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module Fix where
import Control.Monad.IO.Class (liftIO)
import Control.Monad.Trans.Maybe
import Control.Monad
isValid :: String -> Bool
isValid v = '!' `elem` v
maybeExcite :: MaybeT IO String
maybeExcite = do
v <- liftIO getLine
guard $ isValid v
return v
doExcite :: IO ()
doExcite = do
putStrLn "say something excite!"
excite <- runMaybeT maybeExcite
case excite of
Nothing -> putStrLn "MOAR EXCITE"
Just e ->
putStrLn
("Good, was very excite: " ++ e)
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