def mainLoop() : Unit@cps[Future[Any]] = {
  while (true) {
    val fut = Promise.successful(new Array[Byte](1000000*100)).future // 100MB
    
    // This shift is the same as Akka DataFlow's DataflowFuture.apply()
    val result = shift { onComplete: (Array[Byte] => Future[Any]) =>
      fut flatMap onComplete
    }
    
    println(result)
  }
} 

def flatMap[S](f: T => Future[S])(implicit executor: ExecutionContext): Future[S] = {
    val p = Promise[S]()
 
    onComplete {
      case f: Failure[_] => p complete f.asInstanceOf[Failure[S]]
      case Success(v) => {
        val tempP = p
        try {
          f(v).onComplete({
            case f: Failure[_] => tempP complete f.asInstanceOf[Failure[S]]
            case Success(v) => tempP success v
          })(internalExecutor)
        } catch {
          case NonFatal(t) => tempP failure t
        }
      }
    }(executor)
 
    p.future
  }