-- Class Declarations
class {- record -}  ToMaybe m where {
  toMaybe :: m a -> Maybe a;
};

class {- variant -} MyMonad m => ContMonad m r | m -> r where {
  callCC :: ((a -> m b) -> m a) -> m a;
  mkCont :: ((a -> r) -> r) -> m a;
};

class {- variant -} MyMonad m where {
  unit :: a -> m a;
  bind :: m b -> (b -> m a) -> m a;
};

class {- record -}  ToCont m r | m -> r where {
  toCont :: m a -> (a -> r) -> r;
};

-- Data Declarations
data Data''0 r a = 
  C''unit''0 a | 
  forall b . C''bind''0 (Data''0 r b) (b -> Data''0 r a) | 
  forall c . C''callCC''0 ((a -> Data''0 r c) -> Data''0 r a) | 
  C''mkCont''0 ((a -> v1) -> v1);

{-
-- using GADT-style declaration
data Data''0 r a where {
  C''unit''0 :: a -> Data''0 r a;
  C''bind''0 :: Data''0 r b -> (b -> Data''0 r a) -> Data''0 r a;
  C''callCC''0 :: ((a -> Data''0 r c) -> Data''0 r a) -> Data''0 r a;
  C''mkCont''0 :: ((a -> v1) -> v1) -> Data''0 r a;
};
-}

-- Instance Declarations
instance ToCont (Data''0 r) r where {
  toCont (C''unit''0 a) = \ c -> c a;
  toCont (C''bind''0 m k) = \ c -> toCont m (\ a -> toCont (k a) c);
  toCont (C''mkCont''0 m) = m;
  toCont (C''callCC''0 h) = \ c -> let {k = \ a -> mkCont (\ d -> c a);} in toCont (h k) c;
};

instance MyMonad (Data''0 r) where {
  unit = C''unit''0;
  bind = C''bind''0;
};

instance ContMonad (Data''0 r) r where {
  callCC = C''callCC''0;
  mkCont = C''mkCont''0;
};

-- Cast(?) Declarations
id''0 :: Data''0 r Int -> Data''0 r Int;
id''0 x = x;

-- BindGroups
bar = toCont (id''0 (callCC (\ k -> bind (unit 1) (\ x -> k 2))));