diff --git a/test/index.ts b/test/index.ts
index ec29047d..b80a6c2a 100644
--- a/test/index.ts
+++ b/test/index.ts
@@ -4,8 +4,8 @@
  */
 
 import * as assert from 'assert';
-import { expect, test } from '@jest/globals';
-import { Parser, Interpreter, utils, errors, Ast } from '../src';
+import { test } from '@jest/globals';
+import { Parser, Interpreter, Ast } from '../src';
 import { NUM, STR, NULL, ARR, OBJ, BOOL, TRUE, FALSE, ERROR ,FN_NATIVE } from '../src/interpreter/value';
 import { AiScriptSyntaxError, AiScriptRuntimeError, AiScriptIndexOutOfRangeError } from '../src/error';
 import { exe, eq } from './testutils';
@@ -946,1228 +946,6 @@ describe('Location', () => {
 	});
 });
 
-describe('primitive props', () => {
-	describe('num', () => {
-		test.concurrent('to_str', async () => {
-			const res = await exe(`
-			let num = 123
-			<: num.to_str()
-			`);
-			eq(res, STR('123'));
-		});
-		test.concurrent('to_hex', async () => {
-			// TODO -0, 巨大数, 無限小数, Infinity等入力時の結果は未定義
-			const res = await exe(`
-			<: [
-	 			0, 10, 16,
-				-10, -16,
-				0.5,
-		 	].map(@(v){v.to_hex()})
-			`);
-			eq(res, ARR([
-				STR('0'), STR('a'), STR('10'),
-				STR('-a'), STR('-10'),
-				STR('0.8'),
-			]));
-		});
-	});
-
-	describe('str', () => {
-		test.concurrent('len', async () => {
-			const res = await exe(`
-			let str = "hello"
-			<: str.len
-			`);
-			eq(res, NUM(5));
-		});
-
-		test.concurrent('to_num', async () => {
-			const res = await exe(`
-			let str = "123"
-			<: str.to_num()
-			`);
-			eq(res, NUM(123));
-		});
-
-		test.concurrent('upper', async () => {
-			const res = await exe(`
-			let str = "hello"
-			<: str.upper()
-			`);
-			eq(res, STR('HELLO'));
-		});
-
-		test.concurrent('lower', async () => {
-			const res = await exe(`
-			let str = "HELLO"
-			<: str.lower()
-			`);
-			eq(res, STR('hello'));
-		});
-
-		test.concurrent('trim', async () => {
-			const res = await exe(`
-			let str = " hello  "
-			<: str.trim()
-			`);
-			eq(res, STR('hello'));
-		});
-
-		test.concurrent('replace', async () => {
-			const res = await exe(`
-			let str = "hello"
-			<: str.replace("l", "x")
-			`);
-			eq(res, STR('hexxo'));
-		});
-
-		test.concurrent('index_of', async () => {
-			const res = await exe(`
-			let str = '0123401234'
-			<: [
-				str.index_of('3') == 3,
-				str.index_of('5') == -1,
-				str.index_of('3', 3) == 3,
-				str.index_of('3', 4) == 8,
-				str.index_of('3', -1) == -1,
-				str.index_of('3', -2) == 8,
-				str.index_of('3', -7) == 3,
-				str.index_of('3', 10) == -1,
-			].map(@(v){if (v) '1' else '0'}).join()
-			`);
-			eq(res, STR('11111111'));
-		});
-
-		test.concurrent('incl', async () => {
-			const res = await exe(`
-			let str = "hello"
-			<: [str.incl("ll"), str.incl("x")]
-			`);
-			eq(res, ARR([TRUE, FALSE]));
-		});
-
-		test.concurrent('split', async () => {
-			const res = await exe(`
-			let str = "a,b,c"
-			<: str.split(",")
-			`);
-			eq(res, ARR([STR('a'), STR('b'), STR('c')]));
-		});
-
-		test.concurrent('pick', async () => {
-			const res = await exe(`
-			let str = "hello"
-			<: str.pick(1)
-			`);
-			eq(res, STR('e'));
-		});
-
-		test.concurrent('slice', async () => {
-			const res = await exe(`
-			let str = "hello"
-			<: str.slice(1, 3)
-			`);
-			eq(res, STR('el'));
-		});
-
-		test.concurrent("codepoint_at", async () => {
-			const res = await exe(`
-			let str = "𩸽"
-			<: str.codepoint_at(0)
-			`);
-			eq(res, NUM(171581));
-		});
-
-		test.concurrent("to_arr", async () => {
-			const res = await exe(`
-			let str = "𩸽👉🏿👨‍👦"
-			<: str.to_arr()
-			`);
-			eq(
-				res,
-				ARR([STR("𩸽"), STR("👉🏿"), STR("👨‍👦")])
-			);
-		});
-
-		test.concurrent("to_unicode_arr", async () => {
-			const res = await exe(`
-			let str = "𩸽👉🏿👨‍👦"
-			<: str.to_unicode_arr()
-			`);
-			eq(
-				res,
-				ARR([STR("𩸽"), STR("👉"), STR(String.fromCodePoint(0x1F3FF)), STR("👨"), STR("\u200d"), STR("👦")])
-			);
-		});
-
-		test.concurrent("to_unicode_codepoint_arr", async () => {
-			const res = await exe(`
-			let str = "𩸽👉🏿👨‍👦"
-			<: str.to_unicode_codepoint_arr()
-			`);
-			eq(
-				res,
-				ARR([NUM(171581), NUM(128073), NUM(127999), NUM(128104), NUM(8205), NUM(128102)])
-			);
-		});
-
-		test.concurrent("to_char_arr", async () => {
-			const res = await exe(`
-			let str = "abc𩸽👉🏿👨‍👦def"
-			<: str.to_char_arr()
-			`);
-			eq(
-				res,
-				ARR([97, 98, 99, 55399, 56893, 55357, 56393, 55356, 57343, 55357, 56424, 8205, 55357, 56422, 100, 101, 102].map((s) => STR(String.fromCharCode(s))))
-			);
-		});
-
-		test.concurrent("to_charcode_arr", async () => {
-			const res = await exe(`
-			let str = "abc𩸽👉🏿👨‍👦def"
-			<: str.to_charcode_arr()
-			`);
-			eq(
-				res,
-				ARR([NUM(97), NUM(98), NUM(99), NUM(55399), NUM(56893), NUM(55357), NUM(56393), NUM(55356), NUM(57343), NUM(55357), NUM(56424), NUM(8205), NUM(55357), NUM(56422), NUM(100), NUM(101), NUM(102)])
-			);
-		});
-
-		test.concurrent("to_utf8_byte_arr", async () => {
-			const res = await exe(`
-			let str = "abc𩸽👉🏿👨‍👦def"
-			<: str.to_utf8_byte_arr()
-			`);
-			eq(
-				res,
-				ARR([NUM(97), NUM(98), NUM(99), NUM(240), NUM(169), NUM(184), NUM(189), NUM(240), NUM(159), NUM(145), NUM(137), NUM(240), NUM(159), NUM(143), NUM(191), NUM(240), NUM(159), NUM(145), NUM(168), NUM(226), NUM(128), NUM(141), NUM(240), NUM(159), NUM(145), NUM(166), NUM(100), NUM(101), NUM(102)])
-			);
-		});
-
-		test.concurrent('starts_with (no index)', async () => {
-			const res = await exe(`
-			let str = "hello"
-			let empty = ""
-			<: [
-				str.starts_with(""), str.starts_with("hello"),
-				str.starts_with("he"), str.starts_with("ell"),
-				empty.starts_with(""), empty.starts_with("he"),
-			]
-			`);
-			eq(res, ARR([
-				TRUE, TRUE,
-				TRUE, FALSE,
-				TRUE, FALSE, 
-			]));
-		});
-
-		test.concurrent('starts_with (with index)', async () => {
-			const res = await exe(`
-			let str = "hello"
-			let empty = ""
-			<: [
-				str.starts_with("", 4), str.starts_with("he", 0),
-				str.starts_with("ll", 2), str.starts_with("lo", 3),
-				str.starts_with("lo", -2), str.starts_with("hel", -5),
-				str.starts_with("he", 2), str.starts_with("loa", 3),
-				str.starts_with("lo", -6), str.starts_with("", -7),
-				str.starts_with("lo", 6), str.starts_with("", 7),
-				empty.starts_with("", 2), empty.starts_with("ll", 2),
-			]
-			`);
-			eq(res, ARR([
-				TRUE, TRUE,
-				TRUE, TRUE,
-				TRUE, TRUE,
-				FALSE, FALSE,
-				FALSE, TRUE,
-				FALSE, TRUE,
-				TRUE, FALSE,
-			]));
-		});
-
-		test.concurrent('ends_with (no index)', async () => {
-			const res = await exe(`
-			let str = "hello"
-			let empty = ""
-			<: [
-				str.ends_with(""), str.ends_with("hello"),
-				str.ends_with("lo"), str.ends_with("ell"),
-				empty.ends_with(""), empty.ends_with("he"),
-			]
-			`);
-			eq(res, ARR([
-				TRUE, TRUE,
-				TRUE, FALSE,
-				TRUE, FALSE,
-			]));
-		});
-
-		test.concurrent('ends_with (with index)', async () => {
-			const res = await exe(`
-			let str = "hello"
-			let empty = ""
-			<: [
-				str.ends_with("", 3), str.ends_with("lo", 5),
-				str.ends_with("ll", 4), str.ends_with("he", 2),
-				str.ends_with("ll", -1), str.ends_with("he", -3),
-				str.ends_with("he", 5), str.ends_with("lo", 3),
-				str.ends_with("lo", -6), str.ends_with("", -7),
-				str.ends_with("lo", 6), str.ends_with("", 7),
-				empty.ends_with("", 2), empty.ends_with("ll", 2),
-			]
-			`);
-			eq(res, ARR([
-				TRUE, TRUE,
-				TRUE, TRUE,
-				TRUE, TRUE,
-				FALSE, FALSE,
-				FALSE, TRUE,
-				FALSE, TRUE,
-				TRUE, FALSE,
-			]));
-		});
-
-    test.concurrent("pad_start", async () => {
-			const res = await exe(`
-			let str = "abc"
-			<: [
-				str.pad_start(0), str.pad_start(1), str.pad_start(2), str.pad_start(3), str.pad_start(4), str.pad_start(5),
-				str.pad_start(0, "0"), str.pad_start(1, "0"), str.pad_start(2, "0"), str.pad_start(3, "0"), str.pad_start(4, "0"), str.pad_start(5, "0"),
-				str.pad_start(0, "01"), str.pad_start(1, "01"), str.pad_start(2, "01"), str.pad_start(3, "01"), str.pad_start(4, "01"), str.pad_start(5, "01"),
-			]
-			`);
-			eq(res, ARR([
-				STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR(" abc"), STR("  abc"),
-				STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("0abc"), STR("00abc"),
-				STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("0abc"), STR("01abc"),
-			]));
-		});
-
-		test.concurrent("pad_end", async () => {
-			const res = await exe(`
-			let str = "abc"
-			<: [
-				str.pad_end(0), str.pad_end(1), str.pad_end(2), str.pad_end(3), str.pad_end(4), str.pad_end(5),
-				str.pad_end(0, "0"), str.pad_end(1, "0"), str.pad_end(2, "0"), str.pad_end(3, "0"), str.pad_end(4, "0"), str.pad_end(5, "0"),
-				str.pad_end(0, "01"), str.pad_end(1, "01"), str.pad_end(2, "01"), str.pad_end(3, "01"), str.pad_end(4, "01"), str.pad_end(5, "01"),
-			]
-			`);
-			eq(res, ARR([
-				STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("abc "), STR("abc  "),
-				STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("abc0"), STR("abc00"),
-				STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("abc0"), STR("abc01"),
-			]));
-		});
-	});
-
-	describe('arr', () => {
-		test.concurrent('len', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			<: arr.len
-			`);
-			eq(res, NUM(3));
-		});
-
-		test.concurrent('push', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			arr.push(4)
-			<: arr
-			`);
-			eq(res, ARR([NUM(1), NUM(2), NUM(3), NUM(4)]));
-		});
-
-		test.concurrent('unshift', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			arr.unshift(4)
-			<: arr
-			`);
-			eq(res, ARR([NUM(4), NUM(1), NUM(2), NUM(3)]));
-		});
-
-		test.concurrent('pop', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			let popped = arr.pop()
-			<: [popped, arr]
-			`);
-			eq(res, ARR([NUM(3), ARR([NUM(1), NUM(2)])]));
-		});
-
-		test.concurrent('shift', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			let shifted = arr.shift()
-			<: [shifted, arr]
-			`);
-			eq(res, ARR([NUM(1), ARR([NUM(2), NUM(3)])]));
-		});
-
-		test.concurrent('concat', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			let concated = arr.concat([4, 5])
-			<: [concated, arr]
-			`);
-			eq(res, ARR([
-				ARR([NUM(1), NUM(2), NUM(3), NUM(4), NUM(5)]),
-				ARR([NUM(1), NUM(2), NUM(3)])
-			]));
-		});
-
-		test.concurrent('slice', async () => {
-			const res = await exe(`
-			let arr = ["ant", "bison", "camel", "duck", "elephant"]
-			let sliced = arr.slice(2, 4)
-			<: [sliced, arr]
-			`);
-			eq(res, ARR([
-				ARR([STR('camel'), STR('duck')]),
-				ARR([STR('ant'), STR('bison'), STR('camel'), STR('duck'), STR('elephant')])
-			]));
-		});
-
-		test.concurrent('join', async () => {
-			const res = await exe(`
-			let arr = ["a", "b", "c"]
-			<: arr.join("-")
-			`);
-			eq(res, STR('a-b-c'));
-		});
-
-		test.concurrent('map', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			<: arr.map(@(item) { item * 2 })
-			`);
-			eq(res, ARR([NUM(2), NUM(4), NUM(6)]));
-		});
-
-		test.concurrent('map with index', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			<: arr.map(@(item, index) { item * index })
-			`);
-			eq(res, ARR([NUM(0), NUM(2), NUM(6)]));
-		});
-
-		test.concurrent('filter', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			<: arr.filter(@(item) { item != 2 })
-			`);
-			eq(res, ARR([NUM(1), NUM(3)]));
-		});
-
-		test.concurrent('filter with index', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3, 4]
-			<: arr.filter(@(item, index) { item != 2 && index != 3 })
-			`);
-			eq(res, ARR([NUM(1), NUM(3)]));
-		});
-
-		test.concurrent('reduce', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3, 4]
-			<: arr.reduce(@(accumulator, currentValue) { (accumulator + currentValue) })
-			`);
-			eq(res, NUM(10));
-		});
-
-		test.concurrent('reduce with index', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3, 4]
-			<: arr.reduce(@(accumulator, currentValue, index) { (accumulator + (currentValue * index)) }, 0)
-			`);
-			eq(res, NUM(20));
-		});
-
-		test.concurrent('reduce of empty array without initial value', async () => {
-			await expect(exe(`
-			let arr = [1, 2, 3, 4]
-			<: [].reduce(@(){})
-			`)).rejects.toThrow('Reduce of empty array without initial value');
-		});
-
-		test.concurrent('find', async () => {
-			const res = await exe(`
-			let arr = ["abc", "def", "ghi"]
-			<: arr.find(@(item) { item.incl("e") })
-			`);
-			eq(res, STR('def'));
-		});
-
-		test.concurrent('find with index', async () => {
-			const res = await exe(`
-			let arr = ["abc1", "def1", "ghi1", "abc2", "def2", "ghi2"]
-			<: arr.find(@(item, index) { item.incl("e") && index > 1 })
-			`);
-			eq(res, STR('def2'));
-		});
-
-		test.concurrent('incl', async () => {
-			const res = await exe(`
-			let arr = ["abc", "def", "ghi"]
-			<: [arr.incl("def"), arr.incl("jkl")]
-			`);
-			eq(res, ARR([TRUE, FALSE]));
-		});
-
-		test.concurrent('index_of', async () => {
-			const res = await exe(`
-			let arr = [0,1,2,3,4,0,1,2,3,4]
-			<: [
-				arr.index_of(3) == 3,
-				arr.index_of(5) == -1,
-				arr.index_of(3, 3) == 3,
-				arr.index_of(3, 4) == 8,
-				arr.index_of(3, -1) == -1,
-				arr.index_of(3, -2) == 8,
-				arr.index_of(3, -7) == 3,
-				arr.index_of(3, 10) == -1,
-			].map(@(v){if (v) '1' else '0'}).join()
-			`);
-			eq(res, STR('11111111'));
-		});
-
-		test.concurrent('reverse', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			arr.reverse()
-			<: arr
-			`);
-			eq(res, ARR([NUM(3), NUM(2), NUM(1)]));
-		});
-
-		test.concurrent('copy', async () => {
-			const res = await exe(`
-			let arr = [1, 2, 3]
-			let copied = arr.copy()
-			copied.reverse()
-			<: [copied, arr]
-			`);
-			eq(res, ARR([
-				ARR([NUM(3), NUM(2), NUM(1)]),
-				ARR([NUM(1), NUM(2), NUM(3)])
-			]));
-		});
-
-		test.concurrent('sort num array', async () => {
-			const res = await exe(`
-				var arr = [2, 10, 3]
-				let comp = @(a, b) { a - b }
-				arr.sort(comp)
-				<: arr
-			`);
-			eq(res, ARR([NUM(2), NUM(3), NUM(10)]));
-		});
-
-		test.concurrent('sort string array (with Str:lt)', async () => {
-			const res = await exe(`
-				var arr = ["hoge", "huga", "piyo", "hoge"]
-				arr.sort(Str:lt)
-				<: arr
-			`);
-			eq(res, ARR([STR('hoge'), STR('hoge'), STR('huga'), STR('piyo')]));
-		});
-
-		test.concurrent('sort string array (with Str:gt)', async () => {
-			const res = await exe(`
-				var arr = ["hoge", "huga", "piyo", "hoge"]
-				arr.sort(Str:gt)
-				<: arr
-			`);
-			eq(res, ARR([ STR('piyo'),  STR('huga'), STR('hoge'), STR('hoge')]));
-		});
-
-		test.concurrent('sort object array', async () => {
-			const res = await exe(`
-				var arr = [{x: 2}, {x: 10}, {x: 3}]
-				let comp = @(a, b) { a.x - b.x }
-
-				arr.sort(comp)
-				<: arr
-			`);
-			eq(res, ARR([OBJ(new Map([['x', NUM(2)]])), OBJ(new Map([['x', NUM(3)]])), OBJ(new Map([['x', NUM(10)]]))]));
-		});
-
-		test.concurrent('sort (stable)', async () => {
-			const res = await exe(`
-				var arr = [[2, 0], [10, 1], [3, 2], [3, 3], [2, 4]]
-				let comp = @(a, b) { a[0] - b[0] }
-
-				arr.sort(comp)
-				<: arr
-			`);
-			eq(res, ARR([
-				ARR([NUM(2), NUM(0)]),
-				ARR([NUM(2), NUM(4)]),
-				ARR([NUM(3), NUM(2)]),
-				ARR([NUM(3), NUM(3)]),
-				ARR([NUM(10), NUM(1)]),
-			]));
-		});
-		
-		test.concurrent('fill', async () => {
-			const res = await exe(`
-				var arr1 = [0, 1, 2]
-				let arr2 = arr1.fill(3)
-				let arr3 = [0, 1, 2].fill(3, 1)
-				let arr4 = [0, 1, 2].fill(3, 1, 2)
-				let arr5 = [0, 1, 2].fill(3, -2, -1)
-				<: [arr1, arr2, arr3, arr4, arr5]
-			`);
-			eq(res, ARR([
-				ARR([NUM(3), NUM(3), NUM(3)]), //target changed
-				ARR([NUM(3), NUM(3), NUM(3)]),
-				ARR([NUM(0), NUM(3), NUM(3)]),
-				ARR([NUM(0), NUM(3), NUM(2)]),
-				ARR([NUM(0), NUM(3), NUM(2)]),
-			]));
-		});
-		
-		test.concurrent('repeat', async () => {
-			const res = await exe(`
-				var arr1 = [0, 1, 2]
-				let arr2 = arr1.repeat(3)
-				let arr3 = arr1.repeat(0)
-				<: [arr1, arr2, arr3]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0), NUM(1), NUM(2)]), // target not changed
-				ARR([
-					NUM(0), NUM(1), NUM(2),
-					NUM(0), NUM(1), NUM(2),
-					NUM(0), NUM(1), NUM(2),
-				]),
-				ARR([]),
-			]));
-		});
-
-		test.concurrent('splice (full)', async () => {
-			const res = await exe(`
-			    let arr1 = [0, 1, 2, 3]
-				let arr2 = arr1.splice(1, 2, [10])
-				<: [arr1, arr2]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0), NUM(10), NUM(3)]),
-				ARR([NUM(1), NUM(2)]),
-			]));
-		});
-		
-		test.concurrent('splice (negative-index)', async () => {
-			const res = await exe(`
-			    let arr1 = [0, 1, 2, 3]
-				let arr2 = arr1.splice(-1, 0, [10, 20])
-				<: [arr1, arr2]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0), NUM(1), NUM(2), NUM(10), NUM(20), NUM(3)]),
-				ARR([]),
-			]));
-		});
-		
-		test.concurrent('splice (larger-index)', async () => {
-			const res = await exe(`
-				let arr1 = [0, 1, 2, 3]
-				let arr2 = arr1.splice(4, 100, [10, 20])
-				<: [arr1, arr2]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0), NUM(1), NUM(2), NUM(3), NUM(10), NUM(20)]),
-				ARR([]),
-			]));
-		});
-		
-		test.concurrent('splice (single argument)', async () => {
-			const res = await exe(`
-				let arr1 = [0, 1, 2, 3]
-				let arr2 = arr1.splice(1)
-				<: [arr1, arr2]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0)]),
-				ARR([NUM(1), NUM(2), NUM(3)]),
-			]));
-		});
-		
-		test.concurrent('flat', async () => {
-			const res = await exe(`
-				var arr1 = [0, [1], [2, 3], [4, [5, 6]]]
-				let arr2 = arr1.flat()
-				let arr3 = arr1.flat(2)
-				<: [arr1, arr2, arr3]
-			`);
-			eq(res, ARR([
-				ARR([
-					NUM(0), ARR([NUM(1)]), ARR([NUM(2), NUM(3)]),
-					ARR([NUM(4), ARR([NUM(5), NUM(6)])])
-				]), // target not changed
-				ARR([
-					NUM(0), NUM(1), NUM(2), NUM(3),
-					NUM(4), ARR([NUM(5), NUM(6)]),
-				]),
-				ARR([
-					NUM(0), NUM(1), NUM(2), NUM(3),
-					NUM(4), NUM(5), NUM(6),
-				]),
-			]));
-		});
-		
-		test.concurrent('flat_map', async () => {
-			const res = await exe(`
-				let arr1 = [0, 1, 2]
-				let arr2 = ["a", "b"]
-				let arr3 = arr1.flat_map(@(x){ arr2.map(@(y){ [x, y] }) })
-				<: [arr1, arr3]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0), NUM(1), NUM(2)]), // target not changed
-				ARR([
-					ARR([NUM(0), STR("a")]),
-					ARR([NUM(0), STR("b")]),
-					ARR([NUM(1), STR("a")]),
-					ARR([NUM(1), STR("b")]),
-					ARR([NUM(2), STR("a")]),
-					ARR([NUM(2), STR("b")]),
-				]),
-      ]));
-    });
-
-		test.concurrent('every', async () => {
-			const res = await exe(`
-				let arr1 = [0, 1, 2, 3]
-				let res1 = arr1.every(@(v,i){v==0 || i > 0})
-				let res2 = arr1.every(@(v,i){v==0 && i > 0})
-				let res3 = [].every(@(v,i){false})
-				<: [arr1, res1, res2, res3]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0), NUM(1), NUM(2), NUM(3)]), // target not changed
-				TRUE,
-				FALSE,
-				TRUE,
-			]));
-		});
-		
-		test.concurrent('some', async () => {
-			const res = await exe(`
-				let arr1 = [0, 1, 2, 3]
-				let res1 = arr1.some(@(v,i){v%2==0 && i <= 2})
-				let res2 = arr1.some(@(v,i){v%2==0 && i > 2})
-				<: [arr1, res1, res2]
-			`);
-			eq(res, ARR([
-				ARR([NUM(0), NUM(1), NUM(2), NUM(3)]), // target not changed
-				TRUE,
-				FALSE,
-			]));
-		});
-		
-		test.concurrent('insert', async () => {
-			const res = await exe(`
-				let arr1 = [0, 1, 2]
-				let res = []
-				res.push(arr1.insert(3, 10)) // [0, 1, 2, 10]
-				res.push(arr1.insert(2, 20)) // [0, 1, 20, 2, 10]
-				res.push(arr1.insert(0, 30)) // [30, 0, 1, 20, 2, 10]
-				res.push(arr1.insert(-1, 40)) // [30, 0, 1, 20, 2, 40, 10]
-				res.push(arr1.insert(-4, 50)) // [30, 0, 1, 50, 20, 2, 40, 10]
-				res.push(arr1.insert(100, 60)) // [30, 0, 1, 50, 20, 2, 40, 10, 60]
-				res.push(arr1)
-				<: res
-			`);
-			eq(res, ARR([
-				NULL, NULL, NULL, NULL, NULL, NULL, 
-				ARR([NUM(30), NUM(0), NUM(1), NUM(50), NUM(20), NUM(2), NUM(40), NUM(10), NUM(60)])
-			]));
-		});
-		
-		test.concurrent('remove', async () => {
-			const res = await exe(`
-				let arr1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
-				let res = []
-				res.push(arr1.remove(9)) // 9 [0, 1, 2, 3, 4, 5, 6, 7, 8]
-				res.push(arr1.remove(3)) // 3 [0, 1, 2, 4, 5, 6, 7, 8]
-				res.push(arr1.remove(0)) // 0 [1, 2, 4, 5, 6, 7, 8]
-				res.push(arr1.remove(-1)) // 8 [1, 2, 4, 5, 6, 7]
-				res.push(arr1.remove(-5)) // 2 [1, 4, 5, 6, 7]
-				res.push(arr1.remove(100)) // null [1, 4, 5, 6, 7]
-				res.push(arr1)
-				<: res
-			`);
-			eq(res, ARR([
-				NUM(9), NUM(3), NUM(0), NUM(8), NUM(2), NULL, 
-				ARR([NUM(1), NUM(4), NUM(5), NUM(6), NUM(7)])
-			]));
-		});
-		
-		test.concurrent('at (without default value)', async () => {
-			const res = await exe(`
-				let arr1 = [10, 20, 30]
-				<: [
-					arr1
-					arr1.at(0), arr1.at(1), arr1.at(2)
-					arr1.at(-3), arr1.at(-2), arr1.at(-1)
-					arr1.at(3), arr1.at(4), arr1.at(5)
-					arr1.at(-6), arr1.at(-5), arr1.at(-4)
-				]
-			`);
-			eq(res, ARR([
-				ARR([NUM(10), NUM(20), NUM(30)]),
-				NUM(10), NUM(20), NUM(30),
-				NUM(10), NUM(20), NUM(30),
-				NULL, NULL, NULL,
-				NULL, NULL, NULL,
-			]));
-		});
-		
-		test.concurrent('at (with default value)', async () => {
-			const res = await exe(`
-				let arr1 = [10, 20, 30]
-				<: [
-					arr1
-					arr1.at(0, 100), arr1.at(1, 100), arr1.at(2, 100)
-					arr1.at(-3, 100), arr1.at(-2, 100), arr1.at(-1, 100)
-					arr1.at(3, 100), arr1.at(4, 100), arr1.at(5, 100)
-					arr1.at(-6, 100), arr1.at(-5, 100), arr1.at(-4, 100)
-				]
-			`);
-			eq(res, ARR([
-				ARR([NUM(10), NUM(20), NUM(30)]),
-				NUM(10), NUM(20), NUM(30),
-				NUM(10), NUM(20), NUM(30),
-				NUM(100), NUM(100), NUM(100),
-				NUM(100), NUM(100), NUM(100),
-			]));
-		});
-	});
-});
-
-describe('std', () => {
-	describe('Core', () => {
-		test.concurrent('range', async () => {
-			eq(await exe('<: Core:range(1, 10)'), ARR([NUM(1), NUM(2), NUM(3), NUM(4), NUM(5), NUM(6), NUM(7), NUM(8), NUM(9), NUM(10)]));
-			eq(await exe('<: Core:range(1, 1)'), ARR([NUM(1)]));
-			eq(await exe('<: Core:range(9, 7)'), ARR([NUM(9), NUM(8), NUM(7)]));
-		});
-
-		test.concurrent('to_str', async () => {
-			eq(await exe('<: Core:to_str("abc")'), STR('abc'));
-			eq(await exe('<: Core:to_str(123)'), STR('123'));
-			eq(await exe('<: Core:to_str(true)'), STR('true'));
-			eq(await exe('<: Core:to_str(false)'), STR('false'));
-			eq(await exe('<: Core:to_str(null)'), STR('null'));
-			eq(await exe('<: Core:to_str({ a: "abc", b: 1234 })'), STR('{ a: "abc", b: 1234 }'));
-			eq(await exe('<: Core:to_str([ true, 123, null ])'), STR('[ true, 123, null ]'));
-			eq(await exe('<: Core:to_str(@( a, b, c ) {})'), STR('@( a, b, c ) { ... }'));
-			eq(await exe(`
-				let arr = []
-				arr.push(arr)
-				<: Core:to_str(arr)
-			`), STR('[ ... ]'));
-			eq(await exe(`
-				let arr = []
-				arr.push({ value: arr })
-				<: Core:to_str(arr)
-			`), STR('[ { value: ... } ]'));
-		});
-
-		test.concurrent('abort', async () => {
-			assert.rejects(
-				exe('Core:abort("hoge")'),
-				e => e.message.includes('hoge'),
-			);
-		});
-	});
-
-	describe('Arr', () => {
-		test.concurrent('create', async () => {
-			eq(await exe("<: Arr:create(0)"), ARR([]));
-			eq(await exe("<: Arr:create(3)"), ARR([NULL, NULL, NULL]));
-			eq(await exe("<: Arr:create(3, 1)"), ARR([NUM(1), NUM(1), NUM(1)]));
-		});
-	});
-	
-	describe('Math', () => {
-		test.concurrent('trig', async () => {
-			eq(await exe("<: Math:sin(Math:PI / 2)"), NUM(1));
-			eq(await exe("<: Math:sin(0 - (Math:PI / 2))"), NUM(-1));
-			eq(await exe("<: Math:sin(Math:PI / 4) * Math:cos(Math:PI / 4)"), NUM(0.5));
-		});
-
-		test.concurrent('abs', async () => {
-			eq(await exe("<: Math:abs(1 - 6)"), NUM(5));
-		});
-
-		test.concurrent('pow and sqrt', async () => {
-			eq(await exe("<: Math:sqrt(3^2 + 4^2)"), NUM(5));
-		});
-
-		test.concurrent('round', async () => {
-			eq(await exe("<: Math:round(3.14)"), NUM(3));
-			eq(await exe("<: Math:round(-1.414213)"), NUM(-1));
-		});
-
-		test.concurrent('ceil', async () => {
-			eq(await exe("<: Math:ceil(2.71828)"), NUM(3));
-			eq(await exe("<: Math:ceil(0 - Math:PI)"), NUM(-3));
-			eq(await exe("<: Math:ceil(1 / Math:Infinity)"), NUM(0));
-		});
-
-		test.concurrent('floor', async () => {
-			eq(await exe("<: Math:floor(23.14069)"), NUM(23));
-			eq(await exe("<: Math:floor(Math:Infinity / 0)"), NUM(Infinity));
-		});
-
-		test.concurrent('min', async () => {
-			eq(await exe("<: Math:min(2, 3)"), NUM(2));
-		});
-
-		test.concurrent('max', async () => {
-			eq(await exe("<: Math:max(-2, -3)"), NUM(-2));
-		});
-		
-		/* flaky
-		test.concurrent('rnd', async () => {
-			const steps = 512;
-
-			const res = await exe(`
-			let counts = [] // 0 ~ 10 の出現回数を格納する配列
-			for (11) {
-				counts.push(0) // 初期化
-			}
-
-			for (${steps}) {
-				let rnd = Math:rnd(0 10) // 0 以上 10 以下の整数乱数
-				counts[rnd] = counts[rnd] + 1
-			}
-			<: counts`);
-
-			function chiSquareTest(observed: number[], expected: number[]) {
-				let chiSquare = 0; // カイ二乗値
-				for (let i = 0; i < observed.length; i++) {
-					chiSquare += Math.pow(observed[i] - expected[i], 2) / expected[i];
-				}
-				return chiSquare;
-			}
-
-			let observed: Array<number> = [];
-			for (let i = 0; i < res.value.length; i++) {
-				observed.push(res.value[i].value);
-			}
-			let expected = new Array(11).fill(steps / 10);
-			let chiSquare = chiSquareTest(observed, expected);
-
-			// 自由度が (11 - 1) の母分散の カイ二乗分布 95% 信頼区間は [3.94, 18.31]
-			assert.deepEqual(3.94 <= chiSquare && chiSquare <= 18.31, true, `カイ二乗値(${chiSquare})が母分散の95%信頼区間にありません`);
-		});
-		*/
-
-		test.concurrent('rnd with arg', async () => {
-			eq(await exe("<: Math:rnd(1, 1.5)"), NUM(1));
-		});
-
-		test.concurrent('gen_rng', async () => {
-			// 2つのシード値から1~maxの乱数をn回生成して一致率を見る
-			const res = await exe(`
-			@test(seed1, seed2) {
-				let n = 100
-				let max = 100000
-				let threshold = 0.05
-				let random1 = Math:gen_rng(seed1)
-				let random2 = Math:gen_rng(seed2)
-				var same = 0
-				for n {
-					if random1(1, max) == random2(1, max) {
-						same += 1
-					}
-				}
-				let rate = same / n
-				if seed1 == seed2 { rate == 1 }
-				else { rate < threshold }
-			}
-			let seed1 = \`{Util:uuid()}\`
-			let seed2 = \`{Date:year()}\`
-			<: [
-				test(seed1, seed1)
-				test(seed1, seed2)
-			]
-			`)
-			eq(res, ARR([BOOL(true), BOOL(true)]));
-		});
-	});
-
-	describe('Obj', () => {
-		test.concurrent('keys', async () => {
-			const res = await exe(`
-			let o = { a: 1, b: 2, c: 3, }
-
-			<: Obj:keys(o)
-			`);
-			eq(res, ARR([STR('a'), STR('b'), STR('c')]));
-		});
-
-		test.concurrent('vals', async () => {
-			const res = await exe(`
-			let o = { _nul: null, _num: 24, _str: 'hoge', _arr: [], _obj: {}, }
-
-			<: Obj:vals(o)
-			`);
-			eq(res, ARR([NULL, NUM(24), STR('hoge'), ARR([]), OBJ(new Map([]))]));
-		});
-
-		test.concurrent('kvs', async () => {
-			const res = await exe(`
-			let o = { a: 1, b: 2, c: 3, }
-
-			<: Obj:kvs(o)
-			`);
-			eq(res, ARR([
-				ARR([STR('a'), NUM(1)]),
-				ARR([STR('b'), NUM(2)]),
-				ARR([STR('c'), NUM(3)])
-			]));
-		});
-
-		test.concurrent('merge', async () => {
-			const res = await exe(`
-			let o1 = { a: 1, b: 2 }
-			let o2 = { b: 3, c: 4 }
-
-			<: Obj:merge(o1, o2)
-			`);
-			eq(res, utils.jsToVal({ a: 1, b: 3, c: 4}));
-		});
-	});
-
-	describe('Str', () => {
-		test.concurrent('lf', async () => {
-			const res = await exe(`
-			<: Str:lf
-			`);
-			eq(res, STR('\n'));
-		});
-
-		test.concurrent('from_codepoint', async () => {
-			const res = await exe(`
-			<: Str:from_codepoint(65)
-			`);
-			eq(res, STR('A'));
-		});
-
-		test.concurrent('from_unicode_codepoints', async () => {
-			const res = await exe(`
-			<: Str:from_unicode_codepoints([171581, 128073, 127999, 128104, 8205, 128102])
-			`);
-			eq(res, STR('𩸽👉🏿👨‍👦'));
-		});
-
-		test.concurrent('from_utf8_bytes', async () => {
-			const res = await exe(`
-			<: Str:from_utf8_bytes([240, 169, 184, 189, 240, 159, 145, 137, 240, 159, 143, 191, 240, 159, 145, 168, 226, 128, 141, 240, 159, 145, 166])
-			`);
-			eq(res, STR('𩸽👉🏿👨‍👦'));
-		});
-
-		test.concurrent('charcode_at', async () => {
-			let res = await exe(`
-			<: "aiscript".split().map(@(x, _) { x.charcode_at(0) })
-			`);
-			eq(res, ARR([97, 105, 115, 99, 114, 105, 112, 116].map(x => NUM(x))));
-
-			res = await exe(`
-			<: "".charcode_at(0)
-			`);
-			eq(res, NULL);
-		});
-	});
-
-	describe('Uri', () => {
-		test.concurrent('encode_full', async () => {
-			const res = await exe(`
-			<: Uri:encode_full("https://example.com/?q=あいちゃん")
-			`);
-			eq(res, STR('https://example.com/?q=%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93'));
-		});
-
-		test.concurrent('encode_component', async () => {
-			const res = await exe(`
-			<: Uri:encode_component("https://example.com/?q=あいちゃん")
-			`);
-			eq(res, STR('https%3A%2F%2Fexample.com%2F%3Fq%3D%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93'));
-		});
-
-		test.concurrent('decode_full', async () => {
-			const res = await exe(`
-			<: Uri:decode_full("https%3A%2F%2Fexample.com%2F%3Fq%3D%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93")
-			`);
-			eq(res, STR('https%3A%2F%2Fexample.com%2F%3Fq%3Dあいちゃん'));
-		});
-
-		test.concurrent('decode_component', async () => {
-			const res = await exe(`
-			<: Uri:decode_component("https%3A%2F%2Fexample.com%2F%3Fq%3D%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93")
-			`);
-			eq(res, STR('https://example.com/?q=あいちゃん'));
-		});
-	});
-
-	describe('Error', () => {
-		test.concurrent('create', async () => {
-			eq(
-				await exe(`
-				<: Error:create('ai', {chan: 'kawaii'})
-				`),
-				ERROR('ai', OBJ(new Map([['chan', STR('kawaii')]])))
-			);
-		});
-	});
-
-	describe('Json', () => {
-		test.concurrent('stringify: fn', async () => {
-			const res = await exe(`
-			<: Json:stringify(@(){})
-			`);
-			eq(res, STR('"<function>"'));
-		});
-
-		test.concurrent('parsable', async () => {
-			[
-				'null',
-				'"hoge"',
-				'[]',
-				'{}',
-			].forEach(async (str) => {
-				const res = await exe(`
-					<: [
-						Json:parsable('${str}')
-						Json:stringify(Json:parse('${str}'))
-					]
-				`);
-				eq(res, ARR([TRUE, STR(str)]));
-			});
-		});
-		test.concurrent('unparsable', async () => {
-			[
-				'',
-				'hoge',
-				'[',
-			].forEach(async (str) => {
-				const res = await exe(`
-					<: [
-						Json:parsable('${str}')
-						Json:parse('${str}')
-					]
-				`);
-				eq(res, ARR([FALSE, ERROR('not_json')]));
-			});
-		});
-	});
-
-	describe('Date', () => {
-		const example_time = new Date(2024, 1 - 1, 2, 3, 4, 5, 6).getTime();
-		const zero_date = new Date(0);
-		test.concurrent('year', async () => {
-			const res = await exe(`
-				<: [Date:year(0), Date:year(${example_time})]
-			`);
-			eq(res, ARR([NUM(zero_date.getFullYear()), NUM(2024)]));
-		});
-
-		test.concurrent('month', async () => {
-			const res = await exe(`
-				<: [Date:month(0), Date:month(${example_time})]
-			`);
-			eq(res, ARR([NUM(zero_date.getMonth() + 1), NUM(1)]));
-		});
-
-		test.concurrent('day', async () => {
-			const res = await exe(`
-				<: [Date:day(0), Date:day(${example_time})]
-			`);
-			eq(res, ARR([NUM(zero_date.getDate()), NUM(2)]));
-		});
-
-		test.concurrent('hour', async () => {
-			const res = await exe(`
-				<: [Date:hour(0), Date:hour(${example_time})]
-			`);
-			eq(res, ARR([NUM(zero_date.getHours()), NUM(3)]));
-		});
-
-		test.concurrent('minute', async () => {
-			const res = await exe(`
-				<: [Date:minute(0), Date:minute(${example_time})]
-			`);
-			eq(res, ARR([NUM(zero_date.getMinutes()), NUM(4)]));
-		});
-
-		test.concurrent('second', async () => {
-			const res = await exe(`
-				<: [Date:second(0), Date:second(${example_time})]
-			`);
-			eq(res, ARR([NUM(zero_date.getSeconds()), NUM(5)]));
-		});
-
-		test.concurrent('millisecond', async () => {
-			const res = await exe(`
-				<: [Date:millisecond(0), Date:millisecond(${example_time})]
-			`);
-			eq(res, ARR([NUM(zero_date.getMilliseconds()), NUM(6)]));
-		});
-
-		test.concurrent('to_iso_str', async () => {
-			const res = await exe(`
-				let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
-				let s1 = Date:to_iso_str(d1)
-				let d2 = Date:parse(s1)
-				<: [d1, d2, s1]
-			`);
-			eq(res.value[0], res.value[1]);
-			assert.match(res.value[2].value, /^[0-9]{4,4}-[0-9]{2,2}-[0-9]{2,2}T[0-9]{2,2}:[0-9]{2,2}:[0-9]{2,2}\.[0-9]{3,3}(Z|[-+][0-9]{2,2}:[0-9]{2,2})$/);
-		});
-
-		test.concurrent('to_iso_str (UTC)', async () => {
-			const res = await exe(`
-				let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
-				let s1 = Date:to_iso_str(d1, 0)
-				let d2 = Date:parse(s1)
-				<: [d1, d2, s1]
-			`);
-			eq(res.value[0], res.value[1]);
-			eq(res.value[2], STR("2024-04-11T16:47:46.021Z"));
-		});
-
-		test.concurrent('to_iso_str (+09:00)', async () => {
-			const res = await exe(`
-				let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
-				let s1 = Date:to_iso_str(d1, 9*60)
-				let d2 = Date:parse(s1)
-				<: [d1, d2, s1]
-			`);
-			eq(res.value[0], res.value[1]);
-			eq(res.value[2], STR("2024-04-12T01:47:46.021+09:00"));
-		});
-
-		test.concurrent('to_iso_str (-05:18)', async () => {
-			const res = await exe(`
-				let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
-				let s1 = Date:to_iso_str(d1, -5*60-18)
-				let d2 = Date:parse(s1)
-				<: [d1, d2, s1]
-			`);
-			eq(res.value[0], res.value[1]);
-			eq(res.value[2], STR("2024-04-11T11:29:46.021-05:18"));
-		});
-	});
-});
-
 describe('Unicode', () => {
 	test.concurrent('len', async () => {
 		const res = await exe(`
diff --git a/test/primitive-props.ts b/test/primitive-props.ts
new file mode 100644
index 00000000..f0bb2f3f
--- /dev/null
+++ b/test/primitive-props.ts
@@ -0,0 +1,805 @@
+import { expect, test } from '@jest/globals';
+import { NUM, STR, NULL, ARR, OBJ, BOOL, TRUE, FALSE, ERROR ,FN_NATIVE } from '../src/interpreter/value';
+import { exe, eq } from './testutils';
+
+
+describe('num', () => {
+	test.concurrent('to_str', async () => {
+		const res = await exe(`
+		let num = 123
+		<: num.to_str()
+		`);
+		eq(res, STR('123'));
+	});
+	test.concurrent('to_hex', async () => {
+		// TODO -0, 巨大数, 無限小数, Infinity等入力時の結果は未定義
+		const res = await exe(`
+		<: [
+			0, 10, 16,
+			-10, -16,
+			0.5,
+		].map(@(v){v.to_hex()})
+		`);
+		eq(res, ARR([
+			STR('0'), STR('a'), STR('10'),
+			STR('-a'), STR('-10'),
+			STR('0.8'),
+		]));
+	});
+});
+
+describe('str', () => {
+	test.concurrent('len', async () => {
+		const res = await exe(`
+		let str = "hello"
+		<: str.len
+		`);
+		eq(res, NUM(5));
+	});
+
+	test.concurrent('to_num', async () => {
+		const res = await exe(`
+		let str = "123"
+		<: str.to_num()
+		`);
+		eq(res, NUM(123));
+	});
+
+	test.concurrent('upper', async () => {
+		const res = await exe(`
+		let str = "hello"
+		<: str.upper()
+		`);
+		eq(res, STR('HELLO'));
+	});
+
+	test.concurrent('lower', async () => {
+		const res = await exe(`
+		let str = "HELLO"
+		<: str.lower()
+		`);
+		eq(res, STR('hello'));
+	});
+
+	test.concurrent('trim', async () => {
+		const res = await exe(`
+		let str = " hello  "
+		<: str.trim()
+		`);
+		eq(res, STR('hello'));
+	});
+
+	test.concurrent('replace', async () => {
+		const res = await exe(`
+		let str = "hello"
+		<: str.replace("l", "x")
+		`);
+		eq(res, STR('hexxo'));
+	});
+
+	test.concurrent('index_of', async () => {
+		const res = await exe(`
+		let str = '0123401234'
+		<: [
+			str.index_of('3') == 3,
+			str.index_of('5') == -1,
+			str.index_of('3', 3) == 3,
+			str.index_of('3', 4) == 8,
+			str.index_of('3', -1) == -1,
+			str.index_of('3', -2) == 8,
+			str.index_of('3', -7) == 3,
+			str.index_of('3', 10) == -1,
+		].map(@(v){if (v) '1' else '0'}).join()
+		`);
+		eq(res, STR('11111111'));
+	});
+
+	test.concurrent('incl', async () => {
+		const res = await exe(`
+		let str = "hello"
+		<: [str.incl("ll"), str.incl("x")]
+		`);
+		eq(res, ARR([TRUE, FALSE]));
+	});
+
+	test.concurrent('split', async () => {
+		const res = await exe(`
+		let str = "a,b,c"
+		<: str.split(",")
+		`);
+		eq(res, ARR([STR('a'), STR('b'), STR('c')]));
+	});
+
+	test.concurrent('pick', async () => {
+		const res = await exe(`
+		let str = "hello"
+		<: str.pick(1)
+		`);
+		eq(res, STR('e'));
+	});
+
+	test.concurrent('slice', async () => {
+		const res = await exe(`
+		let str = "hello"
+		<: str.slice(1, 3)
+		`);
+		eq(res, STR('el'));
+	});
+
+	test.concurrent("codepoint_at", async () => {
+		const res = await exe(`
+		let str = "𩸽"
+		<: str.codepoint_at(0)
+		`);
+		eq(res, NUM(171581));
+	});
+
+	test.concurrent("to_arr", async () => {
+		const res = await exe(`
+		let str = "𩸽👉🏿👨‍👦"
+		<: str.to_arr()
+		`);
+		eq(
+			res,
+			ARR([STR("𩸽"), STR("👉🏿"), STR("👨‍👦")])
+		);
+	});
+
+	test.concurrent("to_unicode_arr", async () => {
+		const res = await exe(`
+		let str = "𩸽👉🏿👨‍👦"
+		<: str.to_unicode_arr()
+		`);
+		eq(
+			res,
+			ARR([STR("𩸽"), STR("👉"), STR(String.fromCodePoint(0x1F3FF)), STR("👨"), STR("\u200d"), STR("👦")])
+		);
+	});
+
+	test.concurrent("to_unicode_codepoint_arr", async () => {
+		const res = await exe(`
+		let str = "𩸽👉🏿👨‍👦"
+		<: str.to_unicode_codepoint_arr()
+		`);
+		eq(
+			res,
+			ARR([NUM(171581), NUM(128073), NUM(127999), NUM(128104), NUM(8205), NUM(128102)])
+		);
+	});
+
+	test.concurrent("to_char_arr", async () => {
+		const res = await exe(`
+		let str = "abc𩸽👉🏿👨‍👦def"
+		<: str.to_char_arr()
+		`);
+		eq(
+			res,
+			ARR([97, 98, 99, 55399, 56893, 55357, 56393, 55356, 57343, 55357, 56424, 8205, 55357, 56422, 100, 101, 102].map((s) => STR(String.fromCharCode(s))))
+		);
+	});
+
+	test.concurrent("to_charcode_arr", async () => {
+		const res = await exe(`
+		let str = "abc𩸽👉🏿👨‍👦def"
+		<: str.to_charcode_arr()
+		`);
+		eq(
+			res,
+			ARR([NUM(97), NUM(98), NUM(99), NUM(55399), NUM(56893), NUM(55357), NUM(56393), NUM(55356), NUM(57343), NUM(55357), NUM(56424), NUM(8205), NUM(55357), NUM(56422), NUM(100), NUM(101), NUM(102)])
+		);
+	});
+
+	test.concurrent("to_utf8_byte_arr", async () => {
+		const res = await exe(`
+		let str = "abc𩸽👉🏿👨‍👦def"
+		<: str.to_utf8_byte_arr()
+		`);
+		eq(
+			res,
+			ARR([NUM(97), NUM(98), NUM(99), NUM(240), NUM(169), NUM(184), NUM(189), NUM(240), NUM(159), NUM(145), NUM(137), NUM(240), NUM(159), NUM(143), NUM(191), NUM(240), NUM(159), NUM(145), NUM(168), NUM(226), NUM(128), NUM(141), NUM(240), NUM(159), NUM(145), NUM(166), NUM(100), NUM(101), NUM(102)])
+		);
+	});
+
+	test.concurrent('starts_with (no index)', async () => {
+		const res = await exe(`
+		let str = "hello"
+		let empty = ""
+		<: [
+			str.starts_with(""), str.starts_with("hello"),
+			str.starts_with("he"), str.starts_with("ell"),
+			empty.starts_with(""), empty.starts_with("he"),
+		]
+		`);
+		eq(res, ARR([
+			TRUE, TRUE,
+			TRUE, FALSE,
+			TRUE, FALSE, 
+		]));
+	});
+
+	test.concurrent('starts_with (with index)', async () => {
+		const res = await exe(`
+		let str = "hello"
+		let empty = ""
+		<: [
+			str.starts_with("", 4), str.starts_with("he", 0),
+			str.starts_with("ll", 2), str.starts_with("lo", 3),
+			str.starts_with("lo", -2), str.starts_with("hel", -5),
+			str.starts_with("he", 2), str.starts_with("loa", 3),
+			str.starts_with("lo", -6), str.starts_with("", -7),
+			str.starts_with("lo", 6), str.starts_with("", 7),
+			empty.starts_with("", 2), empty.starts_with("ll", 2),
+		]
+		`);
+		eq(res, ARR([
+			TRUE, TRUE,
+			TRUE, TRUE,
+			TRUE, TRUE,
+			FALSE, FALSE,
+			FALSE, TRUE,
+			FALSE, TRUE,
+			TRUE, FALSE,
+		]));
+	});
+
+	test.concurrent('ends_with (no index)', async () => {
+		const res = await exe(`
+		let str = "hello"
+		let empty = ""
+		<: [
+			str.ends_with(""), str.ends_with("hello"),
+			str.ends_with("lo"), str.ends_with("ell"),
+			empty.ends_with(""), empty.ends_with("he"),
+		]
+		`);
+		eq(res, ARR([
+			TRUE, TRUE,
+			TRUE, FALSE,
+			TRUE, FALSE,
+		]));
+	});
+
+	test.concurrent('ends_with (with index)', async () => {
+		const res = await exe(`
+		let str = "hello"
+		let empty = ""
+		<: [
+			str.ends_with("", 3), str.ends_with("lo", 5),
+			str.ends_with("ll", 4), str.ends_with("he", 2),
+			str.ends_with("ll", -1), str.ends_with("he", -3),
+			str.ends_with("he", 5), str.ends_with("lo", 3),
+			str.ends_with("lo", -6), str.ends_with("", -7),
+			str.ends_with("lo", 6), str.ends_with("", 7),
+			empty.ends_with("", 2), empty.ends_with("ll", 2),
+		]
+		`);
+		eq(res, ARR([
+			TRUE, TRUE,
+			TRUE, TRUE,
+			TRUE, TRUE,
+			FALSE, FALSE,
+			FALSE, TRUE,
+			FALSE, TRUE,
+			TRUE, FALSE,
+		]));
+	});
+
+	test.concurrent("pad_start", async () => {
+		const res = await exe(`
+		let str = "abc"
+		<: [
+			str.pad_start(0), str.pad_start(1), str.pad_start(2), str.pad_start(3), str.pad_start(4), str.pad_start(5),
+			str.pad_start(0, "0"), str.pad_start(1, "0"), str.pad_start(2, "0"), str.pad_start(3, "0"), str.pad_start(4, "0"), str.pad_start(5, "0"),
+			str.pad_start(0, "01"), str.pad_start(1, "01"), str.pad_start(2, "01"), str.pad_start(3, "01"), str.pad_start(4, "01"), str.pad_start(5, "01"),
+		]
+		`);
+		eq(res, ARR([
+			STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR(" abc"), STR("  abc"),
+			STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("0abc"), STR("00abc"),
+			STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("0abc"), STR("01abc"),
+		]));
+	});
+
+	test.concurrent("pad_end", async () => {
+		const res = await exe(`
+		let str = "abc"
+		<: [
+			str.pad_end(0), str.pad_end(1), str.pad_end(2), str.pad_end(3), str.pad_end(4), str.pad_end(5),
+			str.pad_end(0, "0"), str.pad_end(1, "0"), str.pad_end(2, "0"), str.pad_end(3, "0"), str.pad_end(4, "0"), str.pad_end(5, "0"),
+			str.pad_end(0, "01"), str.pad_end(1, "01"), str.pad_end(2, "01"), str.pad_end(3, "01"), str.pad_end(4, "01"), str.pad_end(5, "01"),
+		]
+		`);
+		eq(res, ARR([
+			STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("abc "), STR("abc  "),
+			STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("abc0"), STR("abc00"),
+			STR("abc"), STR("abc"), STR("abc"), STR("abc"), STR("abc0"), STR("abc01"),
+		]));
+	});
+});
+
+describe('arr', () => {
+	test.concurrent('len', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		<: arr.len
+		`);
+		eq(res, NUM(3));
+	});
+
+	test.concurrent('push', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		arr.push(4)
+		<: arr
+		`);
+		eq(res, ARR([NUM(1), NUM(2), NUM(3), NUM(4)]));
+	});
+
+	test.concurrent('unshift', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		arr.unshift(4)
+		<: arr
+		`);
+		eq(res, ARR([NUM(4), NUM(1), NUM(2), NUM(3)]));
+	});
+
+	test.concurrent('pop', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		let popped = arr.pop()
+		<: [popped, arr]
+		`);
+		eq(res, ARR([NUM(3), ARR([NUM(1), NUM(2)])]));
+	});
+
+	test.concurrent('shift', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		let shifted = arr.shift()
+		<: [shifted, arr]
+		`);
+		eq(res, ARR([NUM(1), ARR([NUM(2), NUM(3)])]));
+	});
+
+	test.concurrent('concat', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		let concated = arr.concat([4, 5])
+		<: [concated, arr]
+		`);
+		eq(res, ARR([
+			ARR([NUM(1), NUM(2), NUM(3), NUM(4), NUM(5)]),
+			ARR([NUM(1), NUM(2), NUM(3)])
+		]));
+	});
+
+	test.concurrent('slice', async () => {
+		const res = await exe(`
+		let arr = ["ant", "bison", "camel", "duck", "elephant"]
+		let sliced = arr.slice(2, 4)
+		<: [sliced, arr]
+		`);
+		eq(res, ARR([
+			ARR([STR('camel'), STR('duck')]),
+			ARR([STR('ant'), STR('bison'), STR('camel'), STR('duck'), STR('elephant')])
+		]));
+	});
+
+	test.concurrent('join', async () => {
+		const res = await exe(`
+		let arr = ["a", "b", "c"]
+		<: arr.join("-")
+		`);
+		eq(res, STR('a-b-c'));
+	});
+
+	test.concurrent('map', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		<: arr.map(@(item) { item * 2 })
+		`);
+		eq(res, ARR([NUM(2), NUM(4), NUM(6)]));
+	});
+
+	test.concurrent('map with index', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		<: arr.map(@(item, index) { item * index })
+		`);
+		eq(res, ARR([NUM(0), NUM(2), NUM(6)]));
+	});
+
+	test.concurrent('filter', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		<: arr.filter(@(item) { item != 2 })
+		`);
+		eq(res, ARR([NUM(1), NUM(3)]));
+	});
+
+	test.concurrent('filter with index', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3, 4]
+		<: arr.filter(@(item, index) { item != 2 && index != 3 })
+		`);
+		eq(res, ARR([NUM(1), NUM(3)]));
+	});
+
+	test.concurrent('reduce', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3, 4]
+		<: arr.reduce(@(accumulator, currentValue) { (accumulator + currentValue) })
+		`);
+		eq(res, NUM(10));
+	});
+
+	test.concurrent('reduce with index', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3, 4]
+		<: arr.reduce(@(accumulator, currentValue, index) { (accumulator + (currentValue * index)) }, 0)
+		`);
+		eq(res, NUM(20));
+	});
+
+	test.concurrent('reduce of empty array without initial value', async () => {
+		await expect(exe(`
+		let arr = [1, 2, 3, 4]
+		<: [].reduce(@(){})
+		`)).rejects.toThrow('Reduce of empty array without initial value');
+	});
+
+	test.concurrent('find', async () => {
+		const res = await exe(`
+		let arr = ["abc", "def", "ghi"]
+		<: arr.find(@(item) { item.incl("e") })
+		`);
+		eq(res, STR('def'));
+	});
+
+	test.concurrent('find with index', async () => {
+		const res = await exe(`
+		let arr = ["abc1", "def1", "ghi1", "abc2", "def2", "ghi2"]
+		<: arr.find(@(item, index) { item.incl("e") && index > 1 })
+		`);
+		eq(res, STR('def2'));
+	});
+
+	test.concurrent('incl', async () => {
+		const res = await exe(`
+		let arr = ["abc", "def", "ghi"]
+		<: [arr.incl("def"), arr.incl("jkl")]
+		`);
+		eq(res, ARR([TRUE, FALSE]));
+	});
+
+	test.concurrent('index_of', async () => {
+		const res = await exe(`
+		let arr = [0,1,2,3,4,0,1,2,3,4]
+		<: [
+			arr.index_of(3) == 3,
+			arr.index_of(5) == -1,
+			arr.index_of(3, 3) == 3,
+			arr.index_of(3, 4) == 8,
+			arr.index_of(3, -1) == -1,
+			arr.index_of(3, -2) == 8,
+			arr.index_of(3, -7) == 3,
+			arr.index_of(3, 10) == -1,
+		].map(@(v){if (v) '1' else '0'}).join()
+		`);
+		eq(res, STR('11111111'));
+	});
+
+	test.concurrent('reverse', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		arr.reverse()
+		<: arr
+		`);
+		eq(res, ARR([NUM(3), NUM(2), NUM(1)]));
+	});
+
+	test.concurrent('copy', async () => {
+		const res = await exe(`
+		let arr = [1, 2, 3]
+		let copied = arr.copy()
+		copied.reverse()
+		<: [copied, arr]
+		`);
+		eq(res, ARR([
+			ARR([NUM(3), NUM(2), NUM(1)]),
+			ARR([NUM(1), NUM(2), NUM(3)])
+		]));
+	});
+
+	test.concurrent('sort num array', async () => {
+		const res = await exe(`
+			var arr = [2, 10, 3]
+			let comp = @(a, b) { a - b }
+			arr.sort(comp)
+			<: arr
+		`);
+		eq(res, ARR([NUM(2), NUM(3), NUM(10)]));
+	});
+
+	test.concurrent('sort string array (with Str:lt)', async () => {
+		const res = await exe(`
+			var arr = ["hoge", "huga", "piyo", "hoge"]
+			arr.sort(Str:lt)
+			<: arr
+		`);
+		eq(res, ARR([STR('hoge'), STR('hoge'), STR('huga'), STR('piyo')]));
+	});
+
+	test.concurrent('sort string array (with Str:gt)', async () => {
+		const res = await exe(`
+			var arr = ["hoge", "huga", "piyo", "hoge"]
+			arr.sort(Str:gt)
+			<: arr
+		`);
+		eq(res, ARR([ STR('piyo'),  STR('huga'), STR('hoge'), STR('hoge')]));
+	});
+
+	test.concurrent('sort object array', async () => {
+		const res = await exe(`
+			var arr = [{x: 2}, {x: 10}, {x: 3}]
+			let comp = @(a, b) { a.x - b.x }
+
+			arr.sort(comp)
+			<: arr
+		`);
+		eq(res, ARR([OBJ(new Map([['x', NUM(2)]])), OBJ(new Map([['x', NUM(3)]])), OBJ(new Map([['x', NUM(10)]]))]));
+	});
+
+	test.concurrent('sort (stable)', async () => {
+		const res = await exe(`
+			var arr = [[2, 0], [10, 1], [3, 2], [3, 3], [2, 4]]
+			let comp = @(a, b) { a[0] - b[0] }
+
+			arr.sort(comp)
+			<: arr
+		`);
+		eq(res, ARR([
+			ARR([NUM(2), NUM(0)]),
+			ARR([NUM(2), NUM(4)]),
+			ARR([NUM(3), NUM(2)]),
+			ARR([NUM(3), NUM(3)]),
+			ARR([NUM(10), NUM(1)]),
+		]));
+	});
+	
+	test.concurrent('fill', async () => {
+		const res = await exe(`
+			var arr1 = [0, 1, 2]
+			let arr2 = arr1.fill(3)
+			let arr3 = [0, 1, 2].fill(3, 1)
+			let arr4 = [0, 1, 2].fill(3, 1, 2)
+			let arr5 = [0, 1, 2].fill(3, -2, -1)
+			<: [arr1, arr2, arr3, arr4, arr5]
+		`);
+		eq(res, ARR([
+			ARR([NUM(3), NUM(3), NUM(3)]), //target changed
+			ARR([NUM(3), NUM(3), NUM(3)]),
+			ARR([NUM(0), NUM(3), NUM(3)]),
+			ARR([NUM(0), NUM(3), NUM(2)]),
+			ARR([NUM(0), NUM(3), NUM(2)]),
+		]));
+	});
+	
+	test.concurrent('repeat', async () => {
+		const res = await exe(`
+			var arr1 = [0, 1, 2]
+			let arr2 = arr1.repeat(3)
+			let arr3 = arr1.repeat(0)
+			<: [arr1, arr2, arr3]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0), NUM(1), NUM(2)]), // target not changed
+			ARR([
+				NUM(0), NUM(1), NUM(2),
+				NUM(0), NUM(1), NUM(2),
+				NUM(0), NUM(1), NUM(2),
+			]),
+			ARR([]),
+		]));
+	});
+
+	test.concurrent('splice (full)', async () => {
+		const res = await exe(`
+				let arr1 = [0, 1, 2, 3]
+			let arr2 = arr1.splice(1, 2, [10])
+			<: [arr1, arr2]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0), NUM(10), NUM(3)]),
+			ARR([NUM(1), NUM(2)]),
+		]));
+	});
+	
+	test.concurrent('splice (negative-index)', async () => {
+		const res = await exe(`
+				let arr1 = [0, 1, 2, 3]
+			let arr2 = arr1.splice(-1, 0, [10, 20])
+			<: [arr1, arr2]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0), NUM(1), NUM(2), NUM(10), NUM(20), NUM(3)]),
+			ARR([]),
+		]));
+	});
+	
+	test.concurrent('splice (larger-index)', async () => {
+		const res = await exe(`
+			let arr1 = [0, 1, 2, 3]
+			let arr2 = arr1.splice(4, 100, [10, 20])
+			<: [arr1, arr2]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0), NUM(1), NUM(2), NUM(3), NUM(10), NUM(20)]),
+			ARR([]),
+		]));
+	});
+	
+	test.concurrent('splice (single argument)', async () => {
+		const res = await exe(`
+			let arr1 = [0, 1, 2, 3]
+			let arr2 = arr1.splice(1)
+			<: [arr1, arr2]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0)]),
+			ARR([NUM(1), NUM(2), NUM(3)]),
+		]));
+	});
+	
+	test.concurrent('flat', async () => {
+		const res = await exe(`
+			var arr1 = [0, [1], [2, 3], [4, [5, 6]]]
+			let arr2 = arr1.flat()
+			let arr3 = arr1.flat(2)
+			<: [arr1, arr2, arr3]
+		`);
+		eq(res, ARR([
+			ARR([
+				NUM(0), ARR([NUM(1)]), ARR([NUM(2), NUM(3)]),
+				ARR([NUM(4), ARR([NUM(5), NUM(6)])])
+			]), // target not changed
+			ARR([
+				NUM(0), NUM(1), NUM(2), NUM(3),
+				NUM(4), ARR([NUM(5), NUM(6)]),
+			]),
+			ARR([
+				NUM(0), NUM(1), NUM(2), NUM(3),
+				NUM(4), NUM(5), NUM(6),
+			]),
+		]));
+	});
+	
+	test.concurrent('flat_map', async () => {
+		const res = await exe(`
+			let arr1 = [0, 1, 2]
+			let arr2 = ["a", "b"]
+			let arr3 = arr1.flat_map(@(x){ arr2.map(@(y){ [x, y] }) })
+			<: [arr1, arr3]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0), NUM(1), NUM(2)]), // target not changed
+			ARR([
+				ARR([NUM(0), STR("a")]),
+				ARR([NUM(0), STR("b")]),
+				ARR([NUM(1), STR("a")]),
+				ARR([NUM(1), STR("b")]),
+				ARR([NUM(2), STR("a")]),
+				ARR([NUM(2), STR("b")]),
+			]),
+		]));
+	});
+
+	test.concurrent('every', async () => {
+		const res = await exe(`
+			let arr1 = [0, 1, 2, 3]
+			let res1 = arr1.every(@(v,i){v==0 || i > 0})
+			let res2 = arr1.every(@(v,i){v==0 && i > 0})
+			let res3 = [].every(@(v,i){false})
+			<: [arr1, res1, res2, res3]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0), NUM(1), NUM(2), NUM(3)]), // target not changed
+			TRUE,
+			FALSE,
+			TRUE,
+		]));
+	});
+	
+	test.concurrent('some', async () => {
+		const res = await exe(`
+			let arr1 = [0, 1, 2, 3]
+			let res1 = arr1.some(@(v,i){v%2==0 && i <= 2})
+			let res2 = arr1.some(@(v,i){v%2==0 && i > 2})
+			<: [arr1, res1, res2]
+		`);
+		eq(res, ARR([
+			ARR([NUM(0), NUM(1), NUM(2), NUM(3)]), // target not changed
+			TRUE,
+			FALSE,
+		]));
+	});
+	
+	test.concurrent('insert', async () => {
+		const res = await exe(`
+			let arr1 = [0, 1, 2]
+			let res = []
+			res.push(arr1.insert(3, 10)) // [0, 1, 2, 10]
+			res.push(arr1.insert(2, 20)) // [0, 1, 20, 2, 10]
+			res.push(arr1.insert(0, 30)) // [30, 0, 1, 20, 2, 10]
+			res.push(arr1.insert(-1, 40)) // [30, 0, 1, 20, 2, 40, 10]
+			res.push(arr1.insert(-4, 50)) // [30, 0, 1, 50, 20, 2, 40, 10]
+			res.push(arr1.insert(100, 60)) // [30, 0, 1, 50, 20, 2, 40, 10, 60]
+			res.push(arr1)
+			<: res
+		`);
+		eq(res, ARR([
+			NULL, NULL, NULL, NULL, NULL, NULL, 
+			ARR([NUM(30), NUM(0), NUM(1), NUM(50), NUM(20), NUM(2), NUM(40), NUM(10), NUM(60)])
+		]));
+	});
+	
+	test.concurrent('remove', async () => {
+		const res = await exe(`
+			let arr1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+			let res = []
+			res.push(arr1.remove(9)) // 9 [0, 1, 2, 3, 4, 5, 6, 7, 8]
+			res.push(arr1.remove(3)) // 3 [0, 1, 2, 4, 5, 6, 7, 8]
+			res.push(arr1.remove(0)) // 0 [1, 2, 4, 5, 6, 7, 8]
+			res.push(arr1.remove(-1)) // 8 [1, 2, 4, 5, 6, 7]
+			res.push(arr1.remove(-5)) // 2 [1, 4, 5, 6, 7]
+			res.push(arr1.remove(100)) // null [1, 4, 5, 6, 7]
+			res.push(arr1)
+			<: res
+		`);
+		eq(res, ARR([
+			NUM(9), NUM(3), NUM(0), NUM(8), NUM(2), NULL, 
+			ARR([NUM(1), NUM(4), NUM(5), NUM(6), NUM(7)])
+		]));
+	});
+	
+	test.concurrent('at (without default value)', async () => {
+		const res = await exe(`
+			let arr1 = [10, 20, 30]
+			<: [
+				arr1
+				arr1.at(0), arr1.at(1), arr1.at(2)
+				arr1.at(-3), arr1.at(-2), arr1.at(-1)
+				arr1.at(3), arr1.at(4), arr1.at(5)
+				arr1.at(-6), arr1.at(-5), arr1.at(-4)
+			]
+		`);
+		eq(res, ARR([
+			ARR([NUM(10), NUM(20), NUM(30)]),
+			NUM(10), NUM(20), NUM(30),
+			NUM(10), NUM(20), NUM(30),
+			NULL, NULL, NULL,
+			NULL, NULL, NULL,
+		]));
+	});
+	
+	test.concurrent('at (with default value)', async () => {
+		const res = await exe(`
+			let arr1 = [10, 20, 30]
+			<: [
+				arr1
+				arr1.at(0, 100), arr1.at(1, 100), arr1.at(2, 100)
+				arr1.at(-3, 100), arr1.at(-2, 100), arr1.at(-1, 100)
+				arr1.at(3, 100), arr1.at(4, 100), arr1.at(5, 100)
+				arr1.at(-6, 100), arr1.at(-5, 100), arr1.at(-4, 100)
+			]
+		`);
+		eq(res, ARR([
+			ARR([NUM(10), NUM(20), NUM(30)]),
+			NUM(10), NUM(20), NUM(30),
+			NUM(10), NUM(20), NUM(30),
+			NUM(100), NUM(100), NUM(100),
+			NUM(100), NUM(100), NUM(100),
+		]));
+	});
+});
diff --git a/test/std.ts b/test/std.ts
new file mode 100644
index 00000000..e4f8f5e6
--- /dev/null
+++ b/test/std.ts
@@ -0,0 +1,423 @@
+import * as assert from 'assert';
+import { test } from '@jest/globals';
+import { utils } from '../src';
+import { NUM, STR, NULL, ARR, OBJ, BOOL, TRUE, FALSE, ERROR ,FN_NATIVE } from '../src/interpreter/value';
+import { exe, eq } from './testutils';
+
+
+describe('Core', () => {
+	test.concurrent('range', async () => {
+		eq(await exe('<: Core:range(1, 10)'), ARR([NUM(1), NUM(2), NUM(3), NUM(4), NUM(5), NUM(6), NUM(7), NUM(8), NUM(9), NUM(10)]));
+		eq(await exe('<: Core:range(1, 1)'), ARR([NUM(1)]));
+		eq(await exe('<: Core:range(9, 7)'), ARR([NUM(9), NUM(8), NUM(7)]));
+	});
+
+	test.concurrent('to_str', async () => {
+		eq(await exe('<: Core:to_str("abc")'), STR('abc'));
+		eq(await exe('<: Core:to_str(123)'), STR('123'));
+		eq(await exe('<: Core:to_str(true)'), STR('true'));
+		eq(await exe('<: Core:to_str(false)'), STR('false'));
+		eq(await exe('<: Core:to_str(null)'), STR('null'));
+		eq(await exe('<: Core:to_str({ a: "abc", b: 1234 })'), STR('{ a: "abc", b: 1234 }'));
+		eq(await exe('<: Core:to_str([ true, 123, null ])'), STR('[ true, 123, null ]'));
+		eq(await exe('<: Core:to_str(@( a, b, c ) {})'), STR('@( a, b, c ) { ... }'));
+		eq(await exe(`
+			let arr = []
+			arr.push(arr)
+			<: Core:to_str(arr)
+		`), STR('[ ... ]'));
+		eq(await exe(`
+			let arr = []
+			arr.push({ value: arr })
+			<: Core:to_str(arr)
+		`), STR('[ { value: ... } ]'));
+	});
+
+	test.concurrent('abort', async () => {
+		assert.rejects(
+			exe('Core:abort("hoge")'),
+			e => e.message.includes('hoge'),
+		);
+	});
+});
+
+describe('Arr', () => {
+	test.concurrent('create', async () => {
+		eq(await exe("<: Arr:create(0)"), ARR([]));
+		eq(await exe("<: Arr:create(3)"), ARR([NULL, NULL, NULL]));
+		eq(await exe("<: Arr:create(3, 1)"), ARR([NUM(1), NUM(1), NUM(1)]));
+	});
+});
+
+describe('Math', () => {
+	test.concurrent('trig', async () => {
+		eq(await exe("<: Math:sin(Math:PI / 2)"), NUM(1));
+		eq(await exe("<: Math:sin(0 - (Math:PI / 2))"), NUM(-1));
+		eq(await exe("<: Math:sin(Math:PI / 4) * Math:cos(Math:PI / 4)"), NUM(0.5));
+	});
+
+	test.concurrent('abs', async () => {
+		eq(await exe("<: Math:abs(1 - 6)"), NUM(5));
+	});
+
+	test.concurrent('pow and sqrt', async () => {
+		eq(await exe("<: Math:sqrt(3^2 + 4^2)"), NUM(5));
+	});
+
+	test.concurrent('round', async () => {
+		eq(await exe("<: Math:round(3.14)"), NUM(3));
+		eq(await exe("<: Math:round(-1.414213)"), NUM(-1));
+	});
+
+	test.concurrent('ceil', async () => {
+		eq(await exe("<: Math:ceil(2.71828)"), NUM(3));
+		eq(await exe("<: Math:ceil(0 - Math:PI)"), NUM(-3));
+		eq(await exe("<: Math:ceil(1 / Math:Infinity)"), NUM(0));
+	});
+
+	test.concurrent('floor', async () => {
+		eq(await exe("<: Math:floor(23.14069)"), NUM(23));
+		eq(await exe("<: Math:floor(Math:Infinity / 0)"), NUM(Infinity));
+	});
+
+	test.concurrent('min', async () => {
+		eq(await exe("<: Math:min(2, 3)"), NUM(2));
+	});
+
+	test.concurrent('max', async () => {
+		eq(await exe("<: Math:max(-2, -3)"), NUM(-2));
+	});
+	
+	/* flaky
+	test.concurrent('rnd', async () => {
+		const steps = 512;
+
+		const res = await exe(`
+		let counts = [] // 0 ~ 10 の出現回数を格納する配列
+		for (11) {
+			counts.push(0) // 初期化
+		}
+
+		for (${steps}) {
+			let rnd = Math:rnd(0 10) // 0 以上 10 以下の整数乱数
+			counts[rnd] = counts[rnd] + 1
+		}
+		<: counts`);
+
+		function chiSquareTest(observed: number[], expected: number[]) {
+			let chiSquare = 0; // カイ二乗値
+			for (let i = 0; i < observed.length; i++) {
+				chiSquare += Math.pow(observed[i] - expected[i], 2) / expected[i];
+			}
+			return chiSquare;
+		}
+
+		let observed: Array<number> = [];
+		for (let i = 0; i < res.value.length; i++) {
+			observed.push(res.value[i].value);
+		}
+		let expected = new Array(11).fill(steps / 10);
+		let chiSquare = chiSquareTest(observed, expected);
+
+		// 自由度が (11 - 1) の母分散の カイ二乗分布 95% 信頼区間は [3.94, 18.31]
+		assert.deepEqual(3.94 <= chiSquare && chiSquare <= 18.31, true, `カイ二乗値(${chiSquare})が母分散の95%信頼区間にありません`);
+	});
+	*/
+
+	test.concurrent('rnd with arg', async () => {
+		eq(await exe("<: Math:rnd(1, 1.5)"), NUM(1));
+	});
+
+	test.concurrent('gen_rng', async () => {
+		// 2つのシード値から1~maxの乱数をn回生成して一致率を見る
+		const res = await exe(`
+		@test(seed1, seed2) {
+			let n = 100
+			let max = 100000
+			let threshold = 0.05
+			let random1 = Math:gen_rng(seed1)
+			let random2 = Math:gen_rng(seed2)
+			var same = 0
+			for n {
+				if random1(1, max) == random2(1, max) {
+					same += 1
+				}
+			}
+			let rate = same / n
+			if seed1 == seed2 { rate == 1 }
+			else { rate < threshold }
+		}
+		let seed1 = \`{Util:uuid()}\`
+		let seed2 = \`{Date:year()}\`
+		<: [
+			test(seed1, seed1)
+			test(seed1, seed2)
+		]
+		`)
+		eq(res, ARR([BOOL(true), BOOL(true)]));
+	});
+});
+
+describe('Obj', () => {
+	test.concurrent('keys', async () => {
+		const res = await exe(`
+		let o = { a: 1, b: 2, c: 3, }
+
+		<: Obj:keys(o)
+		`);
+		eq(res, ARR([STR('a'), STR('b'), STR('c')]));
+	});
+
+	test.concurrent('vals', async () => {
+		const res = await exe(`
+		let o = { _nul: null, _num: 24, _str: 'hoge', _arr: [], _obj: {}, }
+
+		<: Obj:vals(o)
+		`);
+		eq(res, ARR([NULL, NUM(24), STR('hoge'), ARR([]), OBJ(new Map([]))]));
+	});
+
+	test.concurrent('kvs', async () => {
+		const res = await exe(`
+		let o = { a: 1, b: 2, c: 3, }
+
+		<: Obj:kvs(o)
+		`);
+		eq(res, ARR([
+			ARR([STR('a'), NUM(1)]),
+			ARR([STR('b'), NUM(2)]),
+			ARR([STR('c'), NUM(3)])
+		]));
+	});
+
+	test.concurrent('merge', async () => {
+		const res = await exe(`
+		let o1 = { a: 1, b: 2 }
+		let o2 = { b: 3, c: 4 }
+
+		<: Obj:merge(o1, o2)
+		`);
+		eq(res, utils.jsToVal({ a: 1, b: 3, c: 4}));
+	});
+});
+
+describe('Str', () => {
+	test.concurrent('lf', async () => {
+		const res = await exe(`
+		<: Str:lf
+		`);
+		eq(res, STR('\n'));
+	});
+
+	test.concurrent('from_codepoint', async () => {
+		const res = await exe(`
+		<: Str:from_codepoint(65)
+		`);
+		eq(res, STR('A'));
+	});
+
+	test.concurrent('from_unicode_codepoints', async () => {
+		const res = await exe(`
+		<: Str:from_unicode_codepoints([171581, 128073, 127999, 128104, 8205, 128102])
+		`);
+		eq(res, STR('𩸽👉🏿👨‍👦'));
+	});
+
+	test.concurrent('from_utf8_bytes', async () => {
+		const res = await exe(`
+		<: Str:from_utf8_bytes([240, 169, 184, 189, 240, 159, 145, 137, 240, 159, 143, 191, 240, 159, 145, 168, 226, 128, 141, 240, 159, 145, 166])
+		`);
+		eq(res, STR('𩸽👉🏿👨‍👦'));
+	});
+
+	test.concurrent('charcode_at', async () => {
+		let res = await exe(`
+		<: "aiscript".split().map(@(x, _) { x.charcode_at(0) })
+		`);
+		eq(res, ARR([97, 105, 115, 99, 114, 105, 112, 116].map(x => NUM(x))));
+
+		res = await exe(`
+		<: "".charcode_at(0)
+		`);
+		eq(res, NULL);
+	});
+});
+
+describe('Uri', () => {
+	test.concurrent('encode_full', async () => {
+		const res = await exe(`
+		<: Uri:encode_full("https://example.com/?q=あいちゃん")
+		`);
+		eq(res, STR('https://example.com/?q=%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93'));
+	});
+
+	test.concurrent('encode_component', async () => {
+		const res = await exe(`
+		<: Uri:encode_component("https://example.com/?q=あいちゃん")
+		`);
+		eq(res, STR('https%3A%2F%2Fexample.com%2F%3Fq%3D%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93'));
+	});
+
+	test.concurrent('decode_full', async () => {
+		const res = await exe(`
+		<: Uri:decode_full("https%3A%2F%2Fexample.com%2F%3Fq%3D%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93")
+		`);
+		eq(res, STR('https%3A%2F%2Fexample.com%2F%3Fq%3Dあいちゃん'));
+	});
+
+	test.concurrent('decode_component', async () => {
+		const res = await exe(`
+		<: Uri:decode_component("https%3A%2F%2Fexample.com%2F%3Fq%3D%E3%81%82%E3%81%84%E3%81%A1%E3%82%83%E3%82%93")
+		`);
+		eq(res, STR('https://example.com/?q=あいちゃん'));
+	});
+});
+
+describe('Error', () => {
+	test.concurrent('create', async () => {
+		eq(
+			await exe(`
+			<: Error:create('ai', {chan: 'kawaii'})
+			`),
+			ERROR('ai', OBJ(new Map([['chan', STR('kawaii')]])))
+		);
+	});
+});
+
+describe('Json', () => {
+	test.concurrent('stringify: fn', async () => {
+		const res = await exe(`
+		<: Json:stringify(@(){})
+		`);
+		eq(res, STR('"<function>"'));
+	});
+
+	test.concurrent('parsable', async () => {
+		[
+			'null',
+			'"hoge"',
+			'[]',
+			'{}',
+		].forEach(async (str) => {
+			const res = await exe(`
+				<: [
+					Json:parsable('${str}')
+					Json:stringify(Json:parse('${str}'))
+				]
+			`);
+			eq(res, ARR([TRUE, STR(str)]));
+		});
+	});
+	test.concurrent('unparsable', async () => {
+		[
+			'',
+			'hoge',
+			'[',
+		].forEach(async (str) => {
+			const res = await exe(`
+				<: [
+					Json:parsable('${str}')
+					Json:parse('${str}')
+				]
+			`);
+			eq(res, ARR([FALSE, ERROR('not_json')]));
+		});
+	});
+});
+
+describe('Date', () => {
+	const example_time = new Date(2024, 1 - 1, 2, 3, 4, 5, 6).getTime();
+	const zero_date = new Date(0);
+	test.concurrent('year', async () => {
+		const res = await exe(`
+			<: [Date:year(0), Date:year(${example_time})]
+		`);
+		eq(res, ARR([NUM(zero_date.getFullYear()), NUM(2024)]));
+	});
+
+	test.concurrent('month', async () => {
+		const res = await exe(`
+			<: [Date:month(0), Date:month(${example_time})]
+		`);
+		eq(res, ARR([NUM(zero_date.getMonth() + 1), NUM(1)]));
+	});
+
+	test.concurrent('day', async () => {
+		const res = await exe(`
+			<: [Date:day(0), Date:day(${example_time})]
+		`);
+		eq(res, ARR([NUM(zero_date.getDate()), NUM(2)]));
+	});
+
+	test.concurrent('hour', async () => {
+		const res = await exe(`
+			<: [Date:hour(0), Date:hour(${example_time})]
+		`);
+		eq(res, ARR([NUM(zero_date.getHours()), NUM(3)]));
+	});
+
+	test.concurrent('minute', async () => {
+		const res = await exe(`
+			<: [Date:minute(0), Date:minute(${example_time})]
+		`);
+		eq(res, ARR([NUM(zero_date.getMinutes()), NUM(4)]));
+	});
+
+	test.concurrent('second', async () => {
+		const res = await exe(`
+			<: [Date:second(0), Date:second(${example_time})]
+		`);
+		eq(res, ARR([NUM(zero_date.getSeconds()), NUM(5)]));
+	});
+
+	test.concurrent('millisecond', async () => {
+		const res = await exe(`
+			<: [Date:millisecond(0), Date:millisecond(${example_time})]
+		`);
+		eq(res, ARR([NUM(zero_date.getMilliseconds()), NUM(6)]));
+	});
+
+	test.concurrent('to_iso_str', async () => {
+		const res = await exe(`
+			let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
+			let s1 = Date:to_iso_str(d1)
+			let d2 = Date:parse(s1)
+			<: [d1, d2, s1]
+		`);
+		eq(res.value[0], res.value[1]);
+		assert.match(res.value[2].value, /^[0-9]{4,4}-[0-9]{2,2}-[0-9]{2,2}T[0-9]{2,2}:[0-9]{2,2}:[0-9]{2,2}\.[0-9]{3,3}(Z|[-+][0-9]{2,2}:[0-9]{2,2})$/);
+	});
+
+	test.concurrent('to_iso_str (UTC)', async () => {
+		const res = await exe(`
+			let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
+			let s1 = Date:to_iso_str(d1, 0)
+			let d2 = Date:parse(s1)
+			<: [d1, d2, s1]
+		`);
+		eq(res.value[0], res.value[1]);
+		eq(res.value[2], STR("2024-04-11T16:47:46.021Z"));
+	});
+
+	test.concurrent('to_iso_str (+09:00)', async () => {
+		const res = await exe(`
+			let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
+			let s1 = Date:to_iso_str(d1, 9*60)
+			let d2 = Date:parse(s1)
+			<: [d1, d2, s1]
+		`);
+		eq(res.value[0], res.value[1]);
+		eq(res.value[2], STR("2024-04-12T01:47:46.021+09:00"));
+	});
+
+	test.concurrent('to_iso_str (-05:18)', async () => {
+		const res = await exe(`
+			let d1 = Date:parse("2024-04-12T01:47:46.021+09:00")
+			let s1 = Date:to_iso_str(d1, -5*60-18)
+			let d2 = Date:parse(s1)
+			<: [d1, d2, s1]
+		`);
+		eq(res.value[0], res.value[1]);
+		eq(res.value[2], STR("2024-04-11T11:29:46.021-05:18"));
+	});
+});