-- |
-- Module: Control.ContStuff.Transformers
-- Copyright: (c) 2010 Ertugrul Soeylemez
-- License: BSD3
-- Maintainer: Ertugrul Soeylemez
-- Stability: experimental
--
-- This package provides contstuff transformer class instances for the
-- monad transformers from the transformers package as well as
-- transformers class instances for the monad transformers from
-- contstuff. This makes using both transformer libraries in a single
-- project much more convenient as you get along with a single set of
-- lifting functions.
{-# LANGUAGE TypeFamilies #-}
module Control.ContStuff.Transformers
( -- * Exported from transformers
MonadIO(..),
MonadTrans,
liftT
)
where
import qualified Control.Monad.Trans.Class as T
import qualified Control.ContStuff.Trans as C
import Control.ContStuff.Classes as C
import Control.Monad.IO.Class (MonadIO(..))
import Control.Monad.Trans.Class (MonadTrans)
import Data.Monoid
import qualified Control.Monad.Trans.Cont as T (ContT)
import qualified Control.Monad.Trans.Error as T (Error, ErrorT)
import qualified Control.Monad.Trans.List as T (ListT)
import qualified Control.Monad.Trans.RWS.Lazy as T (RWST)
import qualified Control.Monad.Trans.RWS.Strict as TS (RWST)
import qualified Control.Monad.Trans.Reader as T (ReaderT)
import qualified Control.Monad.Trans.State.Lazy as T (StateT)
import qualified Control.Monad.Trans.State.Strict as TS (StateT)
import qualified Control.Monad.Trans.Writer.Lazy as T (WriterT)
import qualified Control.Monad.Trans.Writer.Strict as TS (WriterT)
-- ====================== --
-- Interface to monads-tf --
-- ====================== --
-- | Interface to 'Control.Monad.Trans.lift'.
liftT :: (Monad m, MonadTrans t) => m a -> t m a
liftT = T.lift
-- ============================================== --
-- monads-tf instances for ContStuff transformers --
-- ============================================== --
instance MonadTrans (C.ChoiceT r i) where lift = C.lift
instance MonadTrans (C.ContT r) where lift = C.lift
instance MonadTrans (C.EitherT r e) where lift = C.lift
instance MonadTrans (C.MaybeT r) where lift = C.lift
instance MonadTrans (C.StateT r s) where lift = C.lift
instance MonadIO m => MonadIO (C.ChoiceT r i m) where liftIO = liftT . liftIO
instance MonadIO m => MonadIO (C.ContT r m) where liftIO = liftT . liftIO
instance MonadIO m => MonadIO (C.EitherT r e m) where liftIO = liftT . liftIO
instance MonadIO m => MonadIO (C.MaybeT r m) where liftIO = liftT . liftIO
instance MonadIO m => MonadIO (C.StateT r s m) where liftIO = liftT . liftIO
-- ============================================== --
-- ContStuff instances for monads-tf transformers --
-- ============================================== --
instance Transformer (T.ContT r) where lift = liftT
instance T.Error e => Transformer (T.ErrorT e) where lift = liftT
instance Transformer (T.ListT) where lift = liftT
instance Monoid w => Transformer (T.RWST r w s) where lift = liftT
instance Monoid w => Transformer (TS.RWST r w s) where lift = liftT
instance Transformer (T.ReaderT r) where lift = liftT
instance Transformer (T.StateT s) where lift = liftT
instance Transformer (TS.StateT s) where lift = liftT
instance Monoid w => Transformer (T.WriterT w) where lift = liftT
instance Monoid w => Transformer (TS.WriterT w) where lift = liftT
instance (LiftBase m, Monad m) => LiftBase (T.ContT r m) where
type Base (T.ContT r m) = Base m; base = lift . base
instance (T.Error e, LiftBase m, Monad m) => LiftBase (T.ErrorT e m) where
type Base (T.ErrorT e m) = Base m; base = lift . base
instance (LiftBase m, Monad m) => LiftBase (T.ListT m) where
type Base (T.ListT m) = Base m; base = lift . base
instance (LiftBase m, Monad m, Monoid w) => LiftBase (T.RWST r w s m) where
type Base (T.RWST r w s m) = Base m; base = lift . base
instance (LiftBase m, Monad m, Monoid w) => LiftBase (TS.RWST r w s m) where
type Base (TS.RWST r w s m) = Base m; base = lift . base
instance (LiftBase m, Monad m) => LiftBase (T.ReaderT r m) where
type Base (T.ReaderT r m) = Base m; base = lift . base
instance (LiftBase m, Monad m) => LiftBase (T.StateT s m) where
type Base (T.StateT s m) = Base m; base = lift . base
instance (LiftBase m, Monad m) => LiftBase (TS.StateT s m) where
type Base (TS.StateT s m) = Base m; base = lift . base
instance (LiftBase m, Monad m, Monoid w) => LiftBase (T.WriterT w m) where
type Base (T.WriterT w m) = Base m; base = lift . base
instance (LiftBase m, Monad m, Monoid w) => LiftBase (TS.WriterT w m) where
type Base (TS.WriterT w m) = Base m; base = lift . base