functor.hs

-- instance Functor ((->) r) where
--   fmap f g = (\ x -> f (g x))

-- instance Functor ((->) r) where
--   fmap = (.)

-- functor laws

-- first law
-- isntance Fucntor Maybe where
--   famp f (Just x) = Just (f x)
--   fmap f Nothing = Nothing

-- second law
data CMaybe a = CNothing | CJust Int a deriving (Show)

instance Functor CMaybe where
  fmap f CNothing = CNothing
  fmap f (CJust counter x) = CJust (succ counter) (f x)