21 lines
406 B
Haskell
21 lines
406 B
Haskell
import qualified Data.Map as M
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import Data.Maybe (isJust)
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mapSample :: M.Map String Int
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mapSample =
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M.fromList
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[ ("alpha", 1)
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, ("beta", 2)
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, ("gamma", 3)
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, ("delta", 4)
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, ("epsilon", 5)
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, ("zeta", 6)
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]
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maybeValue :: String -> Maybe Int
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maybeValue = flip M.lookup mapSample
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main :: IO ()
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main =
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print $ sequence $ filter isJust (maybeValue <$> ["beta", "delta", "zeta"])
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