Communicating in real time through sockets

Sockets provide a convenient way of communicating between programs in real time. Think of them as a chat client.

In this recipe, we will pass messages from one program to another and obtain responses.

How to do it…

Insert the following code in a new file called Main.hs:

1. Create the server code:

   import Network ( listenOn, withSocketsDo, accept
                  , PortID(..), Socket )
   import System.Environment (getArgs)
   import System.IO ( hSetBuffering, hGetLine, hPutStrLn
                    , BufferMode(..), Handle )
   import Control.Concurrent (forkIO)

2. Create a socket connection to listen on, and attach our handler, sockHandler, on it:

   main :: IO ()
   
   main = withSocketsDo $ do
       let port = PortNumber 9001
       sock <- listenOn port
       putStrLn $ "Listening…"
       sockHandler sock

3. Define the handler to process each message received:

   sockHandler :: Socket -> IO ()
   
   sockHandler sock = do
       (h, _, _) <- accept sock
       putStrLn &quot...