter_type == T_FUNC \|\| setter_type == T_CFUNC) {
	ant_value_t result = sv_vm_call(sv_vm_get_active(js), js, setter, obj, &v, 1, NULL, false);
	if (is_err(result)) return result;
	return v;
	}
	}
	}
	}

	if (existing > 0) {
	if (is_const_prop(js, existing)) return js_mkerr(js, "assignment to constant");
	js_saveval(js, existing, v);
	array_define_or_set_index(js, obj, key, klen);
	return v;
	}

	{
	ant_value_t extensibility_error = check_object_extensibility(js, obj);
	if (is_err(extensibility_error)) return extensibility_error;
	if (extensibility_error == js_false) return v;
	}

	ant_value_t k = js_mkstr(js, key, klen);
	if (is_err(k)) return k;
	ant_value_t created = mkprop(js, obj, k, v, 0);
	if (!is_err(created)) array_define_or_set_index(js, obj, key, klen);
	return is_err(created) ? created : v;
	}

	ant_value_t setprop_interned(ant_t js, ant_value_t obj, const char key, size_t len, ant_value_t v) {
	ant_value_t k = js_mkstr(js, key, len);
	if (is_err(k)) return k;
	return js_setprop(js, obj, k, v);
	}

	ant_value_t js_setprop_nonconfigurable(ant_t js, ant_value_t obj, const char key, size_t keylen, ant_value_t v) {
	ant_value_t k = js_mkstr(js, key, keylen);
	if (is_err(k)) return k;
	ant_value_t result = js_setprop(js, obj, k, v);
	if (is_err(result)) return result;

	js_set_descriptor(js, js_as_obj(obj), key, keylen, JS_DESC_W);
	return result;
	}

	static ant_value_t js_setprop_readonly_nonconfigurable(ant_t js, ant_value_t obj, const char key, size_t keylen, ant_value_t v) {
	ant_value_t k = js_mkstr(js, key, keylen);
	if (is_err(k)) return k;
	ant_value_t result = js_setprop(js, obj, k, v);
	if (is_err(result)) return result;

	js_set_descriptor(js, js_as_obj(obj), key, keylen, 0);
	return result;
	}

	#define SYM_FLAG_GLOBAL 1u
	#define SYM_FLAG_WELL_KNOWN 2u

	typedef struct sym_registry_entry {
	const char *key;
	ant_value_t sym;
	UT_hash_handle hh;
	} sym_registry_entry_t;

	ant_value_t js_mksym(ant_t js, const char desc) {
	uint32_t id = (uint32_t)(++js->sym.counter);
	size_t desc_len = (desc && *desc) ? strlen(desc) : 0;
	size_t total = sizeof(ant_symbol_heap_t) + (desc_len ? desc_len + 1 : 0);
	ant_symbol_heap_t sym_ptr = (ant_symbol_heap_t )js_type_alloc(
	js, ANT_ALLOC_SYMBOL, total, _Alignof(ant_symbol_heap_t)
	);
	if (!sym_ptr) return js_mkerr(js, "oom");

	sym_ptr->id = id;
	sym_ptr->flags = 0;
	sym_ptr->key = NULL;
	sym_ptr->desc_len = (uint32_t)desc_len;
	if (desc_len) {
	memcpy(sym_ptr->desc, desc, desc_len);
	sym_ptr->desc[desc_len] = '\0';
	}

	return mkval(T_SYMBOL, (uintptr_t)sym_ptr);
	}

	ant_value_t js_mksym_well_known(ant_t js, const char desc) {
	ant_value_t sym = js_mksym(js, desc);
	if (is_err(sym)) return sym;
	ant_symbol_heap_t ptr = (ant_symbol_heap_t )(uintptr_t)vdata(sym);
	if (ptr) ptr->flags \|= SYM_FLAG_WELL_KNOWN;
	return sym;
	}

	static inline ant_symbol_heap_t *sym_ptr(ant_value_t v) {
	return (ant_symbol_heap_t *)(uintptr_t)vdata(v);
	}

	static inline uint32_t sym_get_id(ant_t *js, ant_value_t v) {
	(void)js;
	ant_symbol_heap_t *ptr = sym_ptr(v);
	return ptr ? ptr->id : 0;
	}

	static inline uint32_t sym_get_flags(ant_t *js, ant_value_t v) {
	(void)js;
	ant_symbol_heap_t *ptr = sym_ptr(v);
	return ptr ? ptr->flags : 0;
	}

	static inline uintptr_t sym_get_key_ptr(ant_t *js, ant_value_t v) {
	(void)js;
	ant_symbol_heap_t *ptr = sym_ptr(v);
	return ptr ? (uintptr_t)ptr->key : 0;
	}

	static const char sym_get_desc(ant_t js, ant_value_t v) {
	(void)js;
	ant_symbol_heap_t *ptr = sym_ptr(v);
	if (!ptr \|\| ptr->desc_len == 0) return NULL;
	return ptr->desc;
	}

	ant_value_t js_mksym_for(ant_t js, const char key) {
	const char *interned = intern_string(key, strlen(key));

	sym_registry_entry_t *reg = js->sym.registry;
	sym_registry_entry_t *found = NULL;
	HASH_FIND_PTR(reg, &interned, found);
	if (found) return found->sym;

	ant_value_t sym = js_mksym(js, key);
	if (is_err(sym)) return sym;

	ant_symbol_heap_t *ptr = sym_ptr(sym);
	if (!ptr) return js_mkerr(js, "oom");
	ptr->flags \|= SYM_FLAG_GLOBAL;
	ptr->key = interned;

	sym_registry_entry_t *entry = ant_calloc(sizeof(sym_registry_entry_t));
	if (entry) {
	entry->key = interned;
	entry->sym = sym;
	HASH_ADD_PTR(reg, key, entry);
	js->sym.registry = reg;
	}

	return sym;
	}

	const char *js_sym_key(ant_value_t sym) {
	if (vtype(sym) != T_SYMBOL) return NULL;
	ant_t *js = rt->js;
	uint32_t flags = sym_get_flags(js, sym);
	if (!(flags & SYM_FLAG_GLOBAL) \|\| (flags & SYM_FLAG_WELL_KNOWN)) return NULL;
	return (const char *)sym_get_key_ptr(js, sym);
	}

	const inline char js_sym_desc(ant_t js, ant_value_t sym) {
	return sym_get_desc(js, sym);
	}

	static inline bool streq(const char buf, size_t len, const char s, size_t n) {
	return len == n && !memcmp(buf, s, n);
	}

	ant_offset_t lkp_interned(ant_t js, ant_value_t obj, const char search_intern, size_t len) {
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!search_intern \|\| !ptr \|\| !ptr->shape) return 0;

	int32_t shape_slot = ant_shape_lookup_interned(ptr->shape, search_intern);
	(void)len;
	if (shape_slot < 0) return 0;
	return propref_make(js, ptr, (uint32_t)shape_slot);
	}

	inline ant_offset_t lkp(ant_t js, ant_value_t obj, const char buf, size_t len) {
	const char *search_intern = intern_string(buf, len);
	if (!search_intern) return 0;
	return lkp_interned(js, obj, search_intern, len);
	}

	inline ant_value_t lkp_interned_val(ant_t js, ant_value_t obj, const char search_intern) {
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!search_intern \|\| !ptr \|\| !ptr->shape) return js_mkundef();
	int32_t slot = ant_shape_lookup_interned(ptr->shape, search_intern);
	if (slot < 0) return js_mkundef();
	return ant_object_prop_get_unchecked(ptr, (uint32_t)slot);
	}

	static inline ant_value_t lkp_val(ant_t js, ant_value_t obj, const char buf, size_t len) {
	const char *interned = intern_string(buf, len);
	if (!interned) return js_mkundef();
	return lkp_interned_val(js, obj, interned);
	}

	ant_offset_t lkp_sym(ant_t *js, ant_value_t obj, ant_offset_t sym_off) {
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| !ptr->shape) return 0;
	int32_t slot = ant_shape_lookup_symbol(ptr->shape, sym_off);
	if (slot < 0) return 0;
	return propref_make(js, ptr, (uint32_t)slot);
	}

	ant_offset_t lkp_sym_proto(ant_t *js, ant_value_t obj, ant_offset_t sym_off) {
	ant_value_t cur = obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);
	while (is_object_type(cur)) {
	obj = cur;
	ant_offset_t off = lkp_sym(js, obj, sym_off);
	if (off != 0) return off;
	ant_value_t proto = get_proto(js, js_as_obj(cur));
	if (!is_object_type(proto)) break;
	cur = proto;
	if (proto_overflow_guard_hit_cycle(js, &guard, cur)) break;
	}
	return 0;
	}

	static inline ant_value_t lkp_sym_proto_val(ant_t *js, ant_value_t obj, ant_offset_t sym_off) {
	ant_value_t cur = obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);

	while (is_object_type(cur)) {
	ant_value_t as_obj = js_as_obj(cur);
	ant_object_t *ptr = js_obj_ptr(as_obj);

	if (ptr && ptr->shape) {
	int32_t slot = ant_shape_lookup_symbol(ptr->shape, sym_off);
	if (slot >= 0) return ant_object_prop_get_unchecked(ptr, (uint32_t)slot);
	}

	ant_value_t proto = get_proto(js, as_obj);
	if (!is_object_type(proto)) break;

	cur = proto;
	if (proto_overflow_guard_hit_cycle(js, &guard, cur)) break;
	}

	return js_mkundef();
	}

	static uintptr_t lkp_with_getter(ant_t js, ant_value_t obj, const char buf, size_t len, ant_value_t getter_out, bool has_getter_out) {
	*has_getter_out = false;
	*getter_out = js_mkundef();
	const char *search_intern = intern_string(buf, len);

	ant_value_t current = obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);

	while (is_object_type(current)) {
	current = js_as_obj(current);
	uintptr_t current_id = (uintptr_t)vdata(current);

	ant_object_t *ptr = js_obj_ptr(current);
	if (ptr && ptr->shape && search_intern) {
	int32_t slot = ant_shape_lookup_interned(ptr->shape, search_intern);
	if (slot >= 0) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, (uint32_t)slot);
	if (prop && prop->has_getter) {
	*getter_out = prop->getter;
	*has_getter_out = true;
	return current_id;
	}
	return propref_make(js, ptr, (uint32_t)slot);
	}
	}

	if (ptr && ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(current, buf, len);
	if (desc && desc->has_getter) {
	*getter_out = desc->getter;
	*has_getter_out = true;
	return current_id;
	}
	}

	ant_value_t proto = get_proto(js, current);
	if (!is_object_type(proto)) break;
	current = proto;
	if (proto_overflow_guard_hit_cycle(js, &guard, current)) break;
	}

	return 0;
	}

	static uintptr_t lkp_with_setter(ant_t js, ant_value_t obj, const char buf, size_t len, ant_value_t setter_out, bool has_setter_out) {
	*has_setter_out = false;
	*setter_out = js_mkundef();
	const char *search_intern = intern_string(buf, len);

	ant_value_t current = obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);
	while (vtype(current) == T_OBJ \|\| vtype(current) == T_FUNC) {
	current = js_as_obj(current);
	uintptr_t current_id = (uintptr_t)vdata(current);

	ant_object_t *ptr = js_obj_ptr(current);
	if (ptr && ptr->shape && search_intern) {
	int32_t slot = ant_shape_lookup_interned(ptr->shape, search_intern);
	if (slot >= 0) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, (uint32_t)slot);
	if (prop && prop->has_setter) {
	*setter_out = prop->setter;
	*has_setter_out = true;
	return current_id;
	}
	return propref_make(js, ptr, (uint32_t)slot);
	}
	}

	if (ptr && ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(current, buf, len);
	if (desc && desc->has_setter) {
	*setter_out = desc->setter;
	*has_setter_out = true;
	return current_id;
	}
	}

	ant_value_t proto = get_proto(js, current);
	if (vtype(proto) != T_OBJ && vtype(proto) != T_FUNC) break;
	current = proto;
	if (proto_overflow_guard_hit_cycle(js, &guard, current)) break;
	}

	return 0;
	}

	static ant_value_t call_proto_accessor(
	ant_t *js, ant_value_t prim, ant_value_t accessor, bool has_accessor,
	ant_value_t *arg, int arg_count, bool is_setter
	) {
	if (!has_accessor \|\| (vtype(accessor) != T_FUNC && vtype(accessor) != T_CFUNC))
	return js_mkundef();

	js_error_site_t saved_errsite = js->errsite;
	ant_value_t result = sv_vm_call(sv_vm_get_active(js), js, accessor, prim, arg, arg_count, NULL, false);

	bool had_throw = js->thrown_exists;
	ant_value_t thrown = js->thrown_value;
	js->errsite = saved_errsite;

	if (had_throw) {
	js->thrown_exists = true;
	js->thrown_value = thrown;
	}

	if (is_setter) return is_err(result) ? result : (arg ? *arg : js_mkundef());
	return result;
	}

	ant_value_t js_get_proto(ant_t *js, ant_value_t obj) {
	uint8_t t = vtype(obj);

	if (!is_object_type(obj)) return js_mknull();
	ant_value_t as_obj = js_as_obj(obj);

	ant_object_t *ptr = js_obj_ptr(as_obj);
	ant_value_t proto = ptr ? ptr->proto : js_mkundef();
	if (is_object_type(proto) \|\| vtype(proto) == T_NULL) return proto;

	if (t != T_OBJ) return get_prototype_for_type(js, t);
	return js_mknull();
	}

	static ant_value_t get_proto(ant_t *js, ant_value_t obj) {
	return js_get_proto(js, obj);
	}

	void js_set_proto(ant_value_t obj, ant_value_t proto) {
	if (!is_object_type(obj)) return;

	ant_value_t as_obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (!ptr) return;

	ptr->proto = proto;
	ant_ic_epoch_bump();
	}

	void js_set_proto_init(ant_value_t obj, ant_value_t proto) {
	if (!is_object_type(obj)) return;
	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	if (!ptr) return;
	ptr->proto = proto;
	}

	static void set_proto(ant_t *js, ant_value_t obj, ant_value_t proto) {
	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	js_set_proto(obj, proto);
	if (ptr) gc_write_barrier(js, ptr, proto);
	}

	void js_set_proto_wb(ant_t *js, ant_value_t obj, ant_value_t proto) {
	set_proto(js, obj, proto);
	}

	ant_value_t js_get_ctor_proto(ant_t js, const char name, size_t len) {
	const char *interned = intern_string(name, len);
	ant_value_t ctor = lkp_interned_val(js, js->global, interned);
	if (vtype(ctor) != T_FUNC) return js_mknull();
	ant_value_t ctor_obj = js_as_obj(ctor);
	ant_value_t proto = lkp_interned_val(js, ctor_obj, js->intern.prototype);
	return vtype(proto) == T_UNDEF ? js_mknull() : proto;
	}

	static inline ant_value_t get_ctor_proto(ant_t js, const char name, size_t len) {
	return js_get_ctor_proto(js, name, len);
	}

	static ant_value_t get_prototype_for_type(ant_t *js, uint8_t type) {
	switch (type) {
	case T_OBJ: return js->sym.object_proto;
	case T_ARR: return js->sym.array_proto;
	case T_STR: return get_ctor_proto(js, "String", 6);
	case T_NUM: return get_ctor_proto(js, "Number", 6);
	case T_BOOL: return get_ctor_proto(js, "Boolean", 7);
	case T_FUNC: return get_ctor_proto(js, "Function", 8);
	case T_PROMISE: return get_ctor_proto(js, "Promise", 7);
	case T_GENERATOR: return js->sym.generator_proto;
	case T_BIGINT: return get_ctor_proto(js, "BigInt", 6);
	case T_SYMBOL: return get_ctor_proto(js, "Symbol", 6);
	default: return js_mknull();
	}}

	ant_offset_t lkp_proto(ant_t js, ant_value_t obj, const char key, size_t len) {
	uint8_t t = vtype(obj);
	const char *key_intern = intern_string(key, len);
	if (!key_intern) return 0;

	ant_value_t cur = obj;
	proto_walk_overflow_guard_t guard;
	proto_walk_overflow_guard_init(&guard);

	while (true) {
	if (t == T_OBJ \|\| t == T_ARR \|\| t == T_FUNC \|\| t == T_PROMISE \|\| t == T_GENERATOR) {
	ant_value_t as_obj = js_as_obj(cur);
	ant_offset_t off = lkp_interned(js, as_obj, key_intern, len);
	if (off != 0) return off;
	} else if (t == T_CFUNC) {
	ant_value_t func_proto = get_ctor_proto(js, "Function", 8);
	uint8_t ft = vtype(func_proto);
	if (ft == T_OBJ \|\| ft == T_ARR \|\| ft == T_FUNC) {
	ant_offset_t off = lkp_interned(js, js_as_obj(func_proto), key_intern, len);
	if (off != 0) return off;
	}
	break;
	} else if (t != T_STR && t != T_NUM && t != T_BOOL && t != T_BIGINT && t != T_SYMBOL) break;

	if (!proto_walk_next(js, &cur, &t, PROTO_WALK_F_LOOKUP)) break;
	if (proto_walk_overflow_guard_hit_cycle(js, &guard, cur, t, PROTO_WALK_F_LOOKUP)) break;
	}

	return 0;
	}

	static ant_value_t js_string_from_utf16_code_unit(ant_t *js, uint32_t code_unit) {
	char buf[4];
	size_t out_len = 0;

	if (code_unit >= 0xD800 && code_unit <= 0xDFFF) {
	buf[0] = (char)(0xE0 \| (code_unit >> 12));
	buf[1] = (char)(0x80 \| ((code_unit >> 6) & 0x3F));
	buf[2] = (char)(0x80 \| (code_unit & 0x3F));
	out_len = 3;
	} else out_len = (size_t)utf8_encode(code_unit, buf);

	return js_mkstr(js, buf, out_len);
	}

	static bool js_try_get_string_index(
	ant_t *js, ant_value_t str,
	const char key, size_t key_len, ant_value_t out
	) {
	if (!is_array_index(key, (ant_offset_t)key_len)) return false;

	unsigned long idx = 0;
	ant_offset_t byte_len = 0;
	ant_offset_t str_off = vstr(js, str, &byte_len);
	const char str_data = (const char )(uintptr_t)(str_off);
	ant_offset_t str_len = (ant_offset_t)utf16_strlen(str_data, byte_len);
	if (!parse_array_index(key, key_len, str_len, &idx)) return false;

	uint32_t code_unit = utf16_code_unit_at(str_data, byte_len, (ant_offset_t)idx);
	if (code_unit == 0xFFFFFFFF) return false;

	*out = js_string_from_utf16_code_unit(js, code_unit);
	return true;
	}

	static ant_value_t getprop_any(ant_t js, ant_value_t obj, const char key, size_t key_len) {
	uint8_t t = vtype(obj);

	if (t == T_STR && is_length_key(key, key_len)) {
	ant_offset_t byte_len;
	ant_offset_t str_off = vstr(js, obj, &byte_len);
	return tov(D(utf16_strlen((const char *)(uintptr_t)(str_off), byte_len)));
	}

	if (t == T_STR) {
	ant_value_t indexed = js_mkundef();
	if (js_try_get_string_index(js, obj, key, key_len, &indexed)) return indexed;
	}

	if (t == T_STR \|\| t == T_NUM \|\| t == T_BOOL \|\| t == T_BIGINT) {
	ant_offset_t off = lkp_proto(js, obj, key, key_len);
	if (off != 0) return propref_load(js, off);
	return js_mkundef();
	}

	if (t == T_OBJ \|\| t == T_ARR \|\| t == T_FUNC) {
	ant_value_t as_obj = js_as_obj(obj);
	ant_offset_t off = lkp(js, as_obj, key, key_len);
	if (off != 0) return propref_load(js, off);
	off = lkp_proto(js, obj, key, key_len);
	if (off != 0) return propref_load(js, off);
	}

	return js_mkundef();
	}

	static ant_value_t try_dynamic_getter(ant_t js, ant_value_t obj, const char key, size_t key_len) {
	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	if (!ptr \|\| !ptr->is_exotic) return js_mkundef();
	if (!ptr->exotic_ops \|\| !ptr->exotic_ops->getter) return js_mkundef();
	return ptr->exotic_ops->getter(js, obj, key, key_len);
	}

	static bool try_dynamic_setter(ant_t js, ant_value_t obj, const char key, size_t key_len, ant_value_t value) {
	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	if (!ptr \|\| !ptr->is_exotic) return false;
	if (!ptr->exotic_ops \|\| !ptr->exotic_ops->setter) return false;
	return ptr->exotic_ops->setter(js, obj, key, key_len, value);
	}

	static bool try_dynamic_deleter(ant_t js, ant_value_t obj, const char key, size_t key_len) {
	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	if (!ptr \|\| !ptr->is_exotic) return false;
	if (!ptr->exotic_ops \|\| !ptr->exotic_ops->deleter) return false;
	return ptr->exotic_ops->deleter(js, obj, key, key_len);
	}

	static bool try_accessor_getter(ant_t js, ant_value_t obj, const char key, size_t key_len, ant_value_t *out) {
	ant_value_t getter = js_mkundef();
	bool has_getter = false;
	lkp_with_getter(js, obj, key, key_len, &getter, &has_getter);

	ant_value_t result = call_proto_accessor(js, obj, getter, has_getter, NULL, 0, false);
	if (vtype(result) != T_UNDEF) {
	*out = result;
	return true;
	}
	return false;
	}

	static bool try_accessor_setter(ant_t js, ant_value_t obj, const char key, size_t key_len, ant_value_t val, ant_value_t *out) {
	ant_value_t setter = js_mkundef();
	bool has_setter = false;

	lkp_with_setter(js, obj, key, key_len, &setter, &has_setter);
	if (!has_setter) return false;

	ant_value_t result = call_proto_accessor(js, obj, setter, has_setter, &val, 1, true);
	if (is_err(result)) {
	*out = result;
	return true;
	}

	*out = val;
	return true;
	}

	ant_value_t js_propref_load(ant_t *js, ant_offset_t handle) {
	return propref_load(js, handle);
	}

	typedef struct {
	char *buffer;
	size_t capacity;
	size_t size;
	bool is_dynamic;
	} string_builder_t;

	static void string_builder_init(string_builder_t sb, char static_buf, size_t static_cap) {
	sb->buffer = static_buf;
	sb->capacity = static_cap;
	sb->size = 0;
	sb->is_dynamic = false;
	}

	static bool string_builder_append(string_builder_t sb, const char data, size_t len) {
	if (sb->size + len > sb->capacity) {
	size_t new_capacity = sb->capacity ? sb->capacity * 2 : 256;
	while (new_capacity < sb->size + len) new_capacity *= 2;

	char new_buffer = (char )ant_calloc(new_capacity);
	if (!new_buffer) return false;

	if (sb->size > 0) memcpy(new_buffer, sb->buffer, sb->size);
	if (sb->is_dynamic) free(sb->buffer);

	sb->buffer = new_buffer;
	sb->capacity = new_capacity;
	sb->is_dynamic = true;
	}

	if (len > 0) {
	memcpy(sb->buffer + sb->size, data, len);
	sb->size += len;
	}

	return true;
	}

	static ant_value_t string_builder_finalize(ant_t js, string_builder_t sb) {
	ant_value_t result = js_mkstr(js, sb->buffer, sb->size);
	if (sb->is_dynamic && sb->buffer) free(sb->buffer);
	return result;
	}

	ant_offset_t str_len_fast(ant_t *js, ant_value_t str) {
	if (vtype(str) != T_STR) return 0;
	if (str_is_heap_rope(str)) return rope_len(str);
	if (str_is_heap_builder(str)) return builder_len(str);
	return assert_flat_string_len(js, str, NULL);
	}

	ant_value_t do_string_op(ant_t *js, uint8_t op, ant_value_t l, ant_value_t r) {
	if (op == TOK_PLUS) {
	if (str_is_heap_builder(l)) {
	l = builder_flatten(js, l);
	if (is_err(l)) return l;
	}

	if (str_is_heap_builder(r)) {
	r = builder_flatten(js, r);
	if (is_err(r)) return r;
	}

	ant_offset_t n1 = str_len_fast(js, l);
	ant_offset_t n2 = str_len_fast(js, r);
	ant_offset_t total_len = n1 + n2;

	if (n2 == 0) return l;
	if (n1 == 0) return r;

	uint16_t left_depth = (vtype(l) == T_STR && str_is_heap_rope(l)) ? rope_depth(l) : 0;
	uint16_t right_depth = (vtype(r) == T_STR && str_is_heap_rope(r)) ? rope_depth(r) : 0;
	unsigned int new_depth = (unsigned int)(left_depth > right_depth ? left_depth : right_depth) + 1u;

	if (new_depth >= ROPE_MAX_DEPTH \|\| total_len >= ROPE_FLATTEN_THRESHOLD) {
	ant_value_t flat_l = l, flat_r = r;
	if (str_is_heap_rope(l)) flat_l = rope_flatten(js, l);
	if (is_err(flat_l)) return flat_l;
	if (str_is_heap_rope(r)) flat_r = rope_flatten(js, r);
	if (is_err(flat_r)) return flat_r;

	ant_offset_t off1, off2, len1, len2;
	off1 = vstr(js, flat_l, &len1);
	off2 = vstr(js, flat_r, &len2);

	string_builder_t sb;
	char static_buffer[512];
	string_builder_init(&sb, static_buffer, sizeof(static_buffer));

	if (
	!string_builder_append(&sb, (char *)(uintptr_t)(off1), len1) \|\|
	!string_builder_append(&sb, (char *)(uintptr_t)(off2), len2)
	) return js_mkerr(js, "string concatenation failed");

	return string_builder_finalize(js, &sb);
	}

	return js_mkrope(js, l, r, total_len, (uint16_t)new_depth);
	}

	ant_offset_t n1, off1 = vstr(js, l, &n1);
	ant_offset_t n2, off2 = vstr(js, r, &n2);

	if (op == TOK_EQ) {
	bool eq = n1 == n2 &&
	memcmp((const void )(uintptr_t)off1, (const void )(uintptr_t)off2, n1) == 0;
	return mkval(T_BOOL, eq ? 1 : 0);
	} else if (op == TOK_NE) {
	bool eq = n1 == n2 &&
	memcmp((const void )(uintptr_t)off1, (const void )(uintptr_t)off2, n1) == 0;
	return mkval(T_BOOL, eq ? 0 : 1);
	} else if (op == TOK_LT \|\| op == TOK_LE \|\| op == TOK_GT \|\| op == TOK_GE) {
	ant_offset_t min_len = n1 < n2 ? n1 : n2;
	int cmp = memcmp((const void )(uintptr_t)off1, (const void )(uintptr_t)off2, min_len);

	if (cmp == 0) {
	if (n1 == n2) {
	return mkval(T_BOOL, (op == TOK_LE \|\| op == TOK_GE) ? 1 : 0);
	} else cmp = (n1 < n2) ? -1 : 1;
	}

	switch (op) {
	case TOK_LT: return mkval(T_BOOL, cmp < 0 ? 1 : 0);
	case TOK_LE: return mkval(T_BOOL, cmp <= 0 ? 1 : 0);
	case TOK_GT: return mkval(T_BOOL, cmp > 0 ? 1 : 0);
	case TOK_GE: return mkval(T_BOOL, cmp >= 0 ? 1 : 0);
	default: return js_mkerr(js, "bad str op");
	}
	} else return js_mkerr(js, "bad str op");
	}


	typedef enum { ITER_CONTINUE, ITER_BREAK, ITER_ERROR } iter_action_t;
	typedef iter_action_t (iter_callback_t)(ant_t js, ant_value_t value, void ctx, ant_value_t out);

	static bool js_try_call_method(ant_t js, ant_value_t obj, const char method, ant_value_t args, int nargs, ant_value_t out_result) {
	ant_value_t fn = js_getprop_fallback(js, obj, method);
	if (is_err(fn)) {
	*out_result = fn;
	return true;
	}

	uint8_t ft = vtype(fn);
	if (ft != T_FUNC && ft != T_CFUNC) return false;

	ant_value_t saved_this = js->this_val;
	js->this_val = obj;

	ant_value_t result;
	if (ft == T_CFUNC) result = ((ant_value_t ()(ant_t , ant_value_t *, int))vdata(fn))(js, args, nargs);
	else result = sv_vm_call(js->vm, js, fn, obj, args, nargs, NULL, false);

	bool had_throw = js->thrown_exists;
	ant_value_t thrown = js->thrown_value;

	js->this_val = saved_this;
	if (had_throw) {
	js->thrown_exists = true;
	js->thrown_value = thrown;
	}

	*out_result = result;
	return true;
	}

	static ant_value_t js_call_method(ant_t js, ant_value_t obj, const char method, ant_value_t *args, int nargs) {
	ant_value_t result;
	if (!js_try_call_method(js, obj, method, args, nargs, &result)) return js_mkundef();
	return result;
	}

	static ant_value_t js_call_toString(ant_t *js, ant_value_t value) {
	ant_value_t result = js_call_method(js, value, "toString", NULL, 0);

	if (is_err(result)) return result;
	if (vtype(result) == T_STR) return result;

	uint8_t rtype = vtype(result);
	if (rtype == T_UNDEF) {
	goto fallback;
	}

	if (rtype != T_OBJ && rtype != T_ARR && rtype != T_FUNC) {
	char buf[256];
	size_t len = tostr(js, result, buf, sizeof(buf));
	return js_mkstr(js, buf, len);
	}

	fallback:;
	char buf[4096];
	size_t len = tostr(js, value, buf, sizeof(buf));
	return js_mkstr(js, buf, len);
	}

	static ant_value_t js_call_valueOf(ant_t *js, ant_value_t value) {
	ant_value_t result = js_call_method(js, value, "valueOf", NULL, 0);
	if (vtype(result) == T_UNDEF) return value;
	return result;
	}

	static inline bool is_primitive(ant_value_t v) {
	uint8_t t = vtype(v);
	return t == T_STR \|\| t == T_NUM \|\| t == T_BOOL \|\| t == T_NULL \|\| t == T_UNDEF \|\| t == T_SYMBOL \|\| t == T_BIGINT;
	}

	static ant_value_t try_exotic_to_primitive(ant_t *js, ant_value_t value, int hint) {
	ant_value_t tp_sym = get_toPrimitive_sym();
	if (vtype(tp_sym) != T_SYMBOL) return mkval(T_UNDEF, 0);
	ant_value_t tp_fn = js_get_sym(js, value, tp_sym);
	uint8_t ft = vtype(tp_fn);

	if (ft == T_UNDEF) return mkval(T_UNDEF, 0);
	if (ft != T_FUNC && ft != T_CFUNC) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Symbol.toPrimitive is not a function");
	}

	const char *hint_str = hint == 1 ? "string" : (hint == 2 ? "number" : "default");
	ant_value_t hint_arg = js_mkstr(js, hint_str, strlen(hint_str));
	ant_value_t result = sv_vm_call(js->vm, js, tp_fn, value, &hint_arg, 1, NULL, false);

	if (is_err(result) \|\| is_primitive(result)) return result;
	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot convert object to primitive value");
	}

	static ant_value_t try_ordinary_to_primitive(ant_t *js, ant_value_t value, int hint) {
	static const char *names[] = {"valueOf", "toString"};

	int first = (hint == 1);
	ant_value_t result;

	for (int i = 0; i < 2; i++) {
	int idx = first ^ i;
	if (js_try_call_method(js, value, names[idx], NULL, 0, &result))
	if (is_err(result) \|\| is_primitive(result)) return result;
	}

	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot convert object to primitive value");
	}

	ant_value_t js_to_primitive(ant_t *js, ant_value_t value, int hint) {
	if (is_primitive(value)) return value;
	if (!is_object_type(value)) return value;

	ant_value_t result = try_exotic_to_primitive(js, value, hint);
	if (vtype(result) != T_UNDEF) return result;

	return try_ordinary_to_primitive(js, value, hint);
	}

	bool strict_eq_values(ant_t *js, ant_value_t l, ant_value_t r) {
	uint8_t t = vtype(l);
	if (t != vtype(r)) return false;
	if (t == T_STR) {
	ant_offset_t n1, n2, off1 = vstr(js, l, &n1), off2 = vstr(js, r, &n2);
	return n1 == n2 &&
	memcmp((const void )(uintptr_t)off1, (const void )(uintptr_t)off2, n1) == 0;
	}
	if (t == T_NUM) return tod(l) == tod(r);
	if (t == T_BIGINT) return bigint_compare(js, l, r) == 0;
	return vdata(l) == vdata(r);
	}

	ant_value_t coerce_to_str(ant_t *js, ant_value_t v) {
	if (vtype(v) == T_STR) return v;

	if (is_object_type(v)) {
	ant_value_t prim = js_to_primitive(js, v, 1);
	if (is_err(prim)) return prim;
	if (vtype(prim) == T_STR) return prim;
	return js_tostring_val(js, prim);
	}

	return js_tostring_val(js, v);
	}

	ant_value_t coerce_to_str_concat(ant_t *js, ant_value_t v) {
	if (vtype(v) == T_STR) return v;

	if (is_object_type(v)) {
	ant_value_t prim = js_to_primitive(js, v, 0);
	if (is_err(prim)) return prim;
	if (vtype(prim) == T_STR) return prim;
	return js_tostring_val(js, prim);
	}

	return js_tostring_val(js, v);
	}

	static ant_value_t check_frozen_sealed(ant_t js, ant_value_t obj, const char action) {
	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	if (!ptr) return js_mkundef();

	if (ptr->frozen) {
	if (sv_is_strict_context(js)) return js_mkerr(js, "cannot %s property of frozen object", action);
	return js_false;
	}
	if (ptr->sealed) {
	if (sv_is_strict_context(js)) return js_mkerr(js, "cannot %s property of sealed object", action);
	return js_false;
	}
	return js_mkundef();
	}

	ant_value_t js_delete_prop(ant_t js, ant_value_t obj, const char key, size_t len) {
	ant_value_t original_obj = obj;
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return js_true;
	if (is_proxy(obj)) {
	ant_value_t result = proxy_delete(js, obj, key, len);
	return is_err(result) ? result : js_bool(js_truthy(js, result));
	}

	ant_value_t err = check_frozen_sealed(js, obj, "delete");
	if (vtype(err) != T_UNDEF) return err;

	if (array_obj_ptr(original_obj) && is_length_key(key, len)) {
	if (sv_is_strict_context(js)) return js_mkerr_typed(js, JS_ERR_TYPE, "cannot delete non-configurable property");
	return js_false;
	}

	if (array_obj_ptr(original_obj)) {
	ant_offset_t doff = get_dense_buf(original_obj);
	unsigned long del_idx = 0;
	if (doff && parse_array_index(key, len, get_array_length(js, original_obj), &del_idx)) {
	ant_offset_t dense_len = dense_iterable_length(js, original_obj);
	if ((ant_offset_t)del_idx < dense_len) dense_set(js, doff, (ant_offset_t)del_idx, T_EMPTY);
	}
	}

	const char *interned = intern_string(key, len);
	if (!interned) {
	try_dynamic_deleter(js, obj, key, len);
	return js_true;
	}

	int32_t shape_slot = ant_shape_lookup_interned(ptr->shape, interned);
	if (shape_slot < 0) {
	try_dynamic_deleter(js, obj, key, len);
	return js_true;
	}

	uint8_t attrs = ant_shape_get_attrs(ptr->shape, (uint32_t)shape_slot);
	if ((attrs & ANT_PROP_ATTR_CONFIGURABLE) == 0) {
	if (sv_is_strict_context(js)) return js_mkerr_typed(js, JS_ERR_TYPE, "cannot delete non-configurable property");
	return js_false;
	}

	if (ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(obj, key, len);
	if (desc && !desc->configurable) {
	if (sv_is_strict_context(js)) return js_mkerr_typed(js, JS_ERR_TYPE, "cannot delete non-configurable property");
	return js_false;
	}
	}

	uint32_t slot = (uint32_t)shape_slot;
	if (!js_obj_ensure_unique_shape(ptr)) return js_mkerr(js, "oom");
	uint32_t swapped_from = slot;
	if (!ant_shape_remove_slot(ptr->shape, slot, &swapped_from)) return js_true;

	obj_remove_prop_slot(ptr, slot);
	propref_adjust_after_swap_delete(js, ptr, slot, swapped_from);
	return js_true;
	}

	ant_value_t js_delete_sym_prop(ant_t *js, ant_value_t obj, ant_value_t sym) {
	obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return js_true;
	if (is_proxy(obj)) {
	ant_value_t result = proxy_delete_val(js, obj, sym);
	return is_err(result) ? result : js_bool(js_truthy(js, result));
	}

	ant_value_t err = check_frozen_sealed(js, obj, "delete");
	if (vtype(err) != T_UNDEF) return err;

	ant_offset_t sym_off = (ant_offset_t)vdata(sym);
	int32_t shape_slot = ant_shape_lookup_symbol(ptr->shape, sym_off);
	if (shape_slot < 0) return js_true;

	uint8_t attrs = ant_shape_get_attrs(ptr->shape, (uint32_t)shape_slot);
	if ((attrs & ANT_PROP_ATTR_CONFIGURABLE) == 0) {
	if (sv_is_strict_context(js)) return js_mkerr_typed(js, JS_ERR_TYPE, "cannot delete non-configurable property");
	return js_false;
	}

	uint32_t slot = (uint32_t)shape_slot;
	if (!js_obj_ensure_unique_shape(ptr)) return js_mkerr(js, "oom");

	uint32_t swapped_from = slot;
	if (!ant_shape_remove_slot(ptr->shape, slot, &swapped_from)) return js_true;

	obj_remove_prop_slot(ptr, slot);
	propref_adjust_after_swap_delete(js, ptr, slot, swapped_from);

	return js_true;
	}

	static ant_value_t iter_call_noargs_with_this(ant_t *js, ant_value_t this_val, ant_value_t method) {
	ant_value_t result = sv_vm_call(js->vm, js, method, this_val, NULL, 0, NULL, false);
	return result;
	}

	static ant_value_t iter_close_iterator(ant_t *js, ant_value_t iterator) {
	ant_offset_t return_off = lkp_proto(js, iterator, "return", 6);
	if (return_off == 0) return js_mkundef();
	ant_value_t return_method = propref_load(js, return_off);
	if (vtype(return_method) != T_FUNC && vtype(return_method) != T_CFUNC) {
	return js_mkerr(js, "iterator.return is not a function");
	}
	return iter_call_noargs_with_this(js, iterator, return_method);
	}

	static ant_value_t iter_foreach(ant_t js, ant_value_t iterable, iter_callback_t cb, void ctx) {
	ant_value_t iter_sym = get_iterator_sym();
	ant_offset_t iter_prop = (vtype(iter_sym) == T_SYMBOL) ? lkp_sym_proto(js, iterable, (ant_offset_t)vdata(iter_sym)) : 0;
	if (iter_prop == 0) return js_mkerr(js, "not iterable");

	ant_value_t iter_method = propref_load(js, iter_prop);
	ant_value_t iterator = iter_call_noargs_with_this(js, iterable, iter_method);
	if (is_err(iterator)) return iterator;

	ant_value_t out = js_mkundef();

	while (true) {
	ant_offset_t next_off = lkp_proto(js, iterator, "next", 4);
	if (next_off == 0) { return js_mkerr(js, "iterator.next is not a function"); }

	ant_value_t next_method = propref_load(js, next_off);
	if (vtype(next_method) != T_FUNC && vtype(next_method) != T_CFUNC) {
	return js_mkerr(js, "iterator.next is not a function");
	}

	ant_value_t result = iter_call_noargs_with_this(js, iterator, next_method);
	if (is_err(result)) { return result; }

	ant_offset_t done_off = lkp(js, result, "done", 4);
	ant_value_t done_val = done_off ? propref_load(js, done_off) : js_mkundef();
	if (js_truthy(js, done_val)) break;

	ant_offset_t value_off = lkp(js, result, "value", 5);
	ant_value_t value = value_off ? propref_load(js, value_off) : js_mkundef();

	iter_action_t action = cb(js, value, ctx, &out);
	if (action == ITER_BREAK) {
	ant_value_t close_result = iter_close_iterator(js, iterator);
	if (is_err(close_result)) { return close_result; }
	break;
	}
	if (action == ITER_ERROR) {
	ant_value_t close_result = iter_close_iterator(js, iterator);
	if (is_err(close_result)) return close_result;
	return out;
	}
	}

	return out;
	}

	ant_value_t js_symbol_to_string(ant_t *js, ant_value_t sym) {
	const char *desc = js_sym_desc(js, sym);
	if (!desc) return js_mkstr(js, "Symbol()", 8);

	size_t desc_len = strlen(desc);
	size_t total = 7 + desc_len + 1;

	char stack_buf[128];
	char *buf = (total + 1 <= sizeof(stack_buf)) ? stack_buf : malloc(total + 1);
	if (!buf) return js_mkerr(js, "out of memory");

	memcpy(buf, "Symbol(", 7);
	memcpy(buf + 7, desc, desc_len);
	buf[7 + desc_len] = ')';
	buf[total] = '\0';

	ant_value_t result = js_mkstr(js, buf, total);
	if (buf != stack_buf) free(buf);
	return result;
	}

	static ant_value_t builtin_String(ant_t js, ant_value_t args, int nargs) {
	ant_value_t sval;

	if (nargs == 0) sval = js_mkstr(js, "", 0);
	else if (vtype(args[0]) == T_STR) sval = args[0];

	else if (vtype(args[0]) == T_SYMBOL) {
	sval = js_symbol_to_string(js, args[0]);
	if (is_err(sval)) return sval;
	} else {
	sval = coerce_to_str(js, args[0]);
	if (is_err(sval)) return sval;
	}

	ant_value_t string_proto = js_get_ctor_proto(js, "String", 6);
	if (is_wrapper_ctor_target(js, js->this_val, string_proto)) {
	set_slot(js->this_val, SLOT_PRIMITIVE, sval);

	ant_offset_t byte_len;
	ant_offset_t str_off = vstr(js, sval, &byte_len);
	const char str_data = (const char )(uintptr_t)(str_off);

	js_setprop(js, js->this_val, js->length_str, tov((double)utf16_strlen(str_data, byte_len)));
	js_set_descriptor(js, js_as_obj(js->this_val), "length", 6, 0);
	}

	return sval;
	}

	static ant_value_t builtin_Number_isNaN(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t arg = args[0];

	if (vtype(arg) != T_NUM) return mkval(T_BOOL, 0);

	double val = tod(arg);
	return mkval(T_BOOL, isnan(val) ? 1 : 0);
	}

	static ant_value_t builtin_Number_isFinite(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t arg = args[0];

	if (vtype(arg) != T_NUM) return mkval(T_BOOL, 0);

	double val = tod(arg);
	return mkval(T_BOOL, isfinite(val) ? 1 : 0);
	}

	static ant_value_t builtin_global_isNaN(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkval(T_BOOL, 1);
	double val = js_to_number(js, args[0]);
	return mkval(T_BOOL, isnan(val) ? 1 : 0);
	}

	static ant_value_t builtin_global_isFinite(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkval(T_BOOL, 0);
	double val = js_to_number(js, args[0]);
	return mkval(T_BOOL, isfinite(val) ? 1 : 0);
	}

	static ant_value_t builtin_eval(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkundef();
	ant_value_t code = args[0];
	if (vtype(code) != T_STR) return code;
	ant_offset_t code_len = 0;
	ant_offset_t code_off = vstr(js, code, &code_len);
	const char code_str = (const char )(uintptr_t)(code_off);
	return js_eval_bytecode_eval_with_strict(js, code_str, (size_t)code_len, false);
	}

	static ant_value_t builtin_Number_isInteger(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t arg = args[0];

	if (vtype(arg) != T_NUM) return mkval(T_BOOL, 0);

	double val = tod(arg);
	if (!isfinite(val)) return mkval(T_BOOL, 0);
	return mkval(T_BOOL, (val == floor(val)) ? 1 : 0);
	}

	static ant_value_t builtin_Number_isSafeInteger(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t arg = args[0];

	if (vtype(arg) != T_NUM) return mkval(T_BOOL, 0);

	double val = tod(arg);
	if (!isfinite(val)) return mkval(T_BOOL, 0);
	if (val != floor(val)) return mkval(T_BOOL, 0);

	return mkval(T_BOOL, (val >= -9007199254740991.0 && val <= 9007199254740991.0) ? 1 : 0);
	}

	static ant_value_t builtin_Number(ant_t js, ant_value_t args, int nargs) {
	ant_value_t nval = tov(nargs > 0 ? js_to_number(js, args[0]) : 0.0);
	ant_value_t number_proto = js_get_ctor_proto(js, "Number", 6);
	if (is_wrapper_ctor_target(js, js->this_val, number_proto)) {
	set_slot(js->this_val, SLOT_PRIMITIVE, nval);
	}
	return nval;
	}

	static ant_value_t builtin_Boolean(ant_t js, ant_value_t args, int nargs) {
	ant_value_t bval = mkval(T_BOOL, nargs > 0 && js_truthy(js, args[0]) ? 1 : 0);
	ant_value_t boolean_proto = js_get_ctor_proto(js, "Boolean", 7);
	if (is_wrapper_ctor_target(js, js->this_val, boolean_proto)) {
	set_slot(js->this_val, SLOT_PRIMITIVE, bval);
	}
	return bval;
	}

	static ant_value_t builtin_Object(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0 \|\| vtype(args[0]) == T_NULL \|\| vtype(args[0]) == T_UNDEF) {
	ant_value_t obj_proto = js->sym.object_proto;
	if (is_unboxed_obj(js, js->this_val, obj_proto)) return js->this_val;
	return js_mkobj(js);
	}

	ant_value_t arg = args[0];
	uint8_t t = vtype(arg);

	if (t == T_OBJ \|\| t == T_ARR \|\| t == T_FUNC) return arg;
	if (t == T_STR \|\| t == T_NUM \|\| t == T_BOOL \|\| t == T_BIGINT) {
	ant_value_t wrapper = js_mkobj(js);
	if (is_err(wrapper)) return wrapper;
	set_slot(wrapper, SLOT_PRIMITIVE, arg);
	ant_value_t proto = get_prototype_for_type(js, t);
	if (vtype(proto) == T_OBJ) js_set_proto_init(wrapper, proto);
	return wrapper;
	}

	return arg;
	}

	static ant_value_t builtin_function_empty(ant_t , ant_value_t , int);

	static ant_value_t build_dynamic_function(ant_t js, ant_value_t args, int nargs, bool is_async, bool is_generator) {
	if (nargs == 0) {
	ant_value_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;

	set_func_code_ptr(js, func_obj, "(){}", 4);
	if (is_async) {
	set_slot(func_obj, SLOT_ASYNC, js_true);
	ant_value_t async_proto = get_slot(js_glob(js), SLOT_ASYNC_PROTO);
	if (vtype(async_proto) == T_FUNC) js_set_proto_init(func_obj, async_proto);
	} else if (is_generator) {
	ant_value_t generator_proto = get_slot(js_glob(js), SLOT_GENERATOR_PROTO);
	if (vtype(generator_proto) == T_FUNC) js_set_proto_init(func_obj, generator_proto);
	} else {
	ant_value_t func_proto = get_slot(js_glob(js), SLOT_FUNC_PROTO);
	ant_value_t instance_proto = js_instance_proto_from_new_target(js, func_proto);
	if (is_object_type(instance_proto)) js_set_proto_init(func_obj, instance_proto);
	}
	set_slot(func_obj, SLOT_CFUNC, js_mkfun(builtin_function_empty));

	ant_value_t func = js_obj_to_func(func_obj);
	ant_value_t proto_setup = setup_func_prototype(js, func);
	if (is_err(proto_setup)) return proto_setup;
	return func;
	}

	size_t total_len = 1;

	for (int i = 0; i < nargs - 1; i++) {
	args[i] = coerce_to_str(js, args[i]);
	if (is_err(args[i])) return args[i];
	total_len += vstrlen(js, args[i]);
	if (i < nargs - 2) total_len += 1;
	}

	total_len += 2;

	ant_value_t body = coerce_to_str(js, args[nargs - 1]);
	if (is_err(body)) return body;
	total_len += vstrlen(js, body);
	total_len += 1;

	char code_buf = (char )malloc(total_len + 1);
	if (!code_buf) return js_mkerr(js, "oom");
	size_t pos = 0;

	code_buf[pos++] = '(';
	for (int i = 0; i < nargs - 1; i++) {
	ant_offset_t param_len, param_off = vstr(js, args[i], &param_len);
	memcpy(code_buf + pos, (const void *)(uintptr_t)param_off, param_len);
	pos += param_len;
	if (i < nargs - 2) code_buf[pos++] = ',';
	}
	code_buf[pos++] = ')';
	code_buf[pos++] = '{';
	ant_offset_t body_len, body_off = vstr(js, body, &body_len);
	memcpy(code_buf + pos, (const void *)(uintptr_t)body_off, body_len);
	pos += body_len;
	code_buf[pos++] = '}';
	code_buf[pos] = '\0';

	ant_value_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) { free(code_buf); return func_obj; }

	sv_func_t *compiled = sv_compile_function(js, code_buf, pos, is_async, is_generator);
	if (!compiled) {
	free(code_buf);
	return js_mkerr_typed(js, JS_ERR_SYNTAX, "invalid function body");
	}

	sv_closure_t *closure = js_closure_alloc(js);
	if (!closure) { free(code_buf); return js_mkerr(js, "oom"); }
	closure->func = compiled;
	closure->bound_this = js_mkundef();
	closure->call_flags = 0;
	closure->func_obj = func_obj;

	size_t params_len = (size_t)(pos - 2) - (size_t)body_len - 2;
	const char *async_prefix = is_async ? "async " : "";
	const char generator_marker = is_generator ? "" : "";
	size_t async_len = is_async ? 6 : 0;
	size_t generator_len = is_generator ? 1 : 0;
	size_t display_len = async_len + 19 + generator_len + params_len + 5 + (size_t)body_len + 2;
	char display = (char )malloc(display_len + 1);
	if (!display) { free(code_buf); return js_mkerr(js, "oom"); }
	size_t n = 0;

	memcpy(display + n, async_prefix, async_len); n += async_len;
	memcpy(display + n, "function", 8); n += 8;
	memcpy(display + n, generator_marker, generator_len); n += generator_len;
	memcpy(display + n, " anonymous(", 11); n += 11;
	memcpy(display + n, code_buf + 1, params_len); n += params_len;
	memcpy(display + n, "\n) {\n", 5); n += 5;
	memcpy(display + n, code_buf + 1 + params_len + 2, (size_t)body_len); n += (size_t)body_len;
	memcpy(display + n, "\n}", 2); n += 2;
	display[n] = '\0';
	set_func_code(js, func_obj, display, display_len);
	free(display);
	free(code_buf);

	if (is_async) {
	set_slot(func_obj, SLOT_ASYNC, js_true);
	ant_value_t async_proto = get_slot(js_glob(js), SLOT_ASYNC_PROTO);
	if (vtype(async_proto) == T_FUNC) js_set_proto_init(func_obj, async_proto);
	} else if (is_generator) {
	ant_value_t generator_proto = get_slot(js_glob(js), SLOT_GENERATOR_PROTO);
	if (vtype(generator_proto) == T_FUNC) js_set_proto_init(func_obj, generator_proto);
	} else {
	ant_value_t func_proto = get_slot(js_glob(js), SLOT_FUNC_PROTO);
	ant_value_t instance_proto = js_instance_proto_from_new_target(js, func_proto);
	if (is_object_type(instance_proto)) js_set_proto_init(func_obj, instance_proto);
	}

	ant_value_t func = mkval(T_FUNC, (uintptr_t)closure);
	ant_value_t proto_setup = setup_func_prototype(js, func);
	if (is_err(proto_setup)) return proto_setup;
	if (is_generator) {
	ant_value_t prototype = js_get(js, func, "prototype");
	if (is_object_type(prototype) && is_object_type(js->sym.generator_proto))
	js_set_proto_wb(js, prototype, js->sym.generator_proto);
	}

	return func;
	}

	static ant_value_t builtin_Function(ant_t js, ant_value_t args, int nargs) {
	return build_dynamic_function(js, args, nargs, false, false);
	}

	static ant_value_t builtin_AsyncFunction(ant_t js, ant_value_t args, int nargs) {
	return build_dynamic_function(js, args, nargs, true, false);
	}

	static ant_value_t builtin_GeneratorFunction(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) {
	ant_value_t empty = js_mkstr(js, "", 0);
	if (is_err(empty)) return empty;
	return build_dynamic_function(js, &empty, 1, false, true);
	}
	return build_dynamic_function(js, args, nargs, false, true);
	}

	static ant_value_t builtin_function_empty(ant_t js, ant_value_t args, int nargs) {
	return js_mkundef();
	}

	static ant_value_t builtin_function_call(ant_t js, ant_value_t args, int nargs) {
	ant_value_t func = js->this_val;
	if (vtype(func) != T_FUNC && vtype(func) != T_CFUNC) {
	return js_mkerr(js, "call requires a function");
	}

	ant_value_t this_arg = (nargs > 0) ? args[0] : js_mkundef();
	ant_value_t *call_args = NULL;

	int call_nargs = (nargs > 1) ? nargs - 1 : 0;
	if (call_nargs > 0) call_args = &args[1];

	return sv_vm_call_explicit_this(js->vm, js, func, this_arg, call_args, call_nargs);
	}

	int extract_array_args(ant_t js, ant_value_t arr, ant_value_t *out_args) {
	int len = (int) get_array_length(js, arr);
	if (len <= 0) return 0;

	ant_value_t args_out = (ant_value_t )ant_calloc(sizeof(ant_value_t) * len);
	if (!args_out) return 0;

	for (int i = 0; i < len; i++) {
	args_out[i] = arr_get(js, arr, (ant_offset_t)i);
	}

	*out_args = args_out;
	return len;
	}

	static ant_value_t builtin_function_toString(ant_t js, ant_value_t args, int nargs) {
	ant_value_t func = js->this_val;
	uint8_t t = vtype(func);

	if (t != T_FUNC && t != T_CFUNC) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Function.prototype.toString requires that 'this' be a Function");
	}

	if (t == T_CFUNC) return ANT_STRING("function() { [native code] }");

	ant_value_t func_obj = js_func_obj(func);
	ant_value_t cfunc_slot = get_slot(func_obj, SLOT_CFUNC);

	if (vtype(cfunc_slot) == T_CFUNC) {
	ant_offset_t name_len = 0;
	const char *name = get_func_name(js, func, &name_len);
	if (name && name_len > 0) {
	size_t total = 9 + name_len + 21 + 1;
	char *buf = ant_calloc(total);
	size_t n = 0;
	n += cpy(buf + n, total - n, "function ", 9);
	n += cpy(buf + n, total - n, name, name_len);
	n += cpy(buf + n, total - n, "() { [native code] }", 20);
	ant_value_t result = js_mkstr(js, buf, n);
	free(buf);
	return result;
	}
	return ANT_STRING("function() { [native code] }");
	}

	ant_value_t code_val = get_slot(func_obj, SLOT_CODE);
	ant_value_t len_val = get_slot(func_obj, SLOT_CODE_LEN);

	if (vtype(code_val) == T_CFUNC && vtype(len_val) == T_NUM) {
	const char code = (const char )(uintptr_t)vdata(code_val);
	size_t code_len = (size_t)tod(len_val);

	if (code && code_len > 0) {
	ant_value_t async_slot = get_slot(func_obj, SLOT_ASYNC);
	sv_closure_t *closure = js_func_closure(func);

	bool is_async = (async_slot == js_true);
	bool is_arrow = (closure->call_flags & SV_CALL_IS_ARROW) != 0;

	if (is_arrow) {
	const char *paren_end = memchr(code, ')', code_len);
	if (!paren_end) goto fallback_arrow;

	size_t params_len = paren_end - code + 1;
	const char *body = paren_end + 1;
	size_t body_len = code_len - params_len;

	size_t len = (is_async ? 6 : 0) + params_len + 4 + body_len + 1;
	char *buf = ant_calloc(len);
	size_t n = 0;

	if (is_async) n += cpy(buf + n, REMAIN(n, len), "async ", 6);
	n += cpy(buf + n, REMAIN(n, len), code, params_len);
	n += cpy(buf + n, REMAIN(n, len), " => ", 4);
	n += cpy(buf + n, REMAIN(n, len), body, body_len);

	ant_value_t result = js_mkstr(js, buf, n);
	free(buf);
	return result;
	fallback_arrow:;
	}

	return js_mkstr(js, code, code_len);
	}
	}

	sv_closure_t *cl = js_func_closure(func);
	if (cl->func != NULL) {
	sv_func_t *fn = cl->func;
	if (fn && fn->source && fn->source_end > fn->source_start) {
	int start = fn->source_start;
	int end = fn->source_end;
	if (start >= 0 && end <= fn->source_len && end > start)
	return js_mkstr(js, fn->source + start, (size_t)(end - start));
	}
	}

	char buf[256];
	size_t len = strfunc(js, func, buf, sizeof(buf));
	return js_mkstr(js, buf, len);
	}

	static ant_value_t builtin_function_apply(ant_t js, ant_value_t args, int nargs) {
	ant_value_t func = js->this_val;
	if (vtype(func) != T_FUNC && vtype(func) != T_CFUNC) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Function.prototype.apply requires that 'this' be a Function");
	}

	ant_value_t this_arg = (nargs > 0) ? args[0] : js_mkundef();
	ant_value_t *call_args = NULL;
	int call_nargs = 0;

	if (nargs > 1) {
	ant_value_t arg_array = args[1];
	uint8_t t = vtype(arg_array);
	if (t == T_ARR \|\| t == T_OBJ) {
	call_nargs = extract_array_args(js, arg_array, &call_args);
	} else if (t != T_UNDEF && t != T_NULL) {}
	}

	ant_value_t result = sv_vm_call_explicit_this(js->vm, js, func, this_arg, call_args, call_nargs);
	if (call_args) free(call_args);

	return result;
	}

	static ant_value_t builtin_function_bind(ant_t js, ant_value_t args, int nargs) {
	ant_value_t func = js->this_val;

	if (vtype(func) != T_FUNC && vtype(func) != T_CFUNC) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "bind requires a function");
	}

	ant_value_t this_arg = (nargs > 0) ? args[0] : js_mkundef();
	int bound_argc = (nargs > 1) ? nargs - 1 : 0;
	ant_value_t *bound_args = (bound_argc > 0) ? &args[1] : NULL;

	int orig_length = 0;
	ant_value_t target_func_obj;

	if (vtype(func) == T_CFUNC) orig_length = 0;
	else {
	target_func_obj = js_func_obj(func);
	ant_value_t len_val = lkp_interned_val(js, target_func_obj, js->intern.length);
	if (vtype(len_val) == T_NUM) orig_length = (int) tod(len_val);
	}

	int bound_length = orig_length - bound_argc;
	if (bound_length < 0) bound_length = 0;

	if (vtype(func) == T_CFUNC) {
	ant_value_t bound_func = mkobj(js, 0);
	if (is_err(bound_func)) return bound_func;

	set_slot(bound_func, SLOT_CFUNC, func);

	ant_value_t func_proto = get_slot(js_glob(js), SLOT_FUNC_PROTO);
	if (vtype(func_proto) == T_FUNC) js_set_proto_init(bound_func, func_proto);

	ant_value_t bound = js_obj_to_func_ex(bound_func, bound_argc > 0 ? SV_CALL_HAS_BOUND_ARGS : 0);
	sv_closure_t *bc = js_func_closure(bound);
	bc->bound_this = this_arg;
	if (bound_argc > 0) {
	bc->bound_argv = malloc(sizeof(ant_value_t) * (size_t)bound_argc);
	memcpy(bc->bound_argv, bound_args, sizeof(ant_value_t) * (size_t)bound_argc);
	bc->bound_argc = bound_argc;
	}
	js_setprop(js, bound_func, js->length_str, tov((double) bound_length));

	ant_value_t proto_setup = setup_func_prototype(js, bound);
	if (is_err(proto_setup)) return proto_setup;

	js_mark_constructor(bound_func, js_is_constructor(js, func));

	return bound;
	}

	ant_value_t func_obj = js_func_obj(func);
	ant_value_t bound_func = mkobj(js, 0);
	if (is_err(bound_func)) return bound_func;

	ant_value_t code_val = get_slot(func_obj, SLOT_CODE);
	if (vtype(code_val) == T_STR \|\| vtype(code_val) == T_CFUNC) {
	set_slot(bound_func, SLOT_CODE, code_val);
	set_slot(bound_func, SLOT_CODE_LEN, get_slot(func_obj, SLOT_CODE_LEN));
	}

	sv_closure_t *orig = js_func_closure(func);
	sv_closure_t *bound_closure = js_closure_alloc(js);
	if (!bound_closure) return js_mkerr(js, "oom");

	bound_closure->func = orig->func;
	bound_closure->call_flags = orig->call_flags;
	bound_closure->upvalues = NULL;
	bound_closure->bound_this = this_arg;
	bound_closure->bound_args = js_mkundef();
	bound_closure->super_val = orig->super_val;
	bound_closure->func_obj = bound_func;

	if (orig->func && orig->func->upvalue_count > 0 && orig->upvalues) {
	size_t upvalue_bytes = sizeof(sv_upvalue_t ) (size_t)orig->func->upvalue_count;
	bound_closure->upvalues = malloc(upvalue_bytes);
	if (!bound_closure->upvalues) return js_mkerr(js, "oom");
	memcpy(bound_closure->upvalues, orig->upvalues, upvalue_bytes);
	}

	if (bound_argc > 0)
	bound_closure->call_flags \|= SV_CALL_HAS_BOUND_ARGS;

	ant_value_t async_slot = get_slot(func_obj, SLOT_ASYNC);
	if (vtype(async_slot) == T_BOOL && vdata(async_slot) == 1) {
	set_slot(bound_func, SLOT_ASYNC, js_true);
	}

	ant_value_t target_proto = get_proto(js, func);
	if (is_object_type(target_proto) \|\| vtype(target_proto) == T_NULL) {
	js_set_proto_init(bound_func, target_proto);
	} else if (vtype(async_slot) == T_BOOL && vdata(async_slot) == 1) {
	ant_value_t async_proto = get_slot(js_glob(js), SLOT_ASYNC_PROTO);
	if (vtype(async_proto) == T_FUNC) js_set_proto_init(bound_func, async_proto);
	} else {
	ant_value_t func_proto = get_slot(js_glob(js), SLOT_FUNC_PROTO);
	if (vtype(func_proto) == T_FUNC) js_set_proto_init(bound_func, func_proto);
	}

	ant_value_t data_slot = get_slot(func_obj, SLOT_DATA);
	if (vtype(data_slot) != T_UNDEF) {
	set_slot(bound_func, SLOT_DATA, data_slot);
	}

	set_slot(bound_func, SLOT_TARGET_FUNC, func);

	if (bound_argc > 0) {
	ant_value_t bound_arr = mkarr(js);
	for (int i = 0; i < bound_argc; i++) arr_set(js, bound_arr, (ant_offset_t)i, bound_args[i]);
	bound_closure->bound_args = bound_arr;
	bound_closure->bound_argv = malloc(sizeof(ant_value_t) * (size_t)bound_argc);
	memcpy(bound_closure->bound_argv, bound_args, sizeof(ant_value_t) * (size_t)bound_argc);
	bound_closure->bound_argc = bound_argc;
	}

	ant_value_t cfunc_slot = get_slot(func_obj, SLOT_CFUNC);
	if (vtype(cfunc_slot) == T_CFUNC) {
	set_slot(bound_func, SLOT_CFUNC, cfunc_slot);
	}

	js_setprop(js, bound_func, js->length_str, tov((double) bound_length));

	ant_value_t bound = mkval(T_FUNC, (uintptr_t)bound_closure);
	ant_value_t proto_setup = setup_func_prototype(js, bound);

	if (is_err(proto_setup)) return proto_setup;
	js_mark_constructor(bound_func, js_is_constructor(js, func));

	return bound;
	}

	static ant_value_t builtin_Array(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = mkarr(js);
	if (is_err(arr)) return arr;

	if (nargs == 1 && vtype(args[0]) == T_NUM) {
	ant_value_t err = validate_array_length(js, args[0]);
	if (is_err(err)) return err;
	ant_offset_t new_len = (ant_offset_t)tod(args[0]);
	ant_offset_t doff = get_dense_buf(arr);
	if (doff && new_len <= 1024) {
	if (new_len > dense_capacity(doff)) doff = dense_grow(js, arr, new_len);
	}
	array_len_set(js, arr, new_len);
	} else if (nargs > 0) {
	for (int i = 0; i < nargs; i++) arr_set(js, arr, (ant_offset_t)i, args[i]);
	}

	ant_value_t array_proto = get_ctor_proto(js, "Array", 5);
	ant_value_t instance_proto = js_instance_proto_from_new_target(js, array_proto);

	if (is_object_type(instance_proto)) js_set_proto_init(arr, instance_proto);
	if (vtype(js->new_target) == T_FUNC \|\| vtype(js->new_target) == T_CFUNC) {
	set_slot(arr, SLOT_CTOR, js->new_target);
	}

	return arr;
	}

	static ant_value_t builtin_error_captureStackTrace(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1 \|\| !is_object_type(args[0])) {
	return js_mkerr(js, "argument must be an object");
	}

	ant_value_t target = args[0];
	ant_value_t error_ctor = lkp_val(js, js->global, "Error", 5);
	ant_value_t prep = js_mkundef();

	if (vtype(error_ctor) == T_FUNC \|\| vtype(error_ctor) == T_CFUNC) {
	prep = lkp_val(js, js_func_obj(error_ctor), "prepareStackTrace", 17);
	}

	if (vtype(prep) == T_FUNC \|\| vtype(prep) == T_CFUNC) {
	ant_value_t callsites = js_build_callsite_array(js);
	ant_value_t prep_args[2] = { target, callsites };
	ant_value_t result = sv_vm_call(js->vm, js, prep, js_mkundef(), prep_args, 2, NULL, false);
	if (js->thrown_exists) return js_mkundef();
	js_set(js, target, "stack", result);
	js_set_descriptor(js, js_as_obj(target), "stack", 5, JS_DESC_W \| JS_DESC_C);
	} else js_capture_stack(js, target);

	return js_mkundef();
	}

	static ant_value_t builtin_error_isError(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_false;
	ant_value_t val = args[0];
	if (!is_object_type(val)) return js_false;
	return get_slot(val, SLOT_ERROR_BRAND) == js_true ? js_true : js_false;
	}

	static ant_value_t builtin_Error(ant_t js, ant_value_t args, int nargs) {
	bool is_new = (vtype(js->new_target) != T_UNDEF);
	ant_value_t this_val = js->this_val;

	ant_value_t target = is_new ? js->new_target : js->current_func;
	ant_value_t name = ANT_STRING("Error");

	if (vtype(target) == T_FUNC) {
	ant_value_t n = lkp_val(js, js_func_obj(target), "name", 4);
	if (vtype(n) != T_UNDEF) name = n;
	}

	if (!is_new) {
	this_val = js_mkobj(js);
	ant_value_t proto = lkp_interned_val(js, js_func_obj(js->current_func), js->intern.prototype);
	if (vtype(proto) != T_UNDEF) js_set_proto_init(this_val, proto);
	else js_set_proto_init(this_val, get_ctor_proto(js, "Error", 5));
	}

	if (nargs > 0) {
	ant_value_t msg = args[0];
	if (vtype(msg) != T_STR) {
	const char *str = js_str(js, msg);
	msg = js_mkstr(js, str, strlen(str));
	}
	js_mkprop_fast(js, this_val, "message", 7, msg);
	}

	if (nargs > 1 && vtype(args[1]) == T_OBJ) {
	ant_offset_t cause_off = lkp(js, args[1], "cause", 5);
	if (cause_off) js_mkprop_fast(js, this_val, "cause", 5, propref_load(js, cause_off));
	}

	js_mkprop_fast(js, this_val, "name", 4, name);
	set_slot(this_val, SLOT_ERROR_BRAND, js_true);
	js_capture_stack(js, this_val);

	return this_val;
	}

	static ant_value_t builtin_Error_toString(ant_t js, ant_value_t args, int nargs) {
	ant_value_t this_val = js_getthis(js);

	ant_value_t name = js_get(js, this_val, "name");
	if (vtype(name) == T_UNDEF) name = js_mkstr(js, "Error", 5);
	else if (vtype(name) != T_STR) {
	const char *s = js_str(js, name);
	name = js_mkstr(js, s, strlen(s));
	}

	ant_value_t msg = js_get(js, this_val, "message");
	if (vtype(msg) == T_UNDEF) msg = js_mkstr(js, "", 0);
	else if (vtype(msg) != T_STR) {
	const char *s = js_str(js, msg);
	msg = js_mkstr(js, s, strlen(s));
	}

	ant_offset_t name_len, msg_len;
	ant_offset_t name_off = vstr(js, name, &name_len);
	ant_offset_t msg_off = vstr(js, msg, &msg_len);

	const char name_str = (const char )(uintptr_t)(name_off);
	const char msg_str = (const char )(uintptr_t)(msg_off);

	if (name_len == 0) return msg;
	if (msg_len == 0) return name;

	size_t total = (size_t)(name_len + 2 + msg_len);
	char *buf = malloc(total + 1);
	if (!buf) return js_mkerr(js, "out of memory");

	memcpy(buf, name_str, (size_t)name_len);
	buf[name_len] = ':';
	buf[name_len + 1] = ' ';
	memcpy(buf + name_len + 2, msg_str, (size_t)msg_len);
	buf[total] = '\0';

	ant_value_t result = js_mkstr(js, buf, total);
	free(buf);
	return result;
	}

	static ant_value_t builtin_AggregateError(ant_t js, ant_value_t args, int nargs) {
	bool is_new = (vtype(js->new_target) != T_UNDEF);
	ant_value_t this_val = js->this_val;

	if (!is_new) {
	this_val = js_mkobj(js);
	ant_offset_t proto_off = lkp_interned(js, js_func_obj(js->current_func), js->intern.prototype, 9);
	if (proto_off) js_set_proto_init(this_val, propref_load(js, proto_off));
	else js_set_proto_init(this_val, get_ctor_proto(js, "AggregateError", 14));
	}

	ant_value_t errors = nargs > 0 ? args[0] : mkarr(js);
	if (vtype(errors) != T_ARR) errors = mkarr(js);
	js_mkprop_fast(js, this_val, "errors", 6, errors);

	if (nargs > 1 && vtype(args[1]) != T_UNDEF) {
	ant_value_t msg = args[1];
	if (vtype(msg) != T_STR) {
	const char *str = js_str(js, msg);
	msg = js_mkstr(js, str, strlen(str));
	}
	js_mkprop_fast(js, this_val, "message", 7, msg);
	}

	if (nargs > 2 && vtype(args[2]) == T_OBJ) {
	ant_offset_t cause_off = lkp(js, args[2], "cause", 5);
	if (cause_off) js_mkprop_fast(js, this_val, "cause", 5, propref_load(js, cause_off));
	}

	js_mkprop_fast(js, this_val, "name", 4, ANT_STRING("AggregateError"));
	set_slot(this_val, SLOT_ERROR_BRAND, js_true);

	return this_val;
	}


	typedef ant_value_t (*dynamic_kv_mapper_fn)(
	ant_t *js,
	ant_value_t key,
	ant_value_t val
	);

	static ant_value_t iterate_dynamic_keys(ant_t *js, ant_value_t obj, dynamic_kv_mapper_fn mapper) {
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| !ptr->exotic_keys \|\| !ptr->exotic_ops \|\| !ptr->exotic_ops->getter) return mkarr(js);
	ant_value_t keys_arr = ptr->exotic_keys(js, obj);
	ant_value_t arr = mkarr(js);
	ant_offset_t len = get_array_length(js, keys_arr);

	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t key_val = arr_get(js, keys_arr, i);
	if (vtype(key_val) != T_STR) continue;
	ant_offset_t klen; ant_offset_t str_off = vstr(js, key_val, &klen);
	const char key = (const char )(uintptr_t)(str_off);
	ant_value_t val = ptr->exotic_ops->getter(js, obj, key, klen);
	js_arr_push(js, arr, mapper ? mapper(js, key_val, val) : val);
	}

	return mkval(T_ARR, vdata(arr));
	}

	static ant_value_t builtin_object_is(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 2) return js_false;

	ant_value_t x = args[0];
	ant_value_t y = args[1];

	uint8_t tx = vtype(x);
	uint8_t ty = vtype(y);
	if (tx != ty) return js_false;

	if (tx == T_UNDEF \|\| tx == T_NULL) return js_true;

	if (tx == T_NUM) {
	double dx = tod(x);
	double dy = tod(y);
	if (isnan(dx) && isnan(dy)) return js_true;
	if (dx == 0.0 && dy == 0.0) {
	bool x_neg = (1.0 / dx) < 0;
	bool y_neg = (1.0 / dy) < 0;
	return x_neg == y_neg ? js_true : js_false;
	}
	return dx == dy ? js_true : js_false;
	}

	if (tx == T_BOOL) return vdata(x) == vdata(y) ? js_true : js_false;
	return strict_eq_values(js, x, y) ? js_true : js_false;
	}

	enum obj_enum_mode {
	OBJ_ENUM_KEYS,
	OBJ_ENUM_VALUES,
	OBJ_ENUM_ENTRIES
	};

	static ant_value_t map_to_entry(ant_t *js, ant_value_t key, ant_value_t val) {
	ant_value_t pair = mkarr(js);
	arr_set(js, pair, 0, key);
	arr_set(js, pair, 1, val);
	return mkval(T_ARR, vdata(pair));
	}

	static ant_value_t object_enum(ant_t *js, ant_value_t obj, enum obj_enum_mode mode) {
	bool is_arr = (vtype(obj) == T_ARR);
	if (vtype(obj) == T_FUNC) obj = js_func_obj(obj);

	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| !ptr->shape) return mkarr(js);
	if (ptr->is_exotic && ptr->exotic_keys) {
	if (mode == OBJ_ENUM_KEYS && (!ptr->exotic_ops \|\| !ptr->exotic_ops->getter)) return ptr->exotic_keys(js, obj);
	if (ptr->exotic_ops && ptr->exotic_ops->getter) {
	dynamic_kv_mapper_fn mapper = (mode == OBJ_ENUM_ENTRIES) ? map_to_entry : NULL;
	return iterate_dynamic_keys(js, obj, mapper);
	}
	}

	ant_value_t arr = mkarr(js);
	ant_offset_t idx = 0;

	if (is_arr) {
	ant_offset_t doff = get_dense_buf(obj);
	ant_offset_t dense_len = doff ? dense_iterable_length(js, obj) : 0;

	for (ant_offset_t i = 0; i < dense_len; i++) {
	ant_value_t v = dense_get(doff, i);
	if (is_empty_slot(v)) continue;
	char idxstr[16]; size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)i);
	ant_value_t key_val = js_mkstr(js, idxstr, idxlen);

	if (mode == OBJ_ENUM_KEYS) arr_set(js, arr, idx, key_val);
	else if (mode == OBJ_ENUM_VALUES) arr_set(js, arr, idx, v);
	else arr_set(js, arr, idx, map_to_entry(js, key_val, v));

	idx++;
	}
	}

	uint32_t shape_count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < shape_count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop \|\| prop->type == ANT_SHAPE_KEY_SYMBOL) continue;
	if (i >= ptr->prop_count) continue;

	const char *key = prop->key.interned;
	ant_offset_t klen = (ant_offset_t)strlen(key);
	ant_value_t val = ant_object_prop_get_unchecked(ptr, i);

	if (is_internal_prop(key, klen)) continue;
	if (is_arr && is_array_index(key, klen)) {
	ant_offset_t doff = get_dense_buf(obj);
	if (doff) {
	unsigned long pidx = 0;
	for (ant_offset_t ci = 0; ci < klen; ci++) pidx = pidx * 10 + (key[ci] - '0');
	if (pidx < dense_iterable_length(js, obj)) continue;
	}}

	bool should_include = (ant_shape_get_attrs(ptr->shape, i) & ANT_PROP_ATTR_ENUMERABLE) != 0;
	if (should_include && ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(js_as_obj(obj), key, (size_t)klen);
	if (desc) should_include = desc->enumerable;
	}
	if (!should_include) continue;

	ant_value_t key_val = js_mkstr(js, key, (size_t)klen);
	if (mode == OBJ_ENUM_KEYS) arr_set(js, arr, idx, key_val);
	else if (mode == OBJ_ENUM_VALUES) arr_set(js, arr, idx, val);
	else arr_set(js, arr, idx, map_to_entry(js, key_val, val));

	idx++;
	}

	return mkval(T_ARR, vdata(arr));
	}

	static ant_value_t builtin_object_keys(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkarr(js);
	ant_value_t obj = args[0];
	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR && vtype(obj) != T_FUNC) return mkarr(js);

	if (is_proxy(obj)) {
	ant_proxy_state_t *data = get_proxy_data(obj);
	if (!data) return mkarr(js);
	if (data->revoked)
	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot perform 'ownKeys' on a proxy that has been revoked");

	ant_offset_t trap_off = lkp(js, data->handler, "ownKeys", 7);
	if (!trap_off) return object_enum(js, data->target, OBJ_ENUM_KEYS);

	ant_value_t trap = propref_load(js, trap_off);
	uint8_t ft = vtype(trap);
	if (ft != T_FUNC && ft != T_CFUNC) return object_enum(js, data->target, OBJ_ENUM_KEYS);

	ant_value_t trap_args[1] = { data->target };
	ant_value_t result = sv_vm_call(js->vm, js, trap, data->handler, trap_args, 1, NULL, false);
	if (is_err(result)) return result;
	if (vtype(result) != T_ARR)
	return js_mkerr_typed(js, JS_ERR_TYPE, "ownKeys trap must return an array");

	ant_offset_t len = get_array_length(js, result);
	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t ki = arr_get(js, result, i);
	if (vtype(ki) != T_STR && vtype(ki) != T_SYMBOL)
	return js_mkerr_typed(js, JS_ERR_TYPE, "ownKeys trap result must contain only strings or symbols");
	ant_offset_t ki_len; ant_offset_t ki_off = vstr(js, ki, &ki_len);
	for (ant_offset_t j = 0; j < i; j++) {
	ant_value_t kj = arr_get(js, result, j);
	ant_offset_t kj_len; ant_offset_t kj_off = vstr(js, kj, &kj_len);
	if (ki_len == kj_len &&
	memcmp((const void )(uintptr_t)ki_off, (const void )(uintptr_t)kj_off, ki_len) == 0)
	return js_mkerr_typed(js, JS_ERR_TYPE, "ownKeys trap result must not contain duplicate entries");
	}
	}
	return result;
	}

	return object_enum(js, obj, OBJ_ENUM_KEYS);
	}

	static ant_value_t for_in_keys_add(ant_t *js, ant_value_t out, ant_value_t seen, ant_value_t key) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, out);
	GC_ROOT_PIN(js, seen);
	GC_ROOT_PIN(js, key);

	if (vtype(key) != T_STR) return js_mkundef();

	ant_offset_t key_len = 0;
	ant_offset_t key_off = vstr(js, key, &key_len);
	const char key_ptr = (const char )(uintptr_t)(key_off);

	if (is_internal_prop(key_ptr, key_len)) goto done;
	if (lkp(js, seen, key_ptr, key_len) != 0) goto done;

	ant_value_t mark = setprop_cstr(js, seen, key_ptr, key_len, js_true);
	if (is_err(mark)) {
	GC_ROOT_RESTORE(js, root_mark);
	return mark;
	}

	if (vtype(out) == T_ARR) js_arr_push(js, out, key);
	done:
	GC_ROOT_RESTORE(js, root_mark);
	return js_mkundef();
	}

	static ant_value_t for_in_keys_add_string_indices(ant_t *js, ant_value_t out, ant_value_t seen, ant_value_t str) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, out);
	GC_ROOT_PIN(js, seen);
	GC_ROOT_PIN(js, str);

	ant_offset_t slen = vstrlen(js, str);
	for (ant_offset_t i = 0; i < slen; i++) {
	char idx[16];
	size_t idx_len = uint_to_str(idx, sizeof(idx), (uint64_t)i);

	ant_value_t key = js_mkstr(js, idx, idx_len);
	GC_ROOT_PIN(js, key);

	ant_value_t r = for_in_keys_add(js, out, seen, key);
	if (is_err(r)) { GC_ROOT_RESTORE(js, root_mark); return r; }
	}

	GC_ROOT_RESTORE(js, root_mark);
	return js_mkundef();
	}

	static inline ant_value_t for_in_keys_collect_chain(
	ant_t *js, ant_value_t out, ant_value_t seen, ant_value_t obj
	) {
	ant_value_t cur = obj;
	GC_ROOT_PIN(js, cur);

	for (int depth = 0; is_object_type(cur) && depth < MAX_PROTO_CHAIN_DEPTH; depth++) {
	GC_ROOT_SAVE(iter_mark, js);
	ant_value_t as_cur = (vtype(cur) == T_FUNC) ? js_func_obj(cur) : cur;
	ant_object_t *cur_ptr = js_obj_ptr(as_cur);
	ant_value_t key, r, proto;
	ant_offset_t doff, dense_len, klen;
	bool is_arr;

	if (!cur_ptr) goto next_proto;
	if (!cur_ptr->is_exotic \|\| !cur_ptr->exotic_keys) goto shape_props;

	{
	ant_value_t ekeys = cur_ptr->exotic_keys(js, as_cur);
	GC_ROOT_PIN(js, ekeys);
	if (vtype(ekeys) != T_ARR) goto next_proto;
	ant_offset_t elen = js_arr_len(js, ekeys);
	for (ant_offset_t i = 0; i < elen; i++) {
	key = js_arr_get(js, ekeys, i);
	GC_ROOT_PIN(js, key);
	r = for_in_keys_add(js, out, seen, key);
	if (is_err(r)) goto err;
	}
	}
	goto next_proto;

	shape_props:
	if (!cur_ptr->shape) goto next_proto;
	is_arr = (vtype(as_cur) == T_ARR);
	if (!is_arr) goto shape_iter;

	doff = get_dense_buf(as_cur);
	dense_len = doff ? dense_iterable_length(js, as_cur) : 0;
	for (ant_offset_t i = 0; i < dense_len; i++) {
	if (is_empty_slot(dense_get(doff, i))) continue;
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)i);
	key = js_mkstr(js, idxstr, idxlen);
	GC_ROOT_PIN(js, key);
	r = for_in_keys_add(js, out, seen, key);
	if (is_err(r)) goto err;
	}

	shape_iter:
	for (uint32_t i = 0; i < ant_shape_count(cur_ptr->shape); i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(cur_ptr->shape, i);
	if (!prop \|\| prop->type == ANT_SHAPE_KEY_SYMBOL) continue;
	if (i >= cur_ptr->prop_count) continue;

	const char *kstr = prop->key.interned;
	klen = (ant_offset_t)strlen(kstr);
	if (is_internal_prop(kstr, klen)) continue;

	if (is_arr && is_array_index(kstr, klen)) {
	doff = get_dense_buf(as_cur);
	if (doff) {
	unsigned long pidx = 0;
	for (ant_offset_t ci = 0; ci < klen; ci++) pidx = pidx * 10 + (kstr[ci] - '0');
	if (pidx < (unsigned long)dense_iterable_length(js, as_cur)) continue;
	}}

	bool enumerable = (ant_shape_get_attrs(cur_ptr->shape, i) & ANT_PROP_ATTR_ENUMERABLE) != 0;
	if (cur_ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(js_as_obj(as_cur), kstr, (size_t)klen);
	if (desc) enumerable = desc->enumerable;
	}

	key = js_mkstr(js, kstr, (size_t)klen);
	GC_ROOT_PIN(js, key);
	r = for_in_keys_add(js, enumerable ? out : js_mkundef(), seen, key);
	if (is_err(r)) goto err;
	}

	next_proto:
	GC_ROOT_RESTORE(js, iter_mark);
	proto = js_get_proto(js, cur);
	if (!is_object_type(proto)) break;
	cur = proto;
	continue;
	err:
	GC_ROOT_RESTORE(js, iter_mark);
	return r;
	}

	return out;
	}

	ant_value_t js_for_in_keys(ant_t *js, ant_value_t obj) {
	GC_ROOT_SAVE(root_mark, js);
	uint8_t t = vtype(obj);
	ant_value_t out = mkarr(js);
	ant_value_t result = out;

	GC_ROOT_PIN(js, obj);
	GC_ROOT_PIN(js, out);

	if (t == T_NULL \|\| t == T_UNDEF) goto done;

	ant_value_t seen = mkobj(js, 0);
	GC_ROOT_PIN(js, seen);

	if (t == T_STR) {
	result = for_in_keys_add_string_indices(js, out, seen, obj);
	if (is_err(result)) goto done;
	result = out;
	goto done;
	}

	if (t == T_OBJ) {
	ant_value_t prim = get_slot(obj, SLOT_PRIMITIVE);
	GC_ROOT_PIN(js, prim);
	if (vtype(prim) == T_STR) {
	result = for_in_keys_add_string_indices(js, out, seen, prim);
	if (is_err(result)) goto done;
	result = out;
	}
	}

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) goto done;
	result = for_in_keys_collect_chain(js, out, seen, obj);

	done:
	GC_ROOT_RESTORE(js, root_mark);
	return result;
	}

	static ant_value_t builtin_object_values(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkarr(js);
	ant_value_t obj = args[0];
	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR && vtype(obj) != T_FUNC) return mkarr(js);
	return object_enum(js, obj, OBJ_ENUM_VALUES);
	}

	static ant_value_t builtin_object_entries(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkarr(js);
	ant_value_t obj = args[0];
	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR && vtype(obj) != T_FUNC) return mkarr(js);
	return object_enum(js, obj, OBJ_ENUM_ENTRIES);
	}

	static ant_value_t builtin_object_getPrototypeOf(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkerr(js, "Object.getPrototypeOf requires an argument");
	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t == T_STR \|\| t == T_NUM \|\| t == T_BOOL \|\| t == T_BIGINT)
	return get_prototype_for_type(js, t);
	if (t == T_CFUNC) return get_prototype_for_type(js, t);

	if (is_object_type(obj)) {
	if (is_proxy(obj)) return proxy_get_prototype_of(js, obj);
	return get_proto(js, obj);
	}

	return js_mknull();
	}

	static ant_value_t builtin_object_setPrototypeOf(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 2) return js_mkerr(js, "Object.setPrototypeOf requires 2 arguments");

	ant_value_t obj = args[0];
	ant_value_t proto = args[1];

	uint8_t t = vtype(obj);
	if (t == T_CFUNC) {
	obj = js_cfunc_promote(js, obj);
	t = T_FUNC;
	}

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) {
	return js_mkerr(js, "Object.setPrototypeOf: first argument must be an object");
	}

	uint8_t pt = vtype(proto);
	if (pt == T_CFUNC) {
	proto = js_cfunc_promote(js, proto);
	pt = T_FUNC;
	}

	if (pt != T_OBJ && pt != T_ARR && pt != T_FUNC && pt != T_NULL) {
	return js_mkerr(js, "Object.setPrototypeOf: prototype must be an object or null");
	}

	if (pt != T_NULL && proto_chain_contains(js, proto, obj))
	return js_mkerr(js, "Cyclic __proto__ value");

	set_proto(js, obj, proto);
	return obj;
	}

	static ant_value_t builtin_proto_getter(ant_t js, ant_value_t args, int nargs) {
	ant_value_t this_val = js->this_val;
	uint8_t t = vtype(this_val);

	if (t == T_UNDEF \|\| t == T_NULL) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot read property '__proto__' of %s", typestr(t));
	}

	if (t == T_OBJ \|\| t == T_ARR \|\| t == T_FUNC) {
	return get_proto(js, this_val);
	}

	return get_prototype_for_type(js, t);
	}

	static ant_value_t builtin_proto_setter(ant_t js, ant_value_t args, int nargs) {
	ant_value_t this_val = js->this_val;
	uint8_t t = vtype(this_val);

	if (t == T_UNDEF \|\| t == T_NULL) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot set property '__proto__' of %s", typestr(t));
	}

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) {
	return js_mkundef();
	}

	if (nargs == 0) return js_mkundef();

	ant_value_t proto = args[0];
	uint8_t pt = vtype(proto);

	if (pt != T_OBJ && pt != T_ARR && pt != T_FUNC && pt != T_NULL) {
	return js_mkundef();
	}

	if (pt != T_NULL && proto_chain_contains(js, proto, this_val))
	return js_mkundef();

	set_proto(js, this_val, proto);
	return js_mkundef();
	}

	static ant_value_t legacy_accessor_this_obj(ant_t *js, ant_value_t this_val) {
	uint8_t t = vtype(this_val);

	if (t == T_UNDEF \|\| t == T_NULL) return js_mkerr_typed(
	js, JS_ERR_TYPE, "Cannot convert undefined or null to object"
	);

	if (t == T_CFUNC) return js_cfunc_promote(js, this_val);
	if (t == T_OBJ \|\| t == T_ARR \|\| t == T_FUNC) return js_as_obj(this_val);

	if (t == T_STR \|\| t == T_NUM \|\| t == T_BOOL \|\| t == T_BIGINT) {
	ant_value_t boxed = builtin_Object(js, &this_val, 1);
	if (is_err(boxed)) return boxed;
	if (is_object_type(boxed)) return js_as_obj(boxed);
	}

	return js_mkerr_typed(js, JS_ERR_TYPE, "Legacy accessor methods require an object receiver");
	}

	static bool legacy_accessor_key(
	ant_t *js, ant_value_t key,
	ant_value_t *key_val_out,
	const char **key_str_out,
	ant_offset_t *key_len_out,
	ant_offset_t *sym_off_out
	) {
	if (key_val_out) *key_val_out = key;
	if (key_str_out) *key_str_out = NULL;
	if (key_len_out) *key_len_out = 0;
	if (sym_off_out) *sym_off_out = 0;

	if (vtype(key) == T_SYMBOL) {
	if (sym_off_out) *sym_off_out = (ant_offset_t)vdata(key);
	return true;
	}

	ant_value_t key_val = (vtype(key) == T_STR) ? key : coerce_to_str(js, key);
	if (is_err(key_val)) return false;
	if (key_val_out) *key_val_out = key_val;

	ant_offset_t key_len = 0;
	ant_offset_t key_off = vstr(js, key_val, &key_len);

	if (key_str_out) key_str_out = (const char )(uintptr_t)key_off;
	if (key_len_out) *key_len_out = key_len;

	return true;
	}

	static ant_value_t builtin_object___defineGetter__(ant_t js, ant_value_t args, int nargs) {
	ant_value_t obj = legacy_accessor_this_obj(js, js->this_val);
	if (is_err(obj)) return obj;
	if (nargs < 2) return js_mkundef();

	ant_value_t getter = args[1];
	uint8_t gt = vtype(getter);

	if (gt != T_FUNC && gt != T_CFUNC) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Object.prototype.__defineGetter__: Expecting function");
	}

	ant_value_t key_val = js_mkundef();
	const char *key_str = NULL;
	ant_offset_t key_len = 0;
	ant_offset_t sym_off = 0;

	if (!legacy_accessor_key(js, args[0], &key_val, &key_str, &key_len, &sym_off)) {
	return key_val;
	}

	if (is_proxy(js_as_obj(obj))) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, obj);
	GC_ROOT_PIN(js, key_val);
	GC_ROOT_PIN(js, getter);

	ant_value_t desc = js_mkobj(js);
	if (is_err(desc)) {
	GC_ROOT_RESTORE(js, root_mark);
	return desc;
	}

	GC_ROOT_PIN(js, desc);
	js_setprop(js, desc, js_mkstr(js, "get", 3), getter);
	js_setprop(js, desc, js_mkstr(js, "enumerable", 10), js_true);
	js_setprop(js, desc, js_mkstr(js, "configurable", 12), js_true);

	ant_value_t define_args[3] = { obj, key_val, desc };
	ant_value_t result = builtin_object_defineProperty(js, define_args, 3);

	GC_ROOT_RESTORE(js, root_mark);
	if (is_err(result)) return result;

	return js_mkundef();
	}

	if (vtype(key_val) == T_SYMBOL) {
	js_set_sym_getter_desc(js, js_as_obj(obj), key_val, getter, JS_DESC_E \| JS_DESC_C);
	} else js_set_getter_desc(js, js_as_obj(obj), key_str, (size_t)key_len, getter, JS_DESC_E \| JS_DESC_C);

	return js_mkundef();
	}

	static ant_value_t builtin_object___defineSetter__(ant_t js, ant_value_t args, int nargs) {
	ant_value_t obj = legacy_accessor_this_obj(js, js->this_val);
	if (is_err(obj)) return obj;
	if (nargs < 2) return js_mkundef();

	ant_value_t setter = args[1];
	uint8_t st = vtype(setter);

	if (st != T_FUNC && st != T_CFUNC) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Object.prototype.__defineSetter__: Expecting function");
	}

	ant_value_t key_val = js_mkundef();
	const char *key_str = NULL;
	ant_offset_t key_len = 0;
	ant_offset_t sym_off = 0;

	if (!legacy_accessor_key(js, args[0], &key_val, &key_str, &key_len, &sym_off)) {
	return key_val;
	}

	if (is_proxy(js_as_obj(obj))) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, obj);
	GC_ROOT_PIN(js, key_val);
	GC_ROOT_PIN(js, setter);

	ant_value_t desc = js_mkobj(js);
	if (is_err(desc)) {
	GC_ROOT_RESTORE(js, root_mark);
	return desc;
	}

	GC_ROOT_PIN(js, desc);
	js_setprop(js, desc, js_mkstr(js, "set", 3), setter);
	js_setprop(js, desc, js_mkstr(js, "enumerable", 10), js_true);
	js_setprop(js, desc, js_mkstr(js, "configurable", 12), js_true);

	ant_value_t define_args[3] = { obj, key_val, desc };
	ant_value_t result = builtin_object_defineProperty(js, define_args, 3);

	GC_ROOT_RESTORE(js, root_mark);
	if (is_err(result)) return result;

	return js_mkundef();
	}

	if (vtype(key_val) == T_SYMBOL) {
	js_set_sym_setter_desc(js, js_as_obj(obj), key_val, setter, JS_DESC_E \| JS_DESC_C);
	} else js_set_setter_desc(js, js_as_obj(obj), key_str, (size_t)key_len, setter, JS_DESC_E \| JS_DESC_C);

	return js_mkundef();
	}

	static ant_value_t legacy_lookup_accessor_from_descriptor(ant_t *js, ant_value_t desc, bool want_getter) {
	if (vtype(desc) != T_OBJ) return js_mkundef();
	ant_offset_t off = lkp_interned(js, desc, want_getter ? js->intern.get : js->intern.set, 3);
	if (off == 0) return js_mkundef();
	return propref_load(js, off);
	}

	static ant_value_t legacy_lookup_accessor(ant_t *js, ant_value_t this_val, ant_value_t key, bool want_getter) {
	ant_value_t obj = legacy_accessor_this_obj(js, this_val);
	if (is_err(obj)) return obj;

	ant_value_t key_val = js_mkundef();
	const char *key_str = NULL;
	ant_offset_t key_len = 0;
	ant_offset_t sym_off = 0;

	if (!legacy_accessor_key(js, key, &key_val, &key_str, &key_len, &sym_off)) {
	return key_val;
	}

	for (ant_value_t cur = obj; is_object_type(cur); ) {
	if (is_proxy(cur)) {
	ant_value_t desc = proxy_get_own_property_descriptor(js, cur, key_val);
	if (is_err(desc)) return desc;
	if (vtype(desc) == T_OBJ) return legacy_lookup_accessor_from_descriptor(js, desc, want_getter);
	cur = proxy_get_prototype_of(js, cur);
	if (is_err(cur)) return cur;
	continue;
	}

	prop_meta_t meta;
	bool has_meta = (vtype(key_val) == T_SYMBOL)
	? lookup_symbol_prop_meta(cur, sym_off, &meta)
	: lookup_string_prop_meta(js, cur, key_str, (size_t)key_len, &meta);
	if (has_meta) {
	if (want_getter) return meta.has_getter ? meta.getter : js_mkundef();
	return meta.has_setter ? meta.setter : js_mkundef();
	}

	if (vtype(key_val) == T_SYMBOL) {
	if (lkp_sym(js, cur, sym_off) != 0) return js_mkundef();
	} else {
	if (array_obj_ptr(cur) && is_length_key(key_str, key_len)) return js_mkundef();
	if (array_obj_ptr(cur) && is_array_index(key_str, key_len)) {
	unsigned long idx = 0;
	if (
	parse_array_index(key_str, key_len, get_array_length(js, cur), &idx) &&
	arr_has(js, cur, (ant_offset_t)idx)
	) return js_mkundef();
	}
	if (lkp(js, cur, key_str, key_len) != 0) return js_mkundef();
	}
	cur = get_proto(js, cur);
	}

	return js_mkundef();
	}

	static ant_value_t builtin_object___lookupGetter__(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkundef();
	return legacy_lookup_accessor(js, js->this_val, args[0], true);
	}

	static ant_value_t builtin_object___lookupSetter__(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkundef();
	return legacy_lookup_accessor(js, js->this_val, args[0], false);
	}

	static ant_value_t builtin_object_create(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkerr(js, "Object.create requires a prototype argument");

	ant_value_t proto = args[0];
	uint8_t pt = vtype(proto);

	if (pt != T_OBJ && pt != T_ARR && pt != T_FUNC && pt != T_NULL) {
	return js_mkerr(js, "Object.create: prototype must be an object or null");
	}

	ant_value_t obj = js_mkobj(js);
	if (pt == T_NULL) {
	js_set_proto_init(obj, js_mknull());
	} else js_set_proto_init(obj, proto);

	if (nargs >= 2 && vtype(args[1]) == T_OBJ) {
	ant_value_t props = args[1];
	ant_iter_t iter = js_prop_iter_begin(js, props);

	const char *key = NULL;
	size_t klen = 0;
	ant_value_t descriptor = js_mkundef();

	while (js_prop_iter_next(&iter, &key, &klen, &descriptor)) {
	if (vtype(descriptor) != T_OBJ) continue;
	ant_offset_t val_off = lkp(js, descriptor, "value", 5);
	if (val_off == 0) continue;
	ant_value_t val = propref_load(js, val_off);
	ant_value_t key_str = js_mkstr(js, key, klen);
	js_setprop(js, obj, key_str, val);
	}

	js_prop_iter_end(&iter);
	}

	return obj;
	}

	static ant_value_t builtin_object_hasOwn(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 2) return mkval(T_BOOL, 0);

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t == T_NULL \|\| t == T_UNDEF) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot convert undefined or null to object");
	}

	ant_value_t key = args[1];
	if (vtype(key) != T_STR) {
	key = js_tostring_val(js, key);
	if (is_err(key)) return key;
	}

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return mkval(T_BOOL, 0);
	ant_value_t as_obj = js_as_obj(obj);
	if (is_proxy(as_obj)) return proxy_has_own(js, as_obj, key);

	ant_offset_t key_len, key_off = vstr(js, key, &key_len);
	const char key_str = (char )(uintptr_t)(key_off);

	ant_offset_t off = lkp(js, as_obj, key_str, key_len);
	return mkval(T_BOOL, off != 0 ? 1 : 0);
	}

	static ant_value_t builtin_object_groupBy(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 2) return js_mkerr_typed(js, JS_ERR_TYPE, "Object.groupBy requires 2 arguments");

	ant_value_t items = args[0];
	ant_value_t callback = args[1];

	if (vtype(callback) != T_FUNC && vtype(callback) != T_CFUNC)
	return js_mkerr_typed(js, JS_ERR_TYPE, "callback is not a function");

	ant_value_t result = js_mkobj(js);
	js_set_proto_init(result, js_mknull());

	ant_offset_t len = get_array_length(js, items);
	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t val = arr_get(js, items, i);
	ant_value_t cb_args[2] = { val, tov((double)i) };
	ant_value_t key = sv_vm_call(js->vm, js, callback, js_mkundef(), cb_args, 2, NULL, false);
	if (is_err(key)) return key;

	ant_value_t key_str = js_tostring_val(js, key);
	if (is_err(key_str)) return key_str;

	ant_offset_t klen;
	ant_offset_t koff = vstr(js, key_str, &klen);
	const char kptr = (char )(uintptr_t)(koff);

	ant_offset_t grp_off = lkp(js, result, kptr, klen);
	ant_value_t group;
	if (grp_off) {
	group = propref_load(js, grp_off);
	} else {
	group = mkarr(js);
	js_setprop(js, result, key_str, group);
	}
	js_arr_push(js, group, val);
	}

	return result;
	}

	// TODO: decompose this huge function into small pieces
	static ant_value_t builtin_object_defineProperty(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 3) return js_mkerr(js, "Object.defineProperty requires 3 arguments");

	ant_value_t obj = args[0];
	ant_value_t prop = args[1];
	ant_value_t descriptor = args[2];
	uint8_t t = vtype(obj);

	if (t == T_CFUNC) {
	obj = js_cfunc_promote(js, obj);
	args[0] = obj;
	t = T_FUNC;
	}

	if (!is_object_type(obj)) {
	return js_mkerr(js, "Object.defineProperty called on non-object");
	}

	bool sym_key = (vtype(prop) == T_SYMBOL);
	if (!sym_key && vtype(prop) != T_STR) {
	char buf[64];
	size_t len = tostr(js, prop, buf, sizeof(buf));
	prop = js_mkstr(js, buf, len);
	}

	if (vtype(descriptor) != T_OBJ) {
	return js_mkerr(js, "Property descriptor must be an object");
	}

	ant_value_t as_obj = js_as_obj(obj);
	if (is_proxy(as_obj)) {
	ant_value_t proxy_result = proxy_define_property(js, as_obj, prop, descriptor);
	if (is_err(proxy_result)) return proxy_result;
	if (!js_truthy(js, proxy_result))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'defineProperty' on proxy: trap returned falsy");
	return obj;
	}

	ant_offset_t prop_len = 0;
	const char *prop_str = NULL;
	ant_offset_t sym_off = 0;

	if (sym_key) {
	sym_off = (ant_offset_t)vdata(prop);
	const char *desc = js_sym_desc(js, prop);
	prop_str = desc ? desc : "symbol";
	prop_len = (ant_offset_t)strlen(prop_str);
	} else {
	ant_offset_t prop_off = vstr(js, prop, &prop_len);
	prop_str = (char *)(uintptr_t)(prop_off);
	if (streq(prop_str, prop_len, STR_PROTO, STR_PROTO_LEN))
	return js_mkerr(js, "Cannot define " STR_PROTO " property");
	}

	bool has_value = false, has_get = false, has_set = false;
	bool has_writable = false, has_enumerable = false, has_configurable = false;
	ant_value_t value = js_mkundef();
	bool writable = false, enumerable = false, configurable = false;

	ant_offset_t value_off = lkp(js, descriptor, "value", 5);
	if (value_off != 0) {
	has_value = true;
	value = propref_load(js, value_off);
	}

	ant_offset_t get_off = lkp_interned(js, descriptor, js->intern.get, 3);
	if (get_off != 0) {
	has_get = true;
	ant_value_t getter = propref_load(js, get_off);
	if (vtype(getter) != T_FUNC && vtype(getter) != T_UNDEF) {
	return js_mkerr(js, "Getter must be a function");
	}
	}

	ant_offset_t set_off = lkp_interned(js, descriptor, js->intern.set, 3);
	if (set_off != 0) {
	has_set = true;
	ant_value_t setter = propref_load(js, set_off);
	if (vtype(setter) != T_FUNC && vtype(setter) != T_UNDEF) {
	return js_mkerr(js, "Setter must be a function");
	}
	}

	ant_offset_t writable_off = lkp(js, descriptor, "writable", 8);
	if (writable_off != 0) {
	has_writable = true;
	ant_value_t w_val = propref_load(js, writable_off);
	writable = js_truthy(js, w_val);
	}

	ant_offset_t enumerable_off = lkp(js, descriptor, "enumerable", 10);
	if (enumerable_off != 0) {
	has_enumerable = true;
	ant_value_t e_val = propref_load(js, enumerable_off);
	enumerable = js_truthy(js, e_val);
	}

	ant_offset_t configurable_off = lkp(js, descriptor, "configurable", 12);
	if (configurable_off != 0) {
	has_configurable = true;
	ant_value_t c_val = propref_load(js, configurable_off);
	configurable = js_truthy(js, c_val);
	}

	if ((has_value \|\| has_writable) && (has_get \|\| has_set)) {
	return js_mkerr(js, "Invalid property descriptor. Cannot both specify accessors and a value or writable attribute");
	}

	ant_object_t *arr_ptr = (!sym_key && is_length_key(prop_str, prop_len))
	? array_obj_ptr(as_obj)
	: NULL;
	if (arr_ptr) {
	if (has_get \|\| has_set) return js_mkerr(js, "Invalid property descriptor. Cannot use accessors for array length");
	if ((has_enumerable && enumerable) \|\| (has_configurable && configurable))
	return js_mkerr(js, "Cannot redefine array length attributes");

	ant_offset_t new_len = (ant_offset_t)arr_ptr->u.array.len;
	if (has_value) {
	ant_value_t len_err = validate_array_length(js, value);
	if (is_err(len_err)) return len_err;
	new_len = (ant_offset_t)tod(value);
	}

	ant_offset_t doff = get_dense_buf(as_obj);
	if (doff) {
	ant_offset_t cap = dense_capacity(doff);
	ant_offset_t cur_len = get_array_length(js, as_obj);
	ant_offset_t clear_to = (cur_len < cap) ? cur_len : cap;
	if (new_len < clear_to) {
	for (ant_offset_t i = new_len; i < clear_to; i++) dense_set(js, doff, i, T_EMPTY);
	}
	}

	array_len_set(js, as_obj, new_len);
	return obj;
	}

	ant_offset_t existing_off = sym_key ? lkp_sym(js, as_obj, sym_off) : lkp(js, as_obj, prop_str, prop_len);
	prop_meta_t existing_sym_meta;
	bool has_existing_sym_meta = sym_key && lookup_symbol_prop_meta(as_obj, sym_off, &existing_sym_meta);
	bool has_existing_prop = (existing_off > 0) \|\| has_existing_sym_meta;
	ant_object_t *obj_ptr = js_obj_ptr(as_obj);

	if (!has_existing_prop) {
	if (obj_ptr && obj_ptr->frozen)
	return js_mkerr(js, "Cannot define property %.*s, object is not extensible", (int)prop_len, prop_str);
	if (obj_ptr && obj_ptr->sealed)
	return js_mkerr(js, "Cannot define property %.*s, object is not extensible", (int)prop_len, prop_str);
	if (obj_ptr && !obj_ptr->extensible)
	return js_mkerr(js, "Cannot define property %.*s, object is not extensible", (int)prop_len, prop_str);
	}

	if (has_existing_sym_meta) {
	if (!has_writable) writable = existing_sym_meta.writable;
	if (!has_enumerable) enumerable = existing_sym_meta.enumerable;
	if (!has_configurable) configurable = existing_sym_meta.configurable;
	} else if (existing_off > 0) {
	ant_prop_ref_t *existing_ref = propref_get(js, existing_off);
	if (existing_ref && existing_ref->obj && existing_ref->obj->shape) {
	const ant_shape_prop_t *existing_prop =
	ant_shape_prop_at(existing_ref->obj->shape, existing_ref->slot);
	if (existing_prop) {
	uint8_t existing_attrs = existing_prop->attrs;
	if (!has_writable) writable = (existing_attrs & ANT_PROP_ATTR_WRITABLE) != 0;
	if (!has_enumerable) enumerable = (existing_attrs & ANT_PROP_ATTR_ENUMERABLE) != 0;
	if (!has_configurable) configurable = (existing_attrs & ANT_PROP_ATTR_CONFIGURABLE) != 0;
	}
	}
	}

	if (has_get \|\| has_set) {
	int desc_flags =
	(enumerable ? JS_DESC_E : 0) \|
	(configurable ? JS_DESC_C : 0);

	ant_value_t getter = has_get ? propref_load(js, get_off) : js_mkundef();
	ant_value_t setter = has_set ? propref_load(js, set_off) : js_mkundef();

	if (sym_key) {
	if (has_get) js_set_sym_getter_desc(js, as_obj, prop, getter, desc_flags);
	if (has_set) js_set_sym_setter_desc(js, as_obj, prop, setter, desc_flags);
	} else {
	if (has_get && has_set) js_set_accessor_desc(js, as_obj, prop_str, prop_len, getter, setter, desc_flags);
	else if (has_get) js_set_getter_desc(js, as_obj, prop_str, prop_len, getter, desc_flags);
	else js_set_setter_desc(js, as_obj, prop_str, prop_len, setter, desc_flags);
	}
	} else {
	int desc_flags =
	(writable ? JS_DESC_W : 0) \|
	(enumerable ? JS_DESC_E : 0) \|
	(configurable ? JS_DESC_C : 0);

	uint8_t attrs = 0;
	if (writable) attrs \|= ANT_PROP_ATTR_WRITABLE;
	if (enumerable) attrs \|= ANT_PROP_ATTR_ENUMERABLE;
	if (configurable) attrs \|= ANT_PROP_ATTR_CONFIGURABLE;

	if (existing_off > 0) {
	bool is_frozen = obj_ptr ? obj_ptr->frozen : false;
	bool is_nonconfig = is_nonconfig_prop(js, existing_off) \|\| is_frozen;
	bool is_readonly = is_const_prop(js, existing_off) \|\| is_frozen;

	if (is_nonconfig) {
	if (configurable) return js_mkerr(js,
	"Cannot redefine property %.*s: cannot change configurable from false to true",
	(int)prop_len, prop_str
	);

	if (is_readonly && has_writable && writable) return js_mkerr(js,
	"Cannot redefine property %.*s: cannot change writable from false to true",
	(int)prop_len, prop_str
	);
	}

	if (is_nonconfig && is_readonly && has_value)
	return js_mkerr(js, "Cannot assign to read-only property '%.*s'", (int)prop_len, prop_str);
	if (has_value) js_saveval(js, existing_off, value);
	if (!sym_key) js_set_descriptor(js, as_obj, prop_str, prop_len, desc_flags);

	ant_prop_ref_t *ref = propref_get(js, existing_off);
	if (ref && ref->obj) {
	if (!js_obj_ensure_unique_shape(ref->obj)) return js_mkerr(js, "oom");
	if (sym_key) ant_shape_set_attrs_symbol(ref->obj->shape, sym_off, attrs);
	else ant_shape_set_attrs_interned(ref->obj->shape, intern_string(prop_str, prop_len), attrs);
	ant_shape_clear_accessor_slot(ref->obj->shape, ref->slot);
	}
	} else {
	if (!has_value) value = js_mkundef();
	ant_value_t prop_key = sym_key ? prop : js_mkstr(js, prop_str, prop_len);
	uint8_t prop_attrs = ANT_PROP_ATTR_ENUMERABLE
	\| (writable ? ANT_PROP_ATTR_WRITABLE : 0)
	\| (configurable ? ANT_PROP_ATTR_CONFIGURABLE : 0);
	mkprop(js, as_obj, prop_key, value, prop_attrs);
	if (!sym_key) js_set_descriptor(js, as_obj, prop_str, prop_len, desc_flags);

	if (obj_ptr && obj_ptr->shape) {
	if (!js_obj_ensure_unique_shape(obj_ptr)) return js_mkerr(js, "oom");
	if (sym_key) {
	ant_shape_set_attrs_symbol(obj_ptr->shape, sym_off, attrs);
	int32_t slot = ant_shape_lookup_symbol(obj_ptr->shape, sym_off);
	if (slot >= 0) ant_shape_clear_accessor_slot(obj_ptr->shape, (uint32_t)slot);
	} else {
	const char *interned = intern_string(prop_str, prop_len);
	if (interned) {
	ant_shape_set_attrs_interned(obj_ptr->shape, interned, attrs);
	int32_t slot = ant_shape_lookup_interned(obj_ptr->shape, interned);
	if (slot >= 0) ant_shape_clear_accessor_slot(obj_ptr->shape, (uint32_t)slot);
	}
	}
	}
	}
	}

	if (!sym_key) array_define_or_set_index(js, as_obj, prop_str, (size_t)prop_len);

	return obj;
	}

	typedef struct {
	bool thrown_exists;
	ant_value_t thrown_value;
	ant_value_t thrown_stack;
	} js_exception_state_t;

	static inline js_exception_state_t js_save_exception(ant_t *js) {
	js_exception_state_t saved = {
	.thrown_exists = js->thrown_exists,
	.thrown_value = js_mkundef(),
	.thrown_stack = js_mkundef(),
	};
	if (saved.thrown_exists) {
	saved.thrown_value = js->thrown_value;
	saved.thrown_stack = js->thrown_stack;
	}
	return saved;
	}

	static inline void js_restore_exception(ant_t js, const js_exception_state_t saved) {
	js->thrown_exists = saved->thrown_exists;
	js->thrown_value = saved->thrown_value;
	js->thrown_stack = saved->thrown_stack;
	}

	static ant_value_t strobj_call_custom_inspect(ant_t *js, ant_value_t obj) {
	ant_value_t inspect_sym = get_inspect_sym();
	if (vtype(inspect_sym) != T_SYMBOL) return js_mkundef();

	ant_value_t inspect_fn = lkp_sym_proto_val(js, obj, (ant_offset_t)vdata(inspect_sym));
	if (!is_callable(inspect_fn)) return js_mkundef();

	js_exception_state_t saved = js_save_exception(js);
	ant_value_t depth_arg = js_mknum((double)(MAX_STRINGIFY_DEPTH - stringify_depth));
	ant_value_t result;

	if (vtype(inspect_fn) == T_CFUNC) {
	ant_value_t saved_this = js->this_val;
	js->this_val = obj;
	result = ((ant_value_t ()(ant_t , ant_value_t *, int))vdata(inspect_fn))(js, &depth_arg, 1);
	js->this_val = saved_this;
	} else {
	result = sv_vm_call(js->vm, js, inspect_fn, obj, &depth_arg, 1, NULL, false);
	}

	if (is_err(result) \|\| js->thrown_exists \|\| vtype(result) != T_STR) {
	js_restore_exception(js, &saved);
	return js_mkundef();
	}

	js_restore_exception(js, &saved);
	return result;
	}

	ant_value_t js_define_property(ant_t *js, ant_value_t obj, ant_value_t prop, ant_value_t descriptor, bool reflect_mode) {
	js_exception_state_t saved = js_save_exception(js);
	ant_value_t args[3] = { obj, prop, descriptor };
	ant_value_t result = builtin_object_defineProperty(js, args, 3);

	if (!reflect_mode) return result;
	if (is_err(result)) {
	js_restore_exception(js, &saved);
	return js_false;
	}
	return js_true;
	}

	static ant_value_t builtin_object_defineProperties(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 2) return js_mkerr(js, "Object.defineProperties requires 2 arguments");

	ant_value_t obj = args[0];
	ant_value_t props = args[1];

	uint8_t t = vtype(obj);
	if (t != T_OBJ && t != T_ARR && t != T_FUNC) {
	return js_mkerr(js, "Object.defineProperties called on non-object");
	}

	if (vtype(props) != T_OBJ) {
	return js_mkerr(js, "Property descriptors must be an object");
	}

	ant_iter_t iter = js_prop_iter_begin(js, props);
	const char *key = NULL;
	size_t key_len = 0;
	ant_value_t descriptor = js_mkundef();

	while (js_prop_iter_next(&iter, &key, &key_len, &descriptor)) {
	if (is_internal_prop(key, key_len)) continue;
	ant_value_t prop_key = js_mkstr(js, key, key_len);
	ant_value_t define_args[3] = { obj, prop_key, descriptor };
	ant_value_t result = builtin_object_defineProperty(js, define_args, 3);
	if (is_err(result)) {
	js_prop_iter_end(&iter);
	return result;
	}
	}
	js_prop_iter_end(&iter);

	return obj;
	}

	static inline bool is_enumerable_prop(
	ant_t js, ant_value_t source, ant_object_t source_ptr,
	ant_value_t prop_key, uint32_t slot
	) {
	if (vtype(prop_key) == T_STR) {
	size_t klen = 0;

	const char *kstr = js_getstr(js, prop_key, &klen);
	if (is_internal_prop(kstr, klen)) return false;

	if (!source_ptr \|\| source_ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(js_as_obj(source), kstr, klen);
	return !desc \|\| desc->enumerable;
	}}

	return (ant_shape_get_attrs(source_ptr->shape, slot) & ANT_PROP_ATTR_ENUMERABLE) != 0;
	}

	static ant_value_t builtin_object_assign(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkerr(js, "Object.assign requires at least 1 argument");

	ant_value_t target = args[0];
	uint8_t t = vtype(target);

	if (t == T_NULL \|\| t == T_UNDEF) {
	return js_mkerr(js, "Cannot convert undefined or null to object");
	}

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) {
	target = js_mkobj(js);
	}

	ant_value_t as_obj = js_as_obj(target);

	for (int i = 1; i < nargs; i++) {
	ant_value_t source = args[i];
	uint8_t st = vtype(source);

	if (st == T_NULL \|\| st == T_UNDEF) continue;
	if (st != T_OBJ && st != T_ARR && st != T_FUNC) continue;

	ant_iter_t iter = js_prop_iter_begin(js, source);
	ant_object_t *source_ptr = js_obj_ptr(js_as_obj(source));

	ant_value_t prop_key = js_mkundef();
	ant_value_t val = js_mkundef();

	while (js_prop_iter_next_val(&iter, &prop_key, &val)) if (
	is_enumerable_prop(js, source, source_ptr, prop_key, (uint32_t)(iter.off - 1))
	) js_setprop(js, as_obj, prop_key, val);

	js_prop_iter_end(&iter);
	}

	return target;
	}

	ant_value_t builtin_object_freeze(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkundef();

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return obj;
	ant_value_t as_obj = js_as_obj(obj);

	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (!ptr \|\| !ptr->shape) return obj;
	if (!js_obj_ensure_unique_shape(ptr)) return js_mkerr(js, "oom");

	uint32_t count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop) continue;

	uint8_t attrs = ant_shape_get_attrs(ptr->shape, i);
	attrs &= (uint8_t)~ANT_PROP_ATTR_WRITABLE;
	attrs &= (uint8_t)~ANT_PROP_ATTR_CONFIGURABLE;

	if (prop->type == ANT_SHAPE_KEY_STRING) {
	const char *key = prop->key.interned;
	size_t klen = strlen(key);
	if (is_internal_prop(key, klen)) continue;
	ant_shape_set_attrs_interned(ptr->shape, key, attrs);
	} else ant_shape_set_attrs_symbol(ptr->shape, prop->key.sym_off, attrs);
	}

	ptr->frozen = 1;
	return obj;
	}

	static ant_value_t builtin_object_isFrozen(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_true;

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return js_true;
	ant_value_t as_obj = js_as_obj(obj);

	ant_object_t *ptr = js_obj_ptr(as_obj);
	return js_bool(ptr && ptr->frozen);
	}

	static ant_value_t builtin_object_seal(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkundef();

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return obj;
	ant_value_t as_obj = js_as_obj(obj);

	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (!ptr \|\| !ptr->shape) return obj;
	if (!js_obj_ensure_unique_shape(ptr)) return js_mkerr(js, "oom");
	ptr->sealed = 1;

	uint32_t count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop) continue;

	uint8_t attrs = ant_shape_get_attrs(ptr->shape, i);
	attrs &= (uint8_t)~ANT_PROP_ATTR_CONFIGURABLE;

	if (prop->type == ANT_SHAPE_KEY_STRING) {
	const char *key = prop->key.interned;
	size_t klen = strlen(key);
	if (is_internal_prop(key, klen)) continue;
	ant_shape_set_attrs_interned(ptr->shape, key, attrs);
	} else {
	ant_shape_set_attrs_symbol(ptr->shape, prop->key.sym_off, attrs);
	}
	}

	return obj;
	}

	static ant_value_t builtin_object_isSealed(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_true;

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return js_true;
	ant_value_t as_obj = js_as_obj(obj);

	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (ptr && (ptr->sealed \|\| ptr->frozen)) return js_true;

	return js_false;
	}

	static ant_value_t builtin_object_fromEntries(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkerr(js, "Object.fromEntries requires an iterable argument");

	ant_value_t iterable = args[0];
	uint8_t t = vtype(iterable);

	if (t != T_ARR && t != T_OBJ) {
	return js_mkerr(js, "Object.fromEntries requires an iterable");
	}

	ant_value_t result = js_mkobj(js);
	ant_offset_t len = get_array_length(js, iterable);
	if (len == 0) return result;

	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t entry = arr_get(js, iterable, i);
	if (vtype(entry) != T_ARR && vtype(entry) != T_OBJ) continue;

	ant_value_t key = arr_get(js, entry, 0);
	if (is_undefined(key)) continue;
	ant_value_t val = arr_get(js, entry, 1);

	if (vtype(key) != T_STR) {
	char buf[64];
	size_t n = tostr(js, key, buf, sizeof(buf));
	key = js_mkstr(js, buf, n);
	}

	js_setprop(js, result, key, val);
	}

	return result;
	}

	static ant_value_t builtin_object_getOwnPropertyDescriptor(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkundef();

	ant_value_t obj = args[0];
	ant_value_t key = args[1];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return js_mkundef();

	const char *key_str;
	ant_offset_t key_len;

	bool is_sym = (vtype(key) == T_SYMBOL);
	if (is_sym) {
	const char *d = js_sym_desc(js, key);
	key_str = d ? d : "symbol";
	key_len = (ant_offset_t)strlen(key_str);
	} else if (vtype(key) == T_STR) {
	ant_offset_t key_off = vstr(js, key, &key_len);
	key_str = (char *)(uintptr_t)(key_off);
	} else {
	char buf[64];
	size_t n = tostr(js, key, buf, sizeof(buf));
	key = js_mkstr(js, buf, n);
	ant_offset_t key_off = vstr(js, key, &key_len);
	key_str = (char *)(uintptr_t)(key_off);
	}

	ant_value_t as_obj = js_as_obj(obj);
	if (is_proxy(as_obj)) {
	return proxy_get_own_property_descriptor(js, as_obj, key);
	}

	bool is_arr_obj = array_obj_ptr(as_obj) != NULL;
	bool is_arr_length = !is_sym && is_arr_obj && is_length_key(key_str, key_len);
	bool has_arr_index = false;
	ant_value_t arr_index_val = js_mkundef();

	if (!is_sym && is_arr_obj && is_array_index(key_str, key_len)) {
	unsigned long idx;
	if (
	parse_array_index(key_str, key_len, get_array_length(js, as_obj), &idx) &&
	arr_has(js, as_obj, (ant_offset_t)idx)
	) { has_arr_index = true; arr_index_val = arr_get(js, as_obj, (ant_offset_t)idx); }
	}

	ant_offset_t sym_off = is_sym ? (ant_offset_t)vdata(key) : 0;
	prop_meta_t sym_meta; prop_meta_t str_meta;

	bool has_sym_meta = is_sym ? lookup_symbol_prop_meta(as_obj, sym_off, &sym_meta) : false;
	bool has_str_meta = is_sym ? false : lookup_string_prop_meta(js, as_obj, key_str, (size_t)key_len, &str_meta);

	ant_offset_t prop_off = is_sym ? lkp_sym(js, as_obj, sym_off) : lkp(js, as_obj, key_str, key_len);
	if (prop_off == 0 && !(is_sym ? has_sym_meta : has_str_meta) && !is_arr_length && !has_arr_index) {
	return js_mkundef();
	}

	bool has_getter = false;
	bool has_setter = false;

	ant_value_t result = js_mkobj(js);
	ant_value_t getter = js_mkundef();
	ant_value_t setter = js_mkundef();

	bool writable = true;
	bool enumerable = true;
	bool configurable = true;

	if (is_sym && has_sym_meta) {
	has_getter = sym_meta.has_getter;
	has_setter = sym_meta.has_setter;
	getter = sym_meta.getter;
	setter = sym_meta.setter;
	writable = sym_meta.writable;
	enumerable = sym_meta.enumerable;
	configurable = sym_meta.configurable;
	} else if (!is_sym && has_str_meta) {
	has_getter = str_meta.has_getter;
	has_setter = str_meta.has_setter;
	getter = str_meta.getter;
	setter = str_meta.setter;
	writable = str_meta.writable;
	enumerable = str_meta.enumerable;
	configurable = str_meta.configurable;
	}

	if (has_getter \|\| has_setter) {
	if (has_getter) js_setprop(js, result, js_mkstr(js, "get", 3), getter);
	if (has_setter) js_setprop(js, result, js_mkstr(js, "set", 3), setter);
	js_setprop(js, result, js_mkstr(js, "enumerable", 10), js_bool(enumerable));
	js_setprop(js, result, js_mkstr(js, "configurable", 12), js_bool(configurable));
	} else {
	ant_value_t prop_val = js_mkundef();
	bool has_value_out = false;
	if (prop_off != 0) {
	prop_val = propref_load(js, prop_off);
	has_value_out = true;
	} else if (has_arr_index) {
	prop_val = arr_index_val;
	has_value_out = true;
	} else if (is_arr_length) {
	prop_val = tov((double)get_array_length(js, as_obj));
	has_value_out = true;
	}
	if (has_value_out) js_setprop(js, result, js_mkstr(js, "value", 5), prop_val);
	js_setprop(js, result, js_mkstr(js, "writable", 8), js_bool(writable));
	js_setprop(js, result, js_mkstr(js, "enumerable", 10), js_bool(enumerable));
	js_setprop(js, result, js_mkstr(js, "configurable", 12), js_bool(configurable));
	}

	return result;
	}

	static inline bool own_prop_names_is_dense_shadow(
	ant_t *js, ant_value_t obj,
	const char *key, ant_offset_t key_len
	) {
	ant_offset_t doff = get_dense_buf(obj);
	if (!doff) return false;

	ant_offset_t dense_len = dense_iterable_length(js, obj);
	if (dense_len <= 0 \|\| !is_array_index(key, key_len)) return false;

	unsigned long dense_idx = 0;
	return parse_array_index(key, (size_t)key_len, dense_len, &dense_idx);
	}

	static ant_value_t builtin_object_getOwnPropertyNames(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkarr(js);
	ant_value_t obj = args[0];

	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR && vtype(obj) != T_FUNC) return mkarr(js);
	if (vtype(obj) == T_FUNC) obj = js_func_obj(obj);

	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| !ptr->shape) return mkarr(js);
	bool is_arr_obj = (vtype(obj) == T_ARR);

	ant_value_t arr = mkarr(js);
	ant_offset_t idx = 0;

	if (is_arr_obj) {
	for (ant_offset_t i = 0;; i++) {
	ant_offset_t doff = get_dense_buf(obj);
	if (!doff) break;

	ant_offset_t dense_len = dense_iterable_length(js, obj);
	if (i >= dense_len) break;

	ant_value_t v = dense_get(doff, i);
	if (is_empty_slot(v)) continue;

	char idxstr[16]; size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)i);
	arr_set(js, arr, idx++, js_mkstr(js, idxstr, idxlen));
	}}

	uint32_t count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop \|\| prop->type == ANT_SHAPE_KEY_SYMBOL) continue;
	const char *key = prop->key.interned;
	ant_offset_t klen = (ant_offset_t)strlen(key);

	if (is_internal_prop(key, klen)) continue;
	if (is_arr_obj && own_prop_names_is_dense_shadow(js, obj, key, klen)) continue;
	arr_set(js, arr, idx++, js_mkstr(js, key, (size_t)klen));
	}

	if (is_arr_obj) arr_set(js, arr, idx++, js->length_str);
	return mkval(T_ARR, vdata(arr));
	}

	static ant_value_t builtin_object_getOwnPropertySymbols(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkarr(js);
	ant_value_t obj = args[0];

	uint8_t t = vtype(obj);
	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return mkarr(js);
	if (t == T_FUNC) obj = js_func_obj(obj);

	ant_object_t *ptr = js_obj_ptr(obj);
	ant_value_t arr = mkarr(js);
	ant_offset_t idx = 0;
	if (!ptr \|\| !ptr->shape) return mkval(T_ARR, vdata(arr));

	uint32_t count = ant_shape_count(ptr->shape);
	for (uint32_t i = 0; i < count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(ptr->shape, i);
	if (!prop \|\| prop->type != ANT_SHAPE_KEY_SYMBOL) continue;
	arr_set(js, arr, idx++, mkval(T_SYMBOL, prop->key.sym_off));
	}

	return mkval(T_ARR, vdata(arr));
	}

	static ant_value_t object_add_descriptors_for_keys(
	ant_t *js,
	ant_value_t result,
	ant_value_t obj,
	ant_value_t keys
	) {
	ant_offset_t len = get_array_length(js, keys);

	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t key = arr_get(js, keys, i);
	if (vtype(key) == T_UNDEF) continue;

	ant_value_t desc_args[2] = { obj, key };
	ant_value_t desc = builtin_object_getOwnPropertyDescriptor(js, desc_args, 2);
	if (is_err(desc)) return desc;
	if (vtype(desc) == T_UNDEF) continue;

	ant_value_t set_result = js_setprop(js, result, key, desc);
	if (is_err(set_result)) return set_result;
	}

	return js_mkundef();
	}

	static ant_value_t builtin_object_getOwnPropertyDescriptors(ant_t js, ant_value_t args, int nargs) {
	ant_value_t result = js_mkobj(js);
	if (nargs == 0 \|\| vtype(args[0]) == T_NULL \|\| vtype(args[0]) == T_UNDEF) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot convert undefined or null to object");
	}

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) {
	obj = builtin_Object(js, &obj, 1);
	if (is_err(obj)) return obj;
	t = vtype(obj);
	}

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return result;
	ant_value_t names = builtin_object_getOwnPropertyNames(js, &obj, 1);
	if (is_err(names)) return names;

	ant_value_t err = object_add_descriptors_for_keys(js, result, obj, names);
	if (is_err(err)) return err;

	ant_value_t symbols = builtin_object_getOwnPropertySymbols(js, &obj, 1);
	if (is_err(symbols)) return symbols;

	err = object_add_descriptors_for_keys(js, result, obj, symbols);
	if (is_err(err)) return err;

	return result;
	}

	static ant_value_t builtin_object_isExtensible(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_true;

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return js_true;
	ant_value_t as_obj = js_as_obj(obj);

	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (!ptr) return js_true;
	if (ptr->frozen \|\| ptr->sealed) return js_false;
	return js_bool(ptr->extensible);
	}

	static ant_value_t builtin_object_preventExtensions(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkundef();

	ant_value_t obj = args[0];
	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return obj;
	ant_value_t as_obj = js_as_obj(obj);

	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (ptr) ptr->extensible = 0;
	return obj;
	}

	static ant_value_t builtin_object_hasOwnProperty(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return mkval(T_BOOL, 0);

	ant_value_t obj = js->this_val;
	ant_value_t key = args[0];

	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return mkval(T_BOOL, 0);
	ant_value_t as_obj = js_as_obj(obj);

	if (is_proxy(as_obj)) return proxy_has_own(js, as_obj, key);
	bool is_arr_obj = array_obj_ptr(as_obj) != NULL;

	if (vtype(key) == T_SYMBOL) {
	ant_offset_t sym_off = (ant_offset_t)vdata(key);
	ant_offset_t off = lkp_sym(js, as_obj, sym_off);
	if (off != 0) return mkval(T_BOOL, 1);
	prop_meta_t meta;
	return mkval(T_BOOL, lookup_symbol_prop_meta(as_obj, sym_off, &meta) ? 1 : 0);
	}

	const char *key_str = NULL;
	ant_offset_t key_len = 0;
	if (vtype(key) != T_STR) {
	char buf[64];
	size_t n = tostr(js, key, buf, sizeof(buf));
	key = js_mkstr(js, buf, n);
	}
	ant_offset_t key_off = vstr(js, key, &key_len);
	key_str = (char *)(uintptr_t)(key_off);

	if (is_arr_obj && is_length_key(key_str, key_len)) return mkval(T_BOOL, 1);
	if (is_arr_obj && is_array_index(key_str, key_len)) {
	unsigned long idx;
	if (parse_array_index(key_str, key_len, get_array_length(js, as_obj), &idx)) {
	return mkval(T_BOOL, arr_has(js, as_obj, (ant_offset_t)idx) ? 1 : 0);
	}
	}

	ant_offset_t off = lkp(js, as_obj, key_str, key_len);
	if (off != 0) return mkval(T_BOOL, 1);
	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (ptr && ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(as_obj, key_str, key_len);
	return mkval(T_BOOL, (desc && (desc->has_getter \|\| desc->has_setter)) ? 1 : 0);
	}
	return mkval(T_BOOL, 0);
	}

	static bool proto_chain_contains_cycle_safe(ant_t *js, ant_value_t start, ant_value_t target);

	bool js_is_prototype_of(ant_t *js, ant_value_t proto_obj, ant_value_t obj) {
	uint8_t obj_type = vtype(obj);
	if (obj_type != T_OBJ && obj_type != T_ARR && obj_type != T_FUNC) return false;
	uint8_t proto_type = vtype(proto_obj);
	if (proto_type != T_OBJ && proto_type != T_ARR && proto_type != T_FUNC) return false;
	ant_value_t current = get_proto(js, obj);
	return proto_chain_contains_cycle_safe(js, current, proto_obj);
	}

	ant_value_t builtin_object_isPrototypeOf(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return mkval(T_BOOL, 0);
	return mkval(T_BOOL, js_is_prototype_of(js, js->this_val, args[0]) ? 1 : 0);
	}

	static ant_value_t builtin_object_propertyIsEnumerable(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return mkval(T_BOOL, 0);

	ant_value_t obj = js->this_val;
	ant_value_t key = args[0];

	uint8_t t = vtype(obj);

	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return mkval(T_BOOL, 0);
	ant_value_t as_obj = js_as_obj(obj);
	bool is_arr_obj = array_obj_ptr(as_obj) != NULL;

	if (vtype(key) == T_SYMBOL) {
	ant_offset_t sym_off = (ant_offset_t)vdata(key);
	ant_offset_t off = lkp_sym(js, as_obj, sym_off);
	if (off == 0) return mkval(T_BOOL, 0);
	prop_meta_t meta;
	if (lookup_symbol_prop_meta(as_obj, sym_off, &meta))
	return mkval(T_BOOL, meta.enumerable ? 1 : 0);
	return mkval(T_BOOL, 1);
	}

	const char *key_str = NULL;
	ant_offset_t key_len = 0;
	if (vtype(key) != T_STR) {
	char buf[64];
	size_t n = tostr(js, key, buf, sizeof(buf));
	key = js_mkstr(js, buf, n);
	}
	ant_offset_t key_off = vstr(js, key, &key_len);
	key_str = (char *)(uintptr_t)(key_off);

	if (is_arr_obj && is_length_key(key_str, key_len)) {
	return mkval(T_BOOL, 0);
	}

	if (is_arr_obj) {
	unsigned long idx;
	if (parse_array_index(key_str, key_len, get_array_length(js, as_obj), &idx)) {
	return mkval(T_BOOL, arr_has(js, as_obj, (ant_offset_t)idx) ? 1 : 0);
	}
	}

	ant_offset_t off = lkp(js, as_obj, key_str, key_len);
	if (off == 0) return mkval(T_BOOL, 0);

	const ant_shape_prop_t *prop_meta = prop_shape_meta(js, off);
	if (prop_meta && !js_obj_ptr(as_obj)->is_exotic) {
	bool enumerable = (prop_meta->attrs & ANT_PROP_ATTR_ENUMERABLE) != 0;
	return mkval(T_BOOL, enumerable ? 1 : 0);
	}

	ant_object_t *ptr = js_obj_ptr(as_obj);
	if (ptr && ptr->is_exotic) {
	prop_meta_t meta;
	if (lookup_string_prop_meta(js, as_obj, key_str, (size_t)key_len, &meta))
	return mkval(T_BOOL, meta.enumerable ? 1 : 0);
	}
	return mkval(T_BOOL, 1);
	}

	static ant_value_t builtin_object_toString(ant_t js, ant_value_t args, int nargs) {
	(void)args; (void)nargs;
	ant_value_t obj = js->this_val;

	uint8_t t = vtype(obj);

	const char *tag = NULL;
	ant_offset_t tag_len = 0;

	ant_value_t tag_sym = get_toStringTag_sym();
	if (vtype(tag_sym) == T_SYMBOL) {
	ant_offset_t sym_off = (ant_offset_t)vdata(tag_sym);
	ant_offset_t tag_off = 0;
	if (is_object_type(obj)) {
	tag_off = lkp_sym_proto(js, obj, sym_off);
	} else {
	ant_value_t proto = get_prototype_for_type(js, t);
	if (is_object_type(proto)) {
	tag_off = lkp_sym_proto(js, proto, sym_off);
	}
	}
	if (tag_off != 0) {
	ant_value_t tag_val = propref_load(js, tag_off);
	if (vtype(tag_val) == T_STR) {
	ant_offset_t str_off = vstr(js, tag_val, &tag_len);
	tag = (const char *)(uintptr_t)(str_off);
	}
	}
	}

	if (!tag) {
	if (is_object_type(obj) && get_slot(obj, SLOT_ERROR_BRAND) == js_true) {
	tag = "Error"; tag_len = 5;
	} else switch (t) {
	case T_UNDEF: tag = "Undefined"; tag_len = 9; break;
	case T_NULL: tag = "Null"; tag_len = 4; break;
	case T_BOOL: tag = "Boolean"; tag_len = 7; break;
	case T_NUM: tag = "Number"; tag_len = 6; break;
	case T_STR: tag = "String"; tag_len = 6; break;
	case T_ARR: tag = "Array"; tag_len = 5; break;
	case T_FUNC: tag = "Function"; tag_len = 8; break;
	case T_CFUNC: tag = "Function"; tag_len = 8; break;
	case T_ERR: tag = "Error"; tag_len = 5; break;
	case T_BIGINT: tag = "BigInt"; tag_len = 6; break;
	case T_PROMISE: tag = "Promise"; tag_len = 7; break;
	case T_OBJ: tag = "Object"; tag_len = 6; break;
	default: tag = "Unknown"; tag_len = 7; break;
	}}

	char static_buf[64];
	string_builder_t sb;

	string_builder_init(&sb, static_buf, sizeof(static_buf));
	string_builder_append(&sb, "[object ", 8);
	string_builder_append(&sb, tag, tag_len);
	string_builder_append(&sb, "]", 1);

	return string_builder_finalize(js, &sb);
	}

	static ant_value_t builtin_object_valueOf(ant_t js, ant_value_t args, int nargs) {
	return js->this_val;
	}

	static ant_value_t builtin_object_toLocaleString(ant_t js, ant_value_t args, int nargs) {
	return js_call_toString(js, js->this_val);
	}

	static inline ant_value_t require_callback(ant_t js, ant_value_t args, int nargs, const char *name) {
	if (nargs == 0 \|\| !is_callable(args[0]))
	return js_mkerr(js, "%s requires a function argument", name);
	return args[0];
	}

	static ant_value_t array_shallow_copy(ant_t *js, ant_value_t arr, ant_offset_t len) {
	ant_value_t result = mkarr(js);
	if (is_err(result)) return result;

	ant_offset_t doff = get_dense_buf(arr);
	if (doff) {
	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t v = dense_get(doff, i);
	arr_set(js, result, i, v);
	}
	return result;
	}

	ant_iter_t iter = js_prop_iter_begin(js, arr);
	const char *key;
	size_t key_len;
	ant_value_t val;

	while (js_prop_iter_next(&iter, &key, &key_len, &val)) {
	if (key_len == 0 \|\| key[0] > '9' \|\| key[0] < '0') continue;
	js_mkprop_fast(js, result, key, key_len, val);
	}

	js_prop_iter_end(&iter);
	array_len_set(js, result, len);
	return result;
	}

	static ant_value_t builtin_array_push(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "push called on non-array");
	}

	if (is_proxy(arr)) {
	ant_offset_t off = lkp_interned(js, arr, js->intern.length, 6);
	ant_offset_t len = 0;
	if (off != 0) {
	ant_value_t len_val = propref_load(js, off);
	if (vtype(len_val) == T_NUM) len = (ant_offset_t) tod(len_val);
	}
	for (int i = 0; i < nargs; i++) {
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)len);
	ant_value_t key = js_mkstr(js, idxstr, idxlen);
	js_setprop(js, arr, key, args[i]);
	len++;
	}

	ant_value_t len_val = tov((double) len);
	js_setprop(js, arr, js->length_str, len_val);
	return len_val;
	}

	ant_offset_t len = get_array_length(js, arr);

	ant_offset_t doff = get_dense_buf(arr);
	if (doff) {
	for (int i = 0; i < nargs; i++) {
	ant_offset_t cap = dense_capacity(doff);
	if (len >= cap) {
	doff = dense_grow(js, arr, len + 1);
	if (doff == 0) return js_mkerr(js, "oom");
	}
	dense_set(js, doff, len, args[i]);
	len++;
	}
	array_len_set(js, arr, len);
	return tov((double) len);
	}

	for (int i = 0; i < nargs; i++) {
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)len);
	js_mkprop_fast(js, arr, idxstr, idxlen, args[i]); len++;
	}

	ant_value_t new_len = tov((double) len);
	array_len_set(js, arr, len);

	return new_len;
	}

	void js_arr_push(ant_t *js, ant_value_t arr, ant_value_t val) {
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) return;

	ant_offset_t doff = get_dense_buf(arr);
	if (doff) {
	ant_offset_t len = get_array_length(js, arr);
	ant_offset_t cap = dense_capacity(doff);
	if (len >= cap) {
	doff = dense_grow(js, arr, len + 1);
	if (doff == 0) return;
	}
	dense_set(js, doff, len, val);
	array_len_set(js, arr, len + 1);
	return;
	}

	ant_offset_t len = get_array_length(js, arr);

	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)len);
	js_mkprop_fast(js, arr, idxstr, idxlen, val);
	array_len_set(js, arr, len + 1);
	}

	static ant_value_t builtin_array_pop(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "pop called on non-array");
	}

	if (is_proxy(arr)) {
	ant_offset_t len = proxy_aware_length(js, arr);
	if (len == 0) {
	js_setprop(js, arr, js->length_str, tov(0.0));
	return js_mkundef();
	}
	len--;
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)len);
	ant_value_t result = proxy_aware_get_elem(js, arr, idxstr, idxlen);
	js_setprop(js, arr, js->length_str, tov((double) len));
	return result;
	}

	ant_offset_t doff = get_dense_buf(arr);
	if (doff) {
	ant_offset_t len = get_array_length(js, arr);
	ant_offset_t dense_len = dense_iterable_length(js, arr);
	if (len == 0) return js_mkundef();
	if (len != dense_len) goto pop_slow;
	len--;
	ant_value_t result = (len < dense_len) ? dense_get(doff, len) : js_mkundef();
	if (is_empty_slot(result)) result = js_mkundef();
	if (len < dense_len) {
	dense_set(js, doff, len, T_EMPTY);
	}
	array_len_set(js, arr, len);
	return result;
	}

	pop_slow:
	ant_offset_t len = get_array_length(js, arr);

	if (len == 0) return js_mkundef();
	len--; char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)len);

	ant_offset_t elem_off = 0;

	if (elem_off == 0) elem_off = lkp(js, arr, idxstr, idxlen);
	ant_value_t result = js_mkundef();
	if (elem_off != 0) result = propref_load(js, elem_off);

	array_len_set(js, arr, len);

	return result;
	}

	static ant_value_t builtin_array_slice(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	ant_value_t string_val = unwrap_primitive(js, arr);
	bool string_like = (vtype(string_val) == T_STR);

	if (!string_like && vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "slice called on non-array");
	}

	ant_offset_t len = 0;
	ant_offset_t string_byte_len = 0;
	ant_offset_t string_off = 0;

	if (string_like) {
	string_off = vstr(js, string_val, &string_byte_len);
	len = (ant_offset_t)utf16_strlen((const char *)(uintptr_t)string_off, string_byte_len);
	} else len = get_array_length(js, arr);

	ant_offset_t start = 0, end = len;
	double dlen = D(len);
	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	double d = tod(args[0]);
	if (d < 0) start = (ant_offset_t) (d + dlen < 0 ? 0 : d + dlen);
	else start = (ant_offset_t) (d > dlen ? dlen : d);
	}

	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	if (d < 0) end = (ant_offset_t) (d + dlen < 0 ? 0 : d + dlen);
	else end = (ant_offset_t) (d > dlen ? dlen : d);
	}

	if (start > end) start = end;
	ant_value_t result = array_alloc_like(js, arr);

	if (is_err(result)) return result;
	ant_offset_t result_idx = 0;

	for (ant_offset_t i = start; i < end; i++) {
	ant_value_t elem = js_mkundef();
	if (string_like) {
	uint32_t code_unit = utf16_code_unit_at((const char *)(uintptr_t)string_off, string_byte_len, i);
	if (code_unit == 0xFFFFFFFF) break;
	elem = js_string_from_utf16_code_unit(js, code_unit);
	} else elem = arr_get(js, arr, i);
	arr_set(js, result, result_idx, elem);
	result_idx++;
	}

	return result;
	}

	static ant_value_t builtin_array_join(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "join called on non-array");
	}
	const char *sep = ",";
	ant_offset_t sep_len = 1;

	if (nargs >= 1) {
	if (vtype(args[0]) == T_STR) {
	sep_len = 0;
	ant_offset_t sep_off = vstr(js, args[0], &sep_len);
	sep = (const char *)(uintptr_t)(sep_off);
	} else if (vtype(args[0]) != T_UNDEF) {
	const char *sep_str = js_str(js, args[0]);
	sep = sep_str;
	sep_len = (ant_offset_t) strlen(sep_str);
	}
	}

	ant_offset_t len = get_array_length(js, arr);

	if (len == 0) return js_mkstr(js, "", 0);

	size_t capacity = 1024;
	size_t result_len = 0;
	char result = (char )ant_calloc(capacity);
	if (!result) return js_mkerr(js, "oom");

	for (ant_offset_t i = 0; i < len; i++) {
	if (i > 0) {
	if (result_len + sep_len >= capacity) {
	capacity = (result_len + sep_len + 1) * 2;
	char new_result = (char )ant_realloc(result, capacity);
	if (!new_result) return js_mkerr(js, "oom");
	result = new_result;
	}
	memcpy(result + result_len, sep, sep_len);
	result_len += sep_len;
	}

	{
	ant_value_t elem = arr_get(js, arr, i);
	uint8_t et = vtype(elem);
	if (et == T_NULL \|\| et == T_UNDEF) continue;

	const char *elem_str = NULL;
	size_t elem_len = 0;
	char numstr[64];
	ant_value_t str_val = js_mkundef();

	if (et == T_STR) {
	ant_offset_t soff, slen;
	soff = vstr(js, elem, &slen);
	elem_str = (const char *)(uintptr_t)(soff);
	elem_len = slen;
	} else if (et == T_NUM) {
	snprintf(numstr, sizeof(numstr), "%g", tod(elem));
	elem_str = numstr;
	elem_len = strlen(numstr);
	} else if (et == T_BOOL) {
	elem_str = vdata(elem) ? "true" : "false";
	elem_len = strlen(elem_str);
	} else if (et == T_ARR \|\| et == T_OBJ \|\| et == T_FUNC \|\| et == T_BIGINT) {
	str_val = to_string_val(js, elem);

	if (is_err(str_val)) {
	free(result);
	return str_val;
	}

	if (vtype(str_val) == T_STR) {
	ant_offset_t soff, slen;
	soff = vstr(js, str_val, &slen);
	elem_str = (const char *)(uintptr_t)(soff);
	elem_len = slen;
	}
	}


	if (elem_str && elem_len > 0) {
	if (result_len + elem_len >= capacity) {
	capacity = (result_len + elem_len + 1) * 2;
	char new_result = (char )ant_realloc(result, capacity);
	if (!new_result) { free(result); return js_mkerr(js, "oom"); }
	result = new_result;
	}
	memcpy(result + result_len, elem_str, elem_len);
	result_len += elem_len;
	}
	}
	}

	ant_value_t ret = js_mkstr(js, result, result_len);
	free(result); return ret;
	}

	static ant_value_t builtin_array_includes(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "includes called on non-array");

	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t search = args[0];

	ant_offset_t len = get_array_length(js, arr);
	if (len == 0) return mkval(T_BOOL, 0);

	ant_offset_t start = 0;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	int s = (int) tod(args[1]);
	if (s < 0) s = (int)len + s;
	if (s < 0) s = 0;
	start = (ant_offset_t) s;
	}

	for (ant_offset_t i = start; i < len; i++) {
	ant_value_t val = arr_get(js, arr, i);
	if (vtype(val) == T_NUM && vtype(search) == T_NUM && isnan(tod(val)) && isnan(tod(search))) return mkval(T_BOOL, 1);
	if (strict_eq_values(js, val, search)) return mkval(T_BOOL, 1);
	}

	return mkval(T_BOOL, 0);
	}

	static ant_value_t builtin_array_every(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "every called on non-array");

	ant_value_t callback = require_callback(js, args, nargs, "every");
	if (is_err(callback)) return callback;
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();

	ant_offset_t len = get_array_length(js, arr);

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t val = arr_get(js, arr, i);
	ant_value_t call_args[3] = { val, tov((double)i), arr };
	ant_value_t result = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);
	if (is_err(result)) return result;
	if (!js_truthy(js, result)) return mkval(T_BOOL, 0);
	}

	return mkval(T_BOOL, 1);
	}

	static ant_value_t builtin_array_forEach(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "forEach called on non-array");

	ant_value_t callback = require_callback(js, args, nargs, "forEach");
	if (is_err(callback)) return callback;
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();

	ant_offset_t len = get_array_length(js, arr);

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t val = arr_get(js, arr, i);
	ant_value_t call_args[3] = { val, tov((double)i), arr };
	ant_value_t result = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);
	if (is_err(result)) return result;
	}

	return js_mkundef();
	}

	static ant_value_t builtin_array_reverse(ant_t js, ant_value_t args, int nargs) {
	(void)args; (void)nargs;
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "reverse called on non-array");

	if (is_proxy(arr)) {
	ant_offset_t len = proxy_aware_length(js, arr);
	if (len <= 1) return arr;
	ant_value_t read_from = proxy_read_target(js, arr);
	ant_offset_t lower = 0;
	while (lower < len / 2) {
	ant_offset_t upper_idx = len - lower - 1;
	bool lower_exists = arr_has(js, read_from, lower);
	bool upper_exists = arr_has(js, read_from, upper_idx);
	ant_value_t lower_val = lower_exists ? arr_get(js, read_from, lower) : js_mkundef();
	ant_value_t upper_val = upper_exists ? arr_get(js, read_from, upper_idx) : js_mkundef();
	if (lower_exists && upper_exists) {
	char s1[16]; size_t l1 = uint_to_str(s1, sizeof(s1), (unsigned)lower);
	js_setprop(js, arr, js_mkstr(js, s1, l1), upper_val);
	char s2[16]; size_t l2 = uint_to_str(s2, sizeof(s2), (unsigned)upper_idx);
	js_setprop(js, arr, js_mkstr(js, s2, l2), lower_val);
	} else if (upper_exists) {
	char s[16]; size_t l = uint_to_str(s, sizeof(s), (unsigned)lower);
	js_setprop(js, arr, js_mkstr(js, s, l), upper_val);
	} else if (lower_exists) {
	char s[16]; size_t l = uint_to_str(s, sizeof(s), (unsigned)upper_idx);
	js_setprop(js, arr, js_mkstr(js, s, l), lower_val);
	} lower++;
	} return arr;
	}

	ant_offset_t len = get_array_length(js, arr);
	if (len <= 1) return arr;

	ant_offset_t doff = get_dense_buf(arr);
	if (doff) {
	for (ant_offset_t i = 0; i < len / 2; i++) {
	ant_value_t a = dense_get(doff, i);
	ant_value_t b = dense_get(doff, len - 1 - i);
	dense_set(js, doff, i, b);
	dense_set(js, doff, len - 1 - i, a);
	}
	return arr;
	}

	for (ant_offset_t lower = 0; lower < len / 2; lower++) {
	ant_offset_t upper = len - lower - 1;
	bool lower_exists = arr_has(js, arr, lower);
	bool upper_exists = arr_has(js, arr, upper);
	ant_value_t lower_val = lower_exists ? arr_get(js, arr, lower) : js_mkundef();
	ant_value_t upper_val = upper_exists ? arr_get(js, arr, upper) : js_mkundef();

	if (lower_exists && upper_exists) {
	arr_set(js, arr, lower, upper_val);
	arr_set(js, arr, upper, lower_val);
	} else if (upper_exists) {
	arr_set(js, arr, lower, upper_val);
	arr_del(js, arr, upper);
	} else if (lower_exists) {
	arr_set(js, arr, upper, lower_val);
	arr_del(js, arr, lower);
	}
	}
	return arr;
	}

	static ant_value_t builtin_array_map(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "map called on non-array");

	ant_value_t callback = require_callback(js, args, nargs, "map");
	if (is_err(callback)) return callback;
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();

	ant_offset_t len = get_array_length(js, arr);
	ant_value_t result = array_alloc_like(js, arr);
	if (is_err(result)) return result;

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t val = arr_get(js, arr, i);
	ant_value_t call_args[3] = { val, tov((double)i), arr };
	ant_value_t mapped = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);
	if (is_err(mapped)) return mapped;
	arr_set(js, result, i, mapped);
	}

	return result;
	}

	static ant_value_t builtin_array_filter(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "filter called on non-array");

	ant_value_t callback = require_callback(js, args, nargs, "filter");
	if (is_err(callback)) return callback;
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();

	ant_offset_t len = get_array_length(js, arr);
	ant_value_t result = array_alloc_like(js, arr);
	if (is_err(result)) return result;

	ant_offset_t result_idx = 0;

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t val = arr_get(js, arr, i);
	ant_value_t call_args[3] = { val, tov((double)i), arr };
	ant_value_t test = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);

	if (is_err(test)) return test;
	if (js_truthy(js, test)) { arr_set(js, result, result_idx, val); result_idx++; }
	}

	return result;
	}

	static ant_value_t builtin_array_reduce(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "reduce called on non-array");

	ant_value_t callback = require_callback(js, args, nargs, "reduce");
	if (is_err(callback)) return callback;
	bool has_initial = (nargs >= 2);

	ant_offset_t len = get_array_length(js, arr);

	ant_value_t accumulator = has_initial ? args[1] : js_mkundef();
	bool first = !has_initial;

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t val = arr_get(js, arr, i);
	if (first) { accumulator = val; first = false; continue; }
	ant_value_t call_args[4] = { accumulator, val, tov((double)i), arr };
	accumulator = sv_vm_call(js->vm, js, callback, js_mkundef(), call_args, 4, NULL, false);
	if (is_err(accumulator)) return accumulator;
	}

	if (first) return js_mkerr(js, "reduce of empty array with no initial value");
	return accumulator;
	}

	static inline void flat_helper(ant_t js, ant_value_t arr, ant_value_t result, ant_offset_t result_idx, int depth) {
	ant_offset_t len = get_array_length(js, arr);
	if (len == 0) return;

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t val = arr_get(js, arr, i);

	if (depth > 0 && vtype(val) == T_ARR) flat_helper(js, val, result, result_idx, depth - 1);
	else { arr_set(js, result, result_idx, val); (result_idx)++; }
	}
	}

	static ant_value_t builtin_array_flat(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "flat called on non-array");
	}

	int depth = 1;
	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	depth = (int) tod(args[0]);
	if (depth < 0) depth = 0;
	}

	ant_value_t result = array_alloc_like(js, arr);
	if (is_err(result)) return result;
	ant_offset_t result_idx = 0;

	flat_helper(js, arr, result, &result_idx, depth);
	return result;
	}

	static ant_value_t builtin_array_concat(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "concat called on non-array");
	}

	ant_value_t result = array_alloc_like(js, arr);
	if (is_err(result)) return result;

	ant_offset_t result_idx = 0;
	for (int a = -1; a < nargs; a++) {
	ant_value_t arg = (a < 0) ? arr : args[a];
	bool spreadable = false;

	if (vtype(arg) == T_ARR \|\| vtype(arg) == T_OBJ) {
	bool array_default_spreadable = (vtype(arg) == T_ARR);
	if (!array_default_spreadable && is_proxy(arg)) {
	ant_value_t target = proxy_read_target(js, arg);
	array_default_spreadable = (vtype(target) == T_ARR);
	}

	ant_value_t spread_val = js_get_sym(js, arg, get_isConcatSpreadable_sym());
	if (is_err(spread_val)) return spread_val;
	if (vtype(spread_val) == T_UNDEF) spreadable = array_default_spreadable;
	else spreadable = js_truthy(js, spread_val);
	}

	if (spreadable) {
	ant_offset_t arg_len = 0;
	ant_value_t len_val = js_get(js, arg, "length");
	if (is_err(len_val)) return len_val;
	if (vtype(len_val) == T_NUM && tod(len_val) > 0) arg_len = (ant_offset_t)tod(len_val);

	for (ant_offset_t i = 0; i < arg_len; i++) {
	char idxstr[32];
	uint_to_str(idxstr, sizeof(idxstr), (uint64_t)i);
	ant_value_t elem = js_get(js, arg, idxstr);
	if (is_err(elem)) return elem;
	arr_set(js, result, result_idx, elem);
	result_idx++;
	}
	} else {
	arr_set(js, result, result_idx, arg);
	result_idx++;
	}
	}

	return result;
	}

	static ant_value_t builtin_array_at(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "at called on non-array");
	}

	if (nargs == 0 \|\| vtype(args[0]) != T_NUM) return js_mkundef();

	ant_offset_t len = get_array_length(js, arr);

	int idx = (int) tod(args[0]);
	if (idx < 0) idx = (int)len + idx;
	if (idx < 0 \|\| (ant_offset_t)idx >= len) return js_mkundef();

	return arr_get(js, arr, (ant_offset_t)idx);
	}

	static ant_value_t builtin_array_fill(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "fill called on non-array");
	}

	ant_value_t value = nargs >= 1 ? args[0] : js_mkundef();

	ant_offset_t len = proxy_aware_length(js, arr);

	ant_offset_t start = 0, end = len;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	int s = (int) tod(args[1]);
	if (s < 0) s = (int)len + s;
	if (s < 0) s = 0;
	start = (ant_offset_t) s;
	}
	if (nargs >= 3 && vtype(args[2]) == T_NUM) {
	int e = (int) tod(args[2]);
	if (e < 0) e = (int)len + e;
	if (e < 0) e = 0;
	end = (ant_offset_t) e;
	}
	if (start > len) start = len;
	if (end > len) end = len;

	for (ant_offset_t i = start; i < end; i++) {
	arr_set(js, arr, i, value);
	}

	return arr;
	}

	static ant_value_t array_find_impl(ant_t js, ant_value_t args, int nargs, bool return_index, const char *name) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "%s called on non-array", name);

	ant_value_t callback = require_callback(js, args, nargs, name);
	if (is_err(callback)) return callback;
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();

	ant_offset_t len = get_array_length(js, arr);
	if (len == 0) return return_index ? tov(-1) : js_mkundef();

	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t val = arr_get(js, arr, i);

	ant_value_t call_args[3] = { val, tov((double)i), arr };
	ant_value_t result = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);

	if (is_err(result)) return result;
	if (js_truthy(js, result)) return return_index ? tov((double)i) : val;
	}

	return return_index ? tov(-1) : js_mkundef();
	}

	static ant_value_t builtin_array_find(ant_t js, ant_value_t args, int nargs) {
	return array_find_impl(js, args, nargs, false, "find");
	}

	static ant_value_t builtin_array_findIndex(ant_t js, ant_value_t args, int nargs) {
	return array_find_impl(js, args, nargs, true, "findIndex");
	}

	static ant_value_t array_find_last_impl(ant_t js, ant_value_t args, int nargs, bool return_index, const char *name) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "%s called on non-array", name);

	ant_value_t callback = require_callback(js, args, nargs, name);
	if (is_err(callback)) return callback;
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();

	ant_offset_t len = get_array_length(js, arr);
	if (len == 0) return return_index ? tov(-1) : js_mkundef();

	for (ant_offset_t i = len; i > 0; i--) {
	ant_value_t val = arr_get(js, arr, i - 1);

	ant_value_t call_args[3] = { val, tov((double)(i - 1)), arr };
	ant_value_t result = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);

	if (is_err(result)) return result;
	if (js_truthy(js, result)) return return_index ? tov((double)(i - 1)) : val;
	}

	return return_index ? tov(-1) : js_mkundef();
	}

	static ant_value_t builtin_array_findLast(ant_t js, ant_value_t args, int nargs) {
	return array_find_last_impl(js, args, nargs, false, "findLast");
	}

	static ant_value_t builtin_array_findLastIndex(ant_t js, ant_value_t args, int nargs) {
	return array_find_last_impl(js, args, nargs, true, "findLastIndex");
	}

	static ant_value_t builtin_array_flatMap(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "flatMap called on non-array");
	}
	if (nargs == 0 \|\| vtype(args[0]) != T_FUNC) {
	return js_mkerr(js, "flatMap requires a function argument");
	}

	ant_value_t callback = args[0];
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();
	ant_offset_t len = get_array_length(js, arr);

	ant_value_t result = mkarr(js);
	if (is_err(result)) return result;
	ant_offset_t result_idx = 0;

	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t elem = arr_get(js, arr, i);
	ant_value_t call_args[3] = { elem, tov((double)i), arr };
	ant_value_t mapped = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);
	if (is_err(mapped)) return mapped;
	if (vtype(mapped) == T_ARR) flat_helper(js, mapped, result, &result_idx, 0);
	else arr_set(js, result, result_idx++, mapped);
	}

	return mkval(T_ARR, vdata(result));
	}

	static const char js_tostring(ant_t js, ant_value_t v) {
	if (vtype(v) == T_STR) {
	ant_offset_t slen, off = vstr(js, v, &slen);
	return (const char *)(uintptr_t)(off);
	}
	return js_str(js, v);
	}

	static int js_compare_values(ant_t *js, ant_value_t a, ant_value_t b, ant_value_t compareFn) {
	uint8_t t = vtype(compareFn);
	if (t == T_FUNC \|\| t == T_CFUNC) {
	ant_value_t call_args[2] = { a, b };
	ant_value_t result = sv_vm_call(js->vm, js, compareFn, js_mkundef(), call_args, 2, NULL, false);
	if (vtype(result) == T_NUM) return (int)tod(result);
	return 0;
	}

	if (vtype(a) == T_STR && vtype(b) == T_STR) {
	ant_offset_t len_a, len_b;
	const char sa = (const char )(uintptr_t)(vstr(js, a, &len_a));
	const char sb = (const char )(uintptr_t)(vstr(js, b, &len_b));
	return strcmp(sa, sb);
	}

	const char *sa = js_tostring(js, a);
	size_t len = strlen(sa);

	char *copy = alloca(len + 1);
	memcpy(copy, sa, len + 1);

	return strcmp(copy, js_tostring(js, b));
	}

	static ant_value_t builtin_array_indexOf(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "indexOf called on non-array");
	}
	if (nargs == 0) return tov(-1);

	ant_value_t search = args[0];
	ant_offset_t len = get_array_length(js, arr);

	ant_offset_t start = 0;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	int s = (int) tod(args[1]);
	if (s < 0) s = (int)len + s;
	if (s < 0) s = 0;
	start = (ant_offset_t) s;
	}

	for (ant_offset_t i = start; i < len; i++) {
	ant_value_t elem = arr_get(js, arr, i);
	if (vtype(elem) == T_UNDEF && !arr_has(js, arr, i)) continue;
	if (strict_eq_values(js, elem, search)) return tov((double)i);
	}
	return tov(-1);
	}

	static ant_value_t builtin_array_lastIndexOf(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "lastIndexOf called on non-array");
	}
	if (nargs == 0) return tov(-1);

	ant_value_t search = args[0];
	ant_offset_t len = get_array_length(js, arr);

	int start = (int)len - 1;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	start = (int) tod(args[1]);
	if (start < 0) start = (int)len + start;
	}
	if (start >= (int)len) start = (int)len - 1;

	for (int i = start; i >= 0; i--) {
	ant_value_t elem = arr_get(js, arr, (ant_offset_t)i);
	if (vtype(elem) == T_UNDEF && !arr_has(js, arr, (ant_offset_t)i)) continue;
	if (strict_eq_values(js, elem, search)) return tov((double)i);
	}
	return tov(-1);
	}

	static ant_value_t builtin_array_reduceRight(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "reduceRight called on non-array");
	}
	if (nargs == 0 \|\| vtype(args[0]) != T_FUNC) {
	return js_mkerr(js, "reduceRight requires a function argument");
	}

	ant_value_t callback = args[0];
	ant_offset_t len = get_array_length(js, arr);

	int start_idx = (int)len - 1;
	ant_value_t accumulator;

	if (nargs >= 2) {
	accumulator = args[1];
	} else {
	if (len == 0) return js_mkerr(js, "reduceRight of empty array with no initial value");
	accumulator = arr_get(js, arr, len - 1);
	start_idx = (int)len - 2;
	}

	for (int i = start_idx; i >= 0; i--) {
	ant_value_t elem = arr_get(js, arr, (ant_offset_t)i);
	ant_value_t call_args[4] = { accumulator, elem, tov((double)i), arr };
	accumulator = sv_vm_call(js->vm, js, callback, js_mkundef(), call_args, 4, NULL, false);
	if (is_err(accumulator)) return accumulator;
	}

	return accumulator;
	}

	static ant_value_t builtin_array_shift(ant_t js, ant_value_t args, int nargs) {
	(void) args;
	(void) nargs;
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "shift called on non-array");
	}

	ant_offset_t len = proxy_aware_length(js, arr);
	if (len == 0) return js_mkundef();

	ant_offset_t doff = get_dense_buf(arr);
	if (doff && !is_proxy(arr)) {
	ant_offset_t d_len = dense_iterable_length(js, arr);
	if (len != d_len) goto shift_slow;
	if (d_len == 0) return js_mkundef();
	ant_value_t *d = dense_data(doff);
	if (!d) return js_mkundef();
	ant_value_t first = dense_get(doff, 0);
	if (is_empty_slot(first)) first = js_mkundef();
	memmove(&d[0], &d[1], sizeof(ant_value_t) * (size_t)(d_len - 1));
	dense_set(js, doff, d_len - 1, T_EMPTY);
	array_len_set(js, arr, len - 1);
	return first;
	}

	shift_slow:
	ant_value_t read_from = is_proxy(arr) ? proxy_read_target(js, arr) : arr;
	ant_value_t first = arr_get(js, read_from, 0);

	for (ant_offset_t i = 1; i < len; i++) {
	if (arr_has(js, read_from, i)) {
	ant_value_t elem = arr_get(js, read_from, i);
	char dst[16];
	size_t dstlen = uint_to_str(dst, sizeof(dst), (unsigned)(i - 1));
	js_setprop(js, arr, js_mkstr(js, dst, dstlen), elem);
	}
	}

	if (array_obj_ptr(arr)) array_len_set(js, arr, len - 1);
	else js_setprop(js, arr, js->length_str, tov((double)(len - 1)));

	return first;
	}

	static ant_value_t builtin_array_unshift(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "unshift called on non-array");
	}

	ant_offset_t len = proxy_aware_length(js, arr);

	ant_offset_t doff = get_dense_buf(arr);
	if (doff && !is_proxy(arr)) {
	ant_offset_t d_len = dense_iterable_length(js, arr);
	if (len != d_len) goto unshift_slow;
	ant_offset_t new_len = len + nargs;
	ant_offset_t cap = dense_capacity(doff);
	if (new_len > cap) {
	doff = dense_grow(js, arr, new_len);
	if (doff == 0) return js_mkerr(js, "oom");
	}
	ant_value_t *d = dense_data(doff);
	if (!d) return js_mkerr(js, "oom");
	memmove(&d[nargs], &d[0], sizeof(ant_value_t) * (size_t)d_len);
	for (int i = 0; i < nargs; i++)
	dense_set(js, doff, (ant_offset_t)i, args[i]);
	array_len_set(js, arr, new_len);
	return tov((double) new_len);
	}

	unshift_slow:
	ant_value_t read_from = is_proxy(arr) ? proxy_read_target(js, arr) : arr;

	for (int i = (int)len - 1; i >= 0; i--) {
	if (arr_has(js, read_from, (ant_offset_t)i)) {
	ant_value_t elem = arr_get(js, read_from, (ant_offset_t)i);
	char dst[16];
	size_t dstlen = uint_to_str(dst, sizeof(dst), (unsigned)(i + nargs));
	js_setprop(js, arr, js_mkstr(js, dst, dstlen), elem);
	}
	}

	for (int i = 0; i < nargs; i++) {
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)i);
	ant_value_t key = js_mkstr(js, idxstr, idxlen);
	js_setprop(js, arr, key, args[i]);
	}

	ant_offset_t new_len = len + nargs;
	if (array_obj_ptr(arr)) array_len_set(js, arr, new_len);
	else js_setprop(js, arr, js->length_str, tov((double) new_len));

	return tov((double) new_len);
	}

	static ant_value_t builtin_array_some(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "some called on non-array");

	ant_value_t callback = require_callback(js, args, nargs, "some");
	if (is_err(callback)) return callback;
	ant_value_t this_arg = (nargs >= 2) ? args[1] : js_mkundef();

	ant_offset_t len = get_array_length(js, arr);
	if (len == 0) return mkval(T_BOOL, 0);

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t val = arr_get(js, arr, i);

	ant_value_t call_args[3] = { val, tov((double)i), arr };
	ant_value_t result = sv_vm_call(js->vm, js, callback, this_arg, call_args, 3, NULL, false);

	if (is_err(result)) return result;
	if (js_truthy(js, result)) return mkval(T_BOOL, 1);
	}

	return mkval(T_BOOL, 0);
	}

	static ant_value_t builtin_array_sort(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	ant_value_t compareFn = js_mkundef();

	ant_value_t result = arr;
	ant_value_t vals = NULL, keys = NULL, temp_vals = NULL, temp_keys = NULL;
	ant_offset_t count = 0, undef_count = 0, len = 0;

	gc_temp_root_scope_t temp_scope = {0};
	bool temp_scope_active = false;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "sort called on non-array");

	if (nargs >= 1) {
	uint8_t t = vtype(args[0]);
	if (t == T_FUNC \|\| t == T_CFUNC) compareFn = args[0];
	else if (t != T_UNDEF) return js_mkerr_typed(js, JS_ERR_TYPE, "compareFn must be a function or undefined");
	}

	gc_temp_root_scope_begin(js, &temp_scope);
	temp_scope_active = true;

	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_scope, arr))) goto oom;
	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_scope, compareFn))) goto oom;

	len = get_array_length(js, arr);
	if (len == 0) goto done;

	ant_offset_t doff = get_dense_buf(arr);
	if (doff) {
	vals = malloc(len * sizeof(ant_value_t));
	if (!vals) goto oom;
	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t v = dense_get(doff, i);
	if (is_empty_slot(v) \|\| vtype(v) == T_UNDEF) undef_count++;
	else vals[count++] = v;
	}
	} else {
	vals = malloc(len * sizeof(ant_value_t));
	if (!vals) goto oom;

	for (ant_offset_t i = 0; i < len; i++) {
	if (!arr_has(js, arr, i)) continue;
	ant_value_t v = arr_get(js, arr, i);
	if (vtype(v) == T_UNDEF) undef_count++;
	else vals[count++] = v;
	}
	}
	if (count <= 1) goto writeback;
	for (ant_offset_t i = 0; i < count; i++) {
	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_scope, vals[i]))) goto oom;
	}

	bool use_keys = (vtype(compareFn) == T_UNDEF);
	if (use_keys) {
	keys = malloc(count * sizeof(ant_value_t));
	if (!keys) goto oom;
	for (ant_offset_t i = 0; i < count; i++) {
	const char *s = js_tostring(js, vals[i]);
	ant_value_t key = js_mkstr(js, s, strlen(s));
	if (is_err(key)) {
	result = key;
	goto done;
	}
	keys[i] = key;
	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_scope, key))) goto oom;
	}
	}

	temp_vals = malloc(count * sizeof(ant_value_t));
	if (use_keys) temp_keys = malloc(count * sizeof(ant_value_t));
	if (!temp_vals \|\| (use_keys && !temp_keys)) goto oom;

	for (ant_offset_t width = 1; width < count; width *= 2) {
	for (ant_offset_t left = 0; left < count; left += width * 2) {
	ant_offset_t mid = left + width;
	ant_offset_t right = (mid + width < count) ? mid + width : count;
	if (mid >= count) break;

	ant_offset_t i = left, j = mid, k = 0;
	while (i < mid && j < right) {
	int cmp;
	if (use_keys) {
	ant_offset_t len_a, len_b;
	const char sa = (const char )(uintptr_t)(vstr(js, keys[i], &len_a));
	const char sb = (const char )(uintptr_t)(vstr(js, keys[j], &len_b));
	cmp = strcmp(sa, sb);
	} else {
	cmp = js_compare_values(js, vals[i], vals[j], compareFn);
	}
	if (cmp <= 0) {
	temp_vals[k] = vals[i];
	if (use_keys) temp_keys[k] = keys[i];
	k++; i++;
	} else {
	temp_vals[k] = vals[j];
	if (use_keys) temp_keys[k] = keys[j];
	k++; j++;
	}
	}
	while (i < mid) {
	temp_vals[k] = vals[i];
	if (use_keys) temp_keys[k] = keys[i];
	k++; i++;
	}
	while (j < right) {
	temp_vals[k] = vals[j];
	if (use_keys) temp_keys[k] = keys[j];
	k++; j++;
	}

	memcpy(&vals[left], temp_vals, k * sizeof(ant_value_t));
	if (use_keys) memcpy(&keys[left], temp_keys, k * sizeof(ant_value_t));
	}
	}

	writeback:
	if (doff) {
	for (ant_offset_t i = 0; i < count; i++) dense_set(js, doff, i, vals[i]);
	for (ant_offset_t i = count; i < count + undef_count; i++) dense_set(js, doff, i, js_mkundef());
	for (ant_offset_t i = count + undef_count; i < len; i++) dense_set(js, doff, i, T_EMPTY);
	} else {
	ant_offset_t out = 0;
	for (; out < count; out++) arr_set(js, arr, out, vals[out]);
	for (ant_offset_t i = 0; i < undef_count; i++, out++) arr_set(js, arr, out, js_mkundef());
	for (; out < len; out++) arr_del(js, arr, out);
	}
	result = arr;
	goto done;

	oom:
	result = js_mkerr(js, "out of memory");

	done:
	if (temp_scope_active) gc_temp_root_scope_end(&temp_scope);
	free(temp_keys);
	free(temp_vals);
	free(keys);
	free(vals);

	return result;
	}

	static ant_value_t builtin_array_splice(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "splice called on non-array");
	}

	ant_offset_t len = proxy_aware_length(js, arr);
	ant_value_t read_from = is_proxy(arr) ? proxy_read_target(js, arr) : arr;

	int start = 0;
	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	start = (int) tod(args[0]);
	if (start < 0) start = (int)len + start;
	if (start < 0) start = 0;
	if (start > (int)len) start = (int)len;
	}

	int deleteCount = (int)len - start;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	deleteCount = (int) tod(args[1]);
	if (deleteCount < 0) deleteCount = 0;
	if (deleteCount > (int)len - start) deleteCount = (int)len - start;
	}

	int insertCount = nargs > 2 ? nargs - 2 : 0;

	ant_value_t removed = array_alloc_like(js, arr);
	if (is_err(removed)) return removed;

	ant_offset_t doff = get_dense_buf(arr);
	if (doff && !is_proxy(arr)) {
	ant_offset_t d_len = dense_iterable_length(js, arr);
	if (d_len != len) goto splice_slow;
	for (int i = 0; i < deleteCount; i++) {
	ant_value_t elem = arr_get(js, arr, (ant_offset_t)(start + i));
	arr_set(js, removed, (ant_offset_t)i, elem);
	}

	int shift = insertCount - deleteCount;
	ant_offset_t new_len = (ant_offset_t)((int)d_len + shift);

	if (shift != 0) {
	if (new_len > dense_capacity(doff)) {
	doff = dense_grow(js, arr, new_len);
	if (doff == 0) return js_mkerr(js, "oom");
	}
	ant_offset_t move_start = (ant_offset_t)(start + deleteCount);
	ant_offset_t move_dest = (ant_offset_t)(start + insertCount);
	ant_offset_t move_count = d_len - move_start;
	ant_value_t *d = dense_data(doff);
	if (!d) return js_mkerr(js, "oom");
	if (move_count > 0) memmove(&d[move_dest], &d[move_start], sizeof(ant_value_t) * (size_t)move_count);
	}

	for (int i = 0; i < insertCount; i++)
	dense_set(js, doff, (ant_offset_t)(start + i), args[2 + i]);

	if (shift < 0) {
	for (ant_offset_t i = new_len; i < d_len; i++)
	dense_set(js, doff, i, T_EMPTY);
	}

	array_len_set(js, arr, new_len);
	return removed;
	}

	splice_slow:
	for (int i = 0; i < deleteCount; i++) {
	char src[16], dst[16];
	snprintf(src, sizeof(src), "%u", (unsigned)(start + i));
	snprintf(dst, sizeof(dst), "%u", (unsigned) i);
	ant_offset_t elem_off = lkp(js, read_from, src, strlen(src));
	if (elem_off != 0) {
	ant_value_t elem = propref_load(js, elem_off);
	ant_value_t key = js_mkstr(js, dst, strlen(dst));
	js_setprop(js, removed, key, elem);
	}
	}

	js_setprop(js, removed, js->length_str, tov((double) deleteCount));
	int shift = insertCount - deleteCount;

	if (shift > 0) {
	for (int i = (int)len - 1; i >= start + deleteCount; i--) {
	char src[16], dst[16];
	snprintf(src, sizeof(src), "%u", (unsigned) i);
	snprintf(dst, sizeof(dst), "%u", (unsigned)(i + shift));
	ant_offset_t elem_off = lkp(js, read_from, src, strlen(src));
	ant_value_t elem = elem_off ? propref_load(js, elem_off) : js_mkundef();
	ant_value_t key = js_mkstr(js, dst, strlen(dst));
	js_setprop(js, arr, key, elem);
	}
	} else if (shift < 0) {
	for (int i = start + deleteCount; i < (int)len; i++) {
	char src[16], dst[16];
	snprintf(src, sizeof(src), "%u", (unsigned) i);
	snprintf(dst, sizeof(dst), "%u", (unsigned)(i + shift));
	ant_offset_t elem_off = lkp(js, read_from, src, strlen(src));
	ant_value_t elem = elem_off ? propref_load(js, elem_off) : js_mkundef();
	ant_value_t key = js_mkstr(js, dst, strlen(dst));
	js_setprop(js, arr, key, elem);
	}
	}

	for (int i = 0; i < insertCount; i++) {
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)(start + i));
	ant_value_t key = js_mkstr(js, idxstr, idxlen);
	js_setprop(js, arr, key, args[2 + i]);
	}

	if (array_obj_ptr(arr)) array_len_set(js, arr, (ant_offset_t)((int)len + shift));
	else js_setprop(js, arr, js->length_str, tov((double)((int)len + shift)));

	return removed;
	}

	static ant_value_t builtin_array_copyWithin(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	ant_value_t result = arr;
	gc_temp_root_scope_t temp_roots = {0};

	bool temp_roots_active = false;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "copyWithin called on non-array");
	}

	ant_offset_t len = proxy_aware_length(js, arr);
	ant_value_t read_from = is_proxy(arr) ? proxy_read_target(js, arr) : arr;

	int target = 0, start = 0, end = (int)len;
	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	target = (int) tod(args[0]);
	if (target < 0) target = (int)len + target;
	if (target < 0) target = 0;
	}
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	start = (int) tod(args[1]);
	if (start < 0) start = (int)len + start;
	if (start < 0) start = 0;
	}
	if (nargs >= 3 && vtype(args[2]) == T_NUM) {
	end = (int) tod(args[2]);
	if (end < 0) end = (int)len + end;
	if (end < 0) end = 0;
	}

	if (end > (int)len) end = (int)len;
	int count = end - start;
	if (count > (int)len - target) count = (int)len - target;
	if (count <= 0) return arr;

	ant_offset_t doff = get_dense_buf(arr);
	if (doff && !is_proxy(arr)) {
	if (start < target) {
	for (int i = count - 1; i >= 0; i--) {
	ant_value_t v = dense_get(doff, (ant_offset_t)(start + i));
	dense_set(js, doff, (ant_offset_t)(target + i), is_empty_slot(v) ? js_mkundef() : v);
	}
	} else {
	for (int i = 0; i < count; i++) {
	ant_value_t v = dense_get(doff, (ant_offset_t)(start + i));
	dense_set(js, doff, (ant_offset_t)(target + i), is_empty_slot(v) ? js_mkundef() : v);
	}
	}
	return arr;
	}

	ant_value_t temp = (ant_value_t )malloc(count * sizeof(ant_value_t));
	if (!temp) return js_mkerr(js, "out of memory");
	gc_temp_root_scope_begin(js, &temp_roots);
	temp_roots_active = true;

	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_roots, arr))) goto oom;
	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_roots, read_from))) goto oom;

	for (int i = 0; i < count; i++) {
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)(start + i));
	ant_offset_t elem_off = lkp(js, read_from, idxstr, idxlen);
	temp[i] = elem_off ? propref_load(js, elem_off) : js_mkundef();
	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_roots, temp[i]))) goto oom;
	}

	for (int i = 0; i < count; i++) {
	char idxstr[16];
	size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)(target + i));
	ant_value_t key = js_mkstr(js, idxstr, idxlen);
	if (is_err(key)) {
	result = key;
	goto done;
	}
	if (!gc_temp_root_handle_valid(gc_temp_root_add(&temp_roots, key))) goto oom;
	ant_value_t set_result = js_setprop(js, arr, key, temp[i]);
	if (is_err(set_result)) {
	result = set_result;
	goto done;
	}
	}

	done:
	if (temp_roots_active) gc_temp_root_scope_end(&temp_roots);
	free(temp);
	return result;

	oom:
	result = js_mkerr(js, "out of memory");
	goto done;
	}

	static ant_value_t builtin_array_toSorted(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "toSorted called on non-array");

	ant_value_t result = array_shallow_copy(js, arr, get_array_length(js, arr));
	if (is_err(result)) return result;

	ant_value_t saved_this = js->this_val;
	js->this_val = result;
	ant_value_t sorted = builtin_array_sort(js, args, nargs);
	js->this_val = saved_this;

	if (is_err(sorted)) return sorted;
	return mkval(T_ARR, vdata(result));
	}

	static ant_value_t builtin_array_toReversed(ant_t js, ant_value_t args, int nargs) {
	(void)args; (void)nargs;
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "toReversed called on non-array");

	ant_value_t result = array_shallow_copy(js, arr, get_array_length(js, arr));
	if (is_err(result)) return result;

	ant_value_t saved_this = js->this_val;
	js->this_val = result;
	ant_value_t reversed = builtin_array_reverse(js, NULL, 0);
	js->this_val = saved_this;

	if (is_err(reversed)) return reversed;
	return mkval(T_ARR, vdata(result));
	}

	static ant_value_t builtin_array_toSpliced(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ)
	return js_mkerr(js, "toSpliced called on non-array");

	ant_value_t result = array_shallow_copy(js, arr, get_array_length(js, arr));
	if (is_err(result)) return result;

	ant_value_t saved_this = js->this_val;
	js->this_val = result;
	builtin_array_splice(js, args, nargs);
	js->this_val = saved_this;

	return mkval(T_ARR, vdata(result));
	}

	static ant_value_t builtin_array_with(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "with called on non-array");
	}

	if (nargs < 2) return js_mkerr(js, "with requires index and value arguments");

	ant_offset_t len = get_array_length(js, arr);

	int idx = (int) tod(args[0]);
	if (idx < 0) idx = (int)len + idx;
	if (idx < 0 \|\| (ant_offset_t)idx >= len) return js_mkerr(js, "Invalid index");

	ant_value_t result = mkarr(js);
	if (is_err(result)) return result;

	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t elem = ((ant_offset_t)idx == i) ? args[1] : arr_get(js, arr, i);
	arr_set(js, result, i, elem);
	}

	return mkval(T_ARR, vdata(result));
	}

	static ant_value_t builtin_array_keys(ant_t js, ant_value_t args, int nargs) {
	if (vtype(js->this_val) != T_ARR && vtype(js->this_val) != T_OBJ)
	return js_mkerr(js, "keys called on non-array");
	return make_array_iterator(js, js->this_val, ARR_ITER_KEYS);
	}

	static ant_value_t builtin_array_values(ant_t js, ant_value_t args, int nargs) {
	if (vtype(js->this_val) != T_ARR && vtype(js->this_val) != T_OBJ)
	return js_mkerr(js, "values called on non-array");
	return make_array_iterator(js, js->this_val, ARR_ITER_VALUES);
	}

	static ant_value_t builtin_array_entries(ant_t js, ant_value_t args, int nargs) {
	if (vtype(js->this_val) != T_ARR && vtype(js->this_val) != T_OBJ)
	return js_mkerr(js, "entries called on non-array");
	return make_array_iterator(js, js->this_val, ARR_ITER_ENTRIES);
	}

	static ant_value_t builtin_array_toString(ant_t js, ant_value_t args, int nargs) {
	ant_value_t arr = js->this_val;
	ant_value_t join_result;

	if (js_try_call_method(js, arr, "join", NULL, 0, &join_result)) {
	if (is_err(join_result)) return join_result;
	return join_result;
	}

	return builtin_object_toString(js, args, nargs);
	}

	static ant_value_t builtin_array_toLocaleString(ant_t js, ant_value_t args, int nargs) {
	(void) args;
	(void) nargs;
	ant_value_t arr = js->this_val;
	if (vtype(arr) != T_ARR) return js_mkerr(js, "toLocaleString called on non-array");

	ant_offset_t len = get_array_length(js, arr);
	if (len == 0) return js_mkstr(js, "", 0);

	char *result = NULL;
	size_t result_len = 0, result_cap = 256;
	result = (char *)ant_calloc(result_cap);
	if (!result) return js_mkerr(js, "oom");

	for (ant_offset_t i = 0; i < len; i++) {
	if (i > 0) {
	if (result_len + 1 >= result_cap) {
	result_cap *= 2;
	char new_result = (char )ant_calloc(result_cap);
	if (!new_result) { free(result); return js_mkerr(js, "oom"); }
	memcpy(new_result, result, result_len);
	free(result);
	result = new_result;
	}
	result[result_len++] = ',';
	}

	if (!arr_has(js, arr, i)) continue;
	ant_value_t elem = arr_get(js, arr, i);
	if (vtype(elem) == T_NULL \|\| vtype(elem) == T_UNDEF) continue;

	char buf[64];
	size_t elem_len = tostr(js, elem, buf, sizeof(buf));

	if (result_len + elem_len >= result_cap) {
	while (result_len + elem_len >= result_cap) result_cap *= 2;
	char new_result = (char )ant_calloc(result_cap);
	if (!new_result) { free(result); return js_mkerr(js, "oom"); }
	memcpy(new_result, result, result_len);
	free(result);
	result = new_result;
	}
	memcpy(result + result_len, buf, elem_len);
	result_len += elem_len;
	}

	ant_value_t ret = js_mkstr(js, result, result_len);
	free(result);
	return ret;
	}

	static ant_value_t builtin_Array_isArray(ant_t js, ant_value_t args, int nargs) {
	(void) js;
	if (nargs == 0) return mkval(T_BOOL, 0);
	return mkval(T_BOOL, vtype(args[0]) == T_ARR ? 1 : 0);
	}

	typedef struct {
	ant_value_t write_target;
	ant_value_t result;
	ant_value_t mapFn;
	ant_value_t mapThis;
	ant_offset_t index;
	} array_from_iter_ctx_t;

	static iter_action_t array_from_iter_cb(ant_t js, ant_value_t value, void ctx, ant_value_t *out) {
	array_from_iter_ctx_t fctx = (array_from_iter_ctx_t )ctx;
	ant_value_t elem = value;

	if (is_callable(fctx->mapFn)) {
	ant_value_t call_args[2] = { elem, tov((double)fctx->index) };
	elem = sv_vm_call(js->vm, js, fctx->mapFn, fctx->mapThis, call_args, 2, NULL, false);
	if (is_err(elem)) { *out = elem; return ITER_ERROR; }
	}

	if (vtype(fctx->write_target) == T_ARR) arr_set(js, fctx->write_target, fctx->index, elem);
	else {
	char idxstr[16]; size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)fctx->index);
	js_setprop(js, fctx->write_target, js_mkstr(js, idxstr, idxlen), elem);
	}

	fctx->index++;
	return ITER_CONTINUE;
	}

	static ant_value_t builtin_Array_from(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return mkarr(js);

	ant_value_t src = args[0];
	ant_value_t mapFn = (nargs >= 2 && is_callable(args[1])) ? args[1] : js_mkundef();
	ant_value_t mapThis = (nargs >= 3) ? args[2] : js_mkundef();

	ant_value_t ctor = js->this_val;
	bool use_ctor = (vtype(ctor) == T_FUNC \|\| vtype(ctor) == T_CFUNC);
	ant_value_t result = use_ctor ? array_alloc_from_ctor_with_length(js, ctor, 0) : mkarr(js);
	if (is_err(result)) return result;

	bool result_is_proxy = is_proxy(result);
	ant_value_t write_target = result_is_proxy ? proxy_read_target(js, result) : result;
	ant_value_t iter_sym = get_iterator_sym();

	if (vtype(src) == T_STR) {
	if (str_is_heap_rope(src) \|\| str_is_heap_builder(src)) {
	src = str_materialize(js, src);
	if (is_err(src)) return src;
	}
	ant_offset_t slen = str_len_fast(js, src);
	array_from_iter_ctx_t ctx = { write_target, result, mapFn, mapThis, 0 };
	for (ant_offset_t i = 0; i < slen; ) {
	ant_offset_t off = vstr(js, src, NULL);
	utf8proc_int32_t cp;
	ant_offset_t cb_len = (ant_offset_t)utf8_next(
	(const utf8proc_uint8_t *)(uintptr_t)(off + i),
	(utf8proc_ssize_t)(slen - i),
	&cp
	);
	ant_value_t ch = js_mkstr(js, (const void *)(uintptr_t)(off + i), cb_len);

	ant_value_t out;
	iter_action_t act = array_from_iter_cb(js, ch, &ctx, &out);

	if (act == ITER_ERROR) return out;
	i += cb_len;
	}
	if (vtype(result) != T_ARR) js_setprop(js, result, js->length_str, tov((double)ctx.index));
	} else if (vtype(src) == T_ARR) {
	ant_offset_t iter_off = (vtype(iter_sym) == T_SYMBOL) ? lkp_sym_proto(js, src, (ant_offset_t)vdata(iter_sym)) : 0;
	bool default_iter = iter_off != 0 && vtype(propref_load(js, iter_off)) == T_CFUNC;

	if (default_iter) {
	array_from_iter_ctx_t ctx = { write_target, result, mapFn, mapThis, 0 };
	ant_offset_t len = get_array_length(js, src);
	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t unused;
	iter_action_t act = array_from_iter_cb(js, arr_get(js, src, i), &ctx, &unused);
	if (act == ITER_ERROR) return unused;
	}
	if (vtype(result) != T_ARR) js_setprop(js, result, js->length_str, tov((double)len));
	} else {
	array_from_iter_ctx_t ctx = { write_target, result, mapFn, mapThis, 0 };
	ant_value_t iter_result = iter_foreach(js, src, array_from_iter_cb, &ctx);
	if (is_err(iter_result)) return iter_result;
	if (vtype(result) != T_ARR) js_setprop(js, result, js->length_str, tov((double)ctx.index));
	}
	} else {
	ant_offset_t iter_prop = (vtype(iter_sym) == T_SYMBOL) ? lkp_sym_proto(js, src, (ant_offset_t)vdata(iter_sym)) : 0;

	if (iter_prop != 0) {
	array_from_iter_ctx_t ctx = { write_target, result, mapFn, mapThis, 0 };
	ant_value_t iter_result = iter_foreach(js, src, array_from_iter_cb, &ctx);
	if (is_err(iter_result)) return iter_result;
	if (vtype(result) != T_ARR) js_setprop(js, result, js->length_str, tov((double)ctx.index));
	} else if (vtype(src) == T_OBJ) {
	array_from_iter_ctx_t ctx = { write_target, result, mapFn, mapThis, 0 };
	ant_offset_t len = get_array_length(js, src);
	for (ant_offset_t i = 0; i < len; i++) {
	ant_value_t unused;
	iter_action_t act = array_from_iter_cb(js, arr_get(js, src, i), &ctx, &unused);
	if (act == ITER_ERROR) return unused;
	}
	if (vtype(result) != T_ARR) js_setprop(js, result, js->length_str, tov((double)len));
	}
	}

	if (!use_ctor) return mkval(T_ARR, vdata(result));
	return result;
	}

	static ant_value_t builtin_Array_of(ant_t js, ant_value_t args, int nargs) {
	ant_value_t ctor = js->this_val;
	bool use_ctor = (vtype(ctor) == T_FUNC \|\| vtype(ctor) == T_CFUNC);
	ant_value_t arr = use_ctor ? array_alloc_from_ctor_with_length(js, ctor, (ant_offset_t)nargs) : mkarr(js);
	if (is_err(arr)) return arr;

	bool arr_is_proxy = is_proxy(arr);
	ant_value_t write_target = arr_is_proxy ? proxy_read_target(js, arr) : arr;

	for (int i = 0; i < nargs; i++) {
	if (vtype(write_target) == T_ARR) arr_set(js, write_target, (ant_offset_t)i, args[i]);
	else {
	char idxstr[16]; size_t idxlen = uint_to_str(idxstr, sizeof(idxstr), (unsigned)i);
	js_setprop(js, write_target, js_mkstr(js, idxstr, idxlen), args[i]);
	}
	}

	if (vtype(arr) != T_ARR) js_setprop(js, arr, js->length_str, tov((double) nargs));
	if (!use_ctor) return mkval(T_ARR, vdata(arr));

	return arr;
	}

	static ant_value_t builtin_string_indexOf(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "indexOf called on non-string");
	if (nargs == 0) return tov(-1);

	ant_value_t search = args[0];
	if (vtype(search) != T_STR) return tov(-1);

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	ant_offset_t search_len, search_off = vstr(js, search, &search_len);

	const char str_ptr = (char )(uintptr_t)(str_off);
	const char search_ptr = (char )(uintptr_t)(search_off);
	size_t utf16_len = utf16_strlen(str_ptr, str_len);

	ant_offset_t start_utf16 = 0;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double pos = tod(args[1]);
	if (pos < 0) pos = 0;
	if (pos > D(utf16_len)) pos = D(utf16_len);
	start_utf16 = (ant_offset_t) pos;
	}

	if (search_len == 0) return tov(D(start_utf16));

	size_t byte_start = 0;
	if (start_utf16 > 0) {
	int off = utf16_index_to_byte_offset(str_ptr, str_len, start_utf16, NULL);
	if (off < 0) return tov(-1);
	byte_start = (size_t)off;
	}

	if (byte_start + search_len > (size_t)str_len) return tov(-1);

	for (size_t i = byte_start; i <= (size_t)str_len - search_len; i++) {
	if (memcmp(str_ptr + i, search_ptr, search_len) == 0)
	return tov(D(byte_offset_to_utf16(str_ptr, i)));
	}
	return tov(-1);
	}

	static ant_value_t builtin_string_substring(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "substring called on non-string");
	ant_offset_t byte_len, str_off = vstr(js, str, &byte_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	size_t utf16_len = utf16_strlen(str_ptr, byte_len);
	ant_offset_t start = 0, end = (ant_offset_t)utf16_len;
	double dstr_len2 = D(utf16_len);

	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	double d = tod(args[0]);
	start = (ant_offset_t) (d < 0 ? 0 : (d > dstr_len2 ? dstr_len2 : d));
	}

	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	end = (ant_offset_t) (d < 0 ? 0 : (d > dstr_len2 ? dstr_len2 : d));
	}

	if (start > end) {
	ant_offset_t tmp = start;
	start = end;
	end = tmp;
	}

	size_t byte_start, byte_end;
	utf16_range_to_byte_range(str_ptr, byte_len, start, end, &byte_start, &byte_end);
	return js_mkstr(js, str_ptr + byte_start, byte_end - byte_start);
	}

	static ant_value_t builtin_string_substr(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "substr called on non-string");
	ant_offset_t byte_len, str_off = vstr(js, str, &byte_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	size_t utf16_len = utf16_strlen(str_ptr, byte_len);

	if (nargs < 1) return js_mkstr(js, str_ptr, byte_len);

	double d_start = tod(args[0]);
	ant_offset_t start;
	if (d_start < 0) {
	start = (ant_offset_t)((double)utf16_len + d_start);
	if ((int)start < 0) start = 0;
	} else {
	start = (ant_offset_t)d_start;
	}
	if (start > (ant_offset_t)utf16_len) start = (ant_offset_t)utf16_len;

	ant_offset_t len = (ant_offset_t)utf16_len - start;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	if (d < 0) d = 0;
	len = (ant_offset_t)d;
	}
	if (start + len > (ant_offset_t)utf16_len) len = (ant_offset_t)utf16_len - start;

	size_t byte_start, byte_end;
	utf16_range_to_byte_range(str_ptr, byte_len, start, start + len, &byte_start, &byte_end);
	return js_mkstr(js, str_ptr + byte_start, byte_end - byte_start);
	}

	static ant_value_t string_split_impl(ant_t js, ant_value_t str, ant_value_t args, int nargs) {
	if (vtype(str) != T_STR) return js_mkerr(js, "split called on non-string");
	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	ant_value_t arr = mkarr(js);

	if (is_err(arr)) return arr;

	uint32_t limit = UINT32_MAX;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	if (d >= 0 && d <= UINT32_MAX) {
	limit = (uint32_t)d;
	}
	}
	if (limit == 0) {
	return mkval(T_ARR, vdata(arr));
	}
	if (nargs == 0) goto return_whole;

	ant_value_t sep_arg = args[0];
	if (vtype(sep_arg) == T_OBJ) {
	ant_offset_t source_off = lkp(js, sep_arg, "source", 6);
	if (source_off == 0) goto return_whole;
	ant_value_t source_val = propref_load(js, source_off);
	if (vtype(source_val) != T_STR) goto return_whole;

	ant_offset_t plen, poff = vstr(js, source_val, &plen);
	const char pattern_ptr = (char )(uintptr_t)(poff);

	if (plen == 0 \|\| (plen == 4 && memcmp(pattern_ptr, "(?:)", 4) == 0)) {
	ant_offset_t idx = 0;
	for (ant_offset_t i = 0; i < str_len && idx < limit; i++) {
	ant_value_t part = js_mkstr(js, str_ptr + i, 1);
	arr_set(js, arr, idx, part);
	idx++;
	}
	return mkval(T_ARR, vdata(arr));
	}

	char pcre2_pattern[512];
	size_t pcre2_len = js_to_pcre2_pattern(pattern_ptr, plen, pcre2_pattern, sizeof(pcre2_pattern), false);

	uint32_t options = PCRE2_UTF \| PCRE2_UCP \| PCRE2_MATCH_UNSET_BACKREF;
	int errcode;
	PCRE2_SIZE erroffset;
	pcre2_code *re = pcre2_compile((PCRE2_SPTR)pcre2_pattern, pcre2_len, options, &errcode, &erroffset, NULL);
	if (re == NULL) goto return_whole;

	pcre2_match_data *match_data = pcre2_match_data_create_from_pattern(re, NULL);
	uint32_t capture_count;
	pcre2_pattern_info(re, PCRE2_INFO_CAPTURECOUNT, &capture_count);

	if (str_len == 0) {
	int rc = pcre2_match(re, (PCRE2_SPTR)str_ptr, 0, 0, 0, match_data, NULL);
	if (rc >= 0) {
	pcre2_match_data_free(match_data);
	pcre2_code_free(re);
	return mkval(T_ARR, vdata(arr));
	}
	}

	ant_offset_t idx = 0;
	PCRE2_SIZE search_pos = 0;
	PCRE2_SIZE segment_start = 0;
	PCRE2_SIZE last_match_end = (PCRE2_SIZE)-1;
	bool had_any_split = false;

	while (idx < limit && search_pos <= str_len) {
	int rc = pcre2_match(re, (PCRE2_SPTR)str_ptr, str_len, search_pos, 0, match_data, NULL);
	if (rc < 0) break;

	PCRE2_SIZE *ovector = pcre2_get_ovector_pointer(match_data);
	PCRE2_SIZE match_start = ovector[0];
	PCRE2_SIZE match_end = ovector[1];

	if (match_start == match_end && match_start == last_match_end) {
	search_pos = match_end + 1;
	continue;
	}

	if (match_start == match_end && capture_count > 0) {
	bool is_pure_empty_capture = true;
	for (uint32_t i = 1; i <= capture_count; i++) {
	PCRE2_SIZE cap_start = ovector[2*i];
	PCRE2_SIZE cap_end = ovector[2*i+1];
	if (cap_start == PCRE2_UNSET \|\| cap_end != cap_start) {
	is_pure_empty_capture = false;
	break;
	}
	}
	if (is_pure_empty_capture) {
	search_pos = match_end + 1;
	continue;
	}
	}

	had_any_split = true;

	ant_value_t part = js_mkstr(js, str_ptr + segment_start, match_start - segment_start);
	arr_set(js, arr, idx, part);
	idx++;

	for (uint32_t i = 1; i <= capture_count && idx < limit; i++) {
	PCRE2_SIZE cap_start = ovector[2*i];
	PCRE2_SIZE cap_end = ovector[2*i+1];
	if (cap_start == PCRE2_UNSET) {
	arr_set(js, arr, idx, js_mkundef());
	} else {
	part = js_mkstr(js, str_ptr + cap_start, cap_end - cap_start);
	arr_set(js, arr, idx, part);
	}
	idx++;
	}

	last_match_end = match_end;
	segment_start = match_end;
	if (match_start == match_end) {
	search_pos = match_end + 1;
	} else {
	search_pos = match_end;
	}
	}

	if (!had_any_split) {
	pcre2_match_data_free(match_data);
	pcre2_code_free(re);
	arr_set(js, arr, 0, js_mkstr(js, str_ptr, str_len));
	return mkval(T_ARR, vdata(arr));
	}

	if (idx < limit) {
	ant_value_t part = js_mkstr(js, str_ptr + segment_start, str_len - segment_start);
	arr_set(js, arr, idx, part);
	idx++;
	}

	pcre2_match_data_free(match_data);
	pcre2_code_free(re);
	return mkval(T_ARR, vdata(arr));
	}

	if (vtype(sep_arg) != T_STR) goto return_whole;

	ant_offset_t sep_len, sep_off = vstr(js, sep_arg, &sep_len);
	const char sep_ptr = (char )(uintptr_t)(sep_off);
	ant_offset_t idx = 0, start = 0;

	if (sep_len == 0) {
	for (ant_offset_t i = 0; i < str_len && idx < limit; i++) {
	ant_value_t part = js_mkstr(js, str_ptr + i, 1);
	arr_set(js, arr, idx, part);
	idx++;
	}
	return mkval(T_ARR, vdata(arr));
	}

	for (ant_offset_t i = 0; i + sep_len <= str_len && idx < limit; i++) {
	if (memcmp(str_ptr + i, sep_ptr, sep_len) != 0) continue;
	ant_value_t part = js_mkstr(js, str_ptr + start, i - start);
	arr_set(js, arr, idx, part);
	idx++;
	start = i + sep_len;
	i += sep_len - 1;
	}
	if (idx < limit && start <= str_len) {
	ant_value_t part = js_mkstr(js, str_ptr + start, str_len - start);
	arr_set(js, arr, idx, part);
	idx++;
	}

	return mkval(T_ARR, vdata(arr));

	return_whole:
	if (limit > 0) {
	arr_set(js, arr, 0, str);
	}
	return mkval(T_ARR, vdata(arr));
	}

	static ant_value_t builtin_string_split(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "split called on non-string");

	if (nargs > 0 && is_object_type(args[0])) {
	bool called = false;
	ant_value_t call_args[2];
	int call_nargs = 1;
	call_args[0] = str;
	if (nargs >= 2) {
	call_args[1] = args[1];
	call_nargs = 2;
	}
	ant_value_t dispatched = maybe_call_symbol_method(
	js, args[0], get_split_sym(), args[0], call_args, call_nargs, &called
	);
	if (is_err(dispatched)) return dispatched;
	if (called) return dispatched;
	}

	return string_split_impl(js, str, args, nargs);
	}

	static ant_value_t builtin_string_slice(ant_t js, ant_value_t args, int nargs) {
	ant_value_t this_unwrapped = unwrap_primitive(js, js->this_val);
	ant_value_t str = js_tostring_val(js, this_unwrapped);
	if (is_err(str)) return str;

	ant_offset_t byte_len, str_off = vstr(js, str, &byte_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	size_t utf16_len = utf16_strlen(str_ptr, byte_len);
	ant_offset_t start = 0, end = (ant_offset_t)utf16_len;
	double dstr_len = D(utf16_len);

	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	double d = tod(args[0]);
	if (d < 0) {
	start = (ant_offset_t) (d + dstr_len < 0 ? 0 : d + dstr_len);
	} else start = (ant_offset_t) (d > dstr_len ? dstr_len : d);
	}

	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	if (d < 0) {
	end = (ant_offset_t) (d + dstr_len < 0 ? 0 : d + dstr_len);
	} else end = (ant_offset_t) (d > dstr_len ? dstr_len : d);
	}

	if (start > end) start = end;
	size_t byte_start, byte_end;
	utf16_range_to_byte_range(str_ptr, byte_len, start, end, &byte_start, &byte_end);
	return js_mkstr(js, str_ptr + byte_start, byte_end - byte_start);
	}

	static ant_value_t builtin_string_includes(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "includes called on non-string");
	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t search = args[0];

	if (is_object_type(search)) {
	ant_value_t maybe_err = reject_regexp_arg(js, search, "includes");
	if (is_err(maybe_err)) return maybe_err;
	}
	search = js_tostring_val(js, search);
	if (is_err(search)) return search;

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	ant_offset_t search_len, search_off = vstr(js, search, &search_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	const char search_ptr = (char )(uintptr_t)(search_off);

	ant_offset_t start = 0;
	if (nargs >= 2) {
	double pos = tod(args[1]);
	if (isnan(pos) \|\| pos < 0) pos = 0;
	if (pos > D(str_len)) return mkval(T_BOOL, 0);
	start = (ant_offset_t) pos;
	}

	if (search_len == 0) return mkval(T_BOOL, 1);
	if (start + search_len > str_len) return mkval(T_BOOL, 0);
	for (ant_offset_t i = start; i <= str_len - search_len; i++) {
	if (memcmp(str_ptr + i, search_ptr, search_len) == 0) return mkval(T_BOOL, 1);
	}

	return mkval(T_BOOL, 0);
	}

	static ant_value_t builtin_string_startsWith(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "startsWith called on non-string");
	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t search = args[0];

	if (is_object_type(search)) {
	ant_value_t maybe_err = reject_regexp_arg(js, search, "startsWith");
	if (is_err(maybe_err)) return maybe_err;
	}
	search = js_tostring_val(js, search);
	if (is_err(search)) return search;

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	ant_offset_t search_len, search_off = vstr(js, search, &search_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	const char search_ptr = (char )(uintptr_t)(search_off);

	if (search_len > str_len) return mkval(T_BOOL, 0);
	if (search_len == 0) return mkval(T_BOOL, 1);

	return mkval(T_BOOL, memcmp(str_ptr, search_ptr, search_len) == 0 ? 1 : 0);
	}

	static ant_value_t builtin_string_endsWith(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "endsWith called on non-string");
	if (nargs == 0) return mkval(T_BOOL, 0);
	ant_value_t search = args[0];

	if (is_object_type(search)) {
	ant_value_t maybe_err = reject_regexp_arg(js, search, "endsWith");
	if (is_err(maybe_err)) return maybe_err;
	}
	search = js_tostring_val(js, search);
	if (is_err(search)) return search;

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	ant_offset_t search_len, search_off = vstr(js, search, &search_len);

	const char str_ptr = (char )(uintptr_t)(str_off);
	const char search_ptr = (char )(uintptr_t)(search_off);

	if (search_len > str_len) return mkval(T_BOOL, 0);
	if (search_len == 0) return mkval(T_BOOL, 1);

	return mkval(T_BOOL, memcmp(str_ptr + str_len - search_len, search_ptr, search_len) == 0 ? 1 : 0);
	}

	static ant_value_t builtin_string_template(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "template called on non-string");
	if (nargs < 1 \|\| vtype(args[0]) != T_OBJ) return str;

	ant_value_t data = args[0];
	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);

	size_t result_cap = str_len + 256;
	size_t result_len = 0;
	char result = (char )ant_calloc(result_cap);
	if (!result) return js_mkerr(js, "oom");
	ant_offset_t i = 0;

	#define ENSURE_CAP(need) do { \
	if (result_len + (need) >= result_cap) { \
	result_cap = (result_len + (need) + 1) * 2; \
	char nr = (char )ant_realloc(result, result_cap); \
	if (!nr) return js_mkerr(js, "oom"); \
	result = nr; \
	} \
	} while(0)

	while (i < str_len) {
	if (i < str_len - 3 && str_ptr[i] == '{' && str_ptr[i + 1] == '{') {
	ant_offset_t start = i + 2;
	ant_offset_t end = start;
	while (end < str_len - 1 && !(str_ptr[end] == '}' && str_ptr[end + 1] == '}')) {
	end++;
	}
	if (end < str_len - 1 && str_ptr[end] == '}' && str_ptr[end + 1] == '}') {
	ant_offset_t key_len = end - start;
	ant_offset_t prop_off = lkp(js, data, str_ptr + start, key_len);

	if (prop_off != 0) {
	ant_value_t value = propref_load(js, prop_off);
	if (vtype(value) == T_STR) {
	ant_offset_t val_len, val_off = vstr(js, value, &val_len);
	ENSURE_CAP(val_len);
	memcpy(result + result_len, (const void *)(uintptr_t)val_off, val_len);
	result_len += val_len;
	} else if (vtype(value) == T_NUM) {
	char numstr[32];
	snprintf(numstr, sizeof(numstr), "%g", tod(value));
	size_t num_len = strlen(numstr);
	ENSURE_CAP(num_len);
	memcpy(result + result_len, numstr, num_len);
	result_len += num_len;
	} else if (vtype(value) == T_BOOL) {
	const char *boolstr = vdata(value) ? "true" : "false";
	size_t bool_len = strlen(boolstr);
	ENSURE_CAP(bool_len);
	memcpy(result + result_len, boolstr, bool_len);
	result_len += bool_len;
	}
	}
	i = end + 2;
	continue;
	}
	}
	ENSURE_CAP(1);
	result[result_len++] = str_ptr[i++];
	}
	ant_value_t ret = js_mkstr(js, result, result_len);
	free(result);
	return ret;
	#undef ENSURE_CAP
	}

	static ant_value_t builtin_string_charCodeAt(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "charCodeAt called on non-string");

	double idx_d = nargs < 1 ? 0.0 : js_to_number(js, args[0]);
	if (isnan(idx_d)) idx_d = 0.0;
	if (isinf(idx_d) \|\| idx_d > (double)LONG_MAX) return tov(JS_NAN);

	long idx_l = (long) idx_d;
	if (idx_l < 0) return tov(JS_NAN);

	ant_offset_t byte_len; ant_offset_t str_off = vstr(js, str, &byte_len);
	const char str_data = (const char )(uintptr_t)(str_off);

	uint32_t code_unit = utf16_code_unit_at(str_data, byte_len, idx_l);
	if (code_unit == 0xFFFFFFFF) return tov(JS_NAN);

	return tov((double) code_unit);
	}

	static ant_value_t builtin_string_codePointAt(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "codePointAt called on non-string");

	double idx_d = nargs < 1 ? 0.0 : js_to_number(js, args[0]);
	if (isnan(idx_d)) idx_d = 0.0;
	if (isinf(idx_d) \|\| idx_d > (double)LONG_MAX) return js_mkundef();

	long idx_l = (long) idx_d;
	if (idx_l < 0) return js_mkundef();

	ant_offset_t byte_len;
	ant_offset_t str_off = vstr(js, str, &byte_len);
	const char str_data = (const char )(uintptr_t)(str_off);

	uint32_t cp = utf16_codepoint_at(str_data, byte_len, idx_l);
	if (cp == 0xFFFFFFFF) return js_mkundef();

	return tov((double) cp);
	}

	static ant_value_t builtin_string_toLowerCase(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "toLowerCase called on non-string");

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	if (str_len == 0) return js_mkstr(js, "", 0);

	const utf8proc_uint8_t src = (const utf8proc_uint8_t )str_ptr;
	utf8proc_ssize_t src_len = (utf8proc_ssize_t)str_len;

	ant_offset_t out_len = 0;
	utf8proc_ssize_t pos = 0;

	while (pos < src_len) {
	utf8proc_int32_t cp;
	utf8proc_ssize_t n = utf8_next(src + pos, src_len - pos, &cp);
	if (cp < 0) { out_len++; pos++; continue; }
	utf8proc_uint8_t tmp[4];
	out_len += (ant_offset_t)utf8proc_encode_char(utf8proc_tolower(cp), tmp);
	pos += n;
	}

	ant_value_t result = js_mkstr(js, NULL, out_len);
	if (is_err(result)) return result;

	ant_offset_t result_len, result_off = vstr(js, result, &result_len);
	char result_ptr = (char )(uintptr_t)(result_off);
	uint8_t ascii_state = STR_ASCII_YES;

	pos = 0;
	ant_offset_t wpos = 0;

	while (pos < src_len) {
	utf8proc_int32_t cp;
	utf8proc_ssize_t n = utf8_next(src + pos, src_len - pos, &cp);

	if (cp < 0) {
	unsigned char byte = src[pos];
	if (byte >= 0x80) ascii_state = STR_ASCII_NO;
	result_ptr[wpos++] = (char)byte;
	pos++; continue;
	}

	utf8proc_int32_t mapped = utf8proc_tolower(cp);
	if (mapped >= 0x80) ascii_state = STR_ASCII_NO;

	wpos += (ant_offset_t)utf8proc_encode_char(mapped, (utf8proc_uint8_t *)(result_ptr + wpos));
	pos += n;
	}

	str_set_ascii_state(result_ptr, ascii_state);
	return result;
	}

	static ant_value_t builtin_string_toUpperCase(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "toUpperCase called on non-string");

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	if (str_len == 0) return js_mkstr(js, "", 0);

	const utf8proc_uint8_t src = (const utf8proc_uint8_t )str_ptr;
	utf8proc_ssize_t src_len = (utf8proc_ssize_t)str_len;

	ant_offset_t out_len = 0;
	utf8proc_ssize_t pos = 0;

	while (pos < src_len) {
	utf8proc_int32_t cp;
	utf8proc_ssize_t n = utf8_next(src + pos, src_len - pos, &cp);
	if (cp < 0) { out_len++; pos++; continue; }
	utf8proc_uint8_t tmp[4];
	out_len += (ant_offset_t)utf8proc_encode_char(utf8proc_toupper(cp), tmp);
	pos += n;
	}

	ant_value_t result = js_mkstr(js, NULL, out_len);
	if (is_err(result)) return result;

	ant_offset_t result_len, result_off = vstr(js, result, &result_len);
	char result_ptr = (char )(uintptr_t)(result_off);
	uint8_t ascii_state = STR_ASCII_YES;

	pos = 0;
	ant_offset_t wpos = 0;

	while (pos < src_len) {
	utf8proc_int32_t cp;
	utf8proc_ssize_t n = utf8_next(src + pos, src_len - pos, &cp);

	if (cp < 0) {
	unsigned char byte = src[pos];
	if (byte >= 0x80) ascii_state = STR_ASCII_NO;
	result_ptr[wpos++] = (char)byte;
	pos++; continue;
	}

	utf8proc_int32_t mapped = utf8proc_toupper(cp);
	if (mapped >= 0x80) ascii_state = STR_ASCII_NO;

	wpos += (ant_offset_t)utf8proc_encode_char(mapped, (utf8proc_uint8_t *)(result_ptr + wpos));
	pos += n;
	}

	str_set_ascii_state(result_ptr, ascii_state);
	return result;
	}

	static ant_value_t builtin_string_trim(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "trim called on non-string");

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);

	ant_offset_t start = 0, end = str_len;
	while (start < end && is_space(str_ptr[start])) start++;
	while (end > start && is_space(str_ptr[end - 1])) end--;

	return js_mkstr(js, str_ptr + start, end - start);
	}

	static ant_value_t builtin_string_trimStart(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "trimStart called on non-string");

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);

	ant_offset_t start = 0;
	while (start < str_len && is_space(str_ptr[start])) start++;

	return js_mkstr(js, str_ptr + start, str_len - start);
	}

	static ant_value_t builtin_string_trimEnd(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "trimEnd called on non-string");

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);

	ant_offset_t end = str_len;
	while (end > 0 && is_space(str_ptr[end - 1])) end--;

	return js_mkstr(js, str_ptr, end);
	}

	static ant_value_t builtin_string_repeat(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "repeat called on non-string");
	if (nargs < 1 \|\| vtype(args[0]) != T_NUM) return js_mkerr(js, "repeat count required");

	double count_d = tod(args[0]);
	if (count_d < 0 \|\| count_d != (double)(long)count_d) return js_mkerr(js, "invalid repeat count");
	ant_offset_t count = (ant_offset_t) count_d;

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);

	if (count == 0 \|\| str_len == 0) return js_mkstr(js, "", 0);

	ant_value_t result = js_mkstr(js, NULL, str_len * count);
	if (is_err(result)) return result;

	ant_offset_t result_len, result_off = vstr(js, result, &result_len);
	char result_ptr = (char )(uintptr_t)(result_off);

	for (ant_offset_t i = 0; i < count; i++) {
	memcpy(result_ptr + i * str_len, str_ptr, str_len);
	}
	str_set_ascii_state(
	result_ptr,
	str_is_ascii(str_ptr) ? STR_ASCII_YES : STR_ASCII_NO
	);

	return result;
	}

	static ant_value_t builtin_string_padStart(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "padStart called on non-string");
	if (nargs < 1 \|\| vtype(args[0]) != T_NUM) return str;

	ant_offset_t target_len = (ant_offset_t)tod(args[0]);
	if (target_len <= 0) return str;
	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	size_t str_utf16_len = utf16_strlen(str_ptr, (size_t)str_len);

	if ((size_t)target_len <= str_utf16_len) return str;

	ant_value_t pad_val = js_mkstr(js, " ", 1);
	if (nargs >= 2 && vtype(args[1]) != T_UNDEF) {
	pad_val = coerce_to_str(js, args[1]);
	if (is_err(pad_val)) return pad_val;
	}
	ant_offset_t pad_len, pad_off = vstr(js, pad_val, &pad_len);
	const char pad_str = (char )(uintptr_t)(pad_off);
	size_t pad_utf16_len = utf16_strlen(pad_str, (size_t)pad_len);

	if (pad_utf16_len == 0) return str;

	size_t fill_utf16_len = (size_t)target_len - str_utf16_len;
	size_t full_repeats = fill_utf16_len / pad_utf16_len;
	size_t rem_utf16 = fill_utf16_len % pad_utf16_len;
	size_t rem_bytes = 0;
	if (rem_utf16 > 0) {
	int off = utf16_index_to_byte_offset(pad_str, (size_t)pad_len, rem_utf16, NULL);
	if (off < 0) return str;
	rem_bytes = (size_t)off;
	}
	size_t fill_bytes = full_repeats * (size_t)pad_len + rem_bytes;
	size_t total_bytes = fill_bytes + (size_t)str_len;

	ant_value_t result = js_mkstr(js, NULL, (ant_offset_t)total_bytes);
	if (is_err(result)) return result;

	ant_offset_t result_len, result_off = vstr(js, result, &result_len);
	char result_ptr = (char )(uintptr_t)(result_off);

	size_t pos = 0;
	for (size_t i = 0; i < full_repeats; i++) {
	memcpy(result_ptr + pos, pad_str, (size_t)pad_len);
	pos += (size_t)pad_len;
	}
	if (rem_bytes > 0) {
	memcpy(result_ptr + pos, pad_str, rem_bytes);
	pos += rem_bytes;
	}
	memcpy(result_ptr + pos, str_ptr, (size_t)str_len);
	str_set_ascii_state(
	result_ptr,
	(str_is_ascii(pad_str) && str_is_ascii(str_ptr)) ? STR_ASCII_YES : STR_ASCII_NO
	);

	return result;
	}

	static ant_value_t builtin_string_padEnd(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "padEnd called on non-string");
	if (nargs < 1 \|\| vtype(args[0]) != T_NUM) return str;

	ant_offset_t target_len = (ant_offset_t)tod(args[0]);
	if (target_len <= 0) return str;
	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	size_t str_utf16_len = utf16_strlen(str_ptr, (size_t)str_len);

	if ((size_t)target_len <= str_utf16_len) return str;

	ant_value_t pad_val = js_mkstr(js, " ", 1);
	if (nargs >= 2 && vtype(args[1]) != T_UNDEF) {
	pad_val = coerce_to_str(js, args[1]);
	if (is_err(pad_val)) return pad_val;
	}
	ant_offset_t pad_len, pad_off = vstr(js, pad_val, &pad_len);
	const char pad_str = (char )(uintptr_t)(pad_off);
	size_t pad_utf16_len = utf16_strlen(pad_str, (size_t)pad_len);

	if (pad_utf16_len == 0) return str;

	size_t fill_utf16_len = (size_t)target_len - str_utf16_len;
	size_t full_repeats = fill_utf16_len / pad_utf16_len;
	size_t rem_utf16 = fill_utf16_len % pad_utf16_len;
	size_t rem_bytes = 0;
	if (rem_utf16 > 0) {
	int off = utf16_index_to_byte_offset(pad_str, (size_t)pad_len, rem_utf16, NULL);
	if (off < 0) return str;
	rem_bytes = (size_t)off;
	}
	size_t fill_bytes = full_repeats * (size_t)pad_len + rem_bytes;
	size_t total_bytes = (size_t)str_len + fill_bytes;

	ant_value_t result = js_mkstr(js, NULL, (ant_offset_t)total_bytes);
	if (is_err(result)) return result;

	ant_offset_t result_len, result_off = vstr(js, result, &result_len);
	char result_ptr = (char )(uintptr_t)(result_off);

	memcpy(result_ptr, str_ptr, (size_t)str_len);
	size_t pos = (size_t)str_len;
	for (size_t i = 0; i < full_repeats; i++) {
	memcpy(result_ptr + pos, pad_str, (size_t)pad_len);
	pos += (size_t)pad_len;
	}
	if (rem_bytes > 0) {
	memcpy(result_ptr + pos, pad_str, rem_bytes);
	pos += rem_bytes;
	}
	str_set_ascii_state(
	result_ptr,
	(str_is_ascii(str_ptr) && str_is_ascii(pad_str)) ? STR_ASCII_YES : STR_ASCII_NO
	);

	return result;
	}

	static ant_value_t builtin_string_charAt(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "charAt called on non-string");

	double idx_d = nargs < 1 ? 0.0 : js_to_number(js, args[0]);
	if (isnan(idx_d)) idx_d = 0;
	else if (idx_d < 0) idx_d = -floor(-idx_d);
	else idx_d = floor(idx_d);
	if (idx_d < 0 \|\| isinf(idx_d)) return js_mkstr(js, "", 0);

	ant_offset_t idx = (ant_offset_t) idx_d;
	ant_offset_t byte_len;
	ant_offset_t str_off = vstr(js, str, &byte_len);

	const char str_data = (const char )(uintptr_t)(str_off);
	uint32_t code_unit = utf16_code_unit_at(str_data, byte_len, idx);
	if (code_unit == 0xFFFFFFFF) return js_mkstr(js, "", 0);

	return js_string_from_utf16_code_unit(js, code_unit);
	}

	static ant_value_t builtin_string_at(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "at called on non-string");

	double idx_d = nargs < 1 ? 0.0 : js_to_number(js, args[0]);
	if (isnan(idx_d) \|\| isinf(idx_d)) return js_mkundef();

	ant_offset_t byte_len; ant_offset_t str_off = vstr(js, str, &byte_len);
	const char str_data = (const char )(uintptr_t)(str_off);
	size_t utf16_len = utf16_strlen(str_data, byte_len);

	long idx = (long) idx_d;
	if (idx < 0) idx += (long) utf16_len;
	if (idx < 0 \|\| idx >= (long) utf16_len) return js_mkundef();

	uint32_t code_unit = utf16_code_unit_at(str_data, byte_len, idx);
	if (code_unit == 0xFFFFFFFF) return js_mkundef();

	return js_string_from_utf16_code_unit(js, code_unit);
	}

	static ant_value_t builtin_string_localeCompare(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "localeCompare called on non-string");
	if (nargs < 1) return tov(0);

	ant_value_t that = args[0];
	if (vtype(that) != T_STR) {
	char buf[64];
	size_t n = tostr(js, that, buf, sizeof(buf));
	that = js_mkstr(js, buf, n);
	}

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	ant_offset_t that_len, that_off = vstr(js, that, &that_len);
	const char str_ptr = (char )(uintptr_t)(str_off);
	const char that_ptr = (char )(uintptr_t)(that_off);

	int result = strcoll(str_ptr, that_ptr);
	if (result < 0) return tov(-1.0);
	if (result > 0) return tov(1.0);

	return tov(0);
	}

	static ant_value_t builtin_string_lastIndexOf(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "lastIndexOf called on non-string");
	if (nargs == 0) return tov(-1);

	ant_value_t search = args[0];
	if (vtype(search) != T_STR) return tov(-1);

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	ant_offset_t search_len, search_off = vstr(js, search, &search_len);

	ant_offset_t max_start = str_len;
	double dstr_len = D(str_len);
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double pos = tod(args[1]);
	if (isnan(pos)) pos = dstr_len;
	if (pos < 0) pos = 0;
	if (pos > dstr_len) pos = dstr_len;
	max_start = (ant_offset_t) pos;
	}

	if (search_len == 0) return tov((double) (max_start > str_len ? str_len : max_start));
	if (search_len > str_len) return tov(-1);

	const char str_ptr = (char )(uintptr_t)(str_off);
	const char search_ptr = (char )(uintptr_t)(search_off);

	ant_offset_t start = (max_start + search_len > str_len) ? str_len - search_len : max_start;
	for (ant_offset_t i = start + 1; i > 0; i--) {
	if (memcmp(str_ptr + i - 1, search_ptr, search_len) == 0) return tov((double)(i - 1));
	}
	return tov(-1);
	}

	static ant_value_t builtin_string_concat(ant_t js, ant_value_t args, int nargs) {
	ant_value_t this_unwrapped = unwrap_primitive(js, js->this_val);
	ant_value_t str = js_tostring_val(js, this_unwrapped);
	if (is_err(str)) return str;

	ant_offset_t total_len;
	ant_offset_t base_off = vstr(js, str, &total_len);

	ant_value_t *str_args = NULL;
	if (nargs > 0) {
	str_args = (ant_value_t )ant_calloc(nargs sizeof(ant_value_t));
	if (!str_args) return js_mkerr(js, "oom");
	for (int i = 0; i < nargs; i++) {
	str_args[i] = js_tostring_val(js, args[i]);
	if (is_err(str_args[i])) {
	free(str_args);
	return str_args[i];
	}
	ant_offset_t arg_len;
	vstr(js, str_args[i], &arg_len);
	total_len += arg_len;
	}
	}

	char result = (char )ant_calloc(total_len + 1);
	if (!result) {
	if (str_args) free(str_args);
	return js_mkerr(js, "oom");
	}

	ant_offset_t base_len;
	base_off = vstr(js, str, &base_len);
	memcpy(result, (const void *)(uintptr_t)base_off, base_len);
	ant_offset_t pos = base_len;

	for (int i = 0; i < nargs; i++) {
	ant_offset_t arg_len, arg_off = vstr(js, str_args[i], &arg_len);
	memcpy(result + pos, (const void *)(uintptr_t)arg_off, arg_len);
	pos += arg_len;
	}
	result[pos] = '\0';

	ant_value_t ret = js_mkstr(js, result, pos);
	free(result); if (str_args) free(str_args);

	return ret;
	}

	static ant_value_t builtin_string_normalize(ant_t js, ant_value_t args, int nargs) {
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "normalize called on non-string");

	ant_offset_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (const char )(uintptr_t)(str_off);

	if (str_len == 0) return js_mkstr(js, "", 0);
	utf8proc_option_t opts = UTF8PROC_COMPOSE \| UTF8PROC_STABLE;

	if (nargs >= 1 && vtype(args[0]) != T_UNDEF) {
	ant_value_t form_val = js_tostring_val(js, args[0]);
	if (is_err(form_val)) return form_val;
	ant_offset_t flen, foff = vstr(js, form_val, &flen);
	const char form = (const char )(uintptr_t)(foff);

	if (flen == 3 && memcmp(form, "NFC", 3) == 0) {
	opts = UTF8PROC_COMPOSE \| UTF8PROC_STABLE;
	} else if (flen == 3 && memcmp(form, "NFD", 3) == 0) {
	opts = UTF8PROC_DECOMPOSE \| UTF8PROC_STABLE;
	} else if (flen == 4 && memcmp(form, "NFKC", 4) == 0) {
	opts = UTF8PROC_COMPOSE \| UTF8PROC_STABLE \| UTF8PROC_COMPAT;
	} else if (flen == 4 && memcmp(form, "NFKD", 4) == 0) {
	opts = UTF8PROC_DECOMPOSE \| UTF8PROC_STABLE \| UTF8PROC_COMPAT;
	} else return js_mkerr_typed(js, JS_ERR_RANGE, "The normalization form should be one of NFC, NFD, NFKC, NFKD");
	}

	utf8proc_uint8_t *result = NULL;
	utf8proc_ssize_t rlen = utf8proc_map(
	(const utf8proc_uint8_t *)str_ptr, (utf8proc_ssize_t)str_len, &result, opts
	);

	if (rlen < 0 \|\| !result) {
	if (result) free(result);
	return js_mkstr(js, str_ptr, str_len);
	}

	ant_value_t ret = js_mkstr(js, (const char *)result, (ant_offset_t)rlen);
	free(result);

	return ret;
	}

	static ant_value_t builtin_string_fromCharCode(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkstr(js, "", 0);

	char buf = (char )ant_calloc(nargs + 1);
	if (!buf) return js_mkerr(js, "oom");

	for (int i = 0; i < nargs; i++) {
	if (vtype(args[i]) != T_NUM) { buf[i] = 0; continue; }
	int code = (int) tod(args[i]);
	buf[i] = (char)(code & 0xFF);
	}
	buf[nargs] = '\0';

	ant_value_t ret = js_mkstr(js, buf, nargs);
	free(buf);
	return ret;
	}

	static ant_value_t builtin_string_fromCodePoint(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return js_mkstr(js, "", 0);

	char buf = (char )ant_calloc(nargs * 4 + 1);
	if (!buf) return js_mkerr(js, "oom");

	size_t len = 0;
	for (int i = 0; i < nargs; i++) {
	if (vtype(args[i]) != T_NUM) continue;
	double d = tod(args[i]);
	if (d < 0 \|\| d > 0x10FFFF \|\| d != floor(d)) {
	free(buf);
	return js_mkerr_typed(js, JS_ERR_RANGE, "Invalid code point");
	}
	uint32_t cp = (uint32_t)d;
	if (cp < 0x80) {
	buf[len++] = (char)cp;
	} else if (cp < 0x800) {
	buf[len++] = (char)(0xC0 \| (cp >> 6));
	buf[len++] = (char)(0x80 \| (cp & 0x3F));
	} else if (cp < 0x10000) {
	buf[len++] = (char)(0xE0 \| (cp >> 12));
	buf[len++] = (char)(0x80 \| ((cp >> 6) & 0x3F));
	buf[len++] = (char)(0x80 \| (cp & 0x3F));
	} else {
	buf[len++] = (char)(0xF0 \| (cp >> 18));
	buf[len++] = (char)(0x80 \| ((cp >> 12) & 0x3F));
	buf[len++] = (char)(0x80 \| ((cp >> 6) & 0x3F));
	buf[len++] = (char)(0x80 \| (cp & 0x3F));
	}
	}
	buf[len] = '\0';

	ant_value_t ret = js_mkstr(js, buf, len);
	free(buf);
	return ret;
	}

	static bool string_builder_append_value(
	ant_t js, char *buf,
	size_t len, size_t cap,
	ant_value_t value, ant_value_t *err
	) {
	ant_value_t s = js_tostring_val(js, value);
	if (is_err(s)) {
	if (err) *err = s;
	return false;
	}

	ant_offset_t slen = 0;
	ant_offset_t soff = vstr(js, s, &slen);

	size_t need = *len + (size_t)slen + 1;
	if (need > *cap) {
	size_t next = (cap == 0) ? 64 : cap;
	while (next < need) next *= 2;
	char grown = (char )realloc(*buf, next);
	if (!grown) {
	if (err) *err = js_mkerr(js, "oom");
	return false;
	}
	*buf = grown;
	*cap = next;
	}

	if (slen > 0) memcpy(buf + len, (const void *)(uintptr_t)soff, (size_t)slen);
	*len += (size_t)slen;
	(buf)[len] = '\0';
	return true;
	}

	static ant_value_t builtin_string_raw(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1 \|\| is_null(args[0]) \|\| is_undefined(args[0])) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "String.raw requires a template object");
	}

	ant_value_t tmpl = args[0];
	if (!is_object_type(tmpl)) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "String.raw requires a template object");
	}

	ant_value_t raw = js_get(js, tmpl, "raw");
	if (is_null(raw) \|\| is_undefined(raw) \|\| !is_object_type(raw)) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "String.raw requires template.raw");
	}

	ant_value_t raw_len_val = js_get(js, raw, "length");
	double raw_len_num = js_to_number(js, raw_len_val);
	if (!isfinite(raw_len_num) \|\| raw_len_num <= 0) return js_mkstr(js, "", 0);

	size_t literal_count = (size_t)raw_len_num;
	if (literal_count == 0) return js_mkstr(js, "", 0);

	char *buf = NULL;
	size_t len = 0; size_t cap = 0;
	ant_value_t err = js_mkundef();

	for (size_t i = 0; i < literal_count; i++) {
	ant_value_t chunk = js_mkundef();
	if (vtype(raw) == T_ARR) chunk = js_arr_get(js, raw, (ant_offset_t)i);
	else {
	char key[32];
	snprintf(key, sizeof(key), "%zu", i);
	chunk = js_get(js, raw, key);
	}

	if (!string_builder_append_value(js, &buf, &len, &cap, chunk, &err)) {
	free(buf);
	return is_err(err) ? err : js_mkerr(js, "oom");
	}

	if (i + 1 < literal_count && (int)(i + 1) < nargs) {
	if (!string_builder_append_value(js, &buf, &len, &cap, args[i + 1], &err)) {
	free(buf); return is_err(err) ? err : js_mkerr(js, "oom");
	}
	}
	}

	ant_value_t out = js_mkstr(js, buf ? buf : "", len);
	free(buf);

	return out;
	}

	static ant_value_t builtin_number_toString(ant_t js, ant_value_t args, int nargs) {
	ant_value_t num = unwrap_primitive(js, js->this_val);
	if (vtype(num) != T_NUM) return js_mkerr(js, "toString called on non-number");

	int radix = 10;
	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	radix = (int)tod(args[0]);
	if (radix < 2 \|\| radix > 36) {
	return js_mkerr(js, "radix must be between 2 and 36");
	}
	}

	if (radix == 10) {
	char buf[64];
	size_t len = strnum(num, buf, sizeof(buf));
	return js_mkstr(js, buf, len);
	}

	double val = tod(num);

	if (isnan(val)) return js_mkstr(js, "NaN", 3);
	if (isinf(val)) return val > 0 ? js_mkstr(js, "Infinity", 8) : js_mkstr(js, "-Infinity", 9);

	char buf[128];
	char *p = buf + sizeof(buf) - 1;
	*p = '\0';

	bool negative = val < 0;
	if (negative) val = -val;

	long long int_part = (long long)val;
	double frac_part = val - (double)int_part;

	if (int_part == 0) {
	*--p = '0';
	} else {
	while (int_part > 0 && p > buf) {
	int digit = int_part % radix;
	*--p = (char)(digit < 10 ? '0' + digit : 'a' + (digit - 10));
	int_part /= radix;
	}
	}

	if (negative && p > buf) {
	*--p = '-';
	}

	size_t int_len = strlen(p);

	if (frac_part > 0.0000001) {
	char frac_buf[64];
	int frac_pos = 0;
	frac_buf[frac_pos++] = '.';

	for (int i = 0; i < 16 && frac_part > 0.0000001 && frac_pos < 63; i++) {
	frac_part *= radix;
	int digit = (int)frac_part;
	frac_buf[frac_pos++] = (char)(digit < 10 ? '0' + digit : 'a' + (digit - 10));
	frac_part -= digit;
	}
	frac_buf[frac_pos] = '\0';

	char result[192];
	snprintf(result, sizeof(result), "%s%s", p, frac_buf);
	return js_mkstr(js, result, strlen(result));
	}

	return js_mkstr(js, p, int_len);
	}

	static ant_value_t builtin_number_toFixed(ant_t js, ant_value_t args, int nargs) {
	ant_value_t num = unwrap_primitive(js, js->this_val);
	if (vtype(num) != T_NUM) return js_mkerr(js, "toFixed called on non-number");

	double d = tod(num);
	if (isnan(d)) return js_mkstr(js, "NaN", 3);
	if (isinf(d)) return d > 0 ? js_mkstr(js, "Infinity", 8) : js_mkstr(js, "-Infinity", 9);

	int digits = 0;
	if (nargs >= 1 && vtype(args[0]) != T_UNDEF) {
	digits = (int) tod(args[0]);
	if (digits < 0 \|\| digits > 100) {
	return js_mkerr_typed(js, JS_ERR_RANGE, "toFixed() digits argument must be between 0 and 100");
	}
	}

	bool negative = d < 0;
	if (negative) d = -d;

	if (d >= 1e21) {
	char buf[64];
	snprintf(buf, sizeof(buf), "%.0f", negative ? -d : d);
	return js_mkstr(js, buf, strlen(buf));
	}

	double scale = pow(10, digits);
	double scaled = d * scale;
	double rounded = floor(scaled + 0.5);

	char digit_buf[128];
	snprintf(digit_buf, sizeof(digit_buf), "%.0f", rounded);
	int digit_len = (int)strlen(digit_buf);

	while (digit_len < digits + 1) {
	memmove(digit_buf + 1, digit_buf, digit_len + 1);
	digit_buf[0] = '0';
	digit_len++;
	}

	char buf[128];
	int pos = 0;

	if (negative && rounded != 0) buf[pos++] = '-';
	int int_digits = digit_len - digits;
	if (int_digits <= 0) int_digits = 1;

	for (int i = 0; i < int_digits; i++) {
	buf[pos++] = digit_buf[i];
	}

	if (digits > 0) {
	buf[pos++] = '.';
	for (int i = int_digits; i < digit_len; i++) {
	buf[pos++] = digit_buf[i];
	}
	}

	buf[pos] = '\0';
	return js_mkstr(js, buf, pos);
	}

	static ant_value_t builtin_number_toPrecision(ant_t js, ant_value_t args, int nargs) {
	ant_value_t num = unwrap_primitive(js, js->this_val);
	if (vtype(num) != T_NUM) return js_mkerr(js, "toPrecision called on non-number");

	double d = tod(num);
	if (isnan(d)) return js_mkstr(js, "NaN", 3);
	if (isinf(d)) return d > 0 ? js_mkstr(js, "Infinity", 8) : js_mkstr(js, "-Infinity", 9);

	if (nargs < 1 \|\| vtype(args[0]) == T_UNDEF) {
	char buf[64];
	size_t len = strnum(num, buf, sizeof(buf));
	return js_mkstr(js, buf, len);
	}

	int precision = (int) tod(args[0]);
	if (precision < 1 \|\| precision > 100) {
	return js_mkerr_typed(js, JS_ERR_RANGE, "toPrecision() argument must be between 1 and 100");
	}

	bool negative = d < 0;
	if (negative) d = -d;

	if (d == 0) {
	char buf[128];
	int pos = 0;
	if (negative) buf[pos++] = '-';
	buf[pos++] = '0';
	if (precision > 1) {
	buf[pos++] = '.';
	for (int i = 1; i < precision; i++) buf[pos++] = '0';
	}
	buf[pos] = '\0';
	return js_mkstr(js, buf, pos);
	}

	int exp = (int) floor(log10(d));
	bool use_exp = (exp < -(precision - 1) - 1) \|\| (exp >= precision);

	if (use_exp) {
	double mantissa = d / pow(10, exp);
	double scale = pow(10, precision - 1);
	double rounded = floor(mantissa * scale + 0.5);

	if (rounded >= scale * 10) {
	rounded /= 10;
	exp++;
	}

	char digit_buf[32];
	snprintf(digit_buf, sizeof(digit_buf), "%.0f", rounded);
	int digit_len = (int)strlen(digit_buf);

	char buf[128];
	int pos = 0;
	if (negative) buf[pos++] = '-';
	buf[pos++] = digit_buf[0];
	if (precision > 1) {
	buf[pos++] = '.';
	for (int i = 1; i < precision; i++) {
	buf[pos++] = (i < digit_len) ? digit_buf[i] : '0';
	}
	}
	buf[pos++] = 'e';
	buf[pos++] = (exp >= 0) ? '+' : '-';
	if (exp < 0) exp = -exp;
	snprintf(buf + pos, sizeof(buf) - pos, "%d", exp);
	return js_mkstr(js, buf, strlen(buf));
	} else {
	int digits_after_point = precision - exp - 1;
	if (digits_after_point < 0) digits_after_point = 0;

	double scale = pow(10, digits_after_point);
	double rounded = floor(d * scale + 0.5);

	char digit_buf[64];
	snprintf(digit_buf, sizeof(digit_buf), "%.0f", rounded);
	int digit_len = (int)strlen(digit_buf);

	while (digit_len < digits_after_point + 1) {
	memmove(digit_buf + 1, digit_buf, digit_len + 1);
	digit_buf[0] = '0';
	digit_len++;
	}

	char buf[128];
	int pos = 0;
	if (negative) buf[pos++] = '-';

	int int_digits = digit_len - digits_after_point;
	for (int i = 0; i < int_digits; i++) {
	buf[pos++] = digit_buf[i];
	}

	if (digits_after_point > 0) {
	buf[pos++] = '.';
	for (int i = int_digits; i < digit_len; i++) {
	buf[pos++] = digit_buf[i];
	}
	}

	buf[pos] = '\0';
	return js_mkstr(js, buf, pos);
	}
	}

	static ant_value_t builtin_number_toExponential(ant_t js, ant_value_t args, int nargs) {
	ant_value_t num = unwrap_primitive(js, js->this_val);
	if (vtype(num) != T_NUM) return js_mkerr(js, "toExponential called on non-number");

	double d = tod(num);
	if (isnan(d)) return js_mkstr(js, "NaN", 3);
	if (isinf(d)) return d > 0 ? js_mkstr(js, "Infinity", 8) : js_mkstr(js, "-Infinity", 9);

	int digits = -1;
	if (nargs >= 1 && vtype(args[0]) != T_UNDEF) {
	digits = (int) tod(args[0]);
	if (digits < 0 \|\| digits > 100) {
	return js_mkerr_typed(js, JS_ERR_RANGE, "toExponential() argument must be between 0 and 100");
	}
	}

	bool negative = d < 0;
	if (negative) d = -d;

	int exp = 0;
	if (d != 0) {
	exp = (int) floor(log10(d));
	double test = d / pow(10, exp);
	if (test >= 10) { exp++; test /= 10; }
	if (test < 1) { exp--; test *= 10; }
	}

	if (digits < 0) {
	char temp[32];
	snprintf(temp, sizeof(temp), "%.15g", d);
	int sig = 0;
	for (int i = 0; temp[i] && temp[i] != 'e' && temp[i] != 'E'; i++) {
	if (temp[i] == '.') continue;
	if (temp[i] >= '0' && temp[i] <= '9') if (temp[i] != '0' \|\| sig > 0) sig++;
	}
	digits = sig > 0 ? sig - 1 : 0;
	if (digits > 20) digits = 20;
	}

	double mantissa = d / pow(10, exp);
	double scale = pow(10, digits);
	double scaled = mantissa * scale;
	double rounded = floor(scaled + 0.5);

	if (rounded >= scale * 10) {
	rounded /= 10;
	exp++;
	}

	char buf[64];
	int pos = 0;

	if (negative) buf[pos++] = '-';

	char digit_buf[32];
	snprintf(digit_buf, sizeof(digit_buf), "%.0f", rounded);
	int digit_len = (int)strlen(digit_buf);

	while (digit_len < digits + 1) {
	memmove(digit_buf + 1, digit_buf, digit_len + 1);
	digit_buf[0] = '0';
	digit_len++;
	}

	buf[pos++] = digit_buf[0];

	if (digits > 0) {
	buf[pos++] = '.';
	for (int i = 1; i <= digits; i++) {
	buf[pos++] = (i < digit_len) ? digit_buf[i] : '0';
	}
	}

	buf[pos++] = 'e';
	buf[pos++] = (exp >= 0) ? '+' : '-';
	if (exp < 0) exp = -exp;
	snprintf(buf + pos, sizeof(buf) - pos, "%d", exp);

	return js_mkstr(js, buf, strlen(buf));
	}

	static ant_value_t builtin_number_valueOf(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t num = unwrap_primitive(js, js->this_val);
	if (vtype(num) != T_NUM) return js_mkerr(js, "valueOf called on non-number");
	return num;
	}

	static ant_value_t builtin_number_toLocaleString(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t num = unwrap_primitive(js, js->this_val);
	if (vtype(num) != T_NUM) return js_mkerr(js, "toLocaleString called on non-number");
	double d = tod(num);
	char raw[64];
	strnum(num, raw, sizeof(raw));
	if (!isfinite(d) \|\| strchr(raw, 'e') \|\| strchr(raw, 'E'))
	return js_mkstr(js, raw, strlen(raw));
	char *dot = strchr(raw, '.');
	size_t int_len = dot ? (size_t)(dot - raw) : strlen(raw);
	size_t start = (raw[0] == '-') ? 1 : 0;
	size_t frac_len = dot ? strlen(dot) : 0;
	char buf[128];
	size_t pos = 0;
	if (start) buf[pos++] = '-';
	for (size_t i = start; i < int_len; i++) {
	buf[pos++] = raw[i];
	size_t remaining = int_len - 1 - i;
	if (remaining > 0 && remaining % 3 == 0) buf[pos++] = ',';
	}
	if (frac_len) memcpy(buf + pos, dot, frac_len);
	pos += frac_len;
	buf[pos] = '\0';
	return js_mkstr(js, buf, pos);
	}

	static ant_value_t builtin_string_valueOf(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t str = to_string_val(js, js->this_val);
	if (vtype(str) != T_STR) return js_mkerr(js, "valueOf called on non-string");
	return str;
	}

	static ant_value_t builtin_string_toString(ant_t js, ant_value_t args, int nargs) {
	return builtin_string_valueOf(js, args, nargs);
	}

	static ant_value_t builtin_boolean_valueOf(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t b = unwrap_primitive(js, js->this_val);
	if (vtype(b) != T_BOOL) return js_mkerr(js, "valueOf called on non-boolean");
	return b;
	}

	static ant_value_t builtin_boolean_toString(ant_t js, ant_value_t args, int nargs) {
	(void) args; (void) nargs;
	ant_value_t b = unwrap_primitive(js, js->this_val);
	if (vtype(b) != T_BOOL) return js_mkerr(js, "toString called on non-boolean");
	return vdata(b) ? js_mkstr(js, "true", 4) : js_mkstr(js, "false", 5);
	}

	static ant_value_t builtin_parseInt(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return tov(JS_NAN);

	ant_value_t str_val = args[0];
	if (vtype(str_val) != T_STR) {
	const char *str = js_str(js, str_val);
	str_val = js_mkstr(js, str, strlen(str));
	}

	ant_offset_t str_len, str_off = vstr(js, str_val, &str_len);
	const char str = (char )(uintptr_t)(str_off);

	int radix = 0;
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	radix = (int) tod(args[1]);
	if (radix != 0 && (radix < 2 \|\| radix > 36)) return tov(JS_NAN);
	}

	ant_offset_t i = 0;
	while (i < str_len && is_space(str[i])) i++;

	if (i >= str_len) return tov(JS_NAN);

	int sign = 1;
	if (str[i] == '-') {
	sign = -1;
	i++;
	} else if (str[i] == '+') {
	i++;
	}

	if ((radix == 0 \|\| radix == 16) && i + 1 < str_len && str[i] == '0' && (str[i + 1] == 'x' \|\| str[i + 1] == 'X')) {
	radix = 16;
	i += 2;
	}

	if (radix == 0) radix = 10;

	double result = 0;
	bool found_digit = false;

	while (i < str_len) {
	char ch = str[i];
	int digit = -1;

	if (ch >= '0' && ch <= '9') {
	digit = ch - '0';
	} else if (ch >= 'a' && ch <= 'z') {
	digit = ch - 'a' + 10;
	} else if (ch >= 'A' && ch <= 'Z') {
	digit = ch - 'A' + 10;
	}

	if (digit < 0 \|\| digit >= radix) break;

	result = result * radix + digit;
	found_digit = true;
	i++;
	}

	if (!found_digit) return tov(JS_NAN);

	return tov(sign * result);
	}

	static ant_value_t builtin_parseFloat(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return tov(JS_NAN);

	ant_value_t str_val = args[0];
	if (vtype(str_val) != T_STR) {
	const char *str = js_str(js, str_val);
	str_val = js_mkstr(js, str, strlen(str));
	}

	ant_offset_t str_len, str_off = vstr(js, str_val, &str_len);
	const char str = (char )(uintptr_t)(str_off);

	ant_offset_t i = 0;
	while (i < str_len && is_space(str[i])) i++;

	if (i >= str_len) return tov(JS_NAN);

	char *end;
	double result = strtod(&str[i], &end);

	if (end == &str[i]) return tov(JS_NAN);

	return tov(result);
	}

	static ant_value_t builtin_btoa(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "btoa requires 1 argument");

	ant_value_t str_val = args[0];
	if (vtype(str_val) != T_STR) {
	const char *str = js_str(js, str_val);
	str_val = js_mkstr(js, str, strlen(str));
	}

	ant_offset_t str_len, str_off = vstr(js, str_val, &str_len);
	const char str = (char )(uintptr_t)(str_off);

	size_t out_len;
	char out = ant_base64_encode((const uint8_t )str, str_len, &out_len);
	if (!out) return js_mkerr(js, "out of memory");

	ant_value_t result = js_mkstr(js, out, out_len);
	free(out);

	return result;
	}

	static ant_value_t builtin_atob(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "atob requires 1 argument");

	ant_value_t str_val = args[0];
	if (vtype(str_val) != T_STR) {
	const char *str = js_str(js, str_val);
	str_val = js_mkstr(js, str, strlen(str));
	}

	ant_offset_t str_len, str_off = vstr(js, str_val, &str_len);
	const char str = (char )(uintptr_t)(str_off);
	if (str_len == 0) return js_mkstr(js, "", 0);

	size_t out_len;
	uint8_t *out = ant_base64_decode(str, str_len, &out_len);
	if (!out) return js_mkerr(js, "atob: invalid base64 string");

	ant_value_t result = js_mkstr(js, (char *)out, out_len);
	free(out);

	return result;
	}

	static ant_value_t builtin_resolve_internal(ant_t js, ant_value_t args, int nargs);
	static ant_value_t builtin_reject_internal(ant_t js, ant_value_t args, int nargs);

	static size_t strpromise(ant_t js, ant_value_t value, char buf, size_t len) {
	uint32_t pid = get_promise_id(js, value);
	ant_promise_state_t *pd = get_promise_data(js, value, false);

	const char *content;
	char *allocated = NULL;

	if (!pd \|\| pd->state == 0) {
	content = "<pending>";
	} else if (pd->state == 2) {
	char *val = tostr_alloc(js, pd->value);
	allocated = ant_calloc(strlen(val) + 12);
	sprintf(allocated, "<rejected> %s", val);
	free(val);
	content = allocated;
	} else { content = allocated = tostr_alloc(js, pd->value); }

	uint32_t trigger_pid = 0;
	if (pd && vtype(pd->trigger_parent) == T_PROMISE) {
	trigger_pid = get_promise_id(js, pd->trigger_parent);
	}
	size_t result = trigger_pid
	? (size_t)snprintf(buf, len, "Promise {\n %s,\n Symbol(async_id): %u,\n Symbol(trigger_async_id): %u\n}", content, pid, trigger_pid)
	: (size_t)snprintf(buf, len, "Promise {\n %s,\n Symbol(async_id): %u\n}", content, pid);

	if (allocated) free(allocated);
	return result;
	}

	static ant_promise_state_t get_promise_data(ant_t js, ant_value_t promise, bool create) {
	if (vtype(promise) != T_PROMISE) return NULL;
	ant_object_t *obj = js_obj_ptr(js_as_obj(promise));
	if (!obj) return NULL;
	if (obj->promise_state) return obj->promise_state;
	if (!create) return NULL;

	ant_promise_state_t entry = (ant_promise_state_t )calloc(1, sizeof(*entry));
	if (!entry) return NULL;
	entry->promise_id = next_promise_id++;
	entry->trigger_parent = js_mkundef();
	entry->inline_handler = (promise_handler_t){ 0 };
	entry->handlers = NULL;
	entry->handler_count = 0;
	entry->state = 0;
	entry->value = js_mkundef();
	entry->trigger_queued = false;
	entry->has_rejection_handler = false;
	entry->processing = false;
	entry->unhandled_reported = false;
	obj->promise_state = entry;
	obj->type_tag = T_PROMISE;
	return entry;
	}

	static uint32_t get_promise_id(ant_t *js, ant_value_t p) {
	ant_promise_state_t *pd = get_promise_data(js, p, false);
	return pd ? pd->promise_id : 0;
	}

	bool js_mark_promise_trigger_queued(ant_t *js, ant_value_t promise) {
	ant_promise_state_t *pd = get_promise_data(js, promise, false);
	if (!pd) return true;
	if (pd->trigger_queued) return false;
	pd->trigger_queued = true;
	return true;
	}

	void js_mark_promise_trigger_dequeued(ant_t *js, ant_value_t promise) {
	ant_promise_state_t *pd = get_promise_data(js, promise, false);
	if (!pd) return;
	pd->trigger_queued = false;
	}

	static ant_value_t make_data_cfunc(
	ant_t *js, ant_value_t data,
	ant_value_t (fn)(ant_t , ant_value_t *, int)
	) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, data);

	ant_value_t obj = mkobj(js, 0);
	if (is_err(obj)) {
	GC_ROOT_RESTORE(js, root_mark);
	return obj;
	}

	GC_ROOT_PIN(js, obj);
	set_slot(obj, SLOT_DATA, data);
	set_slot(obj, SLOT_CFUNC, js_mkfun(fn));

	ant_value_t func = js_obj_to_func(obj);
	GC_ROOT_RESTORE(js, root_mark);
	return func;
	}

	ant_value_t js_mkpromise(ant_t *js) {
	ant_value_t obj = mkobj(js, 0);
	if (is_err(obj)) return obj;
	if (!get_promise_data(js, mkval(T_PROMISE, vdata(obj)), true))
	return js_mkerr(js, "out of memory");

	ant_value_t promise_ctor = js_get(js, js_glob(js), "Promise");
	if (vtype(promise_ctor) == T_FUNC \|\| vtype(promise_ctor) == T_CFUNC) {
	set_slot(obj, SLOT_CTOR, promise_ctor);
	}

	ant_value_t promise_proto = get_ctor_proto(js, "Promise", 7);
	if (is_object_type(promise_proto)) {
	js_set_proto_init(obj, promise_proto);
	}

	return mkval(T_PROMISE, vdata(obj));
	}

	ant_value_t js_mkgenerator(ant_t *js) {
	ant_value_t obj = mkobj(js, 0);
	if (is_err(obj)) return obj;

	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return js_mkerr(js, "invalid generator object");
	ptr->type_tag = T_GENERATOR;

	ant_value_t gen = mkval(T_GENERATOR, vdata(obj));
	if (is_object_type(js->sym.generator_proto)) {
	js_set_proto_init(gen, js->sym.generator_proto);
	}

	return gen;
	}

	ant_value_t js_promise_then(ant_t *js, ant_value_t promise, ant_value_t on_fulfilled, ant_value_t on_rejected) {
	ant_value_t args_then[2] = { on_fulfilled, on_rejected };
	ant_value_t saved_this = js->this_val;

	js->this_val = promise;
	ant_value_t result = builtin_promise_then(js, args_then, 2);
	js->this_val = saved_this;

	return result;
	}

	static inline ant_value_t js_get_thenable_then(ant_t *js, ant_value_t value) {
	if (!is_object_type(value)) return js_mkundef();
	return js_getprop_fallback(js, value, "then");
	}

	js_await_result_t js_promise_await_coroutine(ant_t js, ant_value_t promise, coroutine_t coro) {
	js_await_result_t result = {
	.state = JS_AWAIT_PENDING,
	.value = js_mkundef(),
	};

	if (vtype(promise) != T_PROMISE \|\| !coro) return result;
	ant_promise_state_t *pd = get_promise_data(js, promise, false);

	if (!pd) {
	result.state = JS_AWAIT_ERROR;
	result.value = js_mkerr(js, "invalid promise state");
	return result;
	}

	promise_handler_t h = { js_mkundef(), js_mkundef(), js_mkundef(), coro };
	if (!promise_handler_append(pd, &h)) {
	result.state = JS_AWAIT_ERROR;
	result.value = js_mkerr(js, "out of memory");
	return result;
	}

	if (pd->unhandled_reported) js_fire_rejection_handled(js, promise, pd->value);
	pd->has_rejection_handler = true;
	pd->unhandled_reported = false;

	if (pd->state == 0) gc_root_pending_promise(js_obj_ptr(js_as_obj(promise)));
	else queue_promise_trigger(js, promise);

	return result;
	}

	void js_process_promise_handlers(ant_t *js, ant_value_t promise) {
	ant_object_t *pobj = js_obj_ptr(promise);
	ant_promise_state_t *pd = get_promise_data(js, promise, false);
	if (!pd) return;

	int state = pd->state;
	ant_value_t val = pd->value;

	uint32_t len = promise_handler_count(pd);
	if (len == 0) return;

	gc_root_pending_promise(pobj);
	pd->processing = true;

	for (uint32_t i = 0; i < len; i++) {
	promise_handler_t *h = promise_handler_at(pd, i);
	if (!h) continue;

	if (h->await_coro) {
	coroutine_t *await_coro = h->await_coro;
	h->await_coro = NULL;
	settle_and_resume_coroutine(js, await_coro, val, state != 1);
	continue;
	}

	ant_value_t handler = (state == 1) ? h->onFulfilled : h->onRejected;
	if (vtype(handler) != T_FUNC && vtype(handler) != T_CFUNC) {
	if (state == 1) js_resolve_promise(js, h->nextPromise, val);
	else js_reject_promise(js, h->nextPromise, val);
	continue;
	}

	ant_value_t res = js_mkundef();
	if (vtype(handler) == T_CFUNC) {
	ant_value_t (fn)(ant_t , ant_value_t , int) = (ant_value_t()(ant_t , ant_value_t , int))vdata(handler);
	res = fn(js, &val, 1);
	} else {
	ant_value_t call_args[] = { val };
	res = sv_vm_call(js->vm, js, handler, js_mkundef(), call_args, 1, NULL, false);
	}

	if (!is_err(res)) {
	js_resolve_promise(js, h->nextPromise, res);
	continue;
	}

	ant_value_t reject_val = js->thrown_value;
	if (vtype(reject_val) == T_UNDEF) reject_val = res;

	js->thrown_exists = false;
	js->thrown_value = js_mkundef();
	js->thrown_stack = js_mkundef();
	js_reject_promise(js, h->nextPromise, reject_val);
	}

	pd->processing = false;
	promise_handlers_clear(pd);
	gc_unroot_pending_promise(js_obj_ptr(promise));
	}

	void js_resolve_promise(ant_t *js, ant_value_t p, ant_value_t val) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, p);
	GC_ROOT_PIN(js, val);

	ant_promise_state_t *pd = get_promise_data(js, p, false);
	if (!pd \|\| pd->state != 0) {
	GC_ROOT_RESTORE(js, root_mark);
	return;
	}

	if (vtype(val) == T_PROMISE) {
	if (vdata(js_as_obj(val)) == vdata(js_as_obj(p))) {
	ant_value_t err = js_mkerr(js, "TypeError: Chaining cycle");
	GC_ROOT_PIN(js, err);
	js_reject_promise(js, p, err);
	GC_ROOT_RESTORE(js, root_mark);
	return;
	}

	ant_promise_state_t *src_pd = get_promise_data(js, val, false);
	if (!src_pd) {
	pd->state = 1;
	pd->value = val;
	gc_write_barrier(js, js_obj_ptr(js_as_obj(p)), val);
	GC_ROOT_RESTORE(js, root_mark);
	return;
	}

	pd->trigger_parent = val;

	promise_handler_t h = { js_mkundef(), js_mkundef(), p, NULL };
	if (!promise_handler_append(src_pd, &h)) {
	pd->state = 2;
	pd->value = js_mkerr(js, "out of memory");
	gc_write_barrier(js, js_obj_ptr(js_as_obj(p)), pd->value);
	GC_ROOT_RESTORE(js, root_mark);
	return;
	}

	gc_write_barrier(js, js_obj_ptr(js_as_obj(val)), p);
	if (src_pd->unhandled_reported) js_fire_rejection_handled(js, val, src_pd->value);

	src_pd->has_rejection_handler = true;
	src_pd->unhandled_reported = false;

	if (src_pd->state == 0) gc_root_pending_promise(js_obj_ptr(js_as_obj(val)));
	else queue_promise_trigger(js, val);
	GC_ROOT_RESTORE(js, root_mark);

	return;
	}

	if (is_object_type(val)) {
	ant_value_t res_fn = make_data_cfunc(js, p, builtin_resolve_internal);
	GC_ROOT_PIN(js, res_fn);

	if (is_err(res_fn)) {
	js_reject_promise(js, p, res_fn);
	GC_ROOT_RESTORE(js, root_mark);
	return;
	}

	ant_value_t rej_fn = make_data_cfunc(js, p, builtin_reject_internal);
	GC_ROOT_PIN(js, rej_fn);

	if (is_err(rej_fn)) {
	js_reject_promise(js, p, rej_fn);
	GC_ROOT_RESTORE(js, root_mark);
	return;
	}

	ant_value_t then_prop = js_get_thenable_then(js, val);
	GC_ROOT_PIN(js, then_prop);

	if (vtype(then_prop) == T_FUNC \|\| vtype(then_prop) == T_CFUNC) {
	ant_value_t call_args[] = { res_fn, rej_fn };
	sv_vm_call(js->vm, js, then_prop, val, call_args, 2, NULL, false);
	GC_ROOT_RESTORE(js, root_mark);
	return;
	}
	}

	pd->state = 1;
	pd->value = val;

	gc_write_barrier(js, js_obj_ptr(js_as_obj(p)), val);
	if (promise_has_handlers(pd)) queue_promise_trigger(js, p);
	GC_ROOT_RESTORE(js, root_mark);
	}

	void js_reject_promise(ant_t *js, ant_value_t p, ant_value_t val) {
	if (vtype(val) == T_ERR) {
	if (vdata(val) != 0) val = mkval(T_OBJ, vdata(val));
	else if (js->thrown_exists) val = js->thrown_value;
	else val = js_make_error_silent(js, JS_ERR_INTERNAL, "unknown error");
	}

	ant_promise_state_t *pd = get_promise_data(js, p, false);
	if (!pd \|\| pd->state != 0) return;

	pd->state = 2;
	pd->value = val;
	gc_write_barrier(js, js_obj_ptr(js_as_obj(p)), val);
	pd->unhandled_reported = false;

	if (js->pending_rejections.len >= js->pending_rejections.cap) {
	size_t new_cap = js->pending_rejections.cap ? js->pending_rejections.cap * 2 : 16;
	ant_value_t ns = realloc(js->pending_rejections.items, new_cap sizeof(*ns));
	if (ns) { js->pending_rejections.items = ns; js->pending_rejections.cap = new_cap; }
	}
	if (js->pending_rejections.len < js->pending_rejections.cap)
	js->pending_rejections.items[js->pending_rejections.len++] = p;

	queue_promise_trigger(js, p);
	}

	static ant_value_t builtin_resolve_internal(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	ant_value_t p = get_slot(me, SLOT_DATA);
	if (vtype(p) != T_PROMISE) return js_mkundef();
	js_resolve_promise(js, p, nargs > 0 ? args[0] : js_mkundef());
	return js_mkundef();
	}

	static ant_value_t builtin_reject_internal(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	ant_value_t p = get_slot(me, SLOT_DATA);
	if (vtype(p) != T_PROMISE) return js_mkundef();
	js_reject_promise(js, p, nargs > 0 ? args[0] : js_mkundef());
	return js_mkundef();
	}

	static ant_value_t builtin_Promise(ant_t js, ant_value_t args, int nargs) {
	if (vtype(js->new_target) == T_UNDEF) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Promise constructor cannot be invoked without 'new'");
	}

	if (nargs == 0 \|\| (vtype(args[0]) != T_FUNC && vtype(args[0]) != T_CFUNC)) {
	const char *val_str = nargs == 0 ? "undefined" : js_str(js, args[0]);
	return js_mkerr_typed(js, JS_ERR_TYPE, "Promise resolver %s is not a function", val_str);
	}

	GC_ROOT_SAVE(root_mark, js);
	ant_value_t executor = args[0];
	GC_ROOT_PIN(js, executor);

	ant_value_t p = js_mkpromise(js);
	if (is_err(p)) {
	GC_ROOT_RESTORE(js, root_mark);
	return p;
	}
	GC_ROOT_PIN(js, p);

	ant_value_t new_target = js->new_target;
	ant_value_t p_obj = js_as_obj(p);

	ant_value_t promise_proto = get_ctor_proto(js, "Promise", 7);
	ant_value_t instance_proto = js_instance_proto_from_new_target(js, promise_proto);
	GC_ROOT_PIN(js, instance_proto);

	if (vtype(new_target) == T_FUNC \|\| vtype(new_target) == T_CFUNC) set_slot(p_obj, SLOT_CTOR, new_target);
	if (is_object_type(instance_proto)) js_set_proto_init(p_obj, instance_proto);

	ant_value_t res_fn = make_data_cfunc(js, p, builtin_resolve_internal);
	GC_ROOT_PIN(js, res_fn);
	if (is_err(res_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return res_fn;
	}

	ant_value_t rej_fn = make_data_cfunc(js, p, builtin_reject_internal);
	GC_ROOT_PIN(js, rej_fn);
	if (is_err(rej_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return rej_fn;
	}

	ant_value_t exec_args[] = { res_fn, rej_fn };
	ant_value_t exec_result = sv_vm_call(js->vm, js, executor, js_mkundef(), exec_args, 2, NULL, false);

	if (is_err(exec_result) \|\| js->thrown_exists) {
	ant_value_t reject_val = js->thrown_exists ? js->thrown_value : exec_result;
	js->thrown_exists = false;
	js->thrown_value = js_mkundef();
	js->thrown_stack = js_mkundef();
	js_reject_promise(js, p, reject_val);
	}

	GC_ROOT_RESTORE(js, root_mark);
	return p;
	}

	static ant_value_t builtin_Promise_resolve(ant_t js, ant_value_t args, int nargs) {
	ant_value_t val = nargs > 0 ? args[0] : js_mkundef();
	if (vtype(val) == T_PROMISE) return val;
	ant_value_t p = js_mkpromise(js);
	js_resolve_promise(js, p, val);
	return p;
	}

	static ant_value_t builtin_Promise_reject(ant_t js, ant_value_t args, int nargs) {
	ant_value_t val = nargs > 0 ? args[0] : js_mkundef();
	ant_value_t p = js_mkpromise(js);
	js_reject_promise(js, p, val);
	return p;
	}

	static ant_value_t promise_species_noop_executor(ant_t js, ant_value_t args, int nargs) {
	return js_mkundef();
	}

	static inline bool is_same_heap_value(ant_value_t a, ant_value_t b) {
	return vtype(a) == vtype(b) && vdata(a) == vdata(b);
	}

	static inline bool is_constructor_value(ant_value_t value) {
	return vtype(value) == T_FUNC \|\| vtype(value) == T_CFUNC;
	}

	static void promise_init_derived_promise(
	ant_t *js,
	ant_value_t next_p,
	ant_value_t parent_p,
	ant_value_t species_ctor,
	ant_value_t promise_ctor
	) {
	ant_value_t next_obj = js_as_obj(next_p);

	if (is_constructor_value(species_ctor) && !is_same_heap_value(species_ctor, promise_ctor)) {
	ant_value_t species_proto = js_get(js, species_ctor, "prototype");
	if (is_object_type(species_proto)) js_set_proto_init(next_obj, species_proto);
	set_slot(next_obj, SLOT_CTOR, species_ctor);
	return;
	}

	ant_value_t parent_obj = js_as_obj(parent_p);
	ant_value_t parent_proto = get_slot(parent_obj, SLOT_PROTO);
	if (vtype(parent_proto) == T_OBJ) js_set_proto_init(next_obj, parent_proto);

	ant_value_t parent_ctor = get_slot(parent_obj, SLOT_CTOR);
	if (is_constructor_value(parent_ctor)) set_slot(next_obj, SLOT_CTOR, parent_ctor);
	}

	static ant_value_t builtin_promise_then(ant_t js, ant_value_t args, int nargs) {
	ant_value_t p = js->this_val;
	if (vtype(p) != T_PROMISE) return js_mkerr(js, "not a promise");

	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, p);

	ant_value_t promise_ctor = js_get(js, js_glob(js), "Promise");
	GC_ROOT_PIN(js, promise_ctor);
	ant_value_t species_ctor = promise_ctor;
	GC_ROOT_PIN(js, species_ctor);
	ant_value_t p_obj = js_as_obj(p);
	ant_value_t ctor = js_get(js, p_obj, "constructor");
	GC_ROOT_PIN(js, ctor);

	if (is_err(ctor)) {
	GC_ROOT_RESTORE(js, root_mark);
	return ctor;
	}
	if (vtype(ctor) == T_UNDEF) ctor = get_slot(p_obj, SLOT_CTOR);

	ant_value_t species = get_ctor_species_value(js, ctor);
	GC_ROOT_PIN(js, species);
	if (is_err(species)) {
	GC_ROOT_RESTORE(js, root_mark);
	return species;
	}

	if (vtype(species) == T_FUNC \|\| vtype(species) == T_CFUNC) {
	species_ctor = species;
	} else if (vtype(species) == T_NULL) {
	species_ctor = promise_ctor;
	} else if (vtype(species) != T_UNDEF) {
	ant_value_t err = js_mkerr_typed(js, JS_ERR_TYPE, "Promise species is not a constructor");
	GC_ROOT_RESTORE(js, root_mark);
	return err;
	}

	ant_value_t nextP = js_mkpromise(js);
	GC_ROOT_PIN(js, nextP);
	promise_init_derived_promise(js, nextP, p, species_ctor, promise_ctor);

	ant_value_t onFulfilled = nargs > 0 ? args[0] : js_mkundef();
	ant_value_t onRejected = nargs > 1 ? args[1] : js_mkundef();

	GC_ROOT_PIN(js, onFulfilled);
	GC_ROOT_PIN(js, onRejected);

	ant_promise_state_t *next_pd = get_promise_data(js, nextP, false);
	if (next_pd) next_pd->trigger_parent = p;

	ant_promise_state_t *pd = get_promise_data(js, p, false);
	if (pd) {
	promise_handler_t h = { onFulfilled, onRejected, nextP, NULL };
	if (!promise_handler_append(pd, &h)) {
	GC_ROOT_RESTORE(js, root_mark);
	return js_mkerr(js, "out of memory");
	}

	gc_write_barrier(js, js_obj_ptr(js_as_obj(p)), nextP);
	gc_write_barrier(js, js_obj_ptr(js_as_obj(p)), onFulfilled);
	gc_write_barrier(js, js_obj_ptr(js_as_obj(p)), onRejected);

	if (vtype(onRejected) == T_FUNC \|\| vtype(onRejected) == T_CFUNC) {
	if (pd->unhandled_reported) js_fire_rejection_handled(js, p, pd->value);
	pd->has_rejection_handler = true;
	pd->unhandled_reported = false;
	}

	if (pd->state == 0)
	gc_root_pending_promise(js_obj_ptr(p));
	}

	if (pd && pd->state != 0) queue_promise_trigger(js, p);
	GC_ROOT_RESTORE(js, root_mark);

	return nextP;
	}

	static ant_value_t builtin_promise_catch(ant_t js, ant_value_t args, int nargs) {
	ant_value_t args_then[] = { js_mkundef(), nargs > 0 ? args[0] : js_mkundef() };
	return builtin_promise_then(js, args_then, 2);
	}

	static ant_value_t finally_value_thunk(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	return get_slot(me, SLOT_DATA);
	}

	static ant_value_t finally_thrower(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	ant_value_t reason = get_slot(me, SLOT_DATA);
	ant_value_t rejected = js_mkpromise(js);
	js_reject_promise(js, rejected, reason);
	return rejected;
	}

	static ant_value_t finally_identity_reject(ant_t js, ant_value_t args, int nargs) {
	ant_value_t reason = nargs > 0 ? args[0] : js_mkundef();
	ant_value_t rejected = js_mkpromise(js);
	js_reject_promise(js, rejected, reason);
	return rejected;
	}

	static ant_value_t finally_fulfilled_wrapper(ant_t js, ant_value_t args, int nargs) {
	GC_ROOT_SAVE(root_mark, js);
	ant_value_t me = js->current_func;
	ant_value_t callback = get_slot(me, SLOT_DATA);
	ant_value_t value = nargs > 0 ? args[0] : js_mkundef();
	GC_ROOT_PIN(js, callback);
	GC_ROOT_PIN(js, value);

	ant_value_t result = js_mkundef();
	if (vtype(callback) == T_FUNC \|\| vtype(callback) == T_CFUNC) {
	result = sv_vm_call(js->vm, js, callback, js_mkundef(), NULL, 0, NULL, false);
	if (is_err(result)) {
	GC_ROOT_RESTORE(js, root_mark);
	return result;
	}
	}
	GC_ROOT_PIN(js, result);

	if (vtype(result) == T_PROMISE) {
	ant_value_t thunk_fn = make_data_cfunc(js, value, finally_value_thunk);
	GC_ROOT_PIN(js, thunk_fn);

	if (is_err(thunk_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return thunk_fn;
	}

	ant_value_t identity_rej_fn = js_mkfun(finally_identity_reject);
	ant_value_t ret = js_promise_then(js, result, thunk_fn, identity_rej_fn);
	GC_ROOT_RESTORE(js, root_mark);

	return ret;
	}

	if (is_object_type(result)) {
	ant_value_t then_fn = js_get_thenable_then(js, result);
	GC_ROOT_PIN(js, then_fn);

	if (vtype(then_fn) == T_FUNC \|\| vtype(then_fn) == T_CFUNC) {
	ant_value_t thunk_fn = make_data_cfunc(js, value, finally_value_thunk);
	GC_ROOT_PIN(js, thunk_fn);

	if (is_err(thunk_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return thunk_fn;
	}

	ant_value_t identity_rej_fn = js_mkfun(finally_identity_reject);
	ant_value_t call_args[] = { thunk_fn, identity_rej_fn };
	ant_value_t ret = sv_vm_call(js->vm, js, then_fn, result, call_args, 2, NULL, false);
	GC_ROOT_RESTORE(js, root_mark);

	return ret;
	}}

	GC_ROOT_RESTORE(js, root_mark);
	return value;
	}

	static ant_value_t finally_rejected_wrapper(ant_t js, ant_value_t args, int nargs) {
	GC_ROOT_SAVE(root_mark, js);

	ant_value_t me = js->current_func;
	ant_value_t callback = get_slot(me, SLOT_DATA);
	ant_value_t reason = nargs > 0 ? args[0] : js_mkundef();

	GC_ROOT_PIN(js, callback);
	GC_ROOT_PIN(js, reason);

	ant_value_t result = js_mkundef();
	if (vtype(callback) == T_FUNC \|\| vtype(callback) == T_CFUNC) {
	result = sv_vm_call(js->vm, js, callback, js_mkundef(), NULL, 0, NULL, false);
	if (is_err(result)) {
	GC_ROOT_RESTORE(js, root_mark);
	return result;
	}
	}
	GC_ROOT_PIN(js, result);

	if (vtype(result) == T_PROMISE) {
	ant_value_t thrower_fn = make_data_cfunc(js, reason, finally_thrower);
	GC_ROOT_PIN(js, thrower_fn);
	if (is_err(thrower_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return thrower_fn;
	}
	ant_value_t identity_rej_fn = js_mkfun(finally_identity_reject);
	ant_value_t ret = js_promise_then(js, result, thrower_fn, identity_rej_fn);
	GC_ROOT_RESTORE(js, root_mark);
	return ret;
	}

	if (is_object_type(result)) {
	ant_value_t then_prop = js_get_thenable_then(js, result);
	GC_ROOT_PIN(js, then_prop);

	if (vtype(then_prop) == T_FUNC \|\| vtype(then_prop) == T_CFUNC) {
	ant_value_t thrower_fn = make_data_cfunc(js, reason, finally_thrower);
	GC_ROOT_PIN(js, thrower_fn);

	if (is_err(thrower_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return thrower_fn;
	}

	ant_value_t identity_rej_fn = js_mkfun(finally_identity_reject);
	ant_value_t call_args[] = { thrower_fn, identity_rej_fn };
	ant_value_t ret = sv_vm_call(js->vm, js, then_prop, result, call_args, 2, NULL, false);
	GC_ROOT_RESTORE(js, root_mark);

	return ret;
	}}

	ant_value_t rejected = js_mkpromise(js);
	GC_ROOT_PIN(js, rejected);
	js_reject_promise(js, rejected, reason);
	GC_ROOT_RESTORE(js, root_mark);

	return rejected;
	}

	static ant_value_t builtin_promise_finally(ant_t js, ant_value_t args, int nargs) {
	GC_ROOT_SAVE(root_mark, js);
	ant_value_t callback = nargs > 0 ? args[0] : js_mkundef();
	GC_ROOT_PIN(js, callback);

	ant_value_t fulfilled_fn = make_data_cfunc(js, callback, finally_fulfilled_wrapper);
	GC_ROOT_PIN(js, fulfilled_fn);
	if (is_err(fulfilled_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return fulfilled_fn;
	}

	ant_value_t rejected_fn = make_data_cfunc(js, callback, finally_rejected_wrapper);
	GC_ROOT_PIN(js, rejected_fn);
	if (is_err(rejected_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return rejected_fn;
	}

	ant_value_t args_then[] = { fulfilled_fn, rejected_fn };
	ant_value_t ret = builtin_promise_then(js, args_then, 2);
	GC_ROOT_RESTORE(js, root_mark);

	return ret;
	}

	static ant_value_t builtin_Promise_try(ant_t js, ant_value_t args, int nargs) {
	if (nargs == 0) return builtin_Promise_resolve(js, args, 0);

	ant_value_t fn = args[0];
	ant_value_t *call_args = nargs > 1 ? &args[1] : NULL;
	int call_nargs = nargs > 1 ? nargs - 1 : 0;
	ant_value_t res = sv_vm_call(js->vm, js, fn, js_mkundef(), call_args, call_nargs, NULL, false);

	if (is_err(res)) {
	ant_value_t reject_val = js->thrown_value;
	if (vtype(reject_val) == T_UNDEF) reject_val = res;
	js->thrown_exists = false;
	js->thrown_value = js_mkundef();
	js->thrown_stack = js_mkundef();
	ant_value_t rej_args[] = { reject_val };
	return builtin_Promise_reject(js, rej_args, 1);
	}

	ant_value_t res_args[] = { res };
	return builtin_Promise_resolve(js, res_args, 1);
	}

	static ant_value_t builtin_Promise_withResolvers(ant_t js, ant_value_t args, int nargs) {
	GC_ROOT_SAVE(root_mark, js);
	ant_value_t p = js_mkpromise(js);
	GC_ROOT_PIN(js, p);

	ant_value_t res_fn = make_data_cfunc(js, p, builtin_resolve_internal);
	GC_ROOT_PIN(js, res_fn);
	if (is_err(res_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return res_fn;
	}

	ant_value_t rej_fn = make_data_cfunc(js, p, builtin_reject_internal);
	GC_ROOT_PIN(js, rej_fn);
	if (is_err(rej_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return rej_fn;
	}

	ant_value_t result = js_newobj(js);
	GC_ROOT_PIN(js, result);
	js_setprop(js, result, js_mkstr(js, "promise", 7), p);
	js_setprop(js, result, js_mkstr(js, "resolve", 7), res_fn);
	js_setprop(js, result, js_mkstr(js, "reject", 6), rej_fn);

	GC_ROOT_RESTORE(js, root_mark);
	return result;
	}

	static ant_value_t mkpromise_with_ctor(ant_t *js, ant_value_t ctor) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, ctor);
	ant_value_t p = js_mkpromise(js);
	GC_ROOT_PIN(js, p);
	if (vtype(ctor) != T_FUNC && vtype(ctor) != T_CFUNC) {
	GC_ROOT_RESTORE(js, root_mark);
	return p;
	}

	ant_value_t proto = js_get(js, ctor, "prototype");
	if (is_err(proto)) {
	GC_ROOT_RESTORE(js, root_mark);
	return proto;
	}
	if (is_object_type(proto)) {
	ant_value_t p_obj = js_as_obj(p);
	set_slot(p_obj, SLOT_CTOR, ctor);
	js_set_proto_init(p_obj, proto);
	}
	GC_ROOT_RESTORE(js, root_mark);
	return p;
	}

	static ant_value_t builtin_Promise_all_resolve_handler(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	ant_value_t tracker = js_get(js, me, "tracker");
	ant_value_t index_val = js_get(js, me, "index");

	int index = (int)tod(index_val);
	ant_value_t value = nargs > 0 ? args[0] : js_mkundef();

	ant_value_t results = js_get(js, tracker, "results");
	arr_set(js, results, (ant_offset_t)index, value);

	ant_value_t remaining_val = js_get(js, tracker, "remaining");
	int remaining = (int)tod(remaining_val) - 1;
	js_setprop(js, tracker, js_mkstr(js, "remaining", 9), tov((double)remaining));

	if (remaining == 0) {
	ant_value_t result_promise = get_slot(tracker, SLOT_DATA);
	js_resolve_promise(js, result_promise, mkval(T_ARR, vdata(results)));
	}

	return js_mkundef();
	}

	static ant_value_t builtin_Promise_all_reject_handler(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	ant_value_t tracker = js_get(js, me, "tracker");
	ant_value_t result_promise = get_slot(tracker, SLOT_DATA);

	ant_value_t reason = nargs > 0 ? args[0] : js_mkundef();
	js_reject_promise(js, result_promise, reason);

	return js_mkundef();
	}

	static ant_value_t promise_all_settled_make_result(ant_t *js, bool fulfilled, ant_value_t value) {
	ant_value_t result = mkobj(js, 0);
	if (is_err(result)) return result;

	js_setprop(
	js, result,
	js_mkstr(js, "status", 6),
	js_mkstr(js, fulfilled ? "fulfilled" : "rejected", fulfilled ? 9 : 8)
	);

	js_setprop(
	js, result,
	js_mkstr(js, fulfilled ? "value" : "reason", fulfilled ? 5 : 6), value
	);

	return result;
	}

	static ant_value_t promise_all_settled_store_result(
	ant_t *js,
	ant_value_t tracker,
	int index,
	bool fulfilled,
	ant_value_t value
	) {
	ant_value_t results = js_get(js, tracker, "results");
	ant_value_t result = promise_all_settled_make_result(js, fulfilled, value);
	ant_value_t remaining_val = 0;
	int remaining = 0;

	if (is_err(result)) return result;
	arr_set(js, results, (ant_offset_t)index, result);

	remaining_val = js_get(js, tracker, "remaining");
	remaining = (int)tod(remaining_val) - 1;
	js_setprop(js, tracker, js_mkstr(js, "remaining", 9), tov((double)remaining));

	if (remaining == 0) {
	ant_value_t result_promise = get_slot(tracker, SLOT_DATA);
	js_resolve_promise(js, result_promise, mkval(T_ARR, vdata(results)));
	}

	return js_mkundef();
	}

	static ant_value_t builtin_Promise_allSettled_resolve_handler(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	ant_value_t tracker = js_get(js, me, "tracker");
	ant_value_t index_val = js_get(js, me, "index");
	int index = (int)tod(index_val);
	ant_value_t value = nargs > 0 ? args[0] : js_mkundef();

	return promise_all_settled_store_result(js, tracker, index, true, value);
	}

	static ant_value_t builtin_Promise_allSettled_reject_handler(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	ant_value_t tracker = js_get(js, me, "tracker");
	ant_value_t index_val = js_get(js, me, "index");
	int index = (int)tod(index_val);
	ant_value_t reason = nargs > 0 ? args[0] : js_mkundef();

	return promise_all_settled_store_result(js, tracker, index, false, reason);
	}

	typedef struct {
	ant_value_t tracker;
	int index;
	} promise_all_iter_ctx_t;

	// TODO: move Promise combinator bookkeeping off JS-visible properties and into slots/native state
	static iter_action_t promise_all_iter_cb(ant_t js, ant_value_t value, void ctx, ant_value_t *out) {
	GC_ROOT_SAVE(root_mark, js);
	promise_all_iter_ctx_t pctx = (promise_all_iter_ctx_t )ctx;
	ant_value_t item = value;
	GC_ROOT_PIN(js, item);

	if (vtype(item) != T_PROMISE) {
	ant_value_t wrap_args[] = { item };
	item = builtin_Promise_resolve(js, wrap_args, 1);
	GC_ROOT_PIN(js, item);
	}

	ant_value_t resolve_obj = mkobj(js, 0);
	if (is_err(resolve_obj)) {
	*out = resolve_obj;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_ERROR;
	}
	GC_ROOT_PIN(js, resolve_obj);
	set_slot(resolve_obj, SLOT_CFUNC, js_mkfun(builtin_Promise_all_resolve_handler));
	js_setprop(js, resolve_obj, js_mkstr(js, "index", 5), tov((double)pctx->index));
	js_setprop(js, resolve_obj, js_mkstr(js, "tracker", 7), pctx->tracker);
	ant_value_t resolve_fn = js_obj_to_func(resolve_obj);
	GC_ROOT_PIN(js, resolve_fn);

	ant_value_t reject_obj = mkobj(js, 0);
	if (is_err(reject_obj)) {
	*out = reject_obj;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_ERROR;
	}
	GC_ROOT_PIN(js, reject_obj);
	set_slot(reject_obj, SLOT_CFUNC, js_mkfun(builtin_Promise_all_reject_handler));
	js_setprop(js, reject_obj, js_mkstr(js, "tracker", 7), pctx->tracker);
	ant_value_t reject_fn = js_obj_to_func(reject_obj);
	GC_ROOT_PIN(js, reject_fn);

	ant_value_t then_args[] = { resolve_fn, reject_fn };
	ant_value_t saved_this = js->this_val;
	GC_ROOT_PIN(js, saved_this);
	js->this_val = item;
	ant_value_t then_result = builtin_promise_then(js, then_args, 2);
	js->this_val = saved_this;
	if (is_err(then_result)) {
	*out = then_result;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_ERROR;
	}

	pctx->index++;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_CONTINUE;
	}

	static iter_action_t promise_all_settled_iter_cb(ant_t js, ant_value_t value, void ctx, ant_value_t *out) {
	GC_ROOT_SAVE(root_mark, js);
	promise_all_iter_ctx_t pctx = (promise_all_iter_ctx_t )ctx;
	ant_value_t item = value;
	GC_ROOT_PIN(js, item);

	if (vtype(item) != T_PROMISE) {
	ant_value_t wrap_args[] = { item };
	item = builtin_Promise_resolve(js, wrap_args, 1);
	GC_ROOT_PIN(js, item);
	}

	ant_value_t resolve_obj = mkobj(js, 0);
	if (is_err(resolve_obj)) {
	*out = resolve_obj;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_ERROR;
	}
	GC_ROOT_PIN(js, resolve_obj);
	set_slot(resolve_obj, SLOT_CFUNC, js_mkfun(builtin_Promise_allSettled_resolve_handler));
	js_setprop(js, resolve_obj, js_mkstr(js, "index", 5), tov((double)pctx->index));
	js_setprop(js, resolve_obj, js_mkstr(js, "tracker", 7), pctx->tracker);
	ant_value_t resolve_fn = js_obj_to_func(resolve_obj);
	GC_ROOT_PIN(js, resolve_fn);

	ant_value_t reject_obj = mkobj(js, 0);
	if (is_err(reject_obj)) {
	*out = reject_obj;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_ERROR;
	}
	GC_ROOT_PIN(js, reject_obj);
	set_slot(reject_obj, SLOT_CFUNC, js_mkfun(builtin_Promise_allSettled_reject_handler));
	js_setprop(js, reject_obj, js_mkstr(js, "index", 5), tov((double)pctx->index));
	js_setprop(js, reject_obj, js_mkstr(js, "tracker", 7), pctx->tracker);
	ant_value_t reject_fn = js_obj_to_func(reject_obj);
	GC_ROOT_PIN(js, reject_fn);

	ant_value_t then_args[] = { resolve_fn, reject_fn };
	ant_value_t saved_this = js->this_val;
	GC_ROOT_PIN(js, saved_this);
	js->this_val = item;
	ant_value_t then_result = builtin_promise_then(js, then_args, 2);
	js->this_val = saved_this;
	if (is_err(then_result)) {
	*out = then_result;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_ERROR;
	}

	pctx->index++;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_CONTINUE;
	}

	static ant_value_t builtin_Promise_all(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "Promise.all requires an iterable");

	GC_ROOT_SAVE(root_mark, js);
	ant_value_t iterable = args[0];
	GC_ROOT_PIN(js, iterable);
	uint8_t t = vtype(iterable);
	if (t != T_ARR && t != T_OBJ) {
	ant_value_t err = js_mkerr(js, "Promise.all requires an iterable");
	GC_ROOT_RESTORE(js, root_mark);
	return err;
	}

	ant_value_t ctor = js->this_val;
	GC_ROOT_PIN(js, ctor);
	if (vtype(ctor) != T_FUNC && vtype(ctor) != T_CFUNC) ctor = js_mkundef();

	ant_value_t result_promise = mkpromise_with_ctor(js, ctor);
	GC_ROOT_PIN(js, result_promise);
	if (is_err(result_promise)) {
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	ant_value_t tracker = mkobj(js, 0);
	GC_ROOT_PIN(js, tracker);
	ant_value_t results = mkarr(js);
	GC_ROOT_PIN(js, results);

	js_setprop(js, tracker, js_mkstr(js, "remaining", 9), tov(0.0));
	js_setprop(js, tracker, js_mkstr(js, "results", 7), results);
	set_slot(tracker, SLOT_DATA, result_promise);

	promise_all_iter_ctx_t ctx = { .tracker = tracker, .index = 0 };
	ant_value_t iter_result = iter_foreach(js, iterable, promise_all_iter_cb, &ctx);

	if (is_err(iter_result)) {
	GC_ROOT_RESTORE(js, root_mark);
	return iter_result;
	}

	int len = ctx.index;
	{
	ant_offset_t doff = get_dense_buf(results);
	if (doff) {
	if ((ant_offset_t)len > dense_capacity(doff)) doff = dense_grow(js, results, (ant_offset_t)len);
	if (doff) array_len_set(js, results, (ant_offset_t)len);
	}
	}

	if (len == 0) {
	js_resolve_promise(js, result_promise, mkval(T_ARR, vdata(results)));
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	js_setprop(js, tracker, js_mkstr(js, "remaining", 9), tov((double)len));
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	static ant_value_t builtin_Promise_allSettled(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "Promise.allSettled requires an iterable");

	GC_ROOT_SAVE(root_mark, js);
	ant_value_t iterable = args[0];
	GC_ROOT_PIN(js, iterable);
	uint8_t t = vtype(iterable);
	if (t != T_ARR && t != T_OBJ) {
	ant_value_t err = js_mkerr(js, "Promise.allSettled requires an iterable");
	GC_ROOT_RESTORE(js, root_mark);
	return err;
	}

	ant_value_t ctor = js->this_val;
	GC_ROOT_PIN(js, ctor);
	if (vtype(ctor) != T_FUNC && vtype(ctor) != T_CFUNC) ctor = js_mkundef();

	ant_value_t result_promise = mkpromise_with_ctor(js, ctor);
	GC_ROOT_PIN(js, result_promise);
	if (is_err(result_promise)) {
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	ant_value_t tracker = mkobj(js, 0);
	GC_ROOT_PIN(js, tracker);
	ant_value_t results = mkarr(js);
	GC_ROOT_PIN(js, results);

	js_setprop(js, tracker, js_mkstr(js, "remaining", 9), tov(0.0));
	js_setprop(js, tracker, js_mkstr(js, "results", 7), results);
	set_slot(tracker, SLOT_DATA, result_promise);

	promise_all_iter_ctx_t ctx = { .tracker = tracker, .index = 0 };
	ant_value_t iter_result = iter_foreach(js, iterable, promise_all_settled_iter_cb, &ctx);

	if (is_err(iter_result)) {
	GC_ROOT_RESTORE(js, root_mark);
	return iter_result;
	}

	int len = ctx.index;
	ant_offset_t doff = get_dense_buf(results);
	if (doff) {
	if ((ant_offset_t)len > dense_capacity(doff)) doff = dense_grow(js, results, (ant_offset_t)len);
	if (doff) array_len_set(js, results, (ant_offset_t)len);
	}

	if (len == 0) {
	js_resolve_promise(js, result_promise, mkval(T_ARR, vdata(results)));
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	js_setprop(js, tracker, js_mkstr(js, "remaining", 9), tov((double)len));
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	typedef struct {
	ant_value_t result_promise;
	ant_value_t resolve_fn;
	ant_value_t reject_fn;
	bool settled;
	} promise_race_iter_ctx_t;

	static iter_action_t promise_race_iter_cb(ant_t js, ant_value_t value, void ctx, ant_value_t *out) {
	GC_ROOT_SAVE(root_mark, js);
	promise_race_iter_ctx_t pctx = (promise_race_iter_ctx_t )ctx;
	ant_value_t item = value;
	GC_ROOT_PIN(js, item);

	if (vtype(item) != T_PROMISE) {
	js_resolve_promise(js, pctx->result_promise, item);
	pctx->settled = true;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_BREAK;
	}

	ant_promise_state_t *pd = get_promise_data(js, item, false);
	if (pd) {
	if (pd->state == 1) {
	js_resolve_promise(js, pctx->result_promise, pd->value);
	pctx->settled = true;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_BREAK;
	} else if (pd->state == 2) {
	js_reject_promise(js, pctx->result_promise, pd->value);
	pctx->settled = true;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_BREAK;
	}}

	ant_value_t then_args[] = { pctx->resolve_fn, pctx->reject_fn };
	ant_value_t saved_this = js->this_val;
	GC_ROOT_PIN(js, saved_this);
	js->this_val = item;
	ant_value_t then_result = builtin_promise_then(js, then_args, 2);
	js->this_val = saved_this;
	if (is_err(then_result)) {
	*out = then_result;
	GC_ROOT_RESTORE(js, root_mark);
	return ITER_ERROR;
	}

	GC_ROOT_RESTORE(js, root_mark);
	return ITER_CONTINUE;
	}

	static ant_value_t builtin_Promise_race(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "Promise.race requires an iterable");

	GC_ROOT_SAVE(root_mark, js);
	ant_value_t iterable = args[0];
	GC_ROOT_PIN(js, iterable);
	uint8_t t = vtype(iterable);
	if (t != T_ARR && t != T_OBJ) {
	ant_value_t err = js_mkerr(js, "Promise.race requires an iterable");
	GC_ROOT_RESTORE(js, root_mark);
	return err;
	}

	ant_value_t ctor = js->this_val;
	GC_ROOT_PIN(js, ctor);
	if (vtype(ctor) != T_FUNC && vtype(ctor) != T_CFUNC) ctor = js_mkundef();
	ant_value_t result_promise = mkpromise_with_ctor(js, ctor);
	GC_ROOT_PIN(js, result_promise);
	if (is_err(result_promise)) {
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	ant_value_t resolve_fn = make_data_cfunc(js, result_promise, builtin_resolve_internal);
	GC_ROOT_PIN(js, resolve_fn);
	if (is_err(resolve_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return resolve_fn;
	}

	ant_value_t reject_fn = make_data_cfunc(js, result_promise, builtin_reject_internal);
	GC_ROOT_PIN(js, reject_fn);
	if (is_err(reject_fn)) {
	GC_ROOT_RESTORE(js, root_mark);
	return reject_fn;
	}

	promise_race_iter_ctx_t ctx = {
	.result_promise = result_promise,
	.resolve_fn = resolve_fn,
	.reject_fn = reject_fn,
	.settled = false
	};

	ant_value_t iter_result = iter_foreach(js, iterable, promise_race_iter_cb, &ctx);
	if (is_err(iter_result)) {
	GC_ROOT_RESTORE(js, root_mark);
	return iter_result;
	}

	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	static ant_value_t mk_aggregate_error(ant_t *js, ant_value_t errors) {
	GC_ROOT_SAVE(root_mark, js);
	GC_ROOT_PIN(js, errors);
	ant_value_t args[] = { errors, js_mkstr(js, "All promises were rejected", 26) };
	ant_offset_t off = lkp(js, js_glob(js), "AggregateError", 14);
	ant_value_t ctor = off ? propref_load(js, off) : js_mkundef();
	GC_ROOT_PIN(js, ctor);
	ant_value_t ret = sv_vm_call(js->vm, js, ctor, js_mkundef(), args, 2, NULL, false);
	GC_ROOT_RESTORE(js, root_mark);
	return ret;
	}

	static bool promise_any_try_resolve(ant_t *js, ant_value_t tracker, ant_value_t value) {
	if (js_truthy(js, js_get(js, tracker, "resolved"))) return false;
	js_set(js, tracker, "resolved", js_true);
	js_resolve_promise(js, get_slot(tracker, SLOT_DATA), value);
	return true;
	}

	static void promise_any_record_rejection(ant_t *js, ant_value_t tracker, int index, ant_value_t reason) {
	ant_value_t errors = js_get(js, tracker, "errors");
	arr_set(js, errors, (ant_offset_t)index, reason);

	int remaining = (int)tod(js_get(js, tracker, "remaining")) - 1;
	js_set(js, tracker, "remaining", tov((double)remaining));

	if (remaining == 0) js_reject_promise(js, get_slot(tracker, SLOT_DATA), mk_aggregate_error(js, errors));
	}

	static ant_value_t builtin_Promise_any_resolve_handler(ant_t js, ant_value_t args, int nargs) {
	ant_value_t tracker = js_get(js, js->this_val, "tracker");
	promise_any_try_resolve(js, tracker, nargs > 0 ? args[0] : js_mkundef());
	return js_mkundef();
	}

	static ant_value_t builtin_Promise_any_reject_handler(ant_t js, ant_value_t args, int nargs) {
	ant_value_t tracker = js_get(js, js->this_val, "tracker");
	if (js_truthy(js, js_get(js, tracker, "resolved"))) return js_mkundef();

	int index = (int)tod(js_get(js, js->this_val, "index"));
	promise_any_record_rejection(js, tracker, index, nargs > 0 ? args[0] : js_mkundef());
	return js_mkundef();
	}

	static ant_value_t builtin_Promise_any(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "Promise.any requires an array");

	GC_ROOT_SAVE(root_mark, js);
	ant_value_t arr = args[0];
	GC_ROOT_PIN(js, arr);
	if (vtype(arr) != T_ARR) {
	ant_value_t err = js_mkerr(js, "Promise.any requires an array");
	GC_ROOT_RESTORE(js, root_mark);
	return err;
	}

	int len = (int)get_array_length(js, arr);

	if (len == 0) {
	ant_value_t reject_args[] = { mk_aggregate_error(js, mkarr(js)) };
	ant_value_t ret = builtin_Promise_reject(js, reject_args, 1);
	GC_ROOT_RESTORE(js, root_mark);
	return ret;
	}

	ant_value_t result_promise = js_mkpromise(js);
	GC_ROOT_PIN(js, result_promise);
	ant_value_t tracker = mkobj(js, 0);
	GC_ROOT_PIN(js, tracker);
	ant_value_t errors = mkarr(js);
	GC_ROOT_PIN(js, errors);

	set_slot(tracker, SLOT_DATA, result_promise);

	js_setprop(js, tracker, js_mkstr(js, "remaining", 9), tov((double)len));
	js_setprop(js, tracker, js_mkstr(js, "errors", 6), errors);
	js_setprop(js, tracker, js_mkstr(js, "resolved", 8), js_false);

	{
	ant_offset_t doff = get_dense_buf(errors);
	if (doff) {
	if ((ant_offset_t)len > dense_capacity(doff)) doff = dense_grow(js, errors, (ant_offset_t)len);
	if (doff) array_len_set(js, errors, (ant_offset_t)len);
	}
	}

	for (int i = 0; i < len; i++) {
	ant_value_t item = arr_get(js, arr, (ant_offset_t)i);
	GC_ROOT_PIN(js, item);
	if (vtype(item) != T_PROMISE) {
	promise_any_try_resolve(js, tracker, item);
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	ant_promise_state_t *pd = get_promise_data(js, item, false);
	if (pd) {
	pd->has_rejection_handler = true;
	pd->unhandled_reported = false;

	if (pd->state == 1) {
	promise_any_try_resolve(js, tracker, pd->value);
	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	} else if (pd->state == 2) {
	promise_any_record_rejection(js, tracker, i, pd->value);
	continue;
	}
	}

	ant_value_t resolve_obj = mkobj(js, 0);
	if (is_err(resolve_obj)) {
	GC_ROOT_RESTORE(js, root_mark);
	return resolve_obj;
	}
	GC_ROOT_PIN(js, resolve_obj);
	set_slot(resolve_obj, SLOT_CFUNC, js_mkfun(builtin_Promise_any_resolve_handler));
	js_setprop(js, resolve_obj, js_mkstr(js, "tracker", 7), tracker);

	ant_value_t reject_obj = mkobj(js, 0);
	if (is_err(reject_obj)) {
	GC_ROOT_RESTORE(js, root_mark);
	return reject_obj;
	}
	GC_ROOT_PIN(js, reject_obj);
	set_slot(reject_obj, SLOT_CFUNC, js_mkfun(builtin_Promise_any_reject_handler));
	js_setprop(js, reject_obj, js_mkstr(js, "index", 5), tov((double)i));
	js_setprop(js, reject_obj, js_mkstr(js, "tracker", 7), tracker);

	ant_value_t resolve_fn = js_obj_to_func(resolve_obj);
	GC_ROOT_PIN(js, resolve_fn);
	ant_value_t reject_fn = js_obj_to_func(reject_obj);
	GC_ROOT_PIN(js, reject_fn);
	ant_value_t then_args[] = { resolve_fn, reject_fn };
	ant_value_t saved_this = js->this_val;
	GC_ROOT_PIN(js, saved_this);
	js->this_val = item;
	ant_value_t then_result = builtin_promise_then(js, then_args, 2);
	js->this_val = saved_this;
	if (is_err(then_result)) {
	GC_ROOT_RESTORE(js, root_mark);
	return then_result;
	}
	}

	GC_ROOT_RESTORE(js, root_mark);
	return result_promise;
	}

	static ant_value_t handle_proxy_instanceof(ant_t *js, ant_value_t l, ant_value_t r, uint8_t ltype) {
	ant_value_t target = proxy_read_target(js, r);
	uint8_t ttype = vtype(target);

	if (ttype != T_FUNC && ttype != T_CFUNC) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Right-hand side of 'instanceof' is not callable");
	}

	{
	ant_value_t has_instance = js_get_sym(js, r, get_hasInstance_sym());
	if (is_err(has_instance)) return has_instance;
	uint8_t hit = vtype(has_instance);
	if (hit == T_FUNC \|\| hit == T_CFUNC) {
	ant_value_t args[1] = { l };
	ant_value_t result = sv_vm_call(js->vm, js, has_instance, r, args, 1, NULL, false);
	if (is_err(result)) return result;
	return js_bool(js_truthy(js, result));
	}
	if (hit != T_UNDEF && hit != T_NULL) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Symbol.hasInstance is not callable");
	}
	}

	ant_value_t proto_val = proxy_get(js, r, "prototype", 9);
	uint8_t pt = vtype(proto_val);

	if (pt != T_OBJ && pt != T_ARR && pt != T_FUNC) {
	return mkval(T_BOOL, 0);
	}

	if (ltype != T_OBJ && ltype != T_ARR && ltype != T_FUNC && ltype != T_PROMISE) {
	return mkval(T_BOOL, 0);
	}

	ant_value_t current = get_proto(js, l);
	return mkval(T_BOOL, proto_chain_contains_cycle_safe(js, current, proto_val) ? 1 : 0);
	}

	static ant_value_t handle_cfunc_instanceof(ant_value_t l, ant_value_t r, uint8_t ltype) {
	ant_value_t (fn)(ant_t , ant_value_t , int) = (ant_value_t()(ant_t , ant_value_t , int)) vdata(r);

	if (fn == builtin_Object) return mkval(T_BOOL, ltype == T_OBJ ? 1 : 0);
	if (fn == builtin_Function) return mkval(T_BOOL, (ltype == T_FUNC \|\| ltype == T_CFUNC) ? 1 : 0);
	if (fn == builtin_String) return mkval(T_BOOL, ltype == T_STR ? 1 : 0);
	if (fn == builtin_Number) return mkval(T_BOOL, ltype == T_NUM ? 1 : 0);
	if (fn == builtin_Boolean) return mkval(T_BOOL, ltype == T_BOOL ? 1 : 0);
	if (fn == builtin_Array) return mkval(T_BOOL, ltype == T_ARR ? 1 : 0);
	if (fn == builtin_Promise) return mkval(T_BOOL, ltype == T_PROMISE ? 1 : 0);

	return mkval(T_BOOL, 0);
	}

	static bool proto_chain_contains_cycle_safe(ant_t *js, ant_value_t start, ant_value_t target) {
	if (!is_object_type(start) \|\| !is_object_type(target)) return false;

	bool found = false;
	ant_value_t slow = start;
	ant_value_t fast = start;

	while (is_object_type(slow)) {
	if (same_object_identity(slow, target)) {
	found = true;
	break;
	}
	slow = get_proto(js, slow);

	if (is_object_type(fast)) fast = get_proto(js, fast);
	if (is_object_type(fast)) fast = get_proto(js, fast);

	if (
	is_object_type(slow) &&
	is_object_type(fast) &&
	same_object_identity(slow, fast)
	) break;
	}

	return found;
	}

	static ant_value_t walk_prototype_chain(ant_t *js, ant_value_t l, ant_value_t ctor_proto) {
	ant_value_t current = get_proto(js, l);
	return mkval(T_BOOL, proto_chain_contains_cycle_safe(js, current, ctor_proto) ? 1 : 0);
	}

	static inline ant_object_t cached_function_proto_obj(ant_t js) {
	static ant_object_t *cached = NULL;
	if (cached) return cached;
	ant_value_t proto = get_ctor_proto(js, "Function", 8);
	if (!is_object_type(proto)) return NULL;
	cached = js_obj_ptr(js_as_obj(proto));
	return cached;
	}

	ant_value_t do_instanceof(ant_t *js, ant_value_t l, ant_value_t r) {
	uint8_t ltype = vtype(l);
	uint8_t rtype = vtype(r);

	if (rtype != T_FUNC && rtype != T_CFUNC) {
	if (is_proxy(r)) return handle_proxy_instanceof(js, l, r, ltype);
	return js_mkerr_typed(js, JS_ERR_TYPE, "Right-hand side of 'instanceof' is not callable");
	}

	if (rtype == T_CFUNC) {
	return handle_cfunc_instanceof(l, r, ltype);
	}

	ant_value_t func_obj = js_func_obj(r);
	ant_offset_t has_instance_sym_off = (ant_offset_t)vdata(get_hasInstance_sym());
	bool use_slow_has_instance = false;
	ant_offset_t own_has_instance = lkp_sym(js, func_obj, has_instance_sym_off);
	if (own_has_instance != 0) {
	const ant_shape_prop_t *prop_meta = prop_shape_meta(js, own_has_instance);
	if (prop_meta && (prop_meta->has_getter \|\| prop_meta->has_setter)) {
	use_slow_has_instance = true;
	} else {
	ant_value_t has_instance = propref_load(js, own_has_instance);
	uint8_t hit = vtype(has_instance);
	if (hit == T_FUNC \|\| hit == T_CFUNC) {
	ant_value_t args[1] = { l };
	ant_value_t result = sv_vm_call(js->vm, js, has_instance, r, args, 1, NULL, false);
	if (is_err(result)) return result;
	return js_bool(js_truthy(js, result));
	}
	if (hit != T_UNDEF && hit != T_NULL) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Symbol.hasInstance is not callable");
	}
	}
	} else {
	ant_object_t *func_proto_ptr = cached_function_proto_obj(js);
	if (func_proto_ptr && func_proto_ptr->shape &&
	ant_shape_lookup_symbol(func_proto_ptr->shape, has_instance_sym_off) >= 0) {
	use_slow_has_instance = true;
	} else if (func_proto_ptr && func_proto_ptr->is_exotic) {
	ant_value_t func_proto_obj = mkval(T_OBJ, (uintptr_t)func_proto_ptr);
	if (lookup_sym_descriptor(func_proto_obj, has_instance_sym_off))
	use_slow_has_instance = true;
	}
	}

	if (use_slow_has_instance) {
	ant_value_t has_instance = js_get_sym(js, r, get_hasInstance_sym());
	if (is_err(has_instance)) return has_instance;
	uint8_t hit = vtype(has_instance);
	if (hit == T_FUNC \|\| hit == T_CFUNC) {
	ant_value_t args[1] = { l };
	ant_value_t result = sv_vm_call(js->vm, js, has_instance, r, args, 1, NULL, false);
	if (is_err(result)) return result;
	return js_bool(js_truthy(js, result));
	}
	if (hit != T_UNDEF && hit != T_NULL) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Symbol.hasInstance is not callable");
	}
	}

	ant_offset_t proto_off = lkp_interned(js, func_obj, js->intern.prototype, 9);
	if (proto_off == 0) return mkval(T_BOOL, 0);

	ant_value_t ctor_proto = propref_load(js, proto_off);
	uint8_t pt = vtype(ctor_proto);
	if (pt != T_OBJ && pt != T_ARR && pt != T_FUNC) return mkval(T_BOOL, 0);

	if (ltype == T_STR \|\| ltype == T_NUM \|\| ltype == T_BOOL) {
	ant_value_t type_proto = get_prototype_for_type(js, ltype);
	return mkval(T_BOOL, vdata(ctor_proto) == vdata(type_proto) ? 1 : 0);
	}

	if (ltype != T_OBJ && ltype != T_ARR && ltype != T_FUNC && ltype != T_PROMISE) {
	return mkval(T_BOOL, 0);
	}

	return walk_prototype_chain(js, l, ctor_proto);
	}

	ant_value_t do_in(ant_t *js, ant_value_t l, ant_value_t r) {
	ant_offset_t prop_len;
	const char *prop_name;
	char num_buf[32];

	ant_value_t key = js_to_primitive(js, l, 1);
	if (is_err(key)) return key;

	bool is_sym = (vtype(key) == T_SYMBOL);

	if (is_sym) {
	const char *d = js_sym_desc(js, key);
	prop_name = d ? d : "symbol";
	prop_len = (ant_offset_t)strlen(prop_name);
	} else if (vtype(key) == T_NUM) {
	prop_len = (ant_offset_t)strnum(key, num_buf, sizeof(num_buf));
	prop_name = num_buf;
	} else {
	ant_value_t key_str = js_tostring_val(js, key);
	if (is_err(key_str)) return key_str;
	ant_offset_t prop_off = vstr(js, key_str, &prop_len);
	prop_name = (char *)(uintptr_t)(prop_off);
	}

	if (!is_object_type(r)) {
	if (vtype(r) == T_CFUNC) return mkval(T_BOOL, 0);
	return js_mkerr_typed(js, JS_ERR_TYPE, "Cannot use 'in' operator to search for '%.*s' in non-object", (int)prop_len, prop_name);
	}

	if (is_proxy(r)) {
	ant_value_t result = is_sym ? proxy_has_val(js, r, key) : proxy_has(js, r, prop_name, prop_len);
	if (is_err(result)) return result;
	return js_bool(js_truthy(js, result));
	}

	if (!is_sym && vtype(r) == T_ARR) {
	unsigned long idx;
	ant_offset_t arr_len = get_array_length(js, r);
	if (parse_array_index(prop_name, prop_len, arr_len, &idx)) return mkval(T_BOOL, arr_has(js, r, (ant_offset_t)idx) ? 1 : 0);
	if (is_length_key(prop_name, prop_len)) return mkval(T_BOOL, 1);
	}

	ant_offset_t found = is_sym ? lkp_sym_proto(js, r, (ant_offset_t)vdata(key)) : lkp_proto(js, r, prop_name, prop_len);
	return mkval(T_BOOL, found != 0 ? 1 : 0);
	}

	static ant_value_t builtin_import_tla_resolve(ant_t js, ant_value_t args, int nargs) {
	ant_value_t me = js->current_func;
	return get_slot(me, SLOT_DATA);
	}

	static inline bool js_has_module_filename(const char *filename) {
	return filename && filename[0];
	}

	static ant_value_t js_get_import_func(ant_t *js) {
	ant_value_t glob = js_glob(js);
	ant_offset_t import_off = lkp(js, glob, "import", 6);
	if (import_off == 0) return js_mkundef();
	return propref_load(js, import_off);
	}

	static ant_value_t js_get_module_ctx_import_meta(ant_t *js, ant_value_t module_ctx) {
	if (!is_object_type(module_ctx)) return js_mkundef();
	return js_get(js, module_ctx, "meta");
	}

	static const char js_get_module_ctx_filename(ant_t js, ant_value_t module_ctx) {
	if (!is_object_type(module_ctx)) return NULL;

	ant_value_t filename = js_get(js, module_ctx, "filename");
	if (vtype(filename) != T_STR) return NULL;
	return js_getstr(js, filename, NULL);
	}

	static ant_value_t js_module_ctx_from_func(ant_value_t func) {
	if (vtype(func) != T_FUNC) return js_mkundef();
	ant_value_t module_ctx = get_slot(js_func_obj(func), SLOT_MODULE_CTX);
	return is_object_type(module_ctx) ? module_ctx : js_mkundef();
	}

	static ant_value_t js_get_execution_module_ctx(ant_t *js) {
	sv_vm_t *vm = sv_vm_get_active(js);
	if (vm && vm->fp >= 0) {
	ant_value_t module_ctx = js_module_ctx_from_func(vm->frames[vm->fp].callee);
	if (is_object_type(module_ctx)) return module_ctx;
	}

	return js_module_eval_active_ctx(js);
	}

	static ant_value_t js_get_import_owner_module_ctx(ant_t *js) {
	ant_value_t module_ctx = js_module_ctx_from_func(js_getcurrentfunc(js));
	if (is_object_type(module_ctx)) return module_ctx;
	return js_get_execution_module_ctx(js);
	}

	static const char js_get_execution_module_filename(ant_t js) {
	const char *filename = js_get_module_ctx_filename(js, js_get_execution_module_ctx(js));
	if (js_has_module_filename(filename)) return filename;
	return js->filename;
	}

	ant_value_t js_builtin_import(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "import() requires a string specifier");

	ant_value_t module_ctx = js_get_import_owner_module_ctx(js);
	const char *base_path = js_get_module_ctx_filename(js, module_ctx);

	if (!js_has_module_filename(base_path))
	base_path = js_get_execution_module_filename(js);

	ant_value_t tla_promise = js_mkundef();
	ant_value_t ns = js_esm_import_dynamic(js, args[0], base_path, &tla_promise);

	if (is_err(ns)) return builtin_Promise_reject(js, &ns, 1);

	if (vtype(tla_promise) == T_PROMISE) {
	ant_value_t resolve_fn = make_data_cfunc(js, ns, builtin_import_tla_resolve);
	ant_value_t saved = js->this_val;

	js->this_val = tla_promise;
	ant_value_t then_args[] = { resolve_fn };

	ant_value_t result = builtin_promise_then(js, then_args, 1);
	js->this_val = saved;

	return result;
	}

	ant_value_t promise_args[] = { ns };
	return builtin_Promise_resolve(js, promise_args, 1);
	}

	static ant_value_t js_get_import_meta_prop(ant_t *js) {
	ant_value_t import_fn = js_get_import_func(js);
	if (vtype(import_fn) != T_FUNC) return js_mkundef();
	return js_get(js, js_func_obj(import_fn), "meta");
	}

	static void js_set_import_meta_prop(ant_t *js, ant_value_t import_meta) {
	ant_value_t import_fn = js_get_import_func(js);
	if (vtype(import_fn) != T_FUNC) return;
	setprop_cstr(js, js_func_obj(import_fn), "meta", 4, import_meta);
	}

	static void js_set_import_module_ctx(ant_t *js, ant_value_t module_ctx) {
	if (!is_object_type(module_ctx)) return;
	ant_value_t import_fn = js_get_import_func(js);
	if (vtype(import_fn) != T_FUNC) return;
	js_set_slot_wb(js, js_func_obj(import_fn), SLOT_MODULE_CTX, module_ctx);
	}

	static ant_value_t js_get_current_import_meta(ant_t *js) {
	ant_value_t import_meta = js_get_module_ctx_import_meta(
	js,
	js_get_execution_module_ctx(js)
	);
	if (vtype(import_meta) == T_OBJ) return import_meta;
	return js_get_import_meta_prop(js);
	}

	static ant_value_t builtin_import_meta_resolve(ant_t js, ant_value_t args, int nargs) {
	if (nargs < 1) return js_mkerr(js, "import.meta.resolve() requires a string specifier");

	const char *base_path = NULL;
	ant_value_t import_meta = js_getthis(js);
	ant_value_t module_ctx = js_mkundef();

	if (is_object_type(import_meta)) module_ctx = js_get_slot(import_meta, SLOT_MODULE_CTX);

	if (!is_object_type(module_ctx))
	module_ctx = js_get_import_owner_module_ctx(js);

	base_path = js_get_module_ctx_filename(js, module_ctx);
	if (!js_has_module_filename(base_path))
	base_path = js_get_execution_module_filename(js);

	return js_esm_resolve_specifier(js, args[0], base_path);
	}

	static inline void js_set_import_meta_special_dirname(
	ant_t *js,
	ant_value_t import_meta,
	const char *filename,
	bool is_builtin
	) {
	char *filename_copy = strdup(filename);
	if (!filename_copy) return;

	char *last_slash = strrchr(filename_copy, '/');
	char *scheme_end = strstr(filename_copy, "://");

	if ((is_builtin && last_slash) \|\| (!is_builtin && last_slash && scheme_end && last_slash > scheme_end + 2)) {
	*last_slash = '\0';
	ant_value_t dirname_val = js_mkstr(js, filename_copy, strlen(filename_copy));
	if (!is_err(dirname_val)) setprop_cstr(js, import_meta, "dirname", 7, dirname_val);
	}

	free(filename_copy);
	}

	static inline void js_set_import_meta_path_dirname(
	ant_t *js,
	ant_value_t import_meta,
	const char *filename
	) {
	char *filename_copy = strdup(filename);
	if (!filename_copy) return;

	char *dir = dirname(filename_copy);
	if (dir) {
	ant_value_t dirname_val = js_mkstr(js, dir, strlen(dir));
	if (!is_err(dirname_val)) setprop_cstr(js, import_meta, "dirname", 7, dirname_val);
	}

	free(filename_copy);
	}

	static ant_value_t js_create_import_meta_for_context(
	ant_t *js,
	ant_value_t module_ctx,
	const char *filename,
	bool is_main
	) {
	if (!filename) return js_mkundef();

	ant_value_t import_meta = mkobj(js, 0);
	if (is_err(import_meta)) return import_meta;

	js_set_slot_wb(js, import_meta, SLOT_MODULE_CTX, module_ctx);

	bool is_url = esm_is_url(filename);
	bool is_builtin = esm_has_builtin_scheme(filename);

	ant_value_t url_val = (is_url \|\| is_builtin)
	? js_mkstr(js, filename, strlen(filename))
	: js_esm_make_file_url(js, filename);
	if (!is_err(url_val)) setprop_cstr(js, import_meta, "url", 3, url_val);

	ant_value_t filename_val = js_get(js, module_ctx, "filename");
	if (vtype(filename_val) == T_STR)
	setprop_cstr(js, import_meta, "filename", 8, filename_val);

	if (is_url \|\| is_builtin) js_set_import_meta_special_dirname(js, import_meta, filename, is_builtin);
	else js_set_import_meta_path_dirname(js, import_meta, filename);

	setprop_cstr(js, import_meta, "main", 4, is_main ? js_true : js_false);

	ant_value_t resolve_fn = js_heavy_mkfun(js, builtin_import_meta_resolve, js_mkundef());
	if (vtype(resolve_fn) == T_FUNC)
	js_set_slot_wb(js, js_func_obj(resolve_fn), SLOT_MODULE_CTX, module_ctx);
	setprop_cstr(js, import_meta, "resolve", 7, resolve_fn);

	return import_meta;
	}

	ant_value_t js_create_module_context(ant_t js, const char filename, bool is_main) {
	GC_ROOT_SAVE(root_mark, js);
	if (!js_has_module_filename(filename)) {
	GC_ROOT_RESTORE(js, root_mark);
	return js_mkundef();
	}

	ant_value_t module_ctx = js_mkobj(js);
	if (is_err(module_ctx)) {
	GC_ROOT_RESTORE(js, root_mark);
	return module_ctx;
	}
	GC_ROOT_PIN(js, module_ctx);

	ant_value_t filename_val = js_mkstr(js, filename, strlen(filename));
	if (is_err(filename_val)) {
	GC_ROOT_RESTORE(js, root_mark);
	return filename_val;
	}

	GC_ROOT_PIN(js, filename_val);
	setprop_cstr(js, module_ctx, "filename", 8, filename_val);
	setprop_cstr(js, module_ctx, "displayName", 11, filename_val);

	ant_value_t import_meta = js_create_import_meta_for_context(js, module_ctx, filename, is_main);
	if (is_err(import_meta)) {
	GC_ROOT_RESTORE(js, root_mark);
	return import_meta;
	}

	GC_ROOT_PIN(js, import_meta);
	setprop_cstr(js, module_ctx, "meta", 4, import_meta);
	GC_ROOT_RESTORE(js, root_mark);

	return module_ctx;
	}

	ant_value_t js_create_import_meta(ant_t js, const char filename, bool is_main) {
	ant_value_t module_ctx = js_create_module_context(js, filename, is_main);
	if (is_err(module_ctx)) return module_ctx;
	return js_get_module_ctx_import_meta(js, module_ctx);
	}

	ant_value_t js_get_module_import_binding(ant_t *js) {
	GC_ROOT_SAVE(root_mark, js);

	ant_value_t module_ctx = js_get_execution_module_ctx(js);
	ant_value_t import_meta = js_get_module_ctx_import_meta(js, module_ctx);

	GC_ROOT_PIN(js, module_ctx);
	GC_ROOT_PIN(js, import_meta);

	if (!is_object_type(module_ctx) \|\| vtype(import_meta) != T_OBJ) {
	GC_ROOT_RESTORE(js, root_mark);
	return js_mkundef();
	}

	ant_value_t import_obj = js_mkobj(js);
	if (is_err(import_obj)) {
	GC_ROOT_RESTORE(js, root_mark);
	return import_obj;
	}

	GC_ROOT_PIN(js, import_obj);
	ant_value_t function_proto = js_get_slot(js_glob(js), SLOT_FUNC_PROTO);

	if (vtype(function_proto) == T_UNDEF)
	function_proto = js_get_ctor_proto(js, "Function", 8);
	GC_ROOT_PIN(js, function_proto);

	if (is_object_type(function_proto)) js_set_proto_wb(js, import_obj, function_proto);
	set_slot(import_obj, SLOT_CFUNC, js_mkfun(js_builtin_import));

	js_set_slot_wb(js, import_obj, SLOT_MODULE_CTX, module_ctx);
	setprop_cstr(js, import_obj, "meta", 4, import_meta);

	ant_value_t import_fn = js_obj_to_func(import_obj);
	GC_ROOT_RESTORE(js, root_mark);

	return import_fn;
	}

	void js_setup_import_meta(ant_t js, const char filename) {
	if (!filename) return;

	ant_value_t module_ctx = js_create_module_context(js, filename, true);
	ant_value_t import_meta = js_get_module_ctx_import_meta(js, module_ctx);
	if (is_err(import_meta) \|\| vtype(import_meta) == T_UNDEF) return;

	js_set_import_module_ctx(js, module_ctx);
	js_set_import_meta_prop(js, import_meta);
	}

	void js_module_eval_ctx_push(ant_t js, ant_module_t ctx) {
	if (!js \|\| !ctx) return;

	ctx->prev = js->module;
	ctx->prev_import_meta_prop = js_get_import_meta_prop(js);
	js->module = ctx;

	ant_value_t import_meta = js_get_module_ctx_import_meta(js, ctx->module_ctx);
	if (vtype(import_meta) != T_UNDEF) js_set_import_meta_prop(js, import_meta);
	}

	void js_module_eval_ctx_pop(ant_t js, ant_module_t ctx) {
	if (!js \|\| !ctx) return;

	if (js->module == ctx) {
	js_set_import_meta_prop(js, ctx->prev_import_meta_prop);
	js->module = ctx->prev;
	}
	}

	static ant_proxy_state_t *get_proxy_data(ant_value_t obj) {
	if (vtype(obj) != T_OBJ) return NULL;
	ant_object_t *ptr = js_obj_ptr(obj);
	return ptr ? ptr->proxy_state : NULL;
	}

	bool is_proxy(ant_value_t obj) {
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr \|\| !ptr->is_exotic) return false;
	return get_proxy_data(obj) != NULL;
	}

	static bool js_is_constructor_impl(ant_t *js, ant_value_t value) {
	(void)js;
	ant_value_t slow = value;
	ant_value_t fast = value;

	while (true) {
	uint8_t t = vtype(slow);
	if (t == T_FUNC) {
	ant_object_t *obj = js_obj_ptr(js_func_obj(slow));
	return obj && obj->is_constructor;
	}
	if (t != T_OBJ) return false;

	ant_object_t *obj = js_obj_ptr(slow);
	if (!obj) return false;
	if (obj->is_constructor) return true;
	if (!obj->is_exotic) return false;

	ant_proxy_state_t *data = get_proxy_data(slow);
	if (!data) return false;
	slow = data->target;

	for (int i = 0; i < 2; i++) {
	if (vtype(fast) != T_OBJ) { fast = js_mknull(); break; }
	ant_object_t *fobj = js_obj_ptr(fast);
	if (!fobj \|\| !fobj->is_exotic) { fast = js_mknull(); break; }
	ant_proxy_state_t *fdata = get_proxy_data(fast);
	if (!fdata) { fast = js_mknull(); break; }
	fast = fdata->target;
	}

	if (same_object_identity(slow, fast)) return false;
	}
	}

	bool js_is_constructor(ant_t *js, ant_value_t value) {
	return js_is_constructor_impl(js, value);
	}

	static ant_value_t proxy_read_target(ant_t *js, ant_value_t obj) {
	ant_proxy_state_t *data = get_proxy_data(obj);
	return data ? data->target : obj;
	}

	static ant_offset_t proxy_aware_length(ant_t *js, ant_value_t obj) {
	ant_value_t src = is_proxy(obj) ? proxy_read_target(js, obj) : obj;
	if (vtype(src) == T_ARR) return get_array_length(js, src);
	ant_offset_t off = lkp_interned(js, src, js->intern.length, 6);
	if (off == 0) return 0;
	ant_value_t len_val = propref_load(js, off);
	return vtype(len_val) == T_NUM ? (ant_offset_t)tod(len_val) : 0;
	}

	static ant_value_t proxy_aware_get_elem(ant_t js, ant_value_t obj, const char key, size_t key_len) {
	ant_value_t src = is_proxy(obj) ? proxy_read_target(js, obj) : obj;
	ant_offset_t off = lkp(js, src, key, key_len);
	return off ? propref_load(js, off) : js_mkundef();
	}

	static ant_value_t throw_proxy_error(ant_t js, const char message) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "%s", message);
	}

	static bool proxy_target_is_extensible(ant_value_t obj) {
	uint8_t t = vtype(obj);
	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return false;

	ant_object_t *ptr = js_obj_ptr(js_as_obj(obj));
	if (!ptr) return false;
	if (ptr->frozen \|\| ptr->sealed) return false;
	return ptr->extensible != 0;
	}

	static bool proxy_target_prop_is_nonconfig(ant_t *js, ant_value_t target, ant_offset_t prop_off) {
	(void)target;
	return is_nonconfig_prop(js, prop_off);
	}

	static bool proxy_target_prop_is_const(ant_t *js, ant_value_t target, ant_offset_t prop_off) {
	(void)target;
	return is_const_prop(js, prop_off);
	}

	static ant_value_t proxy_get(ant_t js, ant_value_t proxy, const char key, size_t key_len) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_mkundef();
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'get' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;

	ant_offset_t get_trap_off = vtype(handler) == T_OBJ
	? lkp_interned(js, handler, js->intern.get, 3)
	: 0;

	if (get_trap_off != 0) {
	ant_value_t get_trap = propref_load(js, get_trap_off);
	if (vtype(get_trap) == T_FUNC \|\| vtype(get_trap) == T_CFUNC) {
	ant_value_t key_val = js_mkstr(js, key, key_len);

	ant_value_t args[3] = { target, key_val, proxy };
	ant_value_t result = sv_vm_call(js->vm, js, get_trap, js_mkundef(), args, 3, NULL, false);
	if (is_err(result)) return result;

	ant_offset_t prop_off = lkp(js, target, key, key_len);
	if (prop_off != 0 && proxy_target_prop_is_nonconfig(js, target, prop_off) &&
	proxy_target_prop_is_const(js, target, prop_off)) {
	ant_value_t target_value = propref_load(js, prop_off);
	if (!strict_eq_values(js, result, target_value))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'get' on proxy: trap returned invalid value for non-configurable, non-writable property");
	}

	prop_meta_t meta;
	bool has_meta = lookup_string_prop_meta(js, js_as_obj(target), key, key_len, &meta);
	if (has_meta && !meta.configurable) {
	if (!meta.has_getter && !meta.has_setter && !meta.writable && prop_off != 0) {
	ant_value_t target_value = propref_load(js, prop_off);
	if (!strict_eq_values(js, result, target_value))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'get' on proxy: trap returned invalid value for non-configurable, non-writable property");
	}
	if ((meta.has_getter \|\| meta.has_setter) && !meta.has_getter && vtype(result) != T_UNDEF)
	return js_mkerr_typed(js, JS_ERR_TYPE, "'get' on proxy: trap returned non-undefined for property with undefined getter");
	}

	return result;
	}
	}

	char key_buf[256];
	size_t len = key_len < sizeof(key_buf) - 1 ? key_len : sizeof(key_buf) - 1;
	memcpy(key_buf, key, len);
	key_buf[len] = '\0';

	ant_offset_t off = lkp(js, target, key_buf, len);
	if (off != 0) return propref_load(js, off);

	ant_offset_t proto_off = lkp_proto(js, target, key_buf, len);
	if (proto_off != 0) return propref_load(js, proto_off);

	return js_mkundef();
	}

	static ant_value_t proxy_set(ant_t js, ant_value_t proxy, const char key, size_t key_len, ant_value_t value) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_mkundef();
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'set' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;

	ant_offset_t set_trap_off = vtype(handler) == T_OBJ ? lkp_interned(js, handler, js->intern.set, 3) : 0;
	if (set_trap_off != 0) {
	ant_value_t set_trap = propref_load(js, set_trap_off);
	if (vtype(set_trap) == T_FUNC \|\| vtype(set_trap) == T_CFUNC) {
	ant_value_t key_val = js_mkstr(js, key, key_len);
	ant_value_t args[4] = { target, key_val, value, proxy };
	ant_value_t result = sv_vm_call(js->vm, js, set_trap, js_mkundef(), args, 4, NULL, false);
	if (is_err(result)) return result;
	if (js_truthy(js, result)) {
	ant_offset_t prop_off = lkp(js, target, key, key_len);
	if (prop_off != 0 && proxy_target_prop_is_nonconfig(js, target, prop_off) &&
	proxy_target_prop_is_const(js, target, prop_off)) {
	ant_value_t target_value = propref_load(js, prop_off);
	if (!strict_eq_values(js, value, target_value))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'set' on proxy: trap returned truthy for non-configurable, non-writable property with different value");
	}

	prop_meta_t meta;
	bool has_meta = lookup_string_prop_meta(js, js_as_obj(target), key, key_len, &meta);
	if (has_meta && !meta.configurable) {
	if (!meta.has_getter && !meta.has_setter && !meta.writable && prop_off != 0) {
	ant_value_t target_value = propref_load(js, prop_off);
	if (!strict_eq_values(js, value, target_value))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'set' on proxy: trap returned truthy for non-configurable, non-writable property with different value");
	}
	if ((meta.has_getter \|\| meta.has_setter) && !meta.has_setter)
	return js_mkerr_typed(js, JS_ERR_TYPE, "'set' on proxy: trap returned truthy for property with undefined setter");
	}
	}
	return js_true;
	}
	}

	ant_value_t key_str = js_mkstr(js, key, key_len);
	js_setprop(js, target, key_str, value);
	return js_true;
	}

	static ant_value_t proxy_has(ant_t js, ant_value_t proxy, const char key, size_t key_len) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_false;
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'has' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;

	ant_offset_t has_trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "has", 3) : 0;
	if (has_trap_off != 0) {
	ant_value_t has_trap = propref_load(js, has_trap_off);
	if (vtype(has_trap) == T_FUNC \|\| vtype(has_trap) == T_CFUNC) {
	ant_value_t key_val = js_mkstr(js, key, key_len);
	ant_value_t args[2] = { target, key_val };
	ant_value_t result = sv_vm_call(js->vm, js, has_trap, js_mkundef(), args, 2, NULL, false);
	if (is_err(result)) return result;

	if (!js_truthy(js, result)) {
	ant_offset_t prop_off = lkp(js, target, key, key_len);
	prop_meta_t meta;
	bool has_meta = lookup_string_prop_meta(js, js_as_obj(target), key, key_len, &meta);
	bool has_own = (prop_off != 0) \|\| has_meta;

	if ((prop_off != 0 && proxy_target_prop_is_nonconfig(js, target, prop_off)) \|\| (has_meta && !meta.configurable))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'has' on proxy: trap returned falsy for non-configurable property");

	if (has_own && !proxy_target_is_extensible(target))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'has' on proxy: trap returned falsy for existing property on non-extensible target");
	}

	return result;
	}
	}

	char key_buf[256];
	size_t len = key_len < sizeof(key_buf) - 1 ? key_len : sizeof(key_buf) - 1;
	memcpy(key_buf, key, len);
	key_buf[len] = '\0';

	ant_offset_t off = lkp_proto(js, target, key_buf, len);
	return js_bool(off != 0);
	}

	static ant_value_t proxy_delete(ant_t js, ant_value_t proxy, const char key, size_t key_len) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_true;
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'deleteProperty' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;

	ant_offset_t delete_trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "deleteProperty", 14) : 0;
	if (delete_trap_off != 0) {
	ant_value_t delete_trap = propref_load(js, delete_trap_off);
	if (vtype(delete_trap) == T_FUNC \|\| vtype(delete_trap) == T_CFUNC) {
	ant_value_t key_val = js_mkstr(js, key, key_len);
	ant_value_t args[2] = { target, key_val };
	ant_value_t result = sv_vm_call(js->vm, js, delete_trap, js_mkundef(), args, 2, NULL, false);
	if (is_err(result)) return result;
	if (js_truthy(js, result)) {
	ant_offset_t prop_off = lkp(js, target, key, key_len);
	if (prop_off != 0 && is_nonconfig_prop(js, prop_off))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'deleteProperty' on proxy: trap returned truthy for non-configurable property");
	prop_meta_t meta;
	if (lookup_string_prop_meta(js, js_as_obj(target), key, key_len, &meta) && !meta.configurable)
	return js_mkerr_typed(js, JS_ERR_TYPE, "'deleteProperty' on proxy: trap returned truthy for non-configurable property");
	}
	return result;
	}
	}

	ant_value_t key_str = js_mkstr(js, key, key_len);
	js_setprop(js, target, key_str, js_mkundef());
	return js_true;
	}

	static ant_value_t proxy_get_val(ant_t *js, ant_value_t proxy, ant_value_t key_val) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_mkundef();
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'get' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;
	ant_value_t prop_key = key_val;

	if (vtype(prop_key) != T_SYMBOL) {
	if (is_object_type(prop_key)) {
	prop_key = js_to_primitive(js, prop_key, 1);
	if (is_err(prop_key)) return prop_key;
	}

	if (vtype(prop_key) != T_SYMBOL) {
	prop_key = js_tostring_val(js, prop_key);
	if (is_err(prop_key)) return prop_key;
	}}

	ant_offset_t get_trap_off = vtype(handler) == T_OBJ
	? lkp_interned(js, handler, js->intern.get, 3) : 0;

	if (get_trap_off != 0) {
	ant_value_t get_trap = propref_load(js, get_trap_off);
	if (vtype(get_trap) == T_FUNC \|\| vtype(get_trap) == T_CFUNC) {
	ant_value_t args[3] = { target, prop_key, proxy };
	return sv_vm_call(js->vm, js, get_trap, js_mkundef(), args, 3, NULL, false);
	}}

	if (vtype(prop_key) == T_SYMBOL) {
	ant_offset_t off = lkp_sym_proto(js, target, (ant_offset_t)vdata(prop_key));
	return off != 0 ? propref_load(js, off) : js_mkundef();
	}

	ant_offset_t key_len = 0;
	ant_offset_t key_off = vstr(js, prop_key, &key_len);
	const char key_ptr = (const char )(uintptr_t)key_off;

	return proxy_get(js, proxy, key_ptr, (size_t)key_len);
	}

	static ant_value_t proxy_get_prototype_of(ant_t *js, ant_value_t proxy) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_mknull();

	if (data->revoked)
	return throw_proxy_error(js, "Cannot perform 'getPrototypeOf' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;
	ant_offset_t trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "getPrototypeOf", 14) : 0;

	if (trap_off != 0) {
	ant_value_t trap = propref_load(js, trap_off);
	if (vtype(trap) == T_FUNC \|\| vtype(trap) == T_CFUNC) {
	ant_value_t args[1] = { target };
	ant_value_t result = sv_vm_call(js->vm, js, trap, js_mkundef(), args, 1, NULL, false);
	if (is_err(result)) return result;
	if (is_object_type(result) \|\| vtype(result) == T_NULL) return result;
	return js_mkerr_typed(js, JS_ERR_TYPE, "'getPrototypeOf' on proxy: trap returned neither object nor null");
	}}

	return get_proto(js, target);
	}

	static ant_value_t proxy_has_val(ant_t *js, ant_value_t proxy, ant_value_t key_val) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_false;
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'has' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;
	ant_value_t prop_key = key_val;

	if (vtype(prop_key) != T_SYMBOL) {
	if (is_object_type(prop_key)) {
	prop_key = js_to_primitive(js, prop_key, 1);
	if (is_err(prop_key)) return prop_key;
	}

	if (vtype(prop_key) != T_SYMBOL) {
	prop_key = js_tostring_val(js, prop_key);
	if (is_err(prop_key)) return prop_key;
	}}

	ant_offset_t has_trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "has", 3) : 0;
	if (has_trap_off != 0) {
	ant_value_t has_trap = propref_load(js, has_trap_off);
	if (vtype(has_trap) == T_FUNC \|\| vtype(has_trap) == T_CFUNC) {
	ant_value_t args[2] = { target, prop_key };
	return sv_vm_call(js->vm, js, has_trap, js_mkundef(), args, 2, NULL, false);
	}}

	if (vtype(prop_key) == T_SYMBOL) {
	ant_offset_t off = lkp_sym_proto(js, target, (ant_offset_t)vdata(prop_key));
	return js_bool(off != 0);
	}

	ant_offset_t key_len = 0;
	ant_offset_t key_off = vstr(js, prop_key, &key_len);
	const char key_ptr = (const char )(uintptr_t)key_off;

	return proxy_has(js, proxy, key_ptr, (size_t)key_len);
	}

	static ant_value_t proxy_get_own_property_descriptor(ant_t *js, ant_value_t proxy, ant_value_t key_val) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_mkundef();

	if (data->revoked)
	return throw_proxy_error(js, "Cannot perform 'getOwnPropertyDescriptor' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;
	ant_offset_t trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "getOwnPropertyDescriptor", 24) : 0;

	if (trap_off != 0) {
	ant_value_t trap = propref_load(js, trap_off);
	if (vtype(trap) == T_FUNC \|\| vtype(trap) == T_CFUNC) {
	ant_value_t args[2] = { target, key_val };
	ant_value_t result = sv_vm_call(js->vm, js, trap, js_mkundef(), args, 2, NULL, false);
	if (is_err(result)) return result;
	if (vtype(result) == T_UNDEF \|\| vtype(result) == T_OBJ) return result;
	return js_mkerr_typed(js, JS_ERR_TYPE, "'getOwnPropertyDescriptor' on proxy: trap returned neither object nor undefined");
	}}

	ant_value_t args[2] = { target, key_val };
	return builtin_object_getOwnPropertyDescriptor(js, args, 2);
	}

	static ant_value_t proxy_has_own(ant_t *js, ant_value_t proxy, ant_value_t key_val) {
	ant_value_t desc = proxy_get_own_property_descriptor(js, proxy, key_val);
	if (is_err(desc)) return desc;
	return js_bool(vtype(desc) != T_UNDEF);
	}

	static ant_value_t proxy_define_property(ant_t *js, ant_value_t proxy, ant_value_t key_val, ant_value_t descriptor) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_false;
	if (data->revoked)
	return throw_proxy_error(js, "Cannot perform 'defineProperty' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;
	ant_offset_t trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "defineProperty", 14) : 0;

	if (trap_off != 0) {
	ant_value_t trap = propref_load(js, trap_off);
	if (vtype(trap) == T_FUNC \|\| vtype(trap) == T_CFUNC) {
	ant_value_t args[3] = { target, key_val, descriptor };
	return sv_vm_call(js->vm, js, trap, js_mkundef(), args, 3, NULL, false);
	}}

	ant_value_t args[3] = { target, key_val, descriptor };
	ant_value_t result = builtin_object_defineProperty(js, args, 3);
	if (is_err(result)) return result;
	return js_true;
	}

	static ant_value_t proxy_delete_val(ant_t *js, ant_value_t proxy, ant_value_t key_val) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_true;
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'deleteProperty' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;

	ant_offset_t delete_trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "deleteProperty", 14) : 0;
	if (delete_trap_off != 0) {
	ant_value_t delete_trap = propref_load(js, delete_trap_off);
	if (vtype(delete_trap) == T_FUNC \|\| vtype(delete_trap) == T_CFUNC) {
	ant_value_t args[2] = { target, key_val };
	ant_value_t result = sv_vm_call(js->vm, js, delete_trap, js_mkundef(), args, 2, NULL, false);
	if (is_err(result)) return result;
	if (js_truthy(js, result) && vtype(key_val) == T_SYMBOL) {
	ant_offset_t prop_off = lkp_sym(js, target, (ant_offset_t)vdata(key_val));
	if (prop_off != 0 && is_nonconfig_prop(js, prop_off))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'deleteProperty' on proxy: trap returned truthy for non-configurable property");
	} return result;
	}
	}
	if (vtype(key_val) == T_SYMBOL) return js_delete_sym_prop(js, target, key_val);
	return js_true;
	}

	ant_value_t js_proxy_apply(ant_t js, ant_value_t proxy, ant_value_t this_arg, ant_value_t args, int argc) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_mkerr_typed(js, JS_ERR_TYPE, "object is not a function");
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'apply' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;
	uint8_t target_type = vtype(target);

	if (target_type != T_FUNC && target_type != T_CFUNC && !(target_type == T_OBJ && is_proxy(target)))
	return js_mkerr_typed(js, JS_ERR_TYPE, "%s is not a function", typestr(target_type));

	ant_offset_t trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "apply", 5) : 0;
	if (trap_off != 0) {
	ant_value_t trap = propref_load(js, trap_off);
	if (vtype(trap) == T_FUNC \|\| vtype(trap) == T_CFUNC) {
	ant_value_t args_arr = mkarr(js);
	for (int i = 0; i < argc; i++)
	js_arr_push(js, args_arr, args[i]);
	ant_value_t trap_args[3] = { target, this_arg, args_arr };
	return sv_vm_call(js->vm, js, trap, handler, trap_args, 3, NULL, false);
	}
	}

	return sv_vm_call(js->vm, js, target, this_arg, args, argc, NULL, false);
	}

	ant_value_t js_proxy_construct(ant_t js, ant_value_t proxy, ant_value_t args, int argc, ant_value_t new_target) {
	ant_proxy_state_t *data = get_proxy_data(proxy);
	if (!data) return js_mkerr_typed(js, JS_ERR_TYPE, "not a constructor");
	if (data->revoked) return throw_proxy_error(js, "Cannot perform 'construct' on a proxy that has been revoked");

	ant_value_t target = data->target;
	ant_value_t handler = data->handler;

	if (!js_is_constructor(js, target))
	return js_mkerr_typed(js, JS_ERR_TYPE, "not a constructor");
	if (vtype(target) == T_OBJ && is_proxy(target))
	return js_proxy_construct(js, target, args, argc, new_target);
	if (vtype(target) != T_FUNC)
	return js_mkerr_typed(js, JS_ERR_TYPE, "not a constructor");

	ant_offset_t trap_off = vtype(handler) == T_OBJ ? lkp(js, handler, "construct", 9) : 0;
	if (trap_off != 0) {
	ant_value_t trap = propref_load(js, trap_off);
	if (vtype(trap) == T_FUNC \|\| vtype(trap) == T_CFUNC) {
	ant_value_t args_arr = mkarr(js);
	for (int i = 0; i < argc; i++)
	js_arr_push(js, args_arr, args[i]);
	ant_value_t trap_args[3] = { target, args_arr, new_target };
	ant_value_t result = sv_vm_call(js->vm, js, trap, js_mkundef(), trap_args, 3, NULL, false);
	if (is_err(result)) return result;
	if (!is_object_type(result))
	return js_mkerr_typed(js, JS_ERR_TYPE, "'construct' on proxy: trap returned non-Object");
	return result;
	}
	}

	ant_value_t obj = mkobj(js, 0);
	ant_value_t proto = js_getprop_fallback(js, target, "prototype");
	if (is_object_type(proto)) js_set_proto_init(obj, proto);
	ant_value_t saved = js->new_target;
	js->new_target = new_target;
	ant_value_t ctor_this = obj;
	ant_value_t result = sv_vm_call(js->vm, js, target, obj, args, argc, &ctor_this, true);
	js->new_target = saved;
	if (is_err(result)) return result;
	return is_object_type(result) ? result : (is_object_type(ctor_this) ? ctor_this : obj);
	}

	static ant_value_t mkproxy(ant_t *js, ant_value_t target, ant_value_t handler) {
	ant_value_t proxy_obj = mkobj(js, 0);
	ant_object_t *proxy_ptr = js_obj_ptr(proxy_obj);
	if (!proxy_ptr) return js_mkerr(js, "out of memory");

	ant_proxy_state_t data = (ant_proxy_state_t )ant_calloc(sizeof(ant_proxy_state_t));
	if (!data) return js_mkerr(js, "out of memory");

	data->target = target;
	data->handler = handler;
	data->revoked = false;

	proxy_ptr->is_exotic = 1;
	js_mark_constructor(proxy_obj, js_is_constructor(js, target));
	proxy_ptr->proxy_state = data;
	return proxy_obj;
	}

	static ant_value_t create_proxy_checked(ant_t js, ant_value_t args, int nargs, bool require_new) {
	if (require_new && vtype(js->new_target) == T_UNDEF) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Proxy constructor requires 'new'");
	}
	if (nargs < 2) return js_mkerr(js, "Proxy requires two arguments: target and handler");

	ant_value_t target = args[0];
	ant_value_t handler = args[1];

	uint8_t target_type = vtype(target);
	if (target_type != T_OBJ && target_type != T_FUNC && target_type != T_ARR) {
	return js_mkerr(js, "Proxy target must be an object");
	}

	uint8_t handler_type = vtype(handler);
	if (handler_type != T_OBJ && handler_type != T_FUNC) {
	return js_mkerr(js, "Proxy handler must be an object");
	}

	return mkproxy(js, target, handler);
	}

	static ant_value_t builtin_Proxy(ant_t js, ant_value_t args, int nargs) {
	return create_proxy_checked(js, args, nargs, true);
	}

	static ant_value_t proxy_revoke_fn(ant_t js, ant_value_t args, int nargs) {
	(void)args; (void)nargs;
	ant_value_t func = js->current_func;
	ant_value_t ref_slot = get_slot(func, SLOT_PROXY_REF);

	if (vtype(ref_slot) != T_UNDEF && vdata(ref_slot) != 0) {
	ant_proxy_state_t *data = get_proxy_data(ref_slot);
	if (data) data->revoked = true;
	}

	return js_mkundef();
	}

	static ant_value_t builtin_Proxy_revocable(ant_t js, ant_value_t args, int nargs) {
	ant_value_t proxy = create_proxy_checked(js, args, nargs, false);
	if (is_err(proxy)) return proxy;

	ant_value_t revoke_obj = mkobj(js, 0);
	set_slot(revoke_obj, SLOT_CFUNC, js_mkfun(proxy_revoke_fn));
	set_slot(revoke_obj, SLOT_PROXY_REF, proxy);

	ant_value_t revoke_func = js_obj_to_func(revoke_obj);

	ant_value_t result = mkobj(js, 0);
	js_setprop(js, result, js_mkstr(js, "proxy", 5), proxy);
	js_setprop(js, result, js_mkstr(js, "revoke", 6), revoke_func);

	return result;
	}

	ant_t js_create(void buf, size_t len) {
	ANT_ASSERT(
	(uintptr_t)buf <= ((1ULL << 53) - 1),
	"pointer exceeds 53-bit double-precision integer limit"
	);

	ant_t *js = NULL;

	if (len < sizeof(*js)) return js;
	memset(buf, 0, len);

	js = (ant_t *)buf;
	rt->js = js;
	js_init_intern_cache(js);

	if (!fixed_arena_init(&js->obj_arena, sizeof(ant_object_t), offsetof(ant_object_t, mark_epoch), ANT_ARENA_MAX)) return NULL;
	if (!fixed_arena_init(&js->closure_arena, sizeof(sv_closure_t), offsetof(sv_closure_t, gc_epoch), ANT_CLOSURE_ARENA_MAX)) {
	fixed_arena_destroy(&js->obj_arena);
	return NULL;
	}

	if (!fixed_arena_init(&js->upvalue_arena, sizeof(sv_upvalue_t), offsetof(sv_upvalue_t, gc_epoch), ANT_CLOSURE_ARENA_MAX)) {
	fixed_arena_destroy(&js->closure_arena);
	fixed_arena_destroy(&js->obj_arena);
	return NULL;
	}

	js->c_root_cap = 64;
	js->c_roots = calloc(js->c_root_cap, sizeof(*js->c_roots));

	if (!js->c_roots) {
	fixed_arena_destroy(&js->upvalue_arena);
	fixed_arena_destroy(&js->closure_arena);
	fixed_arena_destroy(&js->obj_arena);
	return NULL;
	}

	js->global = mkobj(js, 0);
	js->this_val = js->global;
	js->new_target = js_mkundef();
	js->length_str = ANT_STRING("length");

	ant_value_t glob = js->global;
	ant_value_t object_proto = js_mkobj(js);
	set_proto(js, object_proto, js_mknull());

	defmethod(js, object_proto, "toString", 8, js_mkfun(builtin_object_toString));
	defmethod(js, object_proto, "valueOf", 7, js_mkfun(builtin_object_valueOf));
	defmethod(js, object_proto, "toLocaleString", 14, js_mkfun(builtin_object_toLocaleString));
	defmethod(js, object_proto, "hasOwnProperty", 14, js_mkfun(builtin_object_hasOwnProperty));
	defmethod(js, object_proto, "isPrototypeOf", 13, js_mkfun(builtin_object_isPrototypeOf));
	defmethod(js, object_proto, "propertyIsEnumerable", 20, js_mkfun(builtin_object_propertyIsEnumerable));
	defmethod(js, object_proto, "__defineGetter__", 16, js_mkfun(builtin_object___defineGetter__));
	defmethod(js, object_proto, "__defineSetter__", 16, js_mkfun(builtin_object___defineSetter__));
	defmethod(js, object_proto, "__lookupGetter__", 16, js_mkfun(builtin_object___lookupGetter__));
	defmethod(js, object_proto, "__lookupSetter__", 16, js_mkfun(builtin_object___lookupSetter__));

	ant_value_t proto_getter = js_mkfun(builtin_proto_getter);
	ant_value_t proto_setter = js_mkfun(builtin_proto_setter);
	js_set_accessor_desc(js, object_proto, STR_PROTO, STR_PROTO_LEN, proto_getter, proto_setter, JS_DESC_C);

	ant_value_t function_proto_obj = js_mkobj(js);
	set_proto(js, function_proto_obj, object_proto);
	set_slot(function_proto_obj, SLOT_CFUNC, js_mkfun(builtin_function_empty));

	defmethod(js, function_proto_obj, "call", 4, js_mkfun(builtin_function_call));
	defmethod(js, function_proto_obj, "apply", 5, js_mkfun(builtin_function_apply));
	defmethod(js, function_proto_obj, "bind", 4, js_mkfun(builtin_function_bind));
	defmethod(js, function_proto_obj, "toString", 8, js_mkfun(builtin_function_toString));

	ant_value_t function_proto = js_obj_to_func(function_proto_obj);
	set_slot(glob, SLOT_FUNC_PROTO, function_proto);

	ant_value_t array_proto = alloc_array_with_proto(js, object_proto);

	defmethod(js, array_proto, "push", 4, js_mkfun(builtin_array_push));
	defmethod(js, array_proto, "pop", 3, js_mkfun(builtin_array_pop));
	defmethod(js, array_proto, "slice", 5, js_mkfun(builtin_array_slice));
	defmethod(js, array_proto, "join", 4, js_mkfun(builtin_array_join));
	defmethod(js, array_proto, "includes", 8, js_mkfun(builtin_array_includes));
	defmethod(js, array_proto, "every", 5, js_mkfun(builtin_array_every));
	defmethod(js, array_proto, "reverse", 7, js_mkfun(builtin_array_reverse));
	defmethod(js, array_proto, "map", 3, js_mkfun(builtin_array_map));
	defmethod(js, array_proto, "filter", 6, js_mkfun(builtin_array_filter));
	defmethod(js, array_proto, "reduce", 6, js_mkfun(builtin_array_reduce));
	defmethod(js, array_proto, "flat", 4, js_mkfun(builtin_array_flat));
	defmethod(js, array_proto, "concat", 6, js_mkfun(builtin_array_concat));
	defmethod(js, array_proto, "at", 2, js_mkfun(builtin_array_at));
	defmethod(js, array_proto, "fill", 4, js_mkfun(builtin_array_fill));
	defmethod(js, array_proto, "find", 4, js_mkfun(builtin_array_find));
	defmethod(js, array_proto, "findIndex", 9, js_mkfun(builtin_array_findIndex));
	defmethod(js, array_proto, "findLast", 8, js_mkfun(builtin_array_findLast));
	defmethod(js, array_proto, "findLastIndex", 13, js_mkfun(builtin_array_findLastIndex));
	defmethod(js, array_proto, "flatMap", 7, js_mkfun(builtin_array_flatMap));
	defmethod(js, array_proto, "forEach", 7, js_mkfun(builtin_array_forEach));
	defmethod(js, array_proto, "indexOf", 7, js_mkfun(builtin_array_indexOf));
	defmethod(js, array_proto, "lastIndexOf", 11, js_mkfun(builtin_array_lastIndexOf));
	defmethod(js, array_proto, "reduceRight", 11, js_mkfun(builtin_array_reduceRight));
	defmethod(js, array_proto, "shift", 5, js_mkfun(builtin_array_shift));
	defmethod(js, array_proto, "unshift", 7, js_mkfun(builtin_array_unshift));
	defmethod(js, array_proto, "some", 4, js_mkfun(builtin_array_some));
	defmethod(js, array_proto, "sort", 4, js_mkfun(builtin_array_sort));
	defmethod(js, array_proto, "splice", 6, js_mkfun(builtin_array_splice));
	defmethod(js, array_proto, "copyWithin", 10, js_mkfun(builtin_array_copyWithin));
	defmethod(js, array_proto, "toReversed", 10, js_mkfun(builtin_array_toReversed));
	defmethod(js, array_proto, "toSorted", 8, js_mkfun(builtin_array_toSorted));
	defmethod(js, array_proto, "toSpliced", 9, js_mkfun(builtin_array_toSpliced));
	defmethod(js, array_proto, "with", 4, js_mkfun(builtin_array_with));
	defmethod(js, array_proto, "keys", 4, js_mkfun(builtin_array_keys));
	defmethod(js, array_proto, "values", 6, js_mkfun(builtin_array_values));
	defmethod(js, array_proto, "entries", 7, js_mkfun(builtin_array_entries));
	defmethod(js, array_proto, "toString", 8, js_mkfun(builtin_array_toString));
	defmethod(js, array_proto, "toLocaleString", 14, js_mkfun(builtin_array_toLocaleString));

	ant_value_t string_proto = js_mkobj(js);
	set_proto(js, string_proto, object_proto);

	defmethod(js, string_proto, "indexOf", 7, js_mkfun(builtin_string_indexOf));
	defmethod(js, string_proto, "substring", 9, js_mkfun(builtin_string_substring));
	defmethod(js, string_proto, "substr", 6, js_mkfun(builtin_string_substr));
	defmethod(js, string_proto, "split", 5, js_mkfun(builtin_string_split));
	defmethod(js, string_proto, "slice", 5, js_mkfun(builtin_string_slice));
	defmethod(js, string_proto, "includes", 8, js_mkfun(builtin_string_includes));
	defmethod(js, string_proto, "startsWith", 10, js_mkfun(builtin_string_startsWith));
	defmethod(js, string_proto, "endsWith", 8, js_mkfun(builtin_string_endsWith));
	defmethod(js, string_proto, "template", 8, js_mkfun(builtin_string_template));
	defmethod(js, string_proto, "charCodeAt", 10, js_mkfun(builtin_string_charCodeAt));
	defmethod(js, string_proto, "codePointAt", 11, js_mkfun(builtin_string_codePointAt));
	defmethod(js, string_proto, "toLowerCase", 11, js_mkfun(builtin_string_toLowerCase));
	defmethod(js, string_proto, "toUpperCase", 11, js_mkfun(builtin_string_toUpperCase));
	defmethod(js, string_proto, "toLocaleLowerCase", 17, js_mkfun(builtin_string_toLowerCase));
	defmethod(js, string_proto, "toLocaleUpperCase", 17, js_mkfun(builtin_string_toUpperCase));
	defmethod(js, string_proto, "trim", 4, js_mkfun(builtin_string_trim));
	defmethod(js, string_proto, "trimStart", 9, js_mkfun(builtin_string_trimStart));
	defmethod(js, string_proto, "trimEnd", 7, js_mkfun(builtin_string_trimEnd));
	defmethod(js, string_proto, "repeat", 6, js_mkfun(builtin_string_repeat));
	defmethod(js, string_proto, "padStart", 8, js_mkfun(builtin_string_padStart));
	defmethod(js, string_proto, "padEnd", 6, js_mkfun(builtin_string_padEnd));
	defmethod(js, string_proto, "charAt", 6, js_mkfun(builtin_string_charAt));
	defmethod(js, string_proto, "at", 2, js_mkfun(builtin_string_at));
	defmethod(js, string_proto, "lastIndexOf", 11, js_mkfun(builtin_string_lastIndexOf));
	defmethod(js, string_proto, "concat", 6, js_mkfun(builtin_string_concat));
	defmethod(js, string_proto, "localeCompare", 13, js_mkfun(builtin_string_localeCompare));
	defmethod(js, string_proto, "normalize", 9, js_mkfun(builtin_string_normalize));
	defmethod(js, string_proto, "valueOf", 7, js_mkfun(builtin_string_valueOf));
	defmethod(js, string_proto, "toString", 8, js_mkfun(builtin_string_toString));

	ant_value_t number_proto = js_mkobj(js);
	set_proto(js, number_proto, object_proto);

	defmethod(js, number_proto, "toString", 8, js_mkfun(builtin_number_toString));
	defmethod(js, number_proto, "toFixed", 7, js_mkfun(builtin_number_toFixed));
	defmethod(js, number_proto, "toPrecision", 11, js_mkfun(builtin_number_toPrecision));
	defmethod(js, number_proto, "toExponential", 13, js_mkfun(builtin_number_toExponential));
	defmethod(js, number_proto, "valueOf", 7, js_mkfun(builtin_number_valueOf));
	defmethod(js, number_proto, "toLocaleString", 14, js_mkfun(builtin_number_toLocaleString));

	ant_value_t boolean_proto = js_mkobj(js);
	set_proto(js, boolean_proto, object_proto);

	defmethod(js, boolean_proto, "valueOf", 7, js_mkfun(builtin_boolean_valueOf));
	defmethod(js, boolean_proto, "toString", 8, js_mkfun(builtin_boolean_toString));

	ant_value_t error_proto = js_mkobj(js);
	set_proto(js, error_proto, object_proto);

	js_setprop(js, error_proto, ANT_STRING("name"), ANT_STRING("Error"));
	js_setprop(js, error_proto, ANT_STRING("message"), js_mkstr(js, "", 0));
	defmethod(js, error_proto, "toString", 8, js_mkfun(builtin_Error_toString));

	ant_value_t err_ctor_obj = mkobj(js, 0);
	set_proto(js, err_ctor_obj, function_proto);
	set_slot(err_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_Error));
	js_setprop_nonconfigurable(js, err_ctor_obj, "prototype", 9, error_proto);
	js_setprop(js, err_ctor_obj, ANT_STRING("name"), ANT_STRING("Error"));

	ant_value_t err_ctor_func = js_obj_to_func(err_ctor_obj);
	js_setprop(js, glob, ANT_STRING("Error"), err_ctor_func);
	js_setprop(js, error_proto, js_mkstr(js, "constructor", 11), err_ctor_func);
	js_set_descriptor(js, error_proto, "constructor", 11, JS_DESC_W \| JS_DESC_C);
	defmethod(js, err_ctor_func, "isError", 7, js_mkfun(builtin_error_isError));
	defmethod(js, err_ctor_func, "captureStackTrace", 17, js_mkfun(builtin_error_captureStackTrace));
	js_setprop(js, err_ctor_func, ANT_STRING("stackTraceLimit"), js_mknum(10));

	#define REGISTER_ERROR_SUBTYPE(name_str) do { \
	ant_value_t proto = js_mkobj(js); \
	set_proto(js, proto, error_proto); \
	js_setprop(js, proto, ANT_STRING("name"), ANT_STRING(name_str)); \
	ant_value_t ctor = mkobj(js, 0); \
	set_proto(js, ctor, function_proto); \
	set_slot(ctor, SLOT_CFUNC, js_mkfun(builtin_Error)); \
	js_setprop_nonconfigurable(js, ctor, "prototype", 9, proto); \
	js_setprop(js, ctor, ANT_STRING("name"), ANT_STRING(name_str)); \
	ant_value_t ctor_func = js_obj_to_func(ctor); \
	js_setprop(js, proto, ANT_STRING("constructor"), ctor_func); \
	js_set_descriptor(js, proto, "constructor", 11, JS_DESC_W \| JS_DESC_C); \
	js_setprop(js, glob, ANT_STRING(name_str), ctor_func); \
	} while(0)

	REGISTER_ERROR_SUBTYPE("EvalError");
	REGISTER_ERROR_SUBTYPE("RangeError");
	REGISTER_ERROR_SUBTYPE("ReferenceError");
	REGISTER_ERROR_SUBTYPE("SyntaxError");
	REGISTER_ERROR_SUBTYPE("TypeError");
	REGISTER_ERROR_SUBTYPE("URIError");
	REGISTER_ERROR_SUBTYPE("InternalError");

	#undef REGISTER_ERROR_SUBTYPE

	ant_value_t proto = js_mkobj(js);
	set_proto(js, proto, error_proto);
	js_setprop(js, proto, ANT_STRING("name"), ANT_STRING("AggregateError"));
	ant_value_t ctor = mkobj(js, 0);
	set_proto(js, ctor, function_proto);
	set_slot(ctor, SLOT_CFUNC, js_mkfun(builtin_AggregateError));
	js_setprop_nonconfigurable(js, ctor, "prototype", 9, proto);
	js_setprop(js, ctor, ANT_STRING("name"), ANT_STRING("AggregateError"));
	js_setprop(js, proto, ANT_STRING("constructor"), js_obj_to_func(ctor));
	js_set_descriptor(js, proto, "constructor", 11, JS_DESC_W \| JS_DESC_C);
	js_setprop(js, glob, ANT_STRING("AggregateError"), js_obj_to_func(ctor));

	ant_value_t promise_proto = js_mkobj(js);
	set_proto(js, promise_proto, object_proto);
	defmethod(js, promise_proto, "then", 4, js_mkfun(builtin_promise_then));
	defmethod(js, promise_proto, "catch", 5, js_mkfun(builtin_promise_catch));
	defmethod(js, promise_proto, "finally", 7, js_mkfun(builtin_promise_finally));

	ant_value_t obj_func_obj = mkobj(js, 0);
	set_proto(js, obj_func_obj, function_proto);
	set_slot(obj_func_obj, SLOT_BUILTIN, tov(BUILTIN_OBJECT));
	js_mark_constructor(obj_func_obj, true);

	defmethod(js, obj_func_obj, "keys", 4, js_mkfun(builtin_object_keys));
	defmethod(js, obj_func_obj, "values", 6, js_mkfun(builtin_object_values));
	defmethod(js, obj_func_obj, "entries", 7, js_mkfun(builtin_object_entries));
	defmethod(js, obj_func_obj, "is", 2, js_mkfun(builtin_object_is));
	defmethod(js, obj_func_obj, "getPrototypeOf", 14, js_mkfun(builtin_object_getPrototypeOf));
	defmethod(js, obj_func_obj, "setPrototypeOf", 14, js_mkfun(builtin_object_setPrototypeOf));
	defmethod(js, obj_func_obj, "create", 6, js_mkfun(builtin_object_create));
	defmethod(js, obj_func_obj, "hasOwn", 6, js_mkfun(builtin_object_hasOwn));
	defmethod(js, obj_func_obj, "groupBy", 7, js_mkfun(builtin_object_groupBy));
	defmethod(js, obj_func_obj, "defineProperty", 14, js_mkfun(builtin_object_defineProperty));
	defmethod(js, obj_func_obj, "defineProperties", 16, js_mkfun(builtin_object_defineProperties));
	defmethod(js, obj_func_obj, "assign", 6, js_mkfun(builtin_object_assign));
	defmethod(js, obj_func_obj, "freeze", 6, js_mkfun(builtin_object_freeze));
	defmethod(js, obj_func_obj, "isFrozen", 8, js_mkfun(builtin_object_isFrozen));
	defmethod(js, obj_func_obj, "seal", 4, js_mkfun(builtin_object_seal));
	defmethod(js, obj_func_obj, "isSealed", 8, js_mkfun(builtin_object_isSealed));
	defmethod(js, obj_func_obj, "fromEntries", 11, js_mkfun(builtin_object_fromEntries));
	defmethod(js, obj_func_obj, "getOwnPropertyDescriptor", 24, js_mkfun(builtin_object_getOwnPropertyDescriptor));
	defmethod(js, obj_func_obj, "getOwnPropertyDescriptors", 25, js_mkfun(builtin_object_getOwnPropertyDescriptors));
	defmethod(js, obj_func_obj, "getOwnPropertyNames", 19, js_mkfun(builtin_object_getOwnPropertyNames));
	defmethod(js, obj_func_obj, "getOwnPropertySymbols", 21, js_mkfun(builtin_object_getOwnPropertySymbols));
	defmethod(js, obj_func_obj, "isExtensible", 12, js_mkfun(builtin_object_isExtensible));
	defmethod(js, obj_func_obj, "preventExtensions", 17, js_mkfun(builtin_object_preventExtensions));

	js_setprop(js, obj_func_obj, ANT_STRING("name"), ANT_STRING("Object"));
	js_setprop_readonly_nonconfigurable(js, obj_func_obj, "prototype", 9, object_proto);
	ant_value_t obj_func = js_obj_to_func(obj_func_obj);
	js_setprop(js, glob, js_mkstr(js, "Object", 6), obj_func);

	ant_value_t func_ctor_obj = mkobj(js, 0);
	set_proto(js, func_ctor_obj, function_proto);
	set_slot(func_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_Function));
	js_setprop_nonconfigurable(js, func_ctor_obj, "prototype", 9, function_proto);
	js_setprop(js, func_ctor_obj, js->length_str, tov(1.0));
	js_set_descriptor(js, func_ctor_obj, "length", 6, JS_DESC_C);
	js_setprop(js, func_ctor_obj, ANT_STRING("name"), ANT_STRING("Function"));
	ant_value_t func_ctor_func = js_obj_to_func(func_ctor_obj);
	js_setprop(js, glob, js_mkstr(js, "Function", 8), func_ctor_func);

	ant_value_t async_func_proto_obj = js_mkobj(js);
	set_proto(js, async_func_proto_obj, function_proto);
	set_slot(async_func_proto_obj, SLOT_ASYNC, js_true);
	ant_value_t async_func_proto = js_obj_to_func(async_func_proto_obj);
	set_slot(glob, SLOT_ASYNC_PROTO, async_func_proto);

	ant_value_t async_func_ctor_obj = mkobj(js, 0);
	set_proto(js, async_func_ctor_obj, function_proto);
	set_slot(async_func_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_AsyncFunction));
	js_setprop_nonconfigurable(js, async_func_ctor_obj, "prototype", 9, async_func_proto);
	js_setprop(js, async_func_ctor_obj, js->length_str, tov(1.0));
	js_set_descriptor(js, async_func_ctor_obj, "length", 6, JS_DESC_C);
	js_setprop(js, async_func_ctor_obj, ANT_STRING("name"), ANT_STRING("AsyncFunction"));
	ant_value_t async_func_ctor = js_obj_to_func(async_func_ctor_obj);

	js_setprop(js, async_func_proto_obj, js_mkstr(js, "constructor", 11), async_func_ctor);
	js_set_descriptor(js, async_func_proto_obj, "constructor", 11, JS_DESC_W \| JS_DESC_C);

	ant_value_t generator_func_proto_obj = js_mkobj(js);
	set_proto(js, generator_func_proto_obj, function_proto);
	ant_value_t generator_func_proto = js_obj_to_func(generator_func_proto_obj);
	set_slot(glob, SLOT_GENERATOR_PROTO, generator_func_proto);

	ant_value_t generator_func_ctor_obj = mkobj(js, 0);
	set_proto(js, generator_func_ctor_obj, function_proto);
	set_slot(generator_func_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_GeneratorFunction));
	js_setprop_nonconfigurable(js, generator_func_ctor_obj, "prototype", 9, generator_func_proto);
	js_setprop(js, generator_func_ctor_obj, js->length_str, tov(1.0));
	js_set_descriptor(js, generator_func_ctor_obj, "length", 6, JS_DESC_C);
	js_setprop(js, generator_func_ctor_obj, ANT_STRING("name"), ANT_STRING("GeneratorFunction"));
	ant_value_t generator_func_ctor = js_obj_to_func(generator_func_ctor_obj);

	js_setprop(js, generator_func_proto_obj, js_mkstr(js, "constructor", 11), generator_func_ctor);
	js_set_descriptor(js, generator_func_proto_obj, "constructor", 11, JS_DESC_W \| JS_DESC_C);

	ant_value_t str_ctor_obj = mkobj(js, 0);
	set_proto(js, str_ctor_obj, function_proto);
	set_slot(str_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_String));
	js_setprop_nonconfigurable(js, str_ctor_obj, "prototype", 9, string_proto);
	defmethod(js, str_ctor_obj, "fromCharCode", 12, js_mkfun(builtin_string_fromCharCode));
	defmethod(js, str_ctor_obj, "fromCodePoint", 13, js_mkfun(builtin_string_fromCodePoint));
	defmethod(js, str_ctor_obj, "raw", 3, js_mkfun(builtin_string_raw));
	js_setprop(js, str_ctor_obj, ANT_STRING("name"), ANT_STRING("String"));
	ant_value_t str_ctor_func = js_obj_to_func(str_ctor_obj);
	js_setprop(js, glob, js_mkstr(js, "String", 6), str_ctor_func);

	ant_value_t number_ctor_obj = mkobj(js, 0);
	set_proto(js, number_ctor_obj, function_proto);

	set_slot(number_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_Number));
	defmethod(js, number_ctor_obj, "isNaN", 5, js_mkfun(builtin_Number_isNaN));
	defmethod(js, number_ctor_obj, "isFinite", 8, js_mkfun(builtin_Number_isFinite));
	defmethod(js, number_ctor_obj, "isInteger", 9, js_mkfun(builtin_Number_isInteger));
	defmethod(js, number_ctor_obj, "isSafeInteger", 13, js_mkfun(builtin_Number_isSafeInteger));
	defmethod(js, number_ctor_obj, "parseInt", 8, js_mkfun(builtin_parseInt));
	defmethod(js, number_ctor_obj, "parseFloat", 10, js_mkfun(builtin_parseFloat));

	js_setprop(js, number_ctor_obj, js_mkstr(js, "MAX_VALUE", 9), tov(1.7976931348623157e+308));
	js_setprop(js, number_ctor_obj, js_mkstr(js, "MIN_VALUE", 9), tov(5e-324));
	js_setprop(js, number_ctor_obj, js_mkstr(js, "MAX_SAFE_INTEGER", 16), tov(9007199254740991.0));
	js_setprop(js, number_ctor_obj, js_mkstr(js, "MIN_SAFE_INTEGER", 16), tov(-9007199254740991.0));
	js_setprop(js, number_ctor_obj, js_mkstr(js, "POSITIVE_INFINITY", 17), tov(JS_INF));
	js_setprop(js, number_ctor_obj, js_mkstr(js, "NEGATIVE_INFINITY", 17), tov(JS_NEG_INF));
	js_setprop(js, number_ctor_obj, js_mkstr(js, "NaN", 3), tov(JS_NAN));
	js_setprop(js, number_ctor_obj, js_mkstr(js, "EPSILON", 7), tov(2.220446049250313e-16));

	js_setprop_nonconfigurable(js, number_ctor_obj, "prototype", 9, number_proto);
	js_setprop(js, number_ctor_obj, ANT_STRING("name"), ANT_STRING("Number"));
	ant_value_t number_ctor_func = js_obj_to_func(number_ctor_obj);
	js_setprop(js, glob, js_mkstr(js, "Number", 6), number_ctor_func);

	ant_value_t bool_ctor_obj = mkobj(js, 0);
	set_proto(js, bool_ctor_obj, function_proto);
	set_slot(bool_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_Boolean));
	js_setprop_nonconfigurable(js, bool_ctor_obj, "prototype", 9, boolean_proto);
	js_setprop(js, bool_ctor_obj, ANT_STRING("name"), ANT_STRING("Boolean"));
	ant_value_t bool_ctor_func = js_obj_to_func(bool_ctor_obj);
	js_setprop(js, glob, js_mkstr(js, "Boolean", 7), bool_ctor_func);

	ant_value_t arr_ctor_obj = mkobj(js, 0);
	set_proto(js, arr_ctor_obj, function_proto);
	set_slot(arr_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_Array));
	js_setprop_readonly_nonconfigurable(js, arr_ctor_obj, "prototype", 9, array_proto);
	defmethod(js, arr_ctor_obj, "isArray", 7, js_mkfun(builtin_Array_isArray));
	defmethod(js, arr_ctor_obj, "from", 4, js_mkfun(builtin_Array_from));
	defmethod(js, arr_ctor_obj, "of", 2, js_mkfun(builtin_Array_of));
	js_setprop(js, arr_ctor_obj, js->length_str, tov(1.0));
	js_set_descriptor(js, arr_ctor_obj, "length", 6, JS_DESC_C);
	js_setprop(js, arr_ctor_obj, ANT_STRING("name"), ANT_STRING("Array"));
	ant_value_t arr_ctor_func = js_obj_to_func(arr_ctor_obj);
	js_setprop(js, glob, js_mkstr(js, "Array", 5), arr_ctor_func);

	ant_value_t proxy_ctor_obj = mkobj(js, 0);
	set_proto(js, proxy_ctor_obj, function_proto);
	set_slot(proxy_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_Proxy));
	js_mark_constructor(proxy_ctor_obj, true);
	defmethod(js, proxy_ctor_obj, "revocable", 9, js_mkfun(builtin_Proxy_revocable));
	js_setprop(js, proxy_ctor_obj, ANT_STRING("name"), ANT_STRING("Proxy"));
	js_setprop(js, glob, js_mkstr(js, "Proxy", 5), js_obj_to_func(proxy_ctor_obj));

	ant_value_t p_ctor_obj = mkobj(js, 0);
	set_proto(js, p_ctor_obj, function_proto);
	set_slot(p_ctor_obj, SLOT_CFUNC, js_mkfun(builtin_Promise));

	defmethod(js, p_ctor_obj, "resolve", 7, js_mkfun(builtin_Promise_resolve));
	defmethod(js, p_ctor_obj, "reject", 6, js_mkfun(builtin_Promise_reject));
	defmethod(js, p_ctor_obj, "try", 3, js_mkfun(builtin_Promise_try));
	defmethod(js, p_ctor_obj, "withResolvers", 13, js_mkfun(builtin_Promise_withResolvers));
	defmethod(js, p_ctor_obj, "all", 3, js_mkfun(builtin_Promise_all));
	defmethod(js, p_ctor_obj, "allSettled", 10, js_mkfun(builtin_Promise_allSettled));
	defmethod(js, p_ctor_obj, "race", 4, js_mkfun(builtin_Promise_race));
	defmethod(js, p_ctor_obj, "any", 3, js_mkfun(builtin_Promise_any));

	js_setprop_nonconfigurable(js, p_ctor_obj, "prototype", 9, promise_proto);
	js_setprop(js, p_ctor_obj, ANT_STRING("name"), ANT_STRING("Promise"));
	js_setprop(js, glob, js_mkstr(js, "Promise", 7), js_obj_to_func(p_ctor_obj));

	defmethod(js, glob, "parseInt", 8, js_mkfun(builtin_parseInt));
	defmethod(js, glob, "parseFloat", 10, js_mkfun(builtin_parseFloat));
	defmethod(js, glob, "eval", 4, js_mkfun(builtin_eval));
	defmethod(js, glob, "isNaN", 5, js_mkfun(builtin_global_isNaN));
	defmethod(js, glob, "isFinite", 8, js_mkfun(builtin_global_isFinite));
	defmethod(js, glob, "btoa", 4, js_mkfun(builtin_btoa));
	defmethod(js, glob, "atob", 4, js_mkfun(builtin_atob));

	js_setprop(js, glob, js_mkstr(js, "NaN", 3), tov(JS_NAN));
	js_set_descriptor(js, glob, "NaN", 3, 0);
	js_setprop(js, glob, js_mkstr(js, "Infinity", 8), tov(JS_INF));
	js_set_descriptor(js, glob, "Infinity", 8, 0);
	js_setprop(js, glob, js_mkstr(js, "undefined", 9), js_mkundef());
	js_set_descriptor(js, glob, "undefined", 9, 0);

	ant_value_t import_obj = mkobj(js, 0);
	set_proto(js, import_obj, function_proto);

	set_slot(import_obj, SLOT_CFUNC, js_mkfun(js_builtin_import));
	js_setprop(js, glob, js_mkstr(js, "import", 6), js_obj_to_func(import_obj));

	js_setprop(js, object_proto, js_mkstr(js, "constructor", 11), obj_func);
	js_set_descriptor(js, object_proto, "constructor", 11, JS_DESC_W \| JS_DESC_C);

	js_setprop(js, function_proto, js_mkstr(js, "constructor", 11), func_ctor_func);
	js_set_descriptor(js, js_as_obj(function_proto), "constructor", 11, JS_DESC_W \| JS_DESC_C);

	js_setprop(js, array_proto, js_mkstr(js, "constructor", 11), arr_ctor_func);
	js_set_descriptor(js, js_as_obj(array_proto), "constructor", 11, JS_DESC_W \| JS_DESC_C);

	js_setprop(js, string_proto, js_mkstr(js, "constructor", 11), str_ctor_func);
	js_set_descriptor(js, string_proto, "constructor", 11, JS_DESC_W \| JS_DESC_C);

	js_setprop(js, number_proto, js_mkstr(js, "constructor", 11), number_ctor_func);
	js_set_descriptor(js, number_proto, "constructor", 11, JS_DESC_W \| JS_DESC_C);

	js_setprop(js, boolean_proto, js_mkstr(js, "constructor", 11), bool_ctor_func);
	js_set_descriptor(js, boolean_proto, "constructor", 11, JS_DESC_W \| JS_DESC_C);

	set_proto(js, glob, object_proto);

	js->sym.object_proto = object_proto;
	js->sym.array_proto = array_proto;
	js->owns_mem = false;
	js->max_size = 0;

	return js;
	}

	ant_t *js_create_dynamic() {
	ant_t js = (ant_t )calloc(1, sizeof(*js));
	if (js == NULL) return NULL;
	if (js_create(js, sizeof(*js)) == NULL) {
	free(js);
	return NULL;
	}
	js->owns_mem = true;
	js->vm = sv_vm_create(js, SV_VM_MAIN);
	return js;
	}

	void js_destroy(ant_t *js) {
	if (js == NULL) return;
	if (js->vm) {
	sv_vm_destroy(js->vm);
	js->vm = NULL;
	}

	js_esm_cleanup_module_cache();
	code_arena_reset();
	cleanup_lmdb_module();

	ant_object_t *lists[] = { js->objects, js->objects_old, js->permanent_objects };
	for (int i = 0; i < 3; i++) for (ant_object_t *obj = lists[i]; obj;) {
	ant_object_t *next = obj->next;
	gc_object_free(js, obj);
	obj = next;
	}

	js->objects = NULL;
	js->objects_old = NULL;
	js->permanent_objects = NULL;

	cleanup_buffer_module();
	cleanup_atomics_module(js);

	fixed_arena_destroy(&js->obj_arena);
	fixed_arena_destroy(&js->closure_arena);
	fixed_arena_destroy(&js->upvalue_arena);

	free(js->prop_refs);
	js->prop_refs = NULL;
	js->prop_refs_len = js->prop_refs_cap = 0;

	free(js->c_roots);
	js->c_roots = NULL;
	js->c_root_count = js->c_root_cap = 0;

	free(js->pending_rejections.items);
	js->pending_rejections.items = NULL;
	js->pending_rejections.len = js->pending_rejections.cap = 0;

	free(js->cfunc_promote_cache.cfunc_ptr);
	free(js->cfunc_promote_cache.promoted);
	js->cfunc_promote_cache.cfunc_ptr = NULL;
	js->cfunc_promote_cache.promoted = NULL;
	js->cfunc_promote_cache.len = js->cfunc_promote_cache.cap = 0;

	js_pool_destroy(&js->pool.rope);
	js_pool_destroy(&js->pool.symbol);
	js_pool_destroy(&js->pool.permanent);

	js_class_pool_destroy(&js->pool.bigint);
	js_string_pool_destroy(&js->pool.string);

	destroy_runtime(js);
	if (js->owns_mem) free(js);
	}

	inline double js_getnum(ant_value_t value) { return tod(value); }
	inline void js_setstackbase(ant_t js, void base) { js->cstk.base = base; js->cstk.main_base = base; }
	inline void js_setstacklimit(ant_t *js, size_t max) { js->cstk.limit = max; }
	inline void js_set_filename(ant_t js, const char filename) { js->filename = filename; }

	inline ant_value_t js_mkundef(void) { return mkval(T_UNDEF, 0); }
	inline ant_value_t js_mknull(void) { return mkval(T_NULL, 0); }
	inline ant_value_t js_mknum(double value) { return tov(value); }
	inline ant_value_t js_mkobj(ant_t *js) { return mkobj(js, 0); }
	inline ant_value_t js_glob(ant_t *js) { return js->global; }
	inline ant_value_t js_mkfun(ant_value_t (fn)(ant_t , ant_value_t , int)) { return mkval(T_CFUNC, (size_t) (void ) fn); }

	inline ant_value_t js_getthis(ant_t *js) { return js->this_val; }
	inline void js_setthis(ant_t *js, ant_value_t val) { js->this_val = val; }
	inline ant_value_t js_getcurrentfunc(ant_t *js) { return js->current_func; }

	ant_value_t js_cfunc_promote(ant_t *js, ant_value_t cfunc) {
	uintptr_t ptr = vdata(cfunc);

	for (uint8_t i = 0; i < js->cfunc_promote_cache.len; i++) {
	if (js->cfunc_promote_cache.cfunc_ptr[i] == ptr)
	return js->cfunc_promote_cache.promoted[i];
	}

	ant_value_t fn_obj = mkobj(js, 0);
	set_slot(fn_obj, SLOT_CFUNC, cfunc);

	ant_value_t proto = get_prototype_for_type(js, T_CFUNC);
	if (is_object_type(proto)) {
	ant_object_t *obj_ptr = js_obj_ptr(js_as_obj(fn_obj));
	if (obj_ptr) obj_ptr->proto = proto;
	}

	ant_value_t promoted = js_obj_to_func(fn_obj);

	if (js->cfunc_promote_cache.len >= js->cfunc_promote_cache.cap) {
	uint8_t new_cap = js->cfunc_promote_cache.cap ? js->cfunc_promote_cache.cap * 2 : 4;
	uintptr_t new_ptrs = realloc(js->cfunc_promote_cache.cfunc_ptr, new_cap sizeof(uintptr_t));
	ant_value_t new_vals = realloc(js->cfunc_promote_cache.promoted, new_cap sizeof(ant_value_t));

	if (new_ptrs && new_vals) {
	js->cfunc_promote_cache.cfunc_ptr = new_ptrs;
	js->cfunc_promote_cache.promoted = new_vals;
	js->cfunc_promote_cache.cap = new_cap;
	}
	}

	if (js->cfunc_promote_cache.len < js->cfunc_promote_cache.cap) {
	uint8_t idx = js->cfunc_promote_cache.len++;
	js->cfunc_promote_cache.cfunc_ptr[idx] = ptr;
	js->cfunc_promote_cache.promoted[idx] = promoted;
	}

	return promoted;
	}

	ant_value_t js_heavy_mkfun(ant_t js, ant_value_t (fn)(ant_t , ant_value_t , int), ant_value_t data) {
	ant_value_t cfunc = js_mkfun(fn);
	ant_value_t fn_obj = mkobj(js, 0);

	set_slot(fn_obj, SLOT_CFUNC, cfunc);
	set_slot(fn_obj, SLOT_DATA, data);

	return js_obj_to_func(fn_obj);
	}

	void js_set(ant_t js, ant_value_t obj, const char key, ant_value_t val) {
	size_t key_len = strlen(key);

	if (vtype(obj) == T_OBJ) {
	ant_offset_t existing = lkp(js, obj, key, key_len);
	if (existing > 0) {
	if (is_const_prop(js, existing)) {
	js_mkerr(js, "assignment to constant");
	return;
	}
	js_saveval(js, existing, val);
	} else {
	ant_value_t key_str = js_mkstr(js, key, key_len);
	mkprop(js, obj, key_str, val, 0);
	}
	} else if (vtype(obj) == T_FUNC) {
	ant_value_t func_obj = js_func_obj(obj);
	ant_offset_t existing = lkp(js, func_obj, key, key_len);
	if (existing > 0) {
	if (is_const_prop(js, existing)) {
	js_mkerr(js, "assignment to constant");
	return;
	}
	js_saveval(js, existing, val);
	} else {
	ant_value_t key_str = js_mkstr(js, key, key_len);
	mkprop(js, func_obj, key_str, val, 0);
	}
	}
	}

	void js_set_sym(ant_t *js, ant_value_t obj, ant_value_t sym, ant_value_t val) {
	if (vtype(sym) != T_SYMBOL) return;
	ant_offset_t sym_off = (ant_offset_t)vdata(sym);

	if (vtype(obj) == T_FUNC) obj = js_func_obj(obj);
	else if (is_object_type(obj)) obj = js_as_obj(obj);
	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR) return;

	ant_offset_t existing = lkp_sym(js, obj, sym_off);
	if (existing > 0) {
	if (is_const_prop(js, existing)) return;
	js_saveval(js, existing, val);
	} else mkprop(js, obj, sym, val, 0);
	}

	void js_set_symbol(ant_t js, ant_value_t obj, const char key, ant_value_t val) {
	ant_value_t sym = js_mksym_for(js, key);
	if (is_err(sym)) return;
	js_set_sym(js, obj, sym, val);
	}

	ant_value_t js_get_sym_with_receiver(ant_t *js, ant_value_t obj, ant_value_t sym, ant_value_t receiver) {
	if (vtype(sym) != T_SYMBOL) return js_mkundef();
	ant_offset_t sym_off = (ant_offset_t)vdata(sym);

	if (vtype(obj) == T_FUNC) obj = js_func_obj(obj);
	uint8_t ot = vtype(obj);

	if (!is_object_type(obj)) {
	if (ot == T_STR \|\| ot == T_NUM \|\| ot == T_BOOL \|\| ot == T_BIGINT \|\| ot == T_SYMBOL) {
	ant_value_t proto = get_prototype_for_type(js, ot);
	if (!is_object_type(proto)) return js_mkundef();
	obj = js_as_obj(proto);
	} else return js_mkundef();
	} else obj = js_as_obj(obj);

	if (is_proxy(obj))
	return proxy_get_val(js, obj, sym);

	ant_value_t cur = obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);

	while (is_object_type(cur)) {
	ant_value_t cur_obj = js_as_obj(cur);
	prop_meta_t meta;
	if (lookup_symbol_prop_meta(cur_obj, sym_off, &meta)) {
	if (meta.has_getter) {
	ant_value_t g = meta.getter;
	if (vtype(g) == T_FUNC \|\| vtype(g) == T_CFUNC)
	return sv_vm_call(js->vm, js, g, receiver, NULL, 0, NULL, false);
	return js_mkundef();
	}
	if (meta.has_setter && !meta.has_getter) return js_mkundef();
	break;
	}

	ant_value_t proto = get_proto(js, cur_obj);
	if (!is_object_type(proto)) break;
	cur = js_as_obj(proto);
	if (proto_overflow_guard_hit_cycle(js, &guard, cur)) break;
	}

	ant_offset_t off = lkp_sym_proto(js, obj, sym_off);
	if (off == 0) return js_mkundef();
	return propref_load(js, off);
	}

	ant_value_t js_get_sym(ant_t *js, ant_value_t obj, ant_value_t sym) {
	return js_get_sym_with_receiver(js, obj, sym, obj);
	}

	ant_value_t js_get_symbol(ant_t js, ant_value_t obj, const char key) {
	ant_value_t sym = js_mksym_for(js, key);
	if (is_err(sym)) return sym;
	return js_get_sym(js, obj, sym);
	}

	static bool js_try_get(ant_t js, ant_value_t obj, const char key, ant_value_t *out) {
	size_t key_len = strlen(key);

	if (vtype(obj) == T_FUNC) {
	if (sv_vm_is_strict(js->vm) &&
	((key_len == 6 && memcmp(key, "caller", 6) == 0) \|\|
	(key_len == 9 && memcmp(key, "arguments", 9) == 0))) {
	*out = js_mkerr_typed(
	js, JS_ERR_TYPE,
	"'%.*s' not allowed on functions in strict mode",
	(int)key_len, key
	);
	return true;
	}

	ant_value_t func_obj = js_func_obj(obj);
	ant_value_t import_meta = js_get_module_ctx_import_meta(js, js_get_slot(func_obj, SLOT_MODULE_CTX));
	if (vtype(import_meta) == T_UNDEF) import_meta = js_get_current_import_meta(js);
	if (key_len == 4 && memcmp(key, "meta", 4) == 0 && vtype(import_meta) != T_UNDEF) {
	ant_value_t cfunc = js_get_slot(func_obj, SLOT_CFUNC);
	if (vtype(cfunc) == T_CFUNC && js_as_cfunc(cfunc) == js_builtin_import) {
	*out = import_meta;
	return true;
	}
	}
	ant_offset_t off = lkp(js, func_obj, key, key_len);
	if (off == 0) {
	ant_value_t accessor_result;
	if (try_accessor_getter(js, obj, key, key_len, &accessor_result)) {
	*out = accessor_result;
	return true;
	}
	return false;
	}

	const ant_shape_prop_t *prop_meta = prop_shape_meta(js, off);
	if (prop_meta && prop_meta->has_getter) {
	ant_value_t accessor_result;
	if (try_accessor_getter(js, obj, key, key_len, &accessor_result)) {
	*out = accessor_result;
	return true;
	}
	}

	*out = propref_load(js, off);
	return true;
	}

	if (array_obj_ptr(obj)) {
	if (
	((key_len == 6 && memcmp(key, "callee", 6) == 0) \|\|
	(key_len == 6 && memcmp(key, "caller", 6) == 0)) &&
	get_slot(obj, SLOT_STRICT_ARGS) == js_true
	) {
	out = js_mkerr_typed(js, JS_ERR_TYPE, "'%.s' not allowed on strict arguments", (int)key_len, key);
	return true;
	}

	if (is_length_key(key, key_len)) {
	*out = tov((double)get_array_length(js, obj));
	return true;
	}

	unsigned long idx;
	ant_offset_t arr_len = get_array_length(js, obj);

	if (parse_array_index(key, key_len, arr_len, &idx)) {
	if (js_arguments_state(obj)) {
	*out = js_arguments_getter(js, obj, key, key_len);
	return true;
	}
	if (arr_has(js, obj, (ant_offset_t)idx)) {
	*out = arr_get(js, obj, (ant_offset_t)idx);
	return true;
	}

	return false;
	}

	ant_value_t arr_obj = js_as_obj(obj);
	ant_offset_t off = lkp(js, arr_obj, key, key_len);

	if (off == 0) {
	ant_value_t accessor_result;
	if (try_accessor_getter(js, arr_obj, key, key_len, &accessor_result)) {
	*out = accessor_result; return true;
	}

	return false;
	}

	const ant_shape_prop_t *prop_meta = prop_shape_meta(js, off);
	if (prop_meta && prop_meta->has_getter) {
	ant_value_t accessor_result;
	if (try_accessor_getter(js, arr_obj, key, key_len, &accessor_result)) {
	*out = accessor_result;
	return true;
	}}

	*out = propref_load(js, off);
	return true;
	}

	uint8_t t = vtype(obj);
	bool is_promise = (t == T_PROMISE);
	if (t == T_OBJ && is_proxy(obj)) {
	*out = proxy_get(js, obj, key, key_len);
	return true;
	}

	if (t == T_STR \|\| t == T_NUM \|\| t == T_BOOL) {
	if (t == T_STR && is_length_key(key, key_len)) {
	ant_offset_t byte_len = 0; ant_offset_t str_off = vstr(js, obj, &byte_len);
	const char str_data = (const char )(uintptr_t)(str_off);
	*out = tov((double)utf16_strlen(str_data, byte_len));
	return true;
	}

	if (t == T_STR && js_try_get_string_index(js, obj, key, key_len, out)) return true;
	ant_value_t boxed = mkobj(js, 0);

	js_set_slot(js_as_obj(boxed), SLOT_PRIMITIVE, obj);
	obj = boxed; t = T_OBJ;
	}

	if (is_promise) obj = js_as_obj(obj);
	else if (t != T_OBJ) return false;
	ant_offset_t off = lkp(js, obj, key, key_len);

	if (off == 0) {
	ant_value_t result = try_dynamic_getter(js, obj, key, key_len);
	if (vtype(result) != T_UNDEF) { *out = result; return true; }
	}

	if (off == 0 && is_promise) {
	ant_value_t promise_proto = get_ctor_proto(js, "Promise", 7);
	if (vtype(promise_proto) != T_UNDEF && vtype(promise_proto) != T_NULL) {
	off = lkp(js, promise_proto, key, key_len);
	if (off != 0) { *out = propref_load(js, off); return true; }
	}
	}

	if (off == 0) {
	ant_value_t accessor_result;
	if (try_accessor_getter(js, obj, key, key_len, &accessor_result)) {
	*out = accessor_result; return true;
	}
	return false;
	}

	const ant_shape_prop_t *prop_meta = prop_shape_meta(js, off);
	if (prop_meta && prop_meta->has_getter) {
	ant_value_t accessor_result;
	if (try_accessor_getter(js, obj, key, key_len, &accessor_result)) {
	*out = accessor_result; return true;
	}
	}

	*out = propref_load(js, off);
	return true;
	}

	ant_value_t js_get(ant_t js, ant_value_t obj, const char key) {
	ant_value_t val;
	if (js_try_get(js, obj, key, &val)) return val;
	return js_mkundef();
	}

	ant_value_t js_getprop_proto(ant_t js, ant_value_t obj, const char key) {
	size_t key_len = strlen(key);
	ant_offset_t off = lkp_proto(js, obj, key, key_len);
	return off == 0 ? js_mkundef() : propref_load(js, off);
	}

	ant_value_t js_getprop_fallback(ant_t js, ant_value_t obj, const char name) {
	if (vtype(obj) == T_CFUNC && js->cfunc_promote_cache.len > 0) {
	ant_value_t promoted = js_cfunc_lookup_promoted(js, obj);
	if (vtype(promoted) != T_CFUNC) return js_getprop_fallback(js, promoted, name);
	}

	ant_value_t val;
	if (js_try_get(js, obj, name, &val)) return val;

	return js_getprop_proto(js, obj, name);
	}

	ant_value_t js_getprop_super(ant_t js, ant_value_t super_obj, ant_value_t receiver, const char name) {
	if (!name) return js_mkundef();

	if (vtype(super_obj) == T_FUNC) super_obj = js_func_obj(super_obj);
	if (!is_object_type(super_obj)) return js_mkundef();

	size_t key_len = strlen(name);
	if (is_proxy(super_obj)) return proxy_get(js, super_obj, name, key_len);

	const char *key_intern = intern_string(name, key_len);
	if (!key_intern) return js_mkundef();

	ant_value_t cur = super_obj;
	proto_overflow_guard_t guard;
	proto_overflow_guard_init(&guard);
	while (is_object_type(cur)) {
	ant_value_t cur_obj = js_as_obj(cur);
	ant_object_t *cur_ptr = js_obj_ptr(cur_obj);
	bool handled = false;

	if (cur_ptr && cur_ptr->shape) {
	int32_t slot = ant_shape_lookup_interned(cur_ptr->shape, key_intern);
	if (slot >= 0) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(cur_ptr->shape, (uint32_t)slot);
	if (prop && prop->has_getter) {
	ant_value_t getter = prop->getter;
	if (vtype(getter) == T_FUNC \|\| vtype(getter) == T_CFUNC)
	return sv_vm_call(js->vm, js, getter, receiver, NULL, 0, NULL, false);
	return js_mkundef();
	}
	if (prop && prop->has_setter) return js_mkundef();
	handled = true;
	}
	}

	if (!handled && cur_ptr && cur_ptr->is_exotic) {
	descriptor_entry_t *desc = lookup_descriptor(cur_obj, name, key_len);
	if (desc) {
	if (desc->has_getter) {
	ant_value_t getter = desc->getter;
	if (vtype(getter) == T_FUNC \|\| vtype(getter) == T_CFUNC)
	return sv_vm_call(js->vm, js, getter, receiver, NULL, 0, NULL, false);
	return js_mkundef();
	}
	if (desc->has_setter) return js_mkundef();
	}
	}

	ant_offset_t prop_off = lkp_interned(js, cur_obj, key_intern, key_len);
	if (prop_off != 0) return propref_load(js, prop_off);

	ant_value_t proto = get_proto(js, cur_obj);
	if (!is_object_type(proto)) break;
	cur = proto;
	if (proto_overflow_guard_hit_cycle(js, &guard, cur)) break;
	}

	return js_mkundef();
	}

	typedef struct {
	bool (callback)(ant_t js, ant_value_t value, void *udata);
	void *udata;
	} js_iter_ctx_t;

	static iter_action_t js_iter_cb(ant_t js, ant_value_t value, void ctx, ant_value_t *out) {
	js_iter_ctx_t ictx = (js_iter_ctx_t )ctx;
	return ictx->callback(js, value, ictx->udata) ? ITER_CONTINUE : ITER_BREAK;
	}

	bool js_iter(ant_t js, ant_value_t iterable, bool (callback)(ant_t js, ant_value_t value, void udata), void *udata) {
	js_iter_ctx_t ctx = { .callback = callback, .udata = udata };
	ant_value_t result = iter_foreach(js, iterable, js_iter_cb, &ctx);
	return !is_err(result);
	}

	char js_getstr(ant_t js, ant_value_t value, size_t *len) {
	(void)js;
	if (vtype(value) != T_STR) return NULL;
	ant_offset_t n, off = vstr(js, value, &n);
	if (len != NULL) *len = n;
	return (char *)(uintptr_t)off;
	}

	void js_merge_obj(ant_t *js, ant_value_t dst, ant_value_t src) {
	if (vtype(dst) != T_OBJ \|\| vtype(src) != T_OBJ) return;
	ant_value_t as_src = js_as_obj(src);
	ant_object_t *src_obj = js_obj_ptr(as_src);
	if (!src_obj \|\| !src_obj->shape) return;

	uint32_t count = ant_shape_count(src_obj->shape);
	for (uint32_t i = 0; i < count; i++) {
	const ant_shape_prop_t *prop = ant_shape_prop_at(src_obj->shape, i);
	if (!prop \|\| prop->type != ANT_SHAPE_KEY_STRING) continue;

	const char *key = prop->key.interned;
	ant_value_t val = (i < src_obj->prop_count) ? ant_object_prop_get_unchecked(src_obj, i) : js_mkundef();
	js_setprop(js, dst, js_mkstr(js, key, strlen(key)), val);
	}
	}

	bool js_chkargs(ant_value_t args, int nargs, const char spec) {
	int i = 0, ok = 1;
	for (; ok && i < nargs && spec[i]; i++) {
	uint8_t t = vtype(args[i]), c = (uint8_t) spec[i];
	ok = (c == 'b' && t == T_BOOL) \|\| (c == 'd' && t == T_NUM) \|\|
	(c == 's' && t == T_STR) \|\| (c == 'j');
	}
	if (spec[i] != '\0' \|\| i != nargs) ok = 0;
	return ok;
	}

	static ant_value_t js_eval_bytecode_mode(ant_t js, const char buf, size_t len, sv_compile_mode_t mode, bool parse_strict) {
	if (len == (size_t)~0U) len = strlen(buf);
	sv_ast_t *program = sv_parse(js, buf, (ant_offset_t)len, parse_strict);

	if (!program) {
	if (js->thrown_exists) return mkval(T_ERR, 0);
	return js_mkerr_typed(js, JS_ERR_INTERNAL \| JS_ERR_NO_STACK, "Unexpected parse error");
	}

	if (mode == SV_COMPILE_MODULE) {
	ant_value_t ns = js_module_eval_active_ns(js);
	if (is_object_type(ns)) esm_predeclare_exports(js, program, ns);
	}

	sv_func_t *func = sv_compile(js, program, mode, buf, (ant_offset_t)len);
	if (!func) {
	if (js->thrown_exists) return mkval(T_ERR, 0);
	return js_mkerr_typed(js, JS_ERR_INTERNAL \| JS_ERR_NO_STACK, "Unexpected compile error");
	}

	js_clear_error_site(js);
	ant_value_t result;
	// TODO: this-newtarget-frame-migration
	ant_value_t saved_this = js->this_val;

	if (sv_dump_bytecode_unlikely) sv_disasm(js, func, js->filename);
	if (func->is_tla) result = sv_execute_entry_tla(js, func, js->this_val);
	else result = sv_execute_entry(sv_vm_get_active(js), func, js->this_val, NULL, 0);

	js->this_val = saved_this;
	return result;
	}

	ant_value_t js_eval_bytecode(ant_t js, const char buf, size_t len) {
	return js_eval_bytecode_mode(js, buf, len, SV_COMPILE_SCRIPT, false);
	}

	ant_value_t js_eval_bytecode_module(ant_t js, const char buf, size_t len) {
	return js_eval_bytecode_mode(js, buf, len, SV_COMPILE_MODULE, false);
	}

	ant_value_t js_eval_bytecode_eval(ant_t js, const char buf, size_t len) {
	return js_eval_bytecode_mode(js, buf, len, SV_COMPILE_EVAL, false);
	}

	ant_value_t js_eval_bytecode_eval_with_strict(ant_t js, const char buf, size_t len, bool inherit_strict) {
	return js_eval_bytecode_mode(js, buf, len, SV_COMPILE_EVAL, inherit_strict);
	}

	ant_value_t js_eval_bytecode_repl(ant_t js, const char buf, size_t len) {
	return js_eval_bytecode_mode(js, buf, len, SV_COMPILE_REPL, false);
	}

	static inline ant_value_t sv_call_cfunc(ant_params_t, ant_bind_t) {
	ant_value_t saved_this = js->this_val;
	js->this_val = this_val;
	ant_value_t res = js_as_cfunc(func)(js, args, nargs);
	js->this_val = saved_this;
	return res;
	}

	static inline ant_value_t sv_call_slot_cfunc(ant_params_t, ant_bind_t, ant_value_t cfunc_slot) {
	ant_value_t saved_func = js->current_func;
	ant_value_t saved_this = js->this_val;
	js->current_func = func;
	js->this_val = this_val;
	ant_value_t res = js_as_cfunc(cfunc_slot)(js, args, nargs);
	js->current_func = saved_func;
	js->this_val = saved_this;
	return res;
	}


	static inline ant_value_t sv_call_object_builtin(ant_params_t, ant_value_t this_val) {
	ant_value_t saved_this = js->this_val;
	js->this_val = this_val;
	ant_value_t res = builtin_Object(js, args, nargs);
	js->this_val = saved_this;
	return res;
	}

	ant_value_t sv_call_native(
	ant_t *js, ant_value_t func, ant_value_t this_val,
	ant_value_t *args, int nargs
	) {
	if (vtype(func) == T_CFUNC) return sv_call_cfunc(js, args, nargs, func, this_val);
	if (vtype(func) == T_FFI) return ffi_call_by_index(js, (unsigned int)vdata(func), args, nargs);

	if (vtype(func) == T_FUNC) {
	ant_value_t func_obj = js_func_obj(func);
	ant_value_t cfunc_slot = get_slot(func_obj, SLOT_CFUNC);

	if (vtype(cfunc_slot) == T_CFUNC)
	return sv_call_slot_cfunc(js, args, nargs, func, this_val, cfunc_slot);

	ant_value_t builtin_slot = get_slot(func_obj, SLOT_BUILTIN);
	if (vtype(builtin_slot) == T_NUM && (int)tod(builtin_slot) == BUILTIN_OBJECT)
	return sv_call_object_builtin(js, args, nargs, this_val);
	}

	return js_mkerr_typed(js, JS_ERR_TYPE, "%s is not a function", typestr(vtype(func)));
	}

	typedef struct {
	ant_t *js;
	ant_object_t *obj;
	uint32_t index;
	} prop_iter_ctx_t;

	ant_iter_t js_prop_iter_begin(ant_t *js, ant_value_t obj) {
	ant_iter_t iter = {.ctx = NULL, .off = 0};
	uint8_t t = vtype(obj);
	if (t != T_OBJ && t != T_ARR && t != T_FUNC) return iter;

	prop_iter_ctx_t ctx = calloc(1, sizeof(ctx));
	if (!ctx) return iter;

	ctx->js = js;
	ctx->obj = js_obj_ptr(js_as_obj(obj));
	ctx->index = 0;

	if (!ctx->obj \|\| !ctx->obj->shape) {
	free(ctx);
	return iter;
	}

	iter.ctx = ctx;
	return iter;
	}

	bool js_prop_iter_next(ant_iter_t iter, const char key, size_t key_len, ant_value_t *value) {
	if (!iter \|\| !iter->ctx) return false;
	prop_iter_ctx_t ctx = (prop_iter_ctx_t )iter->ctx;

	ant_object_t *obj = ctx->obj;
	if (!obj \|\| !obj->shape) return false;

	uint32_t count = ant_shape_count(obj->shape);
	while (ctx->index < count) {
	uint32_t i = ctx->index++;
	const ant_shape_prop_t *prop = ant_shape_prop_at(obj->shape, i);
	if (!prop) continue;
	if (prop->type == ANT_SHAPE_KEY_SYMBOL) continue;
	if (i >= obj->prop_count) continue;

	if (key) {
	*key = prop->key.interned;
	if (key_len) *key_len = strlen(prop->key.interned);
	}

	if (value) *value = ant_object_prop_get_unchecked(obj, i);
	iter->off = i + 1;

	return true;
	}

	return false;
	}

	bool js_prop_iter_next_val(ant_iter_t iter, ant_value_t key_out, ant_value_t *value) {
	if (!iter \|\| !iter->ctx) return false;
	prop_iter_ctx_t ctx = (prop_iter_ctx_t )iter->ctx;

	ant_object_t *obj = ctx->obj;
	if (!obj \|\| !obj->shape) return false;
	uint32_t count = ant_shape_count(obj->shape);

	while (ctx->index < count) {
	uint32_t i = ctx->index++;
	const ant_shape_prop_t *prop = ant_shape_prop_at(obj->shape, i);

	if (!prop) continue;
	if (i >= obj->prop_count) continue;

	if (key_out) {
	if (prop->type == ANT_SHAPE_KEY_SYMBOL) *key_out = mkval(T_SYMBOL, prop->key.sym_off);
	else *key_out = js_mkstr(ctx->js, prop->key.interned, strlen(prop->key.interned));
	}

	if (value) *value = ant_object_prop_get_unchecked(obj, i);
	iter->off = i + 1;

	return true;
	}

	return false;
	}

	void js_prop_iter_end(ant_iter_t *iter) {
	if (!iter) return;
	free(iter->ctx);
	iter->off = 0;
	iter->ctx = NULL;
	}

	void js_check_unhandled_rejections(ant_t *js) {
	size_t keep = 0;

	for (size_t i = 0; i < js->pending_rejections.len; i++) {
	ant_value_t p = js->pending_rejections.items[i];
	ant_promise_state_t *pd = get_promise_data(js, p, false);
	if (!pd \|\| pd->has_rejection_handler \|\| pd->unhandled_reported) continue;

	if (vtype(pd->trigger_parent) == T_PROMISE) {
	ant_promise_state_t *parent = get_promise_data(js, pd->trigger_parent, false);
	if (parent && parent->has_rejection_handler) continue;
	}

	if (js->fatal_error) {
	js->thrown_exists = true;
	js->thrown_value = pd->value;
	print_uncaught_throw(js);
	js_destroy(js); exit(1);
	}

	GC_ROOT_SAVE(root_mark, js);
	ant_value_t reason = pd->value;
	GC_ROOT_PIN(js, p); GC_ROOT_PIN(js, reason);

	if (!js_fire_unhandled_rejection(js, p, reason))
	print_unhandled_promise_rejection(js, reason);

	GC_ROOT_RESTORE(js, root_mark);
	pd->unhandled_reported = true;
	}

	js->pending_rejections.len = keep;
	}

	void js_set_getter(ant_value_t obj, js_getter_fn getter) {
	if (!is_object_type(obj)) return;
	if (vtype(obj) != T_OBJ) obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return;
	ptr->is_exotic = 1;
	ant_exotic_ops_t *ops = obj_ensure_exotic_ops(ptr);
	if (!ops) return;
	ops->getter = getter;
	}

	void js_set_setter(ant_value_t obj, js_setter_fn setter) {
	if (!is_object_type(obj)) return;
	if (vtype(obj) != T_OBJ) obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return;
	ptr->is_exotic = 1;
	ant_exotic_ops_t *ops = obj_ensure_exotic_ops(ptr);
	if (!ops) return;
	ops->setter = setter;
	}

	void js_set_deleter(ant_value_t obj, js_deleter_fn deleter) {
	if (!is_object_type(obj)) return;
	if (vtype(obj) != T_OBJ) obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return;
	ptr->is_exotic = 1;
	ant_exotic_ops_t *ops = obj_ensure_exotic_ops(ptr);
	if (!ops) return;
	ops->deleter = deleter;
	}

	void js_set_finalizer(ant_value_t obj, js_finalizer_fn fn) {
	if (!is_object_type(obj)) return;
	if (vtype(obj) != T_OBJ) obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return;
	ptr->finalizer = fn;
	}

	void js_set_keys(ant_value_t obj, js_keys_fn keys) {
	if (!is_object_type(obj)) return;
	if (vtype(obj) != T_OBJ) obj = js_as_obj(obj);
	ant_object_t *ptr = js_obj_ptr(obj);
	if (!ptr) return;
	ptr->is_exotic = 1;
	ptr->exotic_keys = keys;
	}

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