20 lines
334 B
Haskell
20 lines
334 B
Haskell
{-# LANGUAGE LambdaCase #-}
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import Data.Char
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letters = \case
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2 -> "ABC"
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3 -> "DEF"
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4 -> "GHI"
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5 -> "JKL"
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6 -> "MNO"
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7 -> "PQRS"
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8 -> "TUV"
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9 -> "WXYZ"
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_ -> []
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main :: IO ()
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main = interact $ unlines . possibleWords . digitsOf
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where
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possibleWords = mapM letters
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digitsOf = map digitToInt . filter isDigit
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