Is there sequential Future.find?

Question

I have some side-effectful function,

def f(): Future[Int] = {
  val n = Random.nextInt()
  println(s\"Generated $n\")
  Future(n)
}

and I

Answer 1

If I understand the question, then you will have to block the thread to proceed sequentially. You can use Await to accomplish that.

scala> def f(): Future[Int] = {
 |   val n = Random.nextInt()
 |   println(s"Generated $n")
 |   Future(n)
 | }
f: ()scala.concurrent.Future[Int]

scala> def success(n: Int): Boolean = n % 2 == 0
success: (n: Int)Boolean

scala> val s = Stream.fill(10)(f)

Using your way, I get

scala> Future.find(s)(success) map println
Generated 551866055
Generated -561348666
Generated -1103407834
Generated -812310371
Generated -1544170923
Generated 2131361419
Generated -236722325
Generated -1473890302
Generated -82395856
Some(-561348666)
res16: scala.concurrent.Future[Unit] = scala.concurrent.impl.Promise$DefaultPromise@15a2d71

I should get answer as Some(-561348666), which you can get as

scala> s.find(x => success(Await.result(x,1 seconds))).get onSuccess {case p=> println(p)}
-561348666