-- based on http://scsibug.com/2006/11/28/a-simple-game-with-statet/
-- by tphyahoo@gmail.com
module Main where
import System.Random
import Control.Monad.State
import Control.Exception

main = do answer <- getStdRandom (randomR (1,100)) -- think of a number
          putStrLn "I'm thinking of a number between 1 and 100, can you guess it?"
          guesses  StateT Int IO ()
guessSession answer =
    do g  do lift $ putStrLn "Too low"
                       guessSession answer
              GT -> do lift $ putStrLn "Too high"
                       guessSession answer
              EQ -> lift $ putStrLn "Got it!"

  where getInt =  getLine >>= readM "getInt, bad input"
        safeGetInt = handle ( \e -> do putStrLn "bad input, try again"
                                       safeGetInt  ) getInt


-- inspired (but not quite the same) as stuff in Neil Mitchell's "safe haskell" lib
-- http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Safe-0.1
readM msg s = case [x | (x,t) <- reads s, ("","")  return x
                     []  -> fail $ "Prelude.read: no parse, " ++ msg ++ ", on " ++ prefix
                     _   -> fail $ "Prelude.read: ambiguous parse, " ++ msg ++ ", on " ++ prefix
    where
        prefix = '\"' : a ++ if null b then "\"" else "..."
            where (a,b) = splitAt 10 s