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-- Desugarer outputs of this program when compiled with and without -XStrict
-- should be the same because this program has only one binder (`a` in function
-- `primitive`), but the binder is annotated with a laziness annotation, so
-- -XStrict should have no effect on that binder.
--
-- Derived methods are also effected by -XStrict, but in our case we derive via
-- GND which just generates coercions like
--
-- instance Functor m => Functor (StateT s m) where
-- fmap
-- = coerce
-- @(forall (a_aJ2 :: TYPE LiftedRep) (b_aJ3 :: TYPE LiftedRep).
-- a_aJ2 -> b_aJ3
-- -> StateT s_aDW m_aDX a_aJ2 -> StateT s_aDW m_aDX b_aJ3)
-- @(forall (a_aJ2 :: TYPE LiftedRep) (b_aJ3 :: TYPE LiftedRep).
-- a_aJ2 -> b_aJ3
-- -> StateT s_aDW m_aDX a_aJ2 -> StateT s_aDW m_aDX b_aJ3)
-- fmap
--
-- So really -XStrict shouldn't have any effect on this program.
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UnboxedTuples #-}
module K where
import qualified Control.Monad.State.Strict as S
import Control.Monad.Trans
import GHC.Exts
class Monad m => PrimMonad m where
type PrimState m
primitive :: (State# (PrimState m) -> (# State# (PrimState m), a #)) -> m a
newtype StateT s m a = StateT (S.StateT s m a)
deriving (Functor, Applicative, Monad, MonadTrans)
instance PrimMonad m => PrimMonad (StateT s m) where
type PrimState (StateT s m) = PrimState m
primitive ~a = lift (primitive a) ; {-# INLINE primitive #-}
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