Functor hs

F.hs

module F where 

data Mappable a = A a | B a deriving (Show, Eq)

instance Functor Mappable where
    fmap f (A x) = A (f x)
    fmap f (B x) = B (f x)
   
-- Usage
a = A 3

main = do
    let resultA = fmap (+ 2) a
        resultB = (+ 2) <$> a
    print resultA
    print resultB
    print $ if resultA == resultB then "Equal!" else "Not Equal"