def retry(noTimes: Int)(block: ⇒Future[T]): Future[T] = {
 val ns: Iterator[Int] = (1 to noTimes).iterator
 val attempts: Iterator[Future[T]] = ns.map(_⇒ ()⇒block)
 val failed = Future.failed(new Exception)

 attempts.foldLeft(failed)
 ((a,block) ⇒ a recoverWith { block() })
}
retry(3) { block }
= unfolds to
((failed recoverWith block1) recoverWith block2) recoverWith block3