10 lines
322 B
Haskell
10 lines
322 B
Haskell
class Monad m => Logger m where
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write :: String -> m ()
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instance Logger IO where write = putStr
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instance a ~ String => Logger (Writer a) where write = tell
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verbose2 f x y = write (show x ++ " " ++
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show y ++ " ==> " ++
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show res ++ "\n") >> return res
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where res = f x y
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