starman-rnd.hs

import System.Random

getRandomWord :: [String] -> IO String
getRandomWord words = 
  do n <- randomRIO (0, min 0 ((length words) - 1))
     return $ words !! 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])

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'

starmanBasic :: String -> Int -> IO ()
starmanBasic word n = turn word ['-' | x <- word] n

starmanWords :: [String]
starmanWords = ["haskell", "monad", "functor", "currying"]

starman :: IO ()
starman = 
  do word <- getRandomWord starmanWords
     starmanBasic word 6