Added first example

Author: DzyubSpirit

Haskell/maybe.hs

@@ -0,0 +1,19 @@
+import Prelude hiding (Maybe(..), Functor, fmap, (<$>))
+
+data Maybe a = Just a | Nothing
+  deriving (Show)
+
+class Functor f where
+  fmap  :: (a -> b) -> f a -> f b
+  
+(<$>) :: Functor f => (a -> b) -> f a -> f b
+(<$>) = fmap
+infixl 4 <$>
+
+instance Functor Maybe where
+  fmap f (Just x) = Just $ f x
+  fmap _ Nothing  = Nothing
+
+main = do
+ print $ (* 2) <$> Just 5
+ print $ (* 2) <$> Nothing