harmonize sync and async implementations

src/async.ts

@@ -1,4 +1,4 @@
-import { Accumulator, Action, BiConverter, Comparer, Converter, Enumerable, Equater, Predicate, wrap as wrapSync } from "./sync.js";
+import { Accumulator, Action, BiConverter, Comparer, Converter, Enumerable, Equater, Predicate } from "./sync.js";
 import { AsyncFunction, MaybeAsyncFunction, MaybePromise, asAsyncGenerator, combineAsyncComparers, defaultArrayComparer, identity, isAsyncIterable, operatorCompare, strictEquals } from "./utils.js";
 import { createQueue } from "./queue.js";
 import { selectionSorter } from "./sorting.js";
@@ -33,11 +33,12 @@ export type MaybeAsyncEquater<T> = MaybeAsyncFunction<Equater<T>>;
 export interface AsyncEnumerable<TElement> extends AsyncIterable<TElement> {
   iterator(): AsyncIterator<TElement>;
 
-  apply<TResult>(pipeline: (enumerable: this) => TResult): TResult;
+  apply<TResult>(pipeline: (enumerable: AsyncEnumerable<TElement>) => TResult): TResult;
 
   count(predicate?: MaybeAsyncPredicate<TElement>): Promise<number>;
   nonEnumeratedCount(): Promise<number>;
   fastCount(): Promise<number>;
+  maxCount(): Promise<number>;
 
   select<TResult>(selector: MaybeAsyncConverter<TElement, TResult>): AsyncEnumerable<TResult>;
   selectMany<TResult>(selector: MaybeAsyncConverter<TElement, MaybeAsyncIterable<TResult>>): AsyncEnumerable<TResult>;
@@ -55,7 +56,7 @@ export interface AsyncEnumerable<TElement> extends AsyncIterable<TElement> {
 
   contains(obj: TElement, equater?: MaybeAsyncEquater<TElement>): Promise<boolean>;
 
-  sequenceEqual(iterable: MaybeAsyncIterable<TElement>, equater?: MaybeAsyncEquater<TElement>): Promise<boolean>;
+  sequenceEquals(iterable: MaybeAsyncIterable<TElement>, equater?: MaybeAsyncEquater<TElement>): Promise<boolean>;
 
   append(obj: TElement): AsyncEnumerable<TElement>;
 
@@ -108,6 +109,8 @@ export interface AsyncEnumerable<TElement> extends AsyncIterable<TElement> {
   all(predicate: MaybeAsyncPredicate<TElement>): Promise<boolean>;
   any(predicate: MaybeAsyncPredicate<TElement>): Promise<boolean>;
   any(): Promise<boolean>;
+  none(predicate: Predicate<TElement>): Promise<boolean>;
+  none(): Promise<boolean>;
 
   skip(n: number): AsyncEnumerable<TElement>;
   skipLast(n: number): AsyncEnumerable<TElement>;
@@ -123,18 +126,21 @@ export interface AsyncEnumerable<TElement> extends AsyncIterable<TElement> {
 
   zip<TOther>(iterable: MaybeAsyncIterable<TOther>): AsyncEnumerable<[TElement, TOther]>;
 
-  index(): AsyncEnumerable<[number, TElement]>;
+  indexex(): AsyncEnumerable<[number, TElement]>;
 
-  reverse(): AsyncEnumerable<TElement>;
+  reversed(): AsyncEnumerable<TElement>;
 
-  chunk(size: number): AsyncEnumerable<TElement[]>;
+  chunked(size: number): AsyncEnumerable<TElement[]>;
 
-  cache(): AsyncEnumerable<TElement>;
+  // random(options?: RandomOptions<TElement>): TElement | undefined;
 
+  cached(): AsyncEnumerable<TElement>;
+
+  asArray(): Promise<TElement[]>;
   toArray(): Promise<TElement[]>;
   toMap<TKey, TValue>(keySelector: MaybeAsyncConverter<TElement, TKey>, valueSelector: MaybeAsyncConverter<TElement, TValue>): Promise<Map<TKey, TValue>>;
   toSet(): Promise<Set<TElement>>;
-  toObject<TValue>(keySelector: MaybeAsyncConverter<TElement, PropertyKey>, valueSelector: MaybeAsyncConverter<TElement, TValue>): Promise<Record<PropertyKey, TValue>>;
+  toObject<TKey extends PropertyKey, TValue>(keySelector: MaybeAsyncConverter<TElement, TKey>, valueSelector: MaybeAsyncConverter<TElement, TValue>): Promise<Record<TKey, TValue>>;
 
   collect<TResult>(collector: Collector<TElement, any, TResult>): Promise<TResult>;
 }
@@ -159,6 +165,7 @@ export interface OrderedAsyncEnumerable<TElement> extends AsyncEnumerable<TEleme
 
 //#region wrappers
 
+export namespace AsyncEnumerable {
   export function asAsync<T>(enumerable: Enumerable<T>): AsyncEnumerable<T> {
     return new WrappedEnumerable(enumerable);
   }
@@ -172,7 +179,7 @@ export function wrap<T>(iterable: MaybeAsyncIterable<T>): AsyncEnumerable<T> {
       return sequence(iterable);
     }
 
-  return asAsync(wrapSync(iterable));
+    return asAsync(Enumerable.wrap(iterable));
   }
 
   export function sequence<T>(iterable: AsyncIterable<T>): AsyncEnumerable<T> {
@@ -250,25 +257,8 @@ export function repeat<T>(value: T, count?: number): AsyncEnumerable<T> {
     return new RepeatAsyncEnumerable(value, count);
   }
 
-export namespace sum {
-  export async function number(iterable: AsyncIterable<number>) {
-    let result = 0;
-
-    for await (const n of iterable) {
-      result += n;
-    }
-
-    return result;
-  }
-
-  export async function bigint(iterable: AsyncIterable<bigint>) {
-    let result = 0n;
-
-    for await (const n of iterable) {
-      result += n;
-    }
-
-    return result;
+  export function isAsyncEnumerable<T = any>(obj: any): obj is Enumerable<T> {
+    return obj instanceof AsyncEnumerableMarker;
   }
 }
 
@@ -276,14 +266,18 @@ export namespace sum {
 
 //#region implementations
 
-export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<TElement> {
+class AsyncEnumerableMarker {
+
+}
+
+export abstract class BaseAsyncEnumerable<TElement> extends AsyncEnumerableMarker implements AsyncEnumerable<TElement> {
   [Symbol.asyncIterator]() {
     return this.iterator();
   }
 
   abstract iterator(): AsyncIterator<TElement>;
 
-  apply<TResult>(pipeline: (enumerable: this) => TResult) {
+  apply<TResult>(pipeline: (enumerable: AsyncEnumerable<TElement>) => TResult): TResult {
     return pipeline(this);
   }
 
@@ -304,11 +298,11 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
   }
 
   join<TOther, TKey, TResult>(iterable: MaybeAsyncIterable<TOther>, firstKeySelector: MaybeAsyncConverter<TElement, TKey>, secondKeySelector: MaybeAsyncConverter<TOther, TKey>, resultSelector?: MaybeAsyncBiConverter<TElement, TOther, TResult>, keyComparer?: MaybeAsyncEquater<TKey>): AsyncEnumerable<TResult> {
-    return new JoinAsyncEnumerable<TElement, TOther, TKey, TResult>(this, wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
+    return new JoinAsyncEnumerable<TElement, TOther, TKey, TResult>(this, AsyncEnumerable.wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
   }
 
   groupJoin<TOther, TKey, TResult>(iterable: MaybeAsyncIterable<TOther>, firstKeySelector: MaybeAsyncConverter<TElement, TKey>, secondKeySelector: MaybeAsyncConverter<TOther, TKey>, resultSelector?: MaybeAsyncBiConverter<TElement, AsyncEnumerable<TOther>, TResult>, keyComparer?: MaybeAsyncEquater<TKey>): AsyncEnumerable<TResult> {
-    return new GroupJoinAsyncEnumerable<TElement, TOther, TKey, TResult>(this, wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
+    return new GroupJoinAsyncEnumerable<TElement, TOther, TKey, TResult>(this, AsyncEnumerable.wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
   }
 
   async contains(obj: TElement, equater?: MaybeAsyncEquater<TElement>) {
@@ -325,12 +319,12 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
     return false;
   }
 
-  async sequenceEqual(iterable: MaybeAsyncIterable<TElement>, equater?: MaybeAsyncEquater<TElement>) {
+  async sequenceEquals(iterable: MaybeAsyncIterable<TElement>, equater?: MaybeAsyncEquater<TElement>) {
     if (this === iterable) {
       return true;
     }
 
-    const that = wrap(iterable);
+    const that = AsyncEnumerable.wrap(iterable);
 
     const thisCount = await this.nonEnumeratedCount();
     const thatCount = await that.nonEnumeratedCount();
@@ -351,7 +345,7 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
       const thatNext = await thatIterator.next();
 
       if (thisNext.done) {
-        return thatNext.done === true; // no undefined!
+        return thatNext.done === true;
       }
 
       if (thatNext.done) {
@@ -384,7 +378,7 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
     const arr: AsyncEnumerable<TElement>[] = [this];
 
     for (const iterable of iterables) {
-      arr.push(wrap(iterable));
+      arr.push(AsyncEnumerable.wrap(iterable));
     }
 
     return new ConcatAsyncEnumerable(arr);
@@ -419,6 +413,11 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
     return n >= 0 ? n : await this.count();
   }
 
+  async maxCount() {
+    const n = await this.nonEnumeratedCount();
+    return n >= 0 ? n : Infinity;
+  }
+
   async #tryGetFirst(predicate?: MaybeAsyncPredicate<TElement>) {
     if (predicate) {
       for await (const element of this) {
@@ -723,27 +722,27 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
   }
 
   union(iterable: MaybeAsyncIterable<TElement>, equater?: MaybeAsyncEquater<TElement>): AsyncEnumerable<TElement> {
-    return new UnionAsyncEnumerable<TElement>(this, wrap(iterable), equater);
+    return new UnionAsyncEnumerable<TElement>(this, AsyncEnumerable.wrap(iterable), equater);
   }
 
   unionBy<TBy>(iterable: MaybeAsyncIterable<TElement>, selector: MaybeAsyncConverter<TElement, TBy>, equater?: MaybeAsyncEquater<TBy>): AsyncEnumerable<TElement> {
-    return new UnionByAsyncEnumerable<TElement, TBy>(this, wrap(iterable), selector, equater);
+    return new UnionByAsyncEnumerable<TElement, TBy>(this, AsyncEnumerable.wrap(iterable), selector, equater);
   }
 
   except(iterable: MaybeAsyncIterable<TElement>): AsyncEnumerable<TElement> {
-    return new ExceptAsyncEnumerable<TElement>(this, wrap(iterable));
+    return new ExceptAsyncEnumerable<TElement>(this, AsyncEnumerable.wrap(iterable));
   }
 
   exceptBy<TBy>(iterable: MaybeAsyncIterable<TElement>, selector: MaybeAsyncConverter<TElement, TBy>): AsyncEnumerable<TElement> {
-    return new ExceptByAsyncEnumerable<TElement, TBy>(this, wrap(iterable), selector);
+    return new ExceptByAsyncEnumerable<TElement, TBy>(this, AsyncEnumerable.wrap(iterable), selector);
   }
 
   intersect(iterable: MaybeAsyncIterable<TElement>): AsyncEnumerable<TElement> {
-    return new IntersectAsyncEnumerable<TElement>(this, wrap(iterable));
+    return new IntersectAsyncEnumerable<TElement>(this, AsyncEnumerable.wrap(iterable));
   }
 
   intersectBy<TBy>(iterable: MaybeAsyncIterable<TElement>, selector: MaybeAsyncConverter<TElement, TBy>): AsyncEnumerable<TElement> {
-    return new IntersectByAsyncEnumerable<TElement, TBy>(this, wrap(iterable), selector);
+    return new IntersectByAsyncEnumerable<TElement, TBy>(this, AsyncEnumerable.wrap(iterable), selector);
   }
 
   async all(predicate: MaybeAsyncPredicate<TElement>) {
@@ -782,6 +781,26 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
     return n < 0 ? !(await this.iterator().next()).done : n > 0;
   }
 
+  async none(predicate?: MaybeAsyncPredicate<TElement>) {
+    const n = await this.nonEnumeratedCount();
+
+    if (n === 0) {
+      return true;
+    }
+
+    if (predicate) {
+      for await (const element of this) {
+        if (predicate(element)) {
+          return false;
+        }
+      }
+
+      return true;
+    }
+
+    return n < 0 && (await this.iterator().next()).done === true;
+  }
+
   skip(n: number): AsyncEnumerable<TElement> {
     if (n < 0) {
       throw new Error("Cannot skip a negative number of elements.");
@@ -807,7 +826,7 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
       throw new Error("Cannot take a negative number of elements.");
     }
 
-    return n === 0 ? empty<TElement>() : new TakeAsyncEnumerable<TElement>(this, n);
+    return n === 0 ? AsyncEnumerable.empty<TElement>() : new TakeAsyncEnumerable<TElement>(this, n);
   }
 
   takeLast(n: number): AsyncEnumerable<TElement> {
@@ -815,7 +834,7 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
       throw new Error("Cannot take a negative number of elements.");
     }
 
-    return n === 0 ? empty<TElement>() : new TakeLastAsyncEnumerable<TElement>(this, n);
+    return n === 0 ? AsyncEnumerable.empty<TElement>() : new TakeLastAsyncEnumerable<TElement>(this, n);
   }
 
   takeWhile(predicate: MaybeAsyncPredicate<TElement>): AsyncEnumerable<TElement> {
@@ -833,18 +852,18 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
   }
 
   zip<TOther>(iterable: MaybeAsyncIterable<TOther>): AsyncEnumerable<[TElement, TOther]> {
-    return new ZippedAsyncEnumerable<TElement, TOther>(this, wrap(iterable));
+    return new ZippedAsyncEnumerable<TElement, TOther>(this, AsyncEnumerable.wrap(iterable));
   }
 
-  index(): AsyncEnumerable<[number, TElement]> {
+  indexex(): AsyncEnumerable<[number, TElement]> {
     return new IndexedAsyncEnumerable<TElement>(this);
   }
 
-  reverse(): AsyncEnumerable<TElement> {
+  reversed(): AsyncEnumerable<TElement> {
     return new ReversedAsyncEnumerable<TElement>(this);
   }
 
-  chunk(size: number): AsyncEnumerable<TElement[]> {
+  chunked(size: number): AsyncEnumerable<TElement[]> {
     if (size <= 0) {
       throw new Error("Chunk size must be positive.");
     }
@@ -852,10 +871,14 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
     return new ChunkedAsyncEnumerable<TElement>(this, size);
   }
 
-  cache(): AsyncEnumerable<TElement> {
+  cached(): AsyncEnumerable<TElement> {
     return new CacheAsyncEnumerable<TElement>(this);
   }
 
+  async asArray() {
+    return await this.toArray();
+  }
+
   async toArray() {
     const array: TElement[] = [];
 
@@ -913,28 +936,313 @@ export abstract class BaseAsyncEnumerable<TElement> implements AsyncEnumerable<T
   }
 }
 
-class GroupedAsyncEnumerableImpl<TElement, TKey> extends BaseAsyncEnumerable<TElement> implements GroupedAsyncEnumerable<TKey, TElement> {
-  readonly #key: TKey;
-  readonly #grouping: AsyncEnumerable<TElement>;
+class DelegatedAsyncEnumerable<TElement> extends AsyncEnumerableMarker implements AsyncEnumerable<TElement> {
+  #enumerable: AsyncEnumerable<TElement>;
 
-  constructor(key: TKey, grouping: AsyncEnumerable<TElement>) {
+  constructor(enumerable: AsyncEnumerable<TElement>) {
     super();
 
+    this.#enumerable = enumerable;
+  }
+
+  get enumerable() {
+    return this.#enumerable;
+  }
+
+  protected set enumerable(value: AsyncEnumerable<TElement>) {
+    this.#enumerable = value;
+  }
+
+  [Symbol.asyncIterator]() {
+    return this.iterator();
+  }
+
+  iterator() {
+    return this.#enumerable.iterator();
+  }
+
+  apply<TResult>(pipeline: (enumerable: AsyncEnumerable<TElement>) => TResult) {
+    return this.#enumerable.apply(pipeline);
+  }
+
+  count(predicate?: ((obj: TElement) => MaybePromise<boolean>) | undefined): Promise<number> {
+    return this.#enumerable.count(predicate);
+  }
+
+  nonEnumeratedCount(): Promise<number> {
+    return this.#enumerable.nonEnumeratedCount();
+  }
+
+  fastCount(): Promise<number> {
+    return this.#enumerable.fastCount();
+  }
+
+  maxCount(): Promise<number> {
+    return this.#enumerable.maxCount();
+  }
+
+  select<TResult>(selector: (obj: TElement) => MaybePromise<TResult>): AsyncEnumerable<TResult> {
+    return this.#enumerable.select(selector);
+  }
+
+  selectMany<TResult>(selector: (obj: TElement) => MaybePromise<MaybeAsyncIterable<TResult>>): AsyncEnumerable<TResult> {
+    return this.#enumerable.selectMany(selector);
+  }
+
+  where(predicate: (obj: TElement) => MaybePromise<boolean>): AsyncEnumerable<TElement> {
+    return this.#enumerable.where(predicate);
+  }
+
+  groupBy<TKey>(keySelector: (obj: TElement) => MaybePromise<TKey>, elementSelector?: undefined, keyComparer?: ((first: TKey, second: TKey) => MaybePromise<boolean>) | undefined): AsyncEnumerable<GroupedAsyncEnumerable<TKey, TElement>>;
+  groupBy<TKey, TResult>(keySelector: (obj: TElement) => MaybePromise<TKey>, elementSelector: (obj: TElement) => MaybePromise<TResult>, keyComparer?: ((first: TKey, second: TKey) => MaybePromise<boolean>) | undefined): AsyncEnumerable<GroupedAsyncEnumerable<TKey, TResult>>;
+  groupBy(keySelector: any, elementSelector?: any, keyComparer?: any) {
+    return this.#enumerable.groupBy(keySelector, elementSelector, keyComparer);
+  }
+
+  join<TOther, TKey>(iterable: MaybeAsyncIterable<TOther>, firstKeySelector: (obj: TElement) => MaybePromise<TKey>, secondKeySelector: (obj: TOther) => MaybePromise<TKey>, resultSelector?: undefined, keyComparer?: ((first: TKey, second: TKey) => MaybePromise<boolean>) | undefined): AsyncEnumerable<[TElement, TOther]>;
+  join<TOther, TKey, TResult>(iterable: MaybeAsyncIterable<TOther>, firstKeySelector: (obj: TElement) => MaybePromise<TKey>, secondKeySelector: (obj: TOther) => MaybePromise<TKey>, resultSelector: (first: TElement, second: TOther) => MaybePromise<TResult>, keyComparer?: ((first: TKey, second: TKey) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TResult>;
+  join(iterable: any, firstKeySelector: any, secondKeySelector: any, resultSelector?: any, keyComparer?: any) {
+    return this.#enumerable.join(iterable, firstKeySelector, secondKeySelector, resultSelector, keyComparer);
+  }
+
+  groupJoin<TOther, TKey>(iterable: MaybeAsyncIterable<TOther>, firstKeySelector: (obj: TElement) => MaybePromise<TKey>, secondKeySelector: (obj: TOther) => MaybePromise<TKey>, resultSelector?: undefined, keyComparer?: ((first: TKey, second: TKey) => MaybePromise<boolean>) | undefined): AsyncEnumerable<GroupedAsyncEnumerable<TElement, TOther>>;
+  groupJoin<TOther, TKey, TResult>(iterable: MaybeAsyncIterable<TOther>, firstKeySelector: (obj: TElement) => MaybePromise<TKey>, secondKeySelector: (obj: TOther) => MaybePromise<TKey>, resultSelector: (first: TElement, second: AsyncEnumerable<TOther>) => MaybePromise<TResult>, keyComparer?: ((first: TKey, second: TKey) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TResult>;
+  groupJoin(iterable: any, firstKeySelector: any, secondKeySelector: any, resultSelector?: any, keyComparer?: any) {
+    return this.#enumerable.groupJoin(iterable, firstKeySelector, secondKeySelector, resultSelector, keyComparer);
+  }
+
+  contains(obj: TElement, equater?: ((first: TElement, second: TElement) => MaybePromise<boolean>) | undefined): Promise<boolean> {
+    return this.#enumerable.contains(obj, equater);
+  }
+
+  sequenceEquals(iterable: MaybeAsyncIterable<TElement>, equater?: ((first: TElement, second: TElement) => MaybePromise<boolean>) | undefined): Promise<boolean> {
+    return this.#enumerable.sequenceEquals(iterable, equater);
+  }
+
+  append(obj: TElement): AsyncEnumerable<TElement> {
+    return this.#enumerable.append(obj);
+  }
+
+  prepend(obj: TElement): AsyncEnumerable<TElement> {
+    return this.#enumerable.prepend(obj);
+  }
+
+  remove(obj: TElement, all?: boolean | undefined, equater?: ((first: TElement, second: TElement) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.remove(obj, all, equater);
+  }
+
+  concat(...iterables: MaybeAsyncIterable<TElement>[]): AsyncEnumerable<TElement> {
+    return this.#enumerable.concat(...iterables);
+  }
+
+  first(predicate?: ((obj: TElement) => MaybePromise<boolean>) | undefined): Promise<TElement> {
+    return this.#enumerable.first(predicate);
+  }
+
+  firstOrDefault(predicate?: ((obj: TElement) => MaybePromise<boolean>) | undefined, def?: TElement | undefined): Promise<TElement | undefined> {
+    return this.#enumerable.firstOrDefault(predicate, def);
+  }
+
+  last(predicate?: ((obj: TElement) => MaybePromise<boolean>) | undefined): Promise<TElement> {
+    return this.#enumerable.last(predicate);
+  }
+
+  lastOrDefault(predicate?: ((obj: TElement) => MaybePromise<boolean>) | undefined, def?: TElement | undefined): Promise<TElement | undefined> {
+    return this.#enumerable.lastOrDefault(predicate, def);
+  }
+
+  single(predicate?: ((obj: TElement) => MaybePromise<boolean>) | undefined): Promise<TElement> {
+    return this.#enumerable.single(predicate);
+  }
+
+  singleOrDefault(predicate?: ((obj: TElement) => MaybePromise<boolean>) | undefined, def?: TElement | undefined): Promise<TElement | undefined> {
+    return this.#enumerable.singleOrDefault(predicate, def);
+  }
+
+  elementAt(index: number): Promise<TElement> {
+    return this.#enumerable.elementAt(index);
+  }
+
+  elementAtOrDefault(index: number, def?: TElement | undefined): Promise<TElement | undefined> {
+    return this.#enumerable.elementAtOrDefault(index, def);
+  }
+
+  aggregate(accumulator: (acc: TElement, obj: TElement) => MaybePromise<TElement>): Promise<TElement>;
+  aggregate<TAccumulator>(accumulator: (acc: TAccumulator, obj: TElement) => MaybePromise<TAccumulator>, seed?: TAccumulator | undefined): Promise<TAccumulator>;
+  aggregate<TAccumulator, TResult>(accumulator: (acc: TAccumulator, obj: TElement) => MaybePromise<TAccumulator>, seed?: TAccumulator | undefined, resultSelector?: ((obj: TAccumulator) => MaybePromise<TResult>) | undefined): Promise<TResult>;
+  aggregate(accumulator: any, seed?: any, resultSelector?: any) {
+    return this.#enumerable.aggregate(accumulator, seed, resultSelector);
+  }
+
+  min(): Promise<TElement> {
+    return this.#enumerable.min();
+  }
+
+  minBy<TBy>(selector: (obj: TElement) => MaybePromise<TBy>): Promise<TElement> {
+    return this.#enumerable.minBy(selector);
+  }
+
+  max(): Promise<TElement> {
+    return this.#enumerable.max();
+  }
+
+  maxBy<TBy>(selector: (obj: TElement) => MaybePromise<TBy>): Promise<TElement> {
+    return this.#enumerable.maxBy(selector);
+  }
+
+  order(comparer?: ((first: TElement, second: TElement) => MaybePromise<number>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.order(comparer);
+  }
+
+  orderBy<TBy>(selector: (obj: TElement) => MaybePromise<TBy>, comparer?: ((first: TBy, second: TBy) => MaybePromise<number>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.orderBy(selector, comparer);
+  }
+
+  orderDescending(comparer?: ((first: TElement, second: TElement) => MaybePromise<number>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.orderDescending(comparer);
+  }
+
+  orderByDescending<TBy>(selector: (obj: TElement) => MaybePromise<TBy>, comparer?: ((first: TBy, second: TBy) => MaybePromise<number>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.orderByDescending(selector, comparer);
+  }
+
+  distinct(equater?: ((first: TElement, second: TElement) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.distinct(equater);
+  }
+
+  distinctBy<TBy>(selector: (obj: TElement) => MaybePromise<TBy>, equater?: ((first: TBy, second: TBy) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.distinctBy(selector, equater);
+  }
+
+  union(iterable: MaybeAsyncIterable<TElement>, equater?: ((first: TElement, second: TElement) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.union(iterable, equater);
+  }
+
+  unionBy<TBy>(iterable: MaybeAsyncIterable<TElement>, selector: (obj: TElement) => MaybePromise<TBy>, equater?: ((first: TBy, second: TBy) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.unionBy(iterable, selector, equater);
+  }
+
+  except(iterable: MaybeAsyncIterable<TElement>, equater?: ((first: TElement, second: TElement) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.except(iterable, equater);
+  }
+
+  exceptBy<TBy>(iterable: MaybeAsyncIterable<TElement>, selector: (obj: TElement) => MaybePromise<TBy>, equater?: ((first: TBy, second: TBy) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.exceptBy(iterable, selector, equater);
+  }
+
+  intersect(iterable: MaybeAsyncIterable<TElement>, equater?: ((first: TElement, second: TElement) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.intersect(iterable, equater);
+  }
+
+  intersectBy<TBy>(iterable: MaybeAsyncIterable<TElement>, selector: (obj: TElement) => MaybePromise<TBy>, equater?: ((first: TBy, second: TBy) => MaybePromise<boolean>) | undefined): AsyncEnumerable<TElement> {
+    return this.#enumerable.intersectBy(iterable, selector, equater);
+  }
+
+  all(predicate: (obj: TElement) => MaybePromise<boolean>): Promise<boolean> {
+    return this.#enumerable.all(predicate);
+  }
+
+  any(predicate: (obj: TElement) => MaybePromise<boolean>): Promise<boolean>;
+  any(): Promise<boolean>;
+  any(predicate?: any) {
+    return this.#enumerable.any(predicate);
+  }
+
+  none(predicate: Predicate<TElement>): Promise<boolean>;
+  none(): Promise<boolean>;
+  none(predicate?: any) {
+    return this.#enumerable.none(predicate);
+  }
+
+  skip(n: number): AsyncEnumerable<TElement> {
+    return this.#enumerable.skip(n);
+  }
+
+  skipLast(n: number): AsyncEnumerable<TElement> {
+    return this.#enumerable.skipLast(n);
+  }
+
+  skipWhile(condition: (obj: TElement) => MaybePromise<boolean>): AsyncEnumerable<TElement> {
+    return this.#enumerable.skipWhile(condition);
+  }
+
+  take(n: number): AsyncEnumerable<TElement> {
+    return this.#enumerable.take(n);
+  }
+
+  takeLast(n: number): AsyncEnumerable<TElement> {
+    return this.#enumerable.takeLast(n);
+  }
+
+  takeWhile(condition: (obj: TElement) => MaybePromise<boolean>): AsyncEnumerable<TElement> {
+    return this.#enumerable.takeWhile(condition);
+  }
+
+  peek(action: (obj: TElement) => MaybePromise<void>): AsyncEnumerable<TElement> {
+    return this.#enumerable.peek(action);
+  }
+
+  forEach(action: (obj: TElement) => MaybePromise<void>): Promise<void> {
+    return this.#enumerable.forEach(action);
+  }
+
+  zip<TOther>(iterable: MaybeAsyncIterable<TOther>): AsyncEnumerable<[TElement, TOther]> {
+    return this.#enumerable.zip(iterable);
+  }
+
+  indexex(): AsyncEnumerable<[number, TElement]> {
+    return this.#enumerable.indexex();
+  }
+
+  reversed(): AsyncEnumerable<TElement> {
+    return this.#enumerable.reversed();
+  }
+
+  chunked(size: number): AsyncEnumerable<TElement[]> {
+    return this.#enumerable.chunked(size);
+  }
+
+  cached(): AsyncEnumerable<TElement> {
+    return this.#enumerable.cached();
+  }
+
+  asArray(): Promise<TElement[]> {
+    return this.#enumerable.asArray();
+  }
+
+  toArray(): Promise<TElement[]> {
+    return this.#enumerable.toArray();
+  }
+
+  toMap<TKey, TValue>(keySelector: (obj: TElement) => MaybePromise<TKey>, valueSelector: (obj: TElement) => MaybePromise<TValue>): Promise<Map<TKey, TValue>> {
+    return this.#enumerable.toMap(keySelector, valueSelector);
+  }
+
+  toSet(): Promise<Set<TElement>> {
+    return this.#enumerable.toSet();
+  }
+
+  toObject<TValue>(keySelector: (obj: TElement) => MaybePromise<PropertyKey>, valueSelector: (obj: TElement) => MaybePromise<TValue>): Promise<Record<PropertyKey, TValue>> {
+    return this.#enumerable.toObject(keySelector, valueSelector);
+  }
+
+  collect<TResult>(collector: Collector<TElement, any, TResult>): Promise<TResult> {
+    return this.#enumerable.collect(collector);
+  }
+}
+
+class GroupedAsyncEnumerableImpl<TElement, TKey> extends DelegatedAsyncEnumerable<TElement> implements GroupedAsyncEnumerable<TKey, TElement> {
+  readonly #key: TKey;
+
+  constructor(key: TKey, grouping: AsyncEnumerable<TElement>) {
+    super(grouping);
+
     this.#key = key;
-    this.#grouping = grouping;
   }
 
   public get key() {
     return this.#key;
   }
-
-  override async nonEnumeratedCount() {
-    return await this.#grouping.nonEnumeratedCount();
-  }
-
-  override iterator() {
-    return this.#grouping.iterator();
-  }
 }
 
 abstract class BaseOrderedAsyncEnumerable<TElement> extends BaseAsyncEnumerable<TElement> implements OrderedAsyncEnumerable<TElement> {
@@ -954,6 +1262,10 @@ abstract class BaseOrderedAsyncEnumerable<TElement> extends BaseAsyncEnumerable<
     return await this.#enumerable.nonEnumeratedCount();
   }
 
+  override async maxCount() {
+    return await this.#enumerable.maxCount();
+  }
+
   get comparer() {
     return this.#sorter;
   }
@@ -1922,7 +2234,7 @@ class GroupByAsyncEnumerable<TElement, TKey, TResult> extends BaseAsyncEnumerabl
     }
 
     for await (const entry of groupings) {
-      yield new GroupedAsyncEnumerableImpl(entry[0], array(entry[1]));
+      yield new GroupedAsyncEnumerableImpl(entry[0], AsyncEnumerable.array(entry[1]));
     }
   }
 }
@@ -2032,7 +2344,7 @@ class GroupJoinAsyncEnumerable<TOuter, TInner, TKey, TResult> extends BaseAsyncE
       }
 
       // yield this.#resultSelector(firstObj, this.#second.where(secondObj => this.#keyComparer(firstKey, this.#secondKeySelector(secondObj))));
-      yield this.#resultSelector(firstObj, array(secondObjs));
+      yield this.#resultSelector(firstObj, AsyncEnumerable.array(secondObjs));
     }
   }
 }

src/bitarray.ts

@@ -1,5 +1,5 @@
 import { join } from "./collector.js";
-import { arrayLike, sequence } from "./sync.js";
+import { Enumerable } from "./sync.js";
 import { asArray, isDefined } from "./utils.js";
 
 export interface BitArray extends Iterable<boolean> {
@@ -224,16 +224,16 @@ class BitArrayImpl implements BitArray {
     this.#ensureSameSize(other);
 
     return other instanceof BitArrayImpl ?
-      arrayLike(this.#bits).zip(arrayLike(other.#bits)).all(([a, b]) => (a & b) === b) :
-      sequence(this).zip(sequence(other)).where(([, b]) => b).all(([a, b]) => a && b);
+    Enumerable.arrayLike(this.#bits).zip(Enumerable.arrayLike(other.#bits)).all(([a, b]) => (a & b) === b) :
+    Enumerable.sequence(this).zip(Enumerable.sequence(other)).where(([, b]) => b).all(([a, b]) => a && b);
   }
 
   public intersects(other: BitArray) {
     this.#ensureSameSize(other);
 
     return other instanceof BitArrayImpl ?
-      arrayLike(this.#bits).zip(arrayLike(other.#bits)).any(([a, b]) => (a & b) !== 0) :
-      sequence(this).zip(sequence(other)).any(([a, b]) => a && b);
+    Enumerable.arrayLike(this.#bits).zip(Enumerable.arrayLike(other.#bits)).any(([a, b]) => (a & b) !== 0) :
+    Enumerable.sequence(this).zip(Enumerable.sequence(other)).any(([a, b]) => a && b);
   }
 
   public slice(offset: number, length: number) {
@@ -247,15 +247,15 @@ class BitArrayImpl implements BitArray {
   }
 
   public toArray() {
-    return sequence(this).toArray();
+    return Enumerable.sequence(this).toArray();
   }
 
   public equals(other: BitArray) {
-    return other === this || isDefined(other) && (other instanceof BitArrayImpl ? arrayLike(this.#bits).equals(arrayLike(other.#bits)) : sequence(this).equals(sequence(other)));
+    return other === this || isDefined(other) && (other instanceof BitArrayImpl ? Enumerable.arrayLike(this.#bits).sequenceEquals(Enumerable.arrayLike(other.#bits)) : Enumerable.sequence(this).sequenceEquals(Enumerable.sequence(other)));
   }
 
   public toString() {
-    return sequence(this).select(bit => bit ? '1' : '0').collect(join());
+    return Enumerable.sequence(this).select(bit => bit ? '1' : '0').collect(join());
   }
 }
 
@@ -465,13 +465,13 @@ class BitArraySlice implements BitArray {
   public contains(other: BitArray) {
     this.#ensureSameSize(other);
 
-    return sequence(this).zip(sequence(other)).where(([, b]) => b).all(([a, b]) => a && b);
+    return Enumerable.sequence(this).zip(Enumerable.sequence(other)).where(([, b]) => b).all(([a, b]) => a && b);
   }
 
   public intersects(other: BitArray) {
     this.#ensureSameSize(other);
 
-    return sequence(this).zip(sequence(other)).any(([a, b]) => a && b);
+    return Enumerable.sequence(this).zip(Enumerable.sequence(other)).any(([a, b]) => a && b);
   }
 
   public slice(offset: number, length: number) {
@@ -489,15 +489,15 @@ class BitArraySlice implements BitArray {
   }
 
   public toArray() {
-    return sequence(this).toArray();
+    return Enumerable.sequence(this).toArray();
   }
 
   public equals(other: BitArray) {
-    return other === this || isDefined(other) && sequence(this).equals(sequence(other));
+    return other === this || isDefined(other) && Enumerable.sequence(this).sequenceEquals(Enumerable.sequence(other));
   }
 
   public toString() {
-    return sequence(this).select(bit => bit ? '1' : '0').collect(join());
+    return Enumerable.sequence(this).select(bit => bit ? '1' : '0').collect(join());
   }
 }
 

src/index.ts

@@ -1,4 +1,4 @@
 export * from "./sync.js";
-export * as async from "./async.js";
+export * from "./async.js";
 export * as collectors from "./collector.js";
 export * as random from "./random.js";

src/sync.ts

@@ -41,7 +41,7 @@ export interface Enumerable<TElement> extends Iterable<TElement> {
 
   contains(obj: TElement, equater?: Equater<TElement>): boolean;
 
-  equals(iterable: Iterable<TElement>, equater?: Equater<TElement>): boolean;
+  sequenceEquals(iterable: Iterable<TElement>, equater?: Equater<TElement>): boolean;
 
   append(obj: TElement): Enumerable<TElement>;
 
@@ -146,6 +146,7 @@ export interface OrderedEnumerable<TElement> extends Enumerable<TElement> {
   thenByDescending<TBy>(selector: Converter<TElement, TBy>, comparer?: Comparer<TBy>): OrderedEnumerable<TElement>;
 }
 
+export namespace Enumerable {
   export function wrap<T>(iterable: Iterable<T>): Enumerable<T> {
     if (isEnumerable<T>(iterable)) {
       return iterable;
@@ -288,6 +289,7 @@ export function concat<T>(...enumerables: Enumerable<T>[]): Enumerable<T> {
   export function isEnumerable<T = any>(obj: any): obj is Enumerable<T> {
     return obj instanceof EnumerableMarker;
   }
+}
 
 //#region enumerable implementation
 
@@ -323,11 +325,11 @@ export abstract class BaseEnumerable<TElement> extends EnumerableMarker implemen
   }
 
   join<TOther, TKey, TResult>(iterable: Iterable<TOther>, firstKeySelector: Converter<TElement, TKey>, secondKeySelector: Converter<TOther, TKey>, resultSelector?: BiConverter<TElement, TOther, TResult>, keyComparer?: Equater<TKey>): Enumerable<TResult> {
-    return new JoinEnumerable<TElement, TOther, TKey, TResult>(this, wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
+    return new JoinEnumerable<TElement, TOther, TKey, TResult>(this, Enumerable.wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
   }
 
   groupJoin<TOther, TKey, TResult>(iterable: Iterable<TOther>, firstKeySelector: Converter<TElement, TKey>, secondKeySelector: Converter<TOther, TKey>, resultSelector?: BiConverter<TElement, Enumerable<TOther>, TResult>, keyComparer?: Equater<TKey>): Enumerable<TResult> {
-    return new GroupJoinEnumerable<TElement, TOther, TKey, TResult>(this, wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
+    return new GroupJoinEnumerable<TElement, TOther, TKey, TResult>(this, Enumerable.wrap(iterable), firstKeySelector, secondKeySelector, resultSelector, keyComparer);
   }
 
   contains(obj: TElement, equater?: Equater<TElement>) {
@@ -344,8 +346,12 @@ export abstract class BaseEnumerable<TElement> extends EnumerableMarker implemen
     return false;
   }
 
-  equals(iterable: Iterable<TElement>, equater?: Equater<TElement>) {
-    const that = wrap(iterable);
+  sequenceEquals(iterable: Iterable<TElement>, equater?: Equater<TElement>) {
+    if (this === iterable) {
+      return true;
+    }
+
+    const that = Enumerable.wrap(iterable);
 
     const thisCount = this.nonEnumeratedCount();
     const thatCount = that.nonEnumeratedCount();
@@ -399,7 +405,7 @@ export abstract class BaseEnumerable<TElement> extends EnumerableMarker implemen
     const arr: Enumerable<TElement>[] = [this];
 
     for (const iterable of iterables) {
-      arr.push(wrap(iterable));
+      arr.push(Enumerable.wrap(iterable));
     }
 
     return new ConcatEnumerable(arr);
@@ -743,27 +749,27 @@ export abstract class BaseEnumerable<TElement> extends EnumerableMarker implemen
   }
 
   union(iterable: Iterable<TElement>, equater?: Equater<TElement>): Enumerable<TElement> {
-    return new UnionEnumerable<TElement>(this, wrap(iterable), equater);
+    return new UnionEnumerable<TElement>(this, Enumerable.wrap(iterable), equater);
   }
 
   unionBy<TBy>(iterable: Iterable<TElement>, selector: Converter<TElement, TBy>, equater?: Equater<TBy>): Enumerable<TElement> {
-    return new UnionByEnumerable<TElement, TBy>(this, wrap(iterable), selector, equater);
+    return new UnionByEnumerable<TElement, TBy>(this, Enumerable.wrap(iterable), selector, equater);
   }
 
   except(iterable: Iterable<TElement>): Enumerable<TElement> {
-    return new ExceptEnumerable<TElement>(this, wrap(iterable));
+    return new ExceptEnumerable<TElement>(this, Enumerable.wrap(iterable));
   }
 
   exceptBy<TBy>(iterable: Iterable<TElement>, selector: Converter<TElement, TBy>): Enumerable<TElement> {
-    return new ExceptByEnumerable<TElement, TBy>(this, wrap(iterable), selector);
+    return new ExceptByEnumerable<TElement, TBy>(this, Enumerable.wrap(iterable), selector);
   }
 
   intersect(iterable: Iterable<TElement>): Enumerable<TElement> {
-    return new IntersectEnumerable<TElement>(this, wrap(iterable));
+    return new IntersectEnumerable<TElement>(this, Enumerable.wrap(iterable));
   }
 
   intersectBy<TBy>(iterable: Iterable<TElement>, selector: Converter<TElement, TBy>): Enumerable<TElement> {
-    return new IntersectByEnumerable<TElement, TBy>(this, wrap(iterable), selector);
+    return new IntersectByEnumerable<TElement, TBy>(this, Enumerable.wrap(iterable), selector);
   }
 
   all(predicate: Predicate<TElement>) {
@@ -847,7 +853,7 @@ export abstract class BaseEnumerable<TElement> extends EnumerableMarker implemen
       throw new Error("Cannot take a negative number of elements.");
     }
 
-    return n === 0 ? empty<TElement>() : new TakeEnumerable<TElement>(this, n);
+    return n === 0 ? Enumerable.empty<TElement>() : new TakeEnumerable<TElement>(this, n);
   }
 
   takeLast(n: number): Enumerable<TElement> {
@@ -855,7 +861,7 @@ export abstract class BaseEnumerable<TElement> extends EnumerableMarker implemen
       throw new Error("Cannot take a negative number of elements.");
     }
 
-    return n === 0 ? empty<TElement>() : new TakeLastEnumerable<TElement>(this, n);
+    return n === 0 ? Enumerable.empty<TElement>() : new TakeLastEnumerable<TElement>(this, n);
   }
 
   takeWhile(predicate: Predicate<TElement>): Enumerable<TElement> {
@@ -873,7 +879,7 @@ export abstract class BaseEnumerable<TElement> extends EnumerableMarker implemen
   }
 
   zip<TOther>(iterable: Iterable<TOther>): Enumerable<[TElement, TOther]> {
-    return new ZippedEnumerable<TElement, TOther>(this, wrap(iterable));
+    return new ZippedEnumerable<TElement, TOther>(this, Enumerable.wrap(iterable));
   }
 
   indexed(): Enumerable<[number, TElement]> {
@@ -1025,8 +1031,8 @@ class DelegatedEnumerable<TElement> extends EnumerableMarker implements Enumerab
     return this.#enumerable.contains(obj, equater);
   }
 
-  equals(iterable: Iterable<TElement>, equater?: Equater<TElement>) {
-    return this.#enumerable.equals(iterable, equater);
+  sequenceEquals(iterable: Iterable<TElement>, equater?: Equater<TElement>) {
+    return this.#enumerable.sequenceEquals(iterable, equater);
   }
 
   append(obj: TElement) {
@@ -2495,7 +2501,7 @@ class GroupByEnumerable<TElement, TKey, TResult> extends BaseEnumerable<GroupedE
     }
 
     for (const entry of groupings) {
-      yield new GroupedEnumerableImpl(entry[0], array(entry[1]));
+      yield new GroupedEnumerableImpl(entry[0], Enumerable.array(entry[1]));
     }
   }
 }
@@ -2624,7 +2630,7 @@ class GroupJoinEnumerable<TOuter, TInner, TKey, TResult> extends BaseEnumerable<
         }
       }
 
-      yield this.#resultSelector(firstObj, array(secondObjs));
+      yield this.#resultSelector(firstObj, Enumerable.array(secondObjs));
     }
   }
 }
@@ -2677,7 +2683,7 @@ class CacheEnumerable<T> extends DelegatedEnumerable<T> {
 
   override iterator() {
     if (!this.#cached) {
-      this.enumerable = array(this.enumerable.toArray());
+      this.enumerable = Enumerable.array(this.enumerable.toArray());
       this.#cached = true;
     }