gistfile1.scala

import java.util.concurrent.atomic.AtomicInteger

import scala.concurrent._
import duration._
import ExecutionContext.Implicits.global

def ftraverse[A, B](xs: Seq[A])(f: A => Future[B]): Future[Seq[B]] = {
  if(xs.isEmpty) Future successful Seq.empty[B]
  else f(xs.head) flatMap { fh => ftraverse(xs.tail)(f) map (r => fh +: r) }
}

def testStd(): Future[Unit] = {
  val x = new AtomicInteger()
	val items = 1 to 10000
  Future.traverse(items)(_ => Future(x.incrementAndGet()))

  Future(println(s"When I'm running x == ${x.get}"))
}

def testOp(): Future[Unit] = {
	val x = new AtomicInteger()
	val items = 1 to 10000

  ftraverse(items)(_ => Future(x.incrementAndGet()))
  Future(println(s"When I'm running x == ${x.get}"))
}

Await.result(testOp(), 2.seconds)
Await.result(testStd(), 2.seconds)