-- data Maybe (a) where {
--     Nothing : Maybe (a)
--     Just : a -> Maybe (a)
--     };

-- fmap : (a -> b) -> Maybe (a) -> Maybe (b) ;
-- fmap f ma = case ma of {
--     Nothing => Nothing ;
--     Just a => Just (f a) ;
-- };

-- pure : a -> Maybe (a) ;
-- pure x = Just x ;

-- ap mf ma = case mf of {
--     Just f => case ma of {
--         Nothing => Nothing;
--         Just a => Just (f a);
--     };
--     Nothing => Nothing;
-- };
    
-- return = pure;

-- bind ma f = case ma of {
--     Nothing => Nothing ;
--     Just a => f a ;
-- };