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@petermarks
Created September 20, 2010 20:59
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Number guesser iterations
module Main where
import Data.Char
import Data.List
data Guess
= Guess Int Guess Guess
| GiveUp
| Done
main = do
getLine
guess (guesses 1 100)
guess :: Guess -> IO ()
guess (Guess n lower higher) = do
print n
response <- getLine
guess $ nextGuess response lower higher
guess _ = return ()
nextGuess :: String -> Guess -> Guess -> Guess
nextGuess response lower higher
| "high" `isInfixOf` r = lower
| "low" `isInfixOf` r = higher
| otherwise = Done
where
r = map toLower response
guesses :: Int -> Int -> Guess
guesses lo hi | lo > hi = GiveUp
| otherwise = Guess mid (guesses lo (mid - 1)) (guesses (mid + 1) hi)
where
mid = (lo + hi) `div` 2
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