title: Akka mapTo versus asInstanceOf
body: <p>I'm reading the <a href="http://doc.akka.io/docs/akka/2.1.0/scala/futures.html#futures-scala" rel="noreferrer">Akka Futures Guide</a> and I see this sentence: </p>
  
  <blockquote>
    <p>Also note that the Future returned by an Actor is a Future[Any] since an Actor is dynamic. That is why the asInstanceOf is used in the above sample. When using non-blocking it is better to use the mapTo method to safely try to cast a Future to an expected type</p>
  </blockquote>
  
  <p>Why is mapTo better to use than asInstanceOf for a non-blocking Future? </p>