gathering Scala futures

gather_futures.scala

  def gather_futures[A](xs: Seq[Future[A]]): Future[Seq[A]]= {
    def combine[A,B,C](f1: Future[A], f2: Future[B])(f: (A,B) => C): Future[C] ={
      for(a <- f1; b <- f2)
      yield f(a,b)
    }
    xs.foldLeft(Future{Seq[A]()}){(acc: Future[Seq[A]],x: Future[A]) => combine(x,acc)((a: A,b: Seq[A]) => b ++ Seq(a))}
  }