Made fringe example more type safe.

1 files changed, 20 insertions, 15 deletions

diff --git a/docs/examples/actors/fringe.scala b/docs/examples/actors/fringe.scala
index 96edd396e9..0d00dc857c 100644
--- a/docs/examples/actors/fringe.scala
+++ b/docs/examples/actors/fringe.scala
@@ -5,7 +5,7 @@ import scala.actors.{Channel, OutputChannel}
 
 /**
  @author Philipp Haller
- @version 1.0, 07/09/2007
+ @version 1.1, 09/21/2007
  */
 object fringe extends Application {
 
@@ -13,19 +13,24 @@ object fringe extends Application {
   case class Node(left: Tree, right: Tree) extends Tree
   case class Leaf(v: Int) extends Tree
 
+  case class CompareFringe(t1: Tree, t2: Tree)
+  case class ComputeFringe(t1: Tree, atoms: OutputChannel[Option[Leaf]])
+  case class Equal(atom1: Option[Leaf], atom2: Option[Leaf])
+  case class Extract(tree: Tree)
+
   val comparator = actor {
     val extractor1 = actor(extractorBehavior())
     val extractor2 = actor(extractorBehavior())
-    val ch1 = new Channel[Any]
-    val ch2 = new Channel[Any]
+    val ch1 = new Channel[Option[Leaf]]
+    val ch2 = new Channel[Option[Leaf]]
     loop {
       react {
-        case ('Fringe, tree1, tree2) =>
-          extractor1.send(('Fringe, tree1), ch1)
-          extractor2.send(('Fringe, tree2), ch2)
-          self ! Triple('Equal, ch1.?, ch2.?)
+        case CompareFringe(tree1, tree2) =>
+          extractor1 ! ComputeFringe(tree1, ch1)
+          extractor2 ! ComputeFringe(tree2, ch2)
+          self ! Equal(ch1.?, ch2.?)
 
-        case ('Equal, atom1, atom2) =>
+        case Equal(atom1, atom2) =>
           println("comparing "+atom1+" and "+atom2)
           if (atom1 == atom2) atom1 match {
             case None =>
@@ -42,14 +47,14 @@ object fringe extends Application {
   }
 
   val extractorBehavior = () => {
-    var output: OutputChannel[Any] = null
+    var output: OutputChannel[Option[Leaf]] = null
     loop {
       react {
-        case ('Fringe, tree) =>
-          output = sender
-          self ! ('Extract, tree)
+        case ComputeFringe(tree, leafSink) =>
+          output = leafSink
+          self ! Extract(tree)
 
-        case ('Extract, tree) => tree match {
+        case Extract(tree) => tree match {
           case atom @ Leaf(_) =>
             println("sending "+Some(atom))
             output ! Some(atom)
@@ -61,10 +66,10 @@ object fringe extends Application {
             val cont = actor {
               react {
                 case 'Continue =>
-                  outer.send(('Extract, right), outerCont)
+                  outer.send(Extract(right), outerCont)
               }
             }
-            self.send(('Extract, left), cont)
+            self.send(Extract(left), cont)
         }
 
         case 'Continue =>