buffer.ts

'use strict';

export function* buffer<TSource>(
    source: Iterable<TSource>,
    count: number,
    skip?: number): Iterable<TSource[]> {
  if (skip == null) { skip = count; }
  let buffers: TSource[][] = [],  i = 0;
  for (let item of source)
  {
    if (i % skip === 0) {
      buffers.push([]);
    }

    for (let buffer of buffers) {
      buffer.push(item);
    }

    if (buffers.length > 0 && buffers[0].length === count) {
      yield buffers.shift()!;
    }

    i++;
  }

  while (buffers.length > 0) {
    yield buffers.shift()!;
  }
}

filter.ts

'use strict';

import { bindCallback } from '../internal/bindcallback';

export function* filter<T>(
      source: Iterable<T>,
      predicate: (value: T, index: number) => boolean,
      thisArg?: any): Iterable<T> {
  let fn = bindCallback(predicate, thisArg, 2), i = 0;
  for (let item of source) {
    if (fn(item, i++)) {
      yield item;
    }
  }
}

finally.ts

'use strict';

export function* _finally<TSource>(
    source: Iterable<TSource>,
    action: () => void) {
  try {
    for (let item of source) {
      yield item;
    }
  } finally {
    action();
  }
}

Hi

I mentioned some time ago about https://github.com/marcinnajder/powerseq (ReactiveX/IxJS#1) This is a complete implementation of all IxJS in RxJS5 style. Maybe it will be useful.

Marcin