Simple delayed echo server in Haskell that accepts multiple connections

echoDelay.hs

import Network.Socket hiding (send, sendTo, recv, recvFrom)
import Network.Socket.ByteString
import Control.Concurrent

port = 4242
incomingBufferSize = 4096
delayMicroseconds = 500000

main = do
  -- Listen
  sock <- socket AF_INET Stream 0
  setSocketOption sock ReuseAddr 1
  bind sock (SockAddrInet port iNADDR_ANY)
  listen sock sOMAXCONN
  mainLoop sock

mainLoop :: Socket -> IO ()
mainLoop sock = do
  -- Blocks until connection made
  (conn, _) <- accept sock
  forkIO (echoLoop conn)
  mainLoop sock

echoLoop :: Socket -> IO ()
echoLoop conn = do
  incoming <- recv conn incomingBufferSize
  threadDelay delayMicroseconds
  send conn incoming
  echoLoop conn