stream.ts

class Stream<T> {
  items: T[] = [];
  _unsubscribe?: () => void;

  next(fn: (data: any[]) => void): Stream<T> { return this; }
  error(fn: (error: any) => void): Stream<T> { return this; }
  complete(fn: () => void) { return this; }

  unsubscribe() {
    this._unsubscribe?.();
  }

  /*
   * Returns all items once it has produced any
   */
  async load() {
    return this.items;
  }

  /*
   * Returns the first item produced by the stream once it has produced any
   */
  async loadOne() {
    return this.items[0]!;
  }

  /*
   * Returns the next array of items produced by the stream
   */
  async tail() {
    return this.items;
  }

  async tailOne() {
    return this.items[0]!;
  }

}

function thing() {
  let stream = new Stream().next((data) => {
  }