to free or not to free

freeeeee.hs

-- so I can either have a convention on returning a bare bool value
-- out of this strangeness.
data AndF k = forall f. (AndF :<: f) => And (Free f Bool) (Free f Bool) (Bool -> k)


testProgram :: (AndF :<: f) => Free f Bool
testProgram = do
  asdf <- true .&& false
  hmmm <- false .&& true
  wat  <- pure asdf .&& pure hmmm
  return asdf

-- or, alternatively, I can return a value in the expression language,
-- which makes it easier to use the thing but complicates the type signatures
-- (and how do I get it out I guess??)

data AndF k = forall f. (AndF :<: f) => And (Free f Bool) (Free f Bool) (Free f Bool -> k)

testProgram :: (AndF :<: f) => Free f (Free f Bool)
testProgram = do
  asdf <- true .&& false
  hmmm <- false .&& true
  wat  <- asdf .&& hmmm
  return asdf
  
-- boilerplate stuff:


instance Functor AndF where
  fmap f (And a b k) = And a b (f . k)

(.&&) :: (AndF :<: f) => Free f Bool -> Free f Bool -> Free f Bool
a .&& b = Free . inj $ And a b Pure

true :: Functor f => Free f Bool
true = Pure True

false :: Functor f => Free f Bool
false = Pure False