title: How can Scala actors return a value in response to a message?
body: <p>There are plenty of examples of actors replying with another message back to the sender, but whilst browsing the API docs I noticed the !! and !? operators which are part of the CanReply trait (which seems to be new to 2.8: <a href="http://www.scala-lang.org/archives/rc-api/scala/actors/CanReply.html" rel="noreferrer">http://www.scala-lang.org/archives/rc-api/scala/actors/CanReply.html</a>). I was therefore wondering whether it was just a case of having the receive/react block return a value, i.e. make the PartialFunction return type something other than Unit?</p>
  
  <p>I'll start digging through the source to try to work out how they're meant to be used, but if anyone has any insight or knows of any more in-depth documentation or examples then I'd be most grateful.</p>
  
  <p>Cheers,
  Paul.</p>