tweak Duct code

modules/hub/src/main/Duct.scala

@@ -17,9 +17,8 @@ trait Duct {
   protected val process: Duct.ReceiveAsync
 
   def !(msg: Any): Unit =
-    if (stateRef.single.getAndTransform {
-      case None => Some(Queue.empty)
-      case Some(q) => Some(q enqueue msg)
+    if (stateRef.single.getAndTransform { q =>
+      Some(q.fold(Queue.empty[Any])(_ enqueue msg))
     } isEmpty) run(msg)
 
   def queueSize = stateRef.single().??(_.size)
@@ -36,9 +35,10 @@ trait Duct {
 
   private[this] val postRun = (_: Any) =>
     stateRef.single.getAndTransform {
-      case Some(q) => if (q.isEmpty) None else Some(q.tail)
-      case None => None // Shouldn't happen...
-    } foreach { q => if (q.nonEmpty) run(q.head) }
+      _ flatMap { q =>
+        if (q.isEmpty) None else Some(q.tail)
+      }
+    } flatMap (_.headOption) foreach run
 }
 
 object Duct {