module TypeClass

-- experiment on one option for typeclass (we don't have record yet)

-- we need a bit more than this, but
data Monad : (U -> U) -> U where
  MkMonad : { M : U -> U } ->
            (bind : {A B : U} -> (M A) -> (A -> M B) -> M B) ->
            Monad M

data Maybe : U -> U where
  Just    : {A : U} -> A -> Maybe A
  Nothing : {A : U} -> Maybe A


-- NEXT trying to get this to work. An equivalence is not found in pattern
-- matching

-- [instance]
MaybeMonad : Monad Maybe
-- Agda case lambda might be nice..
-- The {Maybe} isn't solved in type for the case
MaybeMonad = MkMonad {Maybe} (\ {A} ma amb =>
  case ma of
      Nothing => Nothing
      -- It doesn't discover pat$5 is A during pattern matching
      -- oh, but var 0 value is var5
      Just a => amb a)