simple haskell program

makingDialogs.hs

data Dialog = WinDialog { render :: IO (), click :: IO () }
            | MacDialog { render :: IO (), click :: IO () }
            | LnxDialog { render :: IO (), click :: IO () }

askForConfirmThenError :: IO ()
askForConfirmThenError = do
  print "Are you sure? [y/n]"
  ans <- getLine
  if ans == "n"
    then print "Ok, (not) done"
    else error "Ooops, I'm bugged"

askForMoneyThanDo :: IO ()
askForMoneyThanDo = do
  print "Pay first..."
  ans <- getLine
  let money = read ans :: Int
  if money < 10
    then error "No way!"
    else print "Ok, done."

createDialogFor :: String -> Dialog
createDialogFor "w" = WinDialog (print "Hello, I'm a Win dialog") askForConfirmThenError
createDialogFor "m" = MacDialog (print "Hello, I'm a Mac dialog") askForMoneyThanDo
createDialogFor "l" = LnxDialog (print "Hello, I'm a Lnx dialog") (print "the job is done")
createDialogFor _   = error "Error: unknown OS."

main :: IO ()
main = do
  print "Which os? [w/m/l]"
  os <- getLine -- for simplicity, read from keyboard instead of from system
  let dialog = createDialogFor os
  render dialog
  click dialog

Thank you very much for your comments.

As regards the second to last comment of yours (about distinguishing the OS on the type level), I think probably it's a bit to early for me to really understand it. However, as a future reference for myself, would you mind showing me how that would translate in my example, if we say, for instance, that render is platform-specific and click is not?