As the Future is not implemented as an ADT, we can't directly pattern-match on it as we did with other the effects that we looked at in this chapter.

Instead, we can use the null-checking style:

scala> if (runningLong.isCompleted) runningLong.value
res54: Any = Some(Success(()))

Luckily, the value method returns an Option that will be None until the future completes, so we can use this in a pattern match:

scala> runningForever.value match {
 | case Some(Success(value)) => println(s"Finished successfully with $value")
 | case Some(Failure(exception)) => println(s"Failed with $exception")
 | case None => println("Still running")
 | }
Still running

Of course, the most useful methods are defined not in relation to the value of the Future, but in terms of Future as an effect.