simple echo server in Haskell

SimpleEchoServer.hs

import GHC.IO.Handle (Handle, hGetLine)
import GHC.IO.Handle.FD (stdout)
import Network
import Text.Printf


main :: IO ()
main = withSocketsDo $ do
    listenSock <- listenOn $ PortNumber 9999
    (listenHandle, clientHost, clientPort) <- accept listenSock
    hPrintf stdout "Accepted connection from %s:%s\n" clientHost (show clientPort)
    hPrintf listenHandle "Hello %s:%s!\n" clientHost (show clientPort)
    loopOn listenHandle
  where
    loopOn :: Handle -> IO ()
    loopOn someHandle = do
      line <- hGetLine someHandle
      hPrintf stdout "Received %s\n" line
      hPrintf someHandle "backwards: %s\n" (reverse line)
      loopOn someHandle