Looping Echo

echo.hs

import Network (listenOn, PortID(..))
import Network.Socket
import Control.Exception
import Control.Concurrent
import Control.Monad (forever)
import System.IO

type HandlerFn = String -> Socket -> IO ()

loopEcho :: HandlerFn
loopEcho msg cs = do
    forever $ do
        send cs msg
        threadDelay 1000000

server :: PortID -> HandlerFn -> IO ()
server port handler = do
    mastersocket <- listenOn port
    forever $ do
        (cs, _) <- accept mastersocket
        forkIO $ handler "hello" cs `finally` sClose cs

main = server (PortNumber 1234) loopEcho