Haskell ZeroMQ - Hello World!

zeromq.hs

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Control.Monad (forever)
import Control.Concurrent (forkIO)
import qualified Data.ByteString.Char8 as B
import System.ZMQ

connect' :: String -> (Socket Req -> IO ()) -> Context -> IO ()
connect' endpoint f ctx = withSocket ctx Req (\s -> connect s endpoint >> f s)

bind' :: String -> (Socket Rep -> IO ()) -> Context -> IO ()
bind' endpoint f ctx = withSocket ctx Rep (\s -> bind s endpoint >> f s)

requester :: Socket a -> IO ()
requester s = forever $ do
    B.putStrLn $ B.concat [" Sending: ", request]
    send s request []
    reply <- receive s []
    B.putStrLn $ B.concat ["Received: ", reply]
    where request = "Hello world!" :: B.ByteString

replier :: Socket a -> IO ()
replier s = forever $ do
    msg <- receive s []
    B.putStrLn $ B.concat ["Received: ", msg]
    B.putStrLn $ B.concat ["Replying: ", reply]
    send s reply []
    where reply = "Hello!" :: B.ByteString

main = withContext 1 $ \ctx -> do
    forkIO $ bind' "tcp://*:5555" replier ctx
    connect' "tcp://localhost:5555" requester ctx