20 lines
292 B
Haskell
20 lines
292 B
Haskell
module Maybe where
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--
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-- 1
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--
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isJust :: Maybe a -> Bool
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isJust (Just _) = True
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isJust Nothing = False
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isNothing :: Maybe a -> Bool
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isNothing (Just _) = False
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isNothing Nothing = True
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--
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-- 2
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--
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mayybee :: b -> (a -> b) -> Maybe a -> b
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mayybee v f Nothing = b
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mayybee v f (Maybe x) = f x
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