pipe.ts

const pipe = <A, B>(
  iterable: IterableIterator<A>,
  seed: B,
  fn: (a: A) => B
): A => {
  const iterator = iterable[Symbol.iterator]()
  if (iterable instanceof GeneratorFunction) {
    iterator.next()
  }
  let result = iterator.next(seed)
  while (!result.done) {
    result = iterator.next(fn(result.value))
  }
  return result.value
}

GeneratorFunction = (function*(){}).constructor