Composing Futures

gistfile1.txt

import akka.dispatch.Future
import akka.actor.ActorSystem

object FutureMonadic extends App {
  implicit val system = ActorSystem("future")
  val startTime = System.currentTimeMillis
  // we construct List[Future[Int]]
  val futureList = List(1, 2, 3) map { case number => Future(timeTakingIdentityFunction(number)) }
  val future = Future.sequence(futureList)

  future onSuccess {
    case results =>
      val elapsedTime = ((System.currentTimeMillis - startTime) / 1000.0)
      println("Sum of 1, 2 and 3 is " + results.sum + " calculated in " + elapsedTime + " seconds")
  }

  def timeTakingIdentityFunction(number: Int) = {
    Thread.sleep(3000)
    number
  }
}