Hello, I am using the very simple interactTCP example from [1] to play around with Haskell network programming but I just can't get a simple client for that example to work (it works like a charm with my telnet client, as described in the article). This is what I am trying to do with the client: main = withSocketsDo $ do hdl <- connectTo "localhost" (PortNumber 1234) hSetBuffering hdl NoBuffering hPutStr hdl "test message" res <- hGetContents hdl putStrLn (show res) The server looks like this: interactTCP :: Int -> (String -> IO String) -> IO () interactTCP port f = withSocketsDo $ do servSock <- listenOn $ PortNumber (fromIntegral port) waitLoop f servSock waitLoop f servSock = do bracket (fmap (\(h,_,_)->h) $ accept servSock) hClose (\h -> do hSetBuffering h NoBuffering hGetContents h >>= f >>= hPutStr h) waitLoop f servSock main = interactTCP 1234 (return . map toUpper) But is seems as some deadlocking occurs. Both programs just hang around doing nothing. By inserting some debug output I was able to make sure that the client successfully connects, but the data interchange just does not start. Because the whole thing works using telnet, I suspect that I am doing something fundamentally wrong in the client ... Any hints are greatly appreciated. Thanks, Timo [1] http://stephan.walter.name/blog/computers/programming/haskell/interacttcp.ht...