Port 2nd tutorial to Haskell (initial version)

It has a problem with the consumer not printing
any output until there are messages in the
queue by the time it is started.

Author: michaelklishin

haskell/README.md

@@ -18,23 +18,23 @@ Code examples are executed via `runhaskell`:
 
 [Tutorial two: Work Queues](http://www.rabbitmq.com/tutorial-two-python.html):
 
-    runhaskell new_task.hs
+    runhaskell newTask.hs
     runhaskell worker.hs
 
 [Tutorial three: Publish/Subscribe](http://www.rabbitmq.com/tutorial-three-python.html)
 
-    runhaskell receive_logs.hs
-    runhaskell emit_log.hs
+    runhaskell receiveLogs.hs
+    runhaskell emitLog.hs
 
 [Tutorial four: Routing](http://www.rabbitmq.com/tutorial-four-python.html)
 
-    runhaskell receive_logs_direct.hs
-    runhaskell emit_log_direct.hs
+    runhaskell receiveLogsDirect.hs
+    runhaskell emitLogDirect.hs
 
 [Tutorial five: Topics](http://www.rabbitmq.com/tutorial-five-python.html)
 
-    runhaskell receive_logs_topic.hs
-    runhaskell emit_log_topic.hs
+    runhaskell receiveLogsTopic.hs
+    runhaskell emitLogTopic.hs
 
 [Tutorial six: RPC](http://www.rabbitmq.com/tutorial-six-python.html)
 

haskell/newTask.hs

@@ -0,0 +1,20 @@
+{-# OPTIONS -XOverloadedStrings #-}
+
+import Network.AMQP
+import qualified Data.ByteString.Lazy.Char8 as BL
+
+main :: IO ()
+main = do
+     conn <- openConnection "127.0.0.1" "/" "guest" "guest"
+     ch   <- openChannel conn
+
+     declareQueue ch newQueue {queueName       = "task_queue",
+                               queueAutoDelete = False,
+                               queueDurable    = True}
+
+     publishMsg ch "" "task_queue"
+                (newMsg {msgBody         = (BL.pack "a.b.c.d.e"),
+                         msgDeliveryMode = Just Persistent})
+
+     putStrLn " [x] Sent 'a.b.c.d.e'"
+     closeConnection conn

haskell/worker.hs

@@ -0,0 +1,39 @@
+{-# OPTIONS -XOverloadedStrings #-}
+
+import Network.AMQP
+import qualified Data.ByteString.Lazy.Char8 as BL
+
+import Control.Concurrent (threadDelay)
+
+main :: IO ()
+main = do
+     conn <- openConnection "127.0.0.1" "/" "guest" "guest"
+     ch   <- openChannel conn
+
+     declareQueue ch newQueue {queueName       = "task_queue",
+                               queueAutoDelete = False,
+                               queueDurable    = True}
+
+     qos ch 0 1
+
+     putStrLn " [*] Waiting for messages. to Exit press CTRL+C"
+     consumeMsgs ch "task_queue" NoAck deliveryHandler
+
+     -- waits for keypresses
+     getLine
+     closeConnection conn
+
+deliveryHandler :: (Message, Envelope) -> IO ()
+deliveryHandler (msg, metadata) = do
+  putStrLn $ " [x] Received " ++ body
+  -- threadDelay (1000 * n)
+  putStrLn $ " [x] Done"
+  ackEnv metadata
+  where
+    body = (BL.unpack $ msgBody msg)
+    n    = countDots body
+
+
+
+countDots :: [Char] -> Int
+countDots s = length $ filter (\c -> c == '.') s