add Join example

JoinExample.hs

@@ -0,0 +1,32 @@
+module JoinExample
+    where
+
+import Control.Concurrent.Actors
+import Control.Concurrent.Chan.Split
+
+sumTuple :: (SplitChan c x)=> c Int -> Behavior (Int,(Int,Int))
+sumTuple c = Receive $ do
+    (x,(y,z)) <- received
+    send (out c) (x+y+z)
+    return $ sumTuple c
+
+-- try making instance Sources Mailbox, instead be for SplitChan?
+-- look at what we did to get nice defaulting for zippo
+-- make send only work on Mailbox, add function out :: (SplitChan c x)=> c a -> Mailbox a
+
+main = do
+    (i,o) <- newSplitChan
+    sms <- getChanContents o
+    (b1,bTuple) <- spawn $ sumTuple i  
+
+    mapM_ (send bTuple) [(3,1),(2,2),(1,3),(0,4)]
+    mapM_ (send b1) [1..4]
+
+    print $ [5,6,7,8] == (take 4 sms)
+
+    (b1',(b2',b3')) <- spawn $ sumTuple i  
+    mapM_ (send b3') [1..4]
+    mapM_ (send b2') [3,2,1,0]
+    mapM_ (send b1') [1..4]
+
+    print $ [5,6,7,8] == (take 4 sms)