haskell hardware interaction pseudocode

gistfile1.hs

main = do dataFromHW <- readSerialPort
          dataFromUser <- readUIInput
          (answerForDevice, answerForUser) <- goodProcessingFunction dataFromHW dataFromUser
          writeSerialPort deviceAnswer
          writeUIOutput answerForUser
          case processResult answerForUser of
             EOF -> return 0
             Error i -> return i
             Continue -> main   

writeSerialPort deviceAnswer -> writeSerialPort answerForDevice