Using for-comprehensions for futures

In this small recipe, we will see how to use for comprehensions to iterate over futures as we do with Scala collections. As a future is a monad, like a list in Scala, we can operate on it in the same way as we operate on a list. It is also a way of composing futures.

Getting ready

All the prerequisites are the same as before; just import the Hello-Akka project in the IDE.

How to do it...

1. Create a Scala file, ForComprehensions.scala, in the com.packt.chapter4 package.
2. Add the following imports to the top of the file:

        import scala.concurrent.duration._ 
        import scala.concurrent.{Await, Future} 
        import scala.concurrent.ExecutionContext.Implicits.global 

3. Create a test application, as follows:

        object ForComprehensions extends App { 
          val futureA = Future(20 + 20) 
          val futureB = Future(30 + 30) 
          val finalFuture: Future[Int] = for { 
            a <- futureA 
            b <- futureB 
            } yield...