chapter10.hs

import System.IO

act :: IO(Char,Char)
act = do x <- getChar
         getChar
         y <- getChar
         return (x,y)

getLine' :: IO String
getLine' = do x <- getChar
              if x == '\n' then
                return []
              else
                do xs <- getLine'
                   return (x:xs)

putStr' :: String -> IO()
putStr' [] = return ()
putStr' (x:xs) =  do putChar x
                     putStr xs

putStrLn' :: String -> IO ()
putStrLn' xs = do putStr' xs
                  putChar '\n'

strlen :: IO()
strlen = do putStr' "Enter a String: "
            xs <- getLine'
            putStr' "The string has "
            putStr' (show (length xs))
            putStrLn' " characters"

hangman :: IO()
hangman = do  putStrLn' "Enter a word: "
              word <- sgetLine
              putStrLn' "Guess: "
              play word

sgetLine :: IO String
sgetLine = do x <- getCh
              if x == '\n' then
                do putChar x
                   return []
              else
                do putChar '-'
                   xs <- sgetLine
                   return (x:xs)


getCh :: IO Char
getCh = do hSetEcho stdin False
           x <- getChar
           hSetEcho stdin True
           return x

play :: String -> IO()
play word =  do putStr' "? "
                guess <- getLine'
                if guess == word then
                   putStrLn' "You got it"
                else
                  do putStrLn' (match word guess)
                     play word

match :: String -> String -> String
match xs ys = [if x `elem` ys then x else '-' | x <- xs]