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danyx23/MyMaybe.hs

Created May 2, 2016 20:59
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MyMaybe.hs
data MyMaybe a =
MyNothing
| MyJust a
deriving (Show)
instance Functor MyMaybe where
fmap _ MyNothing = MyNothing
fmap f (MyJust a) = MyJust (f a)
maybeAddFive :: MyMaybe Int -> MyMaybe Int
maybeAddFive =
fmap (+ 5)
main :: IO ()
main = do
print $ maybeAddFive $ MyJust 2
print $ maybeAddFive MyNothing
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