diff --git a/.gitignore b/.gitignore
index c2658d7..1eae0cf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
+dist/
 node_modules/
diff --git a/build.js b/build.js
new file mode 100644
index 0000000..43bcf97
--- /dev/null
+++ b/build.js
@@ -0,0 +1,41 @@
+import * as esbuild from 'esbuild'
+import cc from '@apeleghq/esbuild-plugin-closure-compiler'
+
+const closure = cc({ language_in: 'UNSTABLE', compilation_level: 'SIMPLE' })
+
+const cjs = esbuild.build({
+    entryPoints: ['src/index.ts'],
+    bundle: true,
+    format: 'cjs',
+    sourcemap: 'linked',
+    outfile: './dist/index.js',
+})
+
+const cjsmin = esbuild.build({
+    entryPoints: ['src/index.ts'],
+    bundle: true,
+    outfile: './dist/index.min.js',
+    format: 'cjs',
+    sourcemap: 'linked',
+    plugins: [closure]
+})
+
+const esm = esbuild.build({
+    entryPoints: ['src/index.ts'],
+    bundle: true,
+    format: 'esm',
+    sourcemap: 'linked',
+    outfile: './dist/index.esm.js'
+})
+
+const esmmin = esbuild.build({
+    entryPoints: ['src/index.ts'],
+    bundle: true,
+    format: 'esm',
+    sourcemap: 'linked',
+    outfile: './dist/index.esm.min.js',
+    plugins: [closure]
+})
+
+await Promise.all([cjs, cjsmin, esm, esmmin])
+
diff --git a/dist/index.js b/dist/index.js
deleted file mode 100644
index bc59b2b..0000000
--- a/dist/index.js
+++ /dev/null
@@ -1,550 +0,0 @@
-// src/index.ts
-var DoneIteratorResult = Object.freeze({ value: void 0, done: true });
-function hasMethods(methods, obj) {
-  return methods.every((method) => typeof obj[method] === "function");
-}
-function isIterable(value) {
-  return typeof value[Symbol.iterator] === "function";
-}
-function isIterator(value) {
-  return typeof value.next === "function";
-}
-function isBuffer(value) {
-  return ArrayBuffer.isView(value);
-}
-function isArrayLike(value) {
-  return Array.isArray(value) || value instanceof Array;
-}
-var IteratorEnumerator = class _IteratorEnumerator {
-  _iterator;
-  _consumed = false;
-  _current;
-  get current() {
-    return this._current;
-  }
-  constructor(iterator) {
-    this._iterator = iterator;
-  }
-  static from(iterator) {
-    return new _IteratorEnumerator(iterator);
-  }
-  moveNext() {
-    if (!this._consumed) {
-      const { value, done } = this._iterator.next();
-      this._current = value;
-      if (done) {
-        this._consumed = true;
-      }
-      return !done;
-    } else {
-      return false;
-    }
-  }
-  reset() {
-  }
-  toIterator() {
-    return this;
-  }
-  next(...[_value]) {
-    const done = this.moveNext();
-    return { value: this.current, done };
-  }
-  return(value) {
-    return this._iterator.return?.(value) ?? DoneIteratorResult;
-  }
-  throw(e) {
-    return this._iterator.throw?.(e) ?? DoneIteratorResult;
-  }
-};
-var CachedIteratorEnumerator = class _CachedIteratorEnumerator {
-  _iterator;
-  _cache = [];
-  _index = -1;
-  get current() {
-    return this._cache[this._index];
-  }
-  constructor(iterator) {
-    this._iterator = new IteratorEnumerator(iterator);
-  }
-  static from(iterator) {
-    return new _CachedIteratorEnumerator(iterator);
-  }
-  moveNext() {
-    this._index += 1;
-    if (this._cache.length > this._index) {
-      return true;
-    } else if (this._iterator.moveNext()) {
-      this._cache.push(this._iterator.current);
-      return true;
-    } else {
-      return false;
-    }
-  }
-  reset() {
-    this._index = -1;
-  }
-  toIterator() {
-    return this;
-  }
-  next(...[_value]) {
-    const done = this.moveNext();
-    return { value: this.current, done };
-  }
-  return(value) {
-    return this._iterator.return(value);
-  }
-  throw(e) {
-    return this._iterator.throw(e);
-  }
-};
-var IterableEnumerator = class {
-  _iterable;
-  _factory;
-  _enumerator;
-  get current() {
-    return this._enumerator?.current;
-  }
-  constructor(iterable, factory = IteratorEnumerator.from) {
-    this._iterable = iterable;
-    this._factory = factory;
-    this._enumerator = this._createEnumerator();
-  }
-  static fromIterable(iterable, factory) {
-    return new this(iterable, factory);
-  }
-  moveNext() {
-    return this._enumerator?.moveNext() ?? false;
-  }
-  _createIterator() {
-    return this._iterable[Symbol.iterator]();
-  }
-  _createEnumerator() {
-    return this._factory(this._createIterator());
-  }
-  reset() {
-    this._enumerator = this._createEnumerator();
-  }
-  toIterator() {
-    return this._createIterator();
-  }
-  next(...[_value]) {
-    const done = !this.moveNext();
-    return { value: this.current, done };
-  }
-  return(value) {
-    if (isIterator(this._enumerator)) {
-      return this._enumerator?.return?.(value) || DoneIteratorResult;
-    } else {
-      return DoneIteratorResult;
-    }
-  }
-  throw(e) {
-    if (isIterator(this._enumerator)) {
-      return this._enumerator?.throw?.(e) || DoneIteratorResult;
-    } else {
-      return DoneIteratorResult;
-    }
-  }
-};
-function toArrayLikeBuffer(buffer) {
-  return Object.defineProperty(buffer, "length", {
-    get: function() {
-      return buffer.byteLength;
-    }
-  });
-}
-var ArrayEnumerator = class _ArrayEnumerator {
-  _array;
-  _index = -1;
-  get current() {
-    return this._array[this._index];
-  }
-  constructor(array) {
-    this._array = array;
-  }
-  static from(array) {
-    if (ArrayBuffer.isView(array)) {
-      return new _ArrayEnumerator(toArrayLikeBuffer(array));
-    } else {
-      return new _ArrayEnumerator(array);
-    }
-  }
-  [Symbol.iterator]() {
-    return this._array[Symbol.iterator]();
-  }
-  setIndex(index) {
-    this._index = index;
-  }
-  moveNext() {
-    this._index += 1;
-    return this._index < this._array.length;
-  }
-  reset() {
-    this._index = -1;
-  }
-  toIterator() {
-    return this._array[Symbol.iterator]();
-  }
-  next(...[_value]) {
-    const done = this.moveNext();
-    return { value: this.current, done };
-  }
-  return(_value) {
-    return DoneIteratorResult;
-  }
-  throw(_e) {
-    return DoneIteratorResult;
-  }
-};
-var Enumerator = class _Enumerator {
-  _enumerator;
-  _index = 0;
-  get current() {
-    return this._enumerator.current;
-  }
-  constructor(enumerator) {
-    this._enumerator = enumerator;
-  }
-  static fromIterable(iterable) {
-    if (isArrayLike(iterable) || ArrayBuffer.isView(iterable)) {
-      return ArrayEnumerator.from(iterable);
-    } else {
-      return new this(new IterableEnumerator(iterable));
-    }
-  }
-  static fromIterator(iterator, cache = true) {
-    if (cache) {
-      return new CachedIteratorEnumerator(iterator);
-    } else {
-      return new IteratorEnumerator(iterator);
-    }
-  }
-  static toIterator(enumerator) {
-    return new this(enumerator);
-  }
-  [Symbol.iterator]() {
-    return this.toIterator();
-  }
-  toIterator() {
-    return _Enumerator.toIterator(this);
-  }
-  moveNext() {
-    this._index += 1;
-    return this._enumerator.moveNext();
-  }
-  reset() {
-    this._enumerator.reset();
-  }
-  next(...[_value]) {
-    const done = this.moveNext();
-    return { value: this.current, done };
-  }
-  return(_value) {
-    return DoneIteratorResult;
-  }
-  throw(_e) {
-    return DoneIteratorResult;
-  }
-};
-var HelperEnumerator = class _HelperEnumerator {
-  _enumerator;
-  _index = 0;
-  get current() {
-    return this._enumerator.current;
-  }
-  constructor(enumerator) {
-    this._enumerator = enumerator;
-  }
-  static toIterator(enumerator) {
-    return new this(enumerator);
-  }
-  [Symbol.iterator]() {
-    return this.toIterator();
-  }
-  toIterator() {
-    return _HelperEnumerator.toIterator(this);
-  }
-  moveNext() {
-    this._index += 1;
-    return this._enumerator.moveNext();
-  }
-  reset() {
-    this._enumerator.reset();
-  }
-  next(...[_value]) {
-    const done = this.moveNext();
-    return { value: this.current, done };
-  }
-  return(_value) {
-    return DoneIteratorResult;
-  }
-  throw(_e) {
-    return DoneIteratorResult;
-  }
-};
-var DropEnumerator = class extends HelperEnumerator {
-  _limit;
-  constructor(enumerator, limit) {
-    super(enumerator);
-    this._limit = limit;
-  }
-  moveNext() {
-    let next = super.moveNext();
-    while (this._limit > 0 && next) {
-      next = super.moveNext();
-      this._limit -= 1;
-    }
-    return next;
-  }
-};
-var FilterEnumerator = class extends HelperEnumerator {
-  _filter;
-  constructor(enumerator, filter) {
-    super(enumerator);
-    this._filter = filter;
-  }
-  moveNext() {
-    let next = super.moveNext();
-    while (next && !this._filter(this.current, this._index)) {
-      next = super.moveNext();
-    }
-    return next;
-  }
-};
-var FlatMapEnumerator = class {
-  _enumerator;
-  _flatMap;
-  _inner;
-  _index = -1;
-  constructor(enumerator, flatMap) {
-    this._enumerator = enumerator;
-    this._flatMap = flatMap;
-  }
-  get current() {
-    return this._inner?.current;
-  }
-  moveNext() {
-    if (this._inner && this._inner.moveNext()) {
-      return true;
-    }
-    const next = this._enumerator.moveNext();
-    if (!next) {
-      return false;
-    }
-    this._index += 1;
-    this._inner = this._flatMap(this._enumerator.current, this._index);
-    return this._inner.moveNext();
-  }
-  reset() {
-    this._index = -1;
-    this._inner = void 0;
-    this._enumerator.reset();
-  }
-  toIterator() {
-    return HelperEnumerator.toIterator(this);
-  }
-};
-var MapEnumerator = class {
-  _enumerator;
-  _map;
-  _current;
-  _index = -1;
-  get current() {
-    return this._current;
-  }
-  constructor(enumerator, map) {
-    this._enumerator = enumerator;
-    this._map = map;
-  }
-  toIterator() {
-    return HelperEnumerator.toIterator(this);
-  }
-  moveNext() {
-    this._index += 1;
-    const next = this._enumerator.moveNext();
-    if (next) {
-      this._current = this._map(this._enumerator.current, this._index);
-    }
-    return next;
-  }
-  reset() {
-    this._index = -1;
-    this._enumerator.reset();
-  }
-};
-var TakeEnumerator = class extends HelperEnumerator {
-  _limit;
-  constructor(enumerator, limit) {
-    super(enumerator);
-    this._limit = limit;
-  }
-  moveNext() {
-    if (this._limit < 0) {
-      return false;
-    } else {
-      super.moveNext();
-      this._limit -= 1;
-      return true;
-    }
-  }
-};
-var FusedEnumerator = class {
-  _enumerators;
-  _index = 0;
-  get current() {
-    return this._cur()?.current;
-  }
-  constructor(enumerators) {
-    this._enumerators = enumerators;
-  }
-  _cur() {
-    return this._enumerators[this._index];
-  }
-  _done() {
-    return this._index >= this._enumerators.length;
-  }
-  toIterator() {
-    return HelperEnumerator.toIterator(this);
-  }
-  moveNext() {
-    while (!this._done() && !this._cur().moveNext()) {
-      this._index += 1;
-    }
-    return this._done();
-  }
-  reset() {
-    const len = this._enumerators.length;
-    for (let i = 0; i < len; i++) {
-      this._enumerators[i].reset();
-    }
-    this._index = 0;
-  }
-};
-var Enumerable = class _Enumerable {
-  _enumerator;
-  constructor(enumerator) {
-    this._enumerator = enumerator;
-  }
-  static from(value) {
-    if (this.isEnumerable(value)) {
-      return value;
-    } else if (this.isEnumerator(value)) {
-      return new _Enumerable(value);
-    } else if (isIterable(value)) {
-      const enumerator = Enumerator.fromIterable(value);
-      if (isArrayLike(value)) {
-        return new ArrayEnumerble(enumerator);
-      } else {
-        return new _Enumerable(enumerator);
-      }
-    } else if (isIterator(value)) {
-      return new _Enumerable(
-        Enumerator.fromIterator(value)
-      );
-    } else {
-      throw new TypeError("value is not enumerable");
-    }
-  }
-  static isEnumerable(value) {
-    return typeof value["enumerator"] === "function";
-  }
-  static isEnumerator(value) {
-    return hasMethods(["moveNext", "reset", "toIterator"], value);
-  }
-  [Symbol.iterator]() {
-    return this._enumerator.toIterator();
-  }
-  at(index) {
-    while (index >= 0 && this._enumerator.moveNext()) {
-      index -= 1;
-    }
-    const value = this._enumerator.current;
-    this._enumerator.reset();
-    return value;
-  }
-  atOrDefault(index, defaultValue) {
-    const value = this.at(index);
-    return value || defaultValue;
-  }
-  atOrElse(index, defaultValue) {
-    const value = this.at(index);
-    return value || defaultValue();
-  }
-  concat(other) {
-    return new _Enumerable(
-      new FusedEnumerator([this._enumerator, other.enumerator()])
-    );
-  }
-  drop(limit) {
-    return new _Enumerable(new DropEnumerator(this._enumerator, limit));
-  }
-  enumerator() {
-    return this._enumerator;
-  }
-  //entries(): IEnumerator<T> {
-  //}
-  every(predicate) {
-    let index = 0;
-    while (this._enumerator.moveNext()) {
-      if (!predicate(this._enumerator.current, index)) {
-        return false;
-      }
-      index += 1;
-    }
-    this._enumerator.reset();
-    return true;
-  }
-  filter(predicate) {
-    return new _Enumerable(new FilterEnumerator(this._enumerator, predicate));
-  }
-  flatMap(fn) {
-    return new _Enumerable(new FlatMapEnumerator(this._enumerator, fn));
-  }
-  map(fn) {
-    return new _Enumerable(new MapEnumerator(this._enumerator, fn));
-  }
-  some(predicate) {
-    let index = 0;
-    while (this._enumerator.moveNext()) {
-      if (predicate(this._enumerator.current, index)) {
-        return true;
-      }
-      index += 1;
-    }
-    this._enumerator.reset();
-    return false;
-  }
-  take(limit) {
-    return new _Enumerable(new TakeEnumerator(this._enumerator, limit));
-  }
-};
-var ArrayEnumerble = class extends Enumerable {
-  at(index) {
-    if (this._enumerator instanceof ArrayEnumerator) {
-      this._enumerator.setIndex(index);
-      return this._enumerator.current;
-    } else {
-      return super.at(index);
-    }
-  }
-};
-export {
-  ArrayEnumerator,
-  ArrayEnumerble,
-  CachedIteratorEnumerator,
-  DropEnumerator,
-  Enumerable,
-  Enumerator,
-  FilterEnumerator,
-  FlatMapEnumerator,
-  FusedEnumerator,
-  HelperEnumerator,
-  IterableEnumerator,
-  IteratorEnumerator,
-  MapEnumerator,
-  TakeEnumerator,
-  isArrayLike,
-  isBuffer,
-  isIterable,
-  isIterator
-};
diff --git a/package-lock.json b/package-lock.json
index 83f32e8..f9f9aab 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,10 +9,22 @@
       "version": "1.0.0",
       "license": "ISC",
       "devDependencies": {
+        "@apeleghq/esbuild-plugin-closure-compiler": "^1.0.8",
         "esbuild": "^0.25.3",
         "folktest": "git+https://git.kitsu.cafe/rowan/folktest.git"
       }
     },
+    "node_modules/@apeleghq/esbuild-plugin-closure-compiler": {
+      "version": "1.0.8",
+      "resolved": "https://registry.npmjs.org/@apeleghq/esbuild-plugin-closure-compiler/-/esbuild-plugin-closure-compiler-1.0.8.tgz",
+      "integrity": "sha512-2J1hEXsH5FoQ1thKZW4gQrXvSP9FSNf7a4QoM2VaiuOX9zlP5IqAOHkpS20JOlHLvCp7XBjDlaOVe9YkX0t5fA==",
+      "dev": true,
+      "license": "Apache-2.0 WITH LLVM-exception",
+      "peerDependencies": {
+        "esbuild": "^0.17.0 || ^0.18.0 || ^0.19.0 || ^0.20.0 || ^0.21.0 || ^0.22.0|| ^0.23.0 || ^0.24.0 || ^0.25.0",
+        "google-closure-compiler": "*"
+      }
+    },
     "node_modules/@esbuild/aix-ppc64": {
       "version": "0.25.3",
       "resolved": "https://registry.npmjs.org/@esbuild/aix-ppc64/-/aix-ppc64-0.25.3.tgz",
@@ -438,6 +450,114 @@
         "node": ">=18"
       }
     },
+    "node_modules/ansi-styles": {
+      "version": "4.3.0",
+      "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.3.0.tgz",
+      "integrity": "sha512-zbB9rCJAT1rbjiVDb2hqKFHNYLxgtk8NURxZ3IZwD3F6NtxbXZQCnnSi1Lkx+IDohdPlFp222wVALIheZJQSEg==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "color-convert": "^2.0.1"
+      },
+      "engines": {
+        "node": ">=8"
+      },
+      "funding": {
+        "url": "https://github.com/chalk/ansi-styles?sponsor=1"
+      }
+    },
+    "node_modules/chalk": {
+      "version": "4.1.2",
+      "resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
+      "integrity": "sha512-oKnbhFyRIXpUuez8iBMmyEa4nbj4IOQyuhc/wy9kY7/WVPcwIO9VA668Pu8RkO7+0G76SLROeyw9CpQ061i4mA==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "ansi-styles": "^4.1.0",
+        "supports-color": "^7.1.0"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "url": "https://github.com/chalk/chalk?sponsor=1"
+      }
+    },
+    "node_modules/clone": {
+      "version": "2.1.2",
+      "resolved": "https://registry.npmjs.org/clone/-/clone-2.1.2.tgz",
+      "integrity": "sha512-3Pe/CF1Nn94hyhIYpjtiLhdCoEoz0DqQ+988E9gmeEdQZlojxnOb74wctFyuwWQHzqyf9X7C7MG8juUpqBJT8w==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "engines": {
+        "node": ">=0.8"
+      }
+    },
+    "node_modules/clone-buffer": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/clone-buffer/-/clone-buffer-1.0.0.tgz",
+      "integrity": "sha512-KLLTJWrvwIP+OPfMn0x2PheDEP20RPUcGXj/ERegTgdmPEZylALQldygiqrPPu8P45uNuPs7ckmReLY6v/iA5g==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "engines": {
+        "node": ">= 0.10"
+      }
+    },
+    "node_modules/clone-stats": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/clone-stats/-/clone-stats-1.0.0.tgz",
+      "integrity": "sha512-au6ydSpg6nsrigcZ4m8Bc9hxjeW+GJ8xh5G3BJCMt4WXe1H10UNaVOamqQTmrx1kjVuxAHIQSNU6hY4Nsn9/ag==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
+    "node_modules/cloneable-readable": {
+      "version": "1.1.3",
+      "resolved": "https://registry.npmjs.org/cloneable-readable/-/cloneable-readable-1.1.3.tgz",
+      "integrity": "sha512-2EF8zTQOxYq70Y4XKtorQupqF0m49MBz2/yf5Bj+MHjvpG3Hy7sImifnqD6UA+TKYxeSV+u6qqQPawN5UvnpKQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "inherits": "^2.0.1",
+        "process-nextick-args": "^2.0.0",
+        "readable-stream": "^2.3.5"
+      }
+    },
+    "node_modules/color-convert": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/color-convert/-/color-convert-2.0.1.tgz",
+      "integrity": "sha512-RRECPsj7iu/xb5oKYcsFHSppFNnsj/52OVTRKb4zP5onXwVF3zVmmToNcOfGC+CRDpfK/U584fMg38ZHCaElKQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "color-name": "~1.1.4"
+      },
+      "engines": {
+        "node": ">=7.0.0"
+      }
+    },
+    "node_modules/color-name": {
+      "version": "1.1.4",
+      "resolved": "https://registry.npmjs.org/color-name/-/color-name-1.1.4.tgz",
+      "integrity": "sha512-dOy+3AuW3a2wNbZHIuMZpTcgjGuLU/uBL/ubcZF9OXbDo8ff4O8yVp5Bf0efS8uEoYo5q4Fx7dY9OgQGXgAsQA==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
+    "node_modules/core-util-is": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.3.tgz",
+      "integrity": "sha512-ZQBvi1DcpJ4GDqanjucZ2Hj3wEO5pZDS89BWbkcrvdxksJorwUDDZamX9ldFkp9aw2lmBDLgkObEA4DWNJ9FYQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
     "node_modules/esbuild": {
       "version": "0.25.3",
       "resolved": "https://registry.npmjs.org/esbuild/-/esbuild-0.25.3.tgz",
@@ -481,9 +601,256 @@
     },
     "node_modules/folktest": {
       "version": "1.0.0",
-      "resolved": "git+https://git.kitsu.cafe/rowan/folktest.git#cbf48ff3b1334eb883f202a77a5bc89d24534520",
+      "resolved": "git+https://git.kitsu.cafe/rowan/folktest.git#3faea728ab7bb02614e2fb8237ce9c3f7142847e",
       "dev": true,
       "license": "GPL-3.0-or-later"
+    },
+    "node_modules/google-closure-compiler": {
+      "version": "20240317.0.0",
+      "resolved": "https://registry.npmjs.org/google-closure-compiler/-/google-closure-compiler-20240317.0.0.tgz",
+      "integrity": "sha512-PlC5aU2vwsypKbxyFNXOW4psDZfhDoOr2dCwuo8VcgQji+HVIgRi2lviO66x2SfTi0ilm3kI6rq/RSdOMFczcQ==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "peer": true,
+      "dependencies": {
+        "chalk": "4.x",
+        "google-closure-compiler-java": "^20240317.0.0",
+        "minimist": "1.x",
+        "vinyl": "2.x",
+        "vinyl-sourcemaps-apply": "^0.2.0"
+      },
+      "bin": {
+        "google-closure-compiler": "cli.js"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "optionalDependencies": {
+        "google-closure-compiler-linux": "^20240317.0.0",
+        "google-closure-compiler-osx": "^20240317.0.0",
+        "google-closure-compiler-windows": "^20240317.0.0"
+      }
+    },
+    "node_modules/google-closure-compiler-java": {
+      "version": "20240317.0.0",
+      "resolved": "https://registry.npmjs.org/google-closure-compiler-java/-/google-closure-compiler-java-20240317.0.0.tgz",
+      "integrity": "sha512-oWURPChjcCrVfiQOuVtpSoUJVvtOYo41JGEQ2qtArsTGmk/DpWh40vS6hitwKRM/0YzJX/jYUuyt9ibuXXJKmg==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "peer": true
+    },
+    "node_modules/google-closure-compiler-linux": {
+      "version": "20240317.0.0",
+      "resolved": "https://registry.npmjs.org/google-closure-compiler-linux/-/google-closure-compiler-linux-20240317.0.0.tgz",
+      "integrity": "sha512-dYLtcbbJdbbBS0lTy9SzySdVv/aGkpyTekQiW4ADhT/i1p1b4r0wQTKj6kpVVmFvbZ6t9tW/jbXc9EXXNUahZw==",
+      "cpu": [
+        "x32",
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "peer": true
+    },
+    "node_modules/google-closure-compiler-osx": {
+      "version": "20240317.0.0",
+      "resolved": "https://registry.npmjs.org/google-closure-compiler-osx/-/google-closure-compiler-osx-20240317.0.0.tgz",
+      "integrity": "sha512-0mABwjD4HP11rikFd8JRIb9OgPqn9h3o3wS0otufMfmbwS7zRpnnoJkunifhORl3VoR1gFm6vcTC9YziTEFdOw==",
+      "cpu": [
+        "x32",
+        "x64",
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "peer": true
+    },
+    "node_modules/google-closure-compiler-windows": {
+      "version": "20240317.0.0",
+      "resolved": "https://registry.npmjs.org/google-closure-compiler-windows/-/google-closure-compiler-windows-20240317.0.0.tgz",
+      "integrity": "sha512-fTueVFzNOWURFlXZmrFkAB7yA+jzpA2TeDOYeBEFwVlVGHwi8PV3Q9vCIWlbkE8wLpukKEg5wfRHYrLwVPINCA==",
+      "cpu": [
+        "x32",
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "win32"
+      ],
+      "peer": true
+    },
+    "node_modules/has-flag": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-4.0.0.tgz",
+      "integrity": "sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "engines": {
+        "node": ">=8"
+      }
+    },
+    "node_modules/inherits": {
+      "version": "2.0.4",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
+      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
+      "dev": true,
+      "license": "ISC",
+      "peer": true
+    },
+    "node_modules/isarray": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/isarray/-/isarray-1.0.0.tgz",
+      "integrity": "sha512-VLghIWNM6ELQzo7zwmcg0NmTVyWKYjvIeM83yjp0wRDTmUnrM678fQbcKBo6n2CJEF0szoG//ytg+TKla89ALQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
+    "node_modules/minimist": {
+      "version": "1.2.8",
+      "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.8.tgz",
+      "integrity": "sha512-2yyAR8qBkN3YuheJanUpWC5U3bb5osDywNB8RzDVlDwDHbocAJveqqj1u8+SVD7jkWT4yvsHCpWqqWqAxb0zCA==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "funding": {
+        "url": "https://github.com/sponsors/ljharb"
+      }
+    },
+    "node_modules/process-nextick-args": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.1.tgz",
+      "integrity": "sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
+    "node_modules/readable-stream": {
+      "version": "2.3.8",
+      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.8.tgz",
+      "integrity": "sha512-8p0AUk4XODgIewSi0l8Epjs+EVnWiK7NoDIEGU0HhE7+ZyY8D1IMY7odu5lRrFXGg71L15KG8QrPmum45RTtdA==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "core-util-is": "~1.0.0",
+        "inherits": "~2.0.3",
+        "isarray": "~1.0.0",
+        "process-nextick-args": "~2.0.0",
+        "safe-buffer": "~5.1.1",
+        "string_decoder": "~1.1.1",
+        "util-deprecate": "~1.0.1"
+      }
+    },
+    "node_modules/remove-trailing-separator": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/remove-trailing-separator/-/remove-trailing-separator-1.1.0.tgz",
+      "integrity": "sha512-/hS+Y0u3aOfIETiaiirUFwDBDzmXPvO+jAfKTitUngIPzdKc6Z0LoFjM/CK5PL4C+eKwHohlHAb6H0VFfmmUsw==",
+      "dev": true,
+      "license": "ISC",
+      "peer": true
+    },
+    "node_modules/replace-ext": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/replace-ext/-/replace-ext-1.0.1.tgz",
+      "integrity": "sha512-yD5BHCe7quCgBph4rMQ+0KkIRKwWCrHDOX1p1Gp6HwjPM5kVoCdKGNhN7ydqqsX6lJEnQDKZ/tFMiEdQ1dvPEw==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "engines": {
+        "node": ">= 0.10"
+      }
+    },
+    "node_modules/safe-buffer": {
+      "version": "5.1.2",
+      "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
+      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
+    "node_modules/source-map": {
+      "version": "0.5.7",
+      "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.5.7.tgz",
+      "integrity": "sha512-LbrmJOMUSdEVxIKvdcJzQC+nQhe8FUZQTXQy6+I75skNgn3OoQ0DZA8YnFa7gp8tqtL3KPf1kmo0R5DoApeSGQ==",
+      "dev": true,
+      "license": "BSD-3-Clause",
+      "peer": true,
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
+    "node_modules/string_decoder": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
+      "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "safe-buffer": "~5.1.0"
+      }
+    },
+    "node_modules/supports-color": {
+      "version": "7.2.0",
+      "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",
+      "integrity": "sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "has-flag": "^4.0.0"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
+    "node_modules/util-deprecate": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
+      "integrity": "sha512-EPD5q1uXyFxJpCrLnCc1nHnq3gOa6DZBocAIiI2TaSCA7VCJ1UJDMagCzIkXNsUYfD1daK//LTEQ8xiIbrHtcw==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
+    "node_modules/vinyl": {
+      "version": "2.2.1",
+      "resolved": "https://registry.npmjs.org/vinyl/-/vinyl-2.2.1.tgz",
+      "integrity": "sha512-LII3bXRFBZLlezoG5FfZVcXflZgWP/4dCwKtxd5ky9+LOtM4CS3bIRQsmR1KMnMW07jpE8fqR2lcxPZ+8sJIcw==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "clone": "^2.1.1",
+        "clone-buffer": "^1.0.0",
+        "clone-stats": "^1.0.0",
+        "cloneable-readable": "^1.0.0",
+        "remove-trailing-separator": "^1.0.1",
+        "replace-ext": "^1.0.0"
+      },
+      "engines": {
+        "node": ">= 0.10"
+      }
+    },
+    "node_modules/vinyl-sourcemaps-apply": {
+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/vinyl-sourcemaps-apply/-/vinyl-sourcemaps-apply-0.2.1.tgz",
+      "integrity": "sha512-+oDh3KYZBoZC8hfocrbrxbLUeaYtQK7J5WU5Br9VqWqmCll3tFJqKp97GC9GmMsVIL0qnx2DgEDVxdo5EZ5sSw==",
+      "dev": true,
+      "license": "ISC",
+      "peer": true,
+      "dependencies": {
+        "source-map": "^0.5.1"
+      }
     }
   }
 }
diff --git a/package.json b/package.json
index 6f7cd4b..856a9c8 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "description": "",
   "main": "index.js",
   "scripts": {
-    "build": "esbuild src/index.ts --bundle --platform=node --format=esm --outfile=./dist/index.js",
+    "build": "node build.js",
     "test": "./test/index.js"
   },
   "keywords": [],
@@ -12,6 +12,7 @@
   "license": "ISC",
   "type": "module",
   "devDependencies": {
+    "@apeleghq/esbuild-plugin-closure-compiler": "^1.0.8",
     "esbuild": "^0.25.3",
     "folktest": "git+https://git.kitsu.cafe/rowan/folktest.git"
   }
diff --git a/test/unit/common.js b/test/unit/common.js
new file mode 100644
index 0000000..125ae66
--- /dev/null
+++ b/test/unit/common.js
@@ -0,0 +1,36 @@
+import { Enumerable } from '../../dist/index.esm.min.js'
+
+export const createIterator = (arr = []) => {
+  let index = 0
+  return {
+    next() {
+      return index < arr.length ? {
+        value: arr[index++],
+        done: false
+      } : { done: true }
+    }
+  }
+}
+
+export const createIterable = arr => ({
+  [Symbol.iterator]() {
+    return createIterator(arr)
+  }
+})
+
+export const createEnumerator = (arr = []) => {
+  let index = -1
+  return {
+    get current() { return arr[index] },
+    moveNext() {
+      index += 1
+      return index < arr.length
+    },
+    reset() {
+      index = -1
+    }
+  }
+}
+
+export const createEnumerable = arr => new Enumerable(createEnumerator(arr))
+
diff --git a/test/unit/enumerable.js b/test/unit/enumerable.js
index 7727cd7..51b2e26 100644
--- a/test/unit/enumerable.js
+++ b/test/unit/enumerable.js
@@ -1,27 +1,7 @@
 import { it, assert, assertEq, assertErr } from 'folktest'
-import { ArrayEnumerator, CachedIteratorEnumerator, DropEnumerator, Enumerable, Enumerator, FilterEnumerator, FlatMapEnumerator, FusedEnumerator, IterableEnumerator, IteratorEnumerator, MapEnumerator, TakeEnumerator } from '../../dist/index.js'
+import { createIterator, createIterable, createEnumerator, createEnumerable } from './common.js'
+import { ArrayEnumerator, CachedIteratorEnumerator, DropEnumerator, Enumerable, Enumerator, FilterEnumerator, FlatMapEnumerator, FusedEnumerator, IterableEnumerator, IteratorEnumerator, MapEnumerator, TakeEnumerator } from '../../dist/index.esm.min.js'
 
-const createIterator = (arr = []) => {
-  let index = 0
-  return {
-    next() {
-      return index < arr.length ? {
-        value: arr[index++],
-        done: false
-      } : { done: true }
-    }
-  }
-}
-
-const createIterable = arr => ({
-  [Symbol.iterator]() {
-    return createIterator(arr)
-  }
-})
-
-const createEnumerator = arr => Enumerator.fromIterable(createIterable(arr))
-
-const createEnumerable = arr => Enumerable.from(createIterator(arr))
 
 const helpers = {
   concat: {
@@ -190,68 +170,3 @@ export const EnumerableMethod = [
   })
 ]
 
-export const EnumerableHelpers = [
-  it('FusedEnumerator', () => {
-    const expected = [1, 2, 3, 10, 20, 30]
-    const e1 = createEnumerator([1, 2, 3])
-    const e2 = createEnumerator([10, 20, 30])
-    const fe = new FusedEnumerator([e1, e2])
-    expected.forEach(n => {
-      fe.moveNext()
-      assertEq(fe.current, n)
-    })
-  }),
-
-  it('DropEnumerator', () => {
-    const expected = [4, 5, 6]
-    const e = new DropEnumerator(createEnumerator([1, 2, 3, 4, 5, 6]), 3)
-    expected.forEach(n => {
-      e.moveNext()
-      assertEq(e.current, n)
-    })
-  }),
-
-  it('FilterEnumerator', () => {
-    const expected = [1, 3, 5]
-    const e = new FilterEnumerator(createEnumerator([1, 2, 3, 4, 5, 6]), x => x % 2 !== 0)
-    expected.forEach(n => {
-      e.moveNext()
-      assertEq(e.current, n)
-    })
-  }),
-
-  it('FlatMapEnumerator', () => {
-    const expected = [1, 2, 2, 3, 3, 3]
-    const e = new FlatMapEnumerator(
-      createEnumerator([1, 2, 3]),
-      n => {
-        const arr = Array.from({ length: n }).fill(n)
-        return createEnumerator(arr)
-      }
-    )
-
-    expected.forEach(n => {
-      e.moveNext()
-      assertEq(e.current, n)
-    })
-  }),
-
-  it('MapEnumerator', () => {
-    const expected = [1, 4, 9]
-    const e = new MapEnumerator(createEnumerator([1, 2, 3]), n => n * n)
-    expected.forEach(n => {
-      e.moveNext()
-      assertEq(e.current, n)
-    })
-  }),
-
-  it('TakeEnumerator', () => {
-    const expected = [1, 2, 3]
-    const e = new TakeEnumerator(createEnumerator([1, 2, 3, 4, 5, 6]), 3)
-    expected.forEach(n => {
-      e.moveNext()
-      assertEq(e.current, n)
-    })
-  })
-]
-
diff --git a/test/unit/enumerator.js b/test/unit/enumerator.js
new file mode 100644
index 0000000..25f2804
--- /dev/null
+++ b/test/unit/enumerator.js
@@ -0,0 +1,86 @@
+import { assert, assertEq, it } from 'folktest'
+import { createIterator, createIterable, createEnumerator, createEnumerable } from './common.js'
+import { CachedIteratorEnumerator, DropEnumerator, Enumerator, FilterEnumerator, FlatMapEnumerator, FusedEnumerator, IterableEnumerator, IteratorEnumerator, MapEnumerator, TakeEnumerator } from '../../dist/index.esm.min.js'
+
+export const EnumeratorFrom = [
+  it('from iterator', () => {
+    const iterator = createIterator()
+    const enumerator1 = Enumerator.fromIterator(iterator)
+    assert(enumerator1 instanceof CachedIteratorEnumerator)
+
+    const enumerator2 = Enumerator.fromIterator(iterator, false)
+    assert(enumerator2 instanceof IteratorEnumerator)
+  }),
+
+  it('from iterable', () => {
+    const iterable = createIterable()
+    const enumerator = Enumerator.fromIterable(iterable)._enumerator
+    assert(enumerator instanceof IterableEnumerator, `${enumerator.constructor.name} is not instance of 'IterableEnumerator'`)
+  })
+]
+
+export const HelperEnumerator = [
+  it('FusedEnumerator', () => {
+    const expected = [1, 2, 3, 10, 20, 30]
+    const e1 = createEnumerator([1, 2, 3])
+    const e2 = createEnumerator([10, 20, 30])
+    const fe = new FusedEnumerator([e1, e2])
+    expected.forEach(n => {
+      fe.moveNext()
+      assertEq(fe.current, n)
+    })
+  }),
+
+  it('DropEnumerator', () => {
+    const expected = [4, 5, 6]
+    const e = new DropEnumerator(createEnumerator([1, 2, 3, 4, 5, 6]), 3)
+    expected.forEach(n => {
+      e.moveNext()
+      assertEq(e.current, n)
+    })
+  }),
+
+  it('FilterEnumerator', () => {
+    const expected = [1, 3, 5]
+    const e = new FilterEnumerator(createEnumerator([1, 2, 3, 4, 5, 6]), x => x % 2 !== 0)
+    expected.forEach(n => {
+      e.moveNext()
+      assertEq(e.current, n)
+    })
+  }),
+
+  it('FlatMapEnumerator', () => {
+    const expected = [1, 2, 2, 3, 3, 3]
+    const e = new FlatMapEnumerator(
+      createEnumerator([1, 2, 3]),
+      n => {
+        const arr = Array.from({ length: n }).fill(n)
+        return createEnumerator(arr)
+      }
+    )
+
+    expected.forEach(n => {
+      e.moveNext()
+      assertEq(e.current, n)
+    })
+  }),
+
+  it('MapEnumerator', () => {
+    const expected = [1, 4, 9]
+    const e = new MapEnumerator(createEnumerator([1, 2, 3]), n => n * n)
+    expected.forEach(n => {
+      e.moveNext()
+      assertEq(e.current, n)
+    })
+  }),
+
+  it('TakeEnumerator', () => {
+    const expected = [1, 2, 3]
+    const e = new TakeEnumerator(createEnumerator([1, 2, 3, 4, 5, 6]), 3)
+    expected.forEach(n => {
+      e.moveNext()
+      assertEq(e.current, n)
+    })
+  })
+]
+
diff --git a/test/unit/index.js b/test/unit/index.js
index ea657d2..cb92d43 100644
--- a/test/unit/index.js
+++ b/test/unit/index.js
@@ -1,2 +1,3 @@
 export * from './enumerable.js'
+export * from './enumerator.js'