guess dog or cat

starman.hs

import System.Random

starman :: Int -> IO ()
starman n = do 
  let allWords = ["cat", "dog"]
  index <- randomRIO(0, (length allWords) - 1)
  let word = allWords !! index
  turn word ['-' | x <- word] n

turn :: String -> String -> Int -> IO ()
turn word display n =
  do if n==0
       then putStrLn "You lose"
       else if word==display
              then putStrLn "You win!"
              else mkguess word display n

mkguess :: String -> String -> Int -> IO ()
mkguess word display n =
  do putStrLn (display ++ "  " ++ take n (repeat '*'))
     putStr "  Enter your guess: "
     q <- getLine
     let (correct, display') = check word display (q!!0)
     let n' = if correct then n else n-1
     turn word display' n'

check :: String -> String -> Char -> (Bool, String)
check word display c
  = (c `elem` word, [if x==c
          then c
          else y | (x,y) <- zip word display])