module Control.Monad.Except.Extras
( MonadError1 (..)
) where
#if __GLASGOW_HASKELL__ < 710
import Data.Monoid
#endif
import Control.Monad.Trans.Class
import Control.Monad.Except
import qualified Control.Monad.Trans.Except as E
import qualified Control.Monad.Trans.Identity as I
import qualified Control.Monad.Trans.List as L
import qualified Control.Monad.Trans.Maybe as M
import qualified Control.Monad.Trans.Reader as R
import qualified Control.Monad.Trans.RWS.Lazy as RWS.Lazy
import qualified Control.Monad.Trans.RWS.Strict as RWS.Strict
import qualified Control.Monad.Trans.State.Lazy as S.Lazy
import qualified Control.Monad.Trans.State.Strict as S.Strict
import qualified Control.Monad.Trans.Writer.Lazy as W.Lazy
import qualified Control.Monad.Trans.Writer.Strict as W.Strict
class MonadTrans t => MonadError1 t where
catchError1 :: MonadError e m => t m a -> (e -> t m a) -> t m a
instance MonadError1 (E.ExceptT e) where
catchError1 m h = E.ExceptT $ catchError (E.runExceptT m) (E.runExceptT . h)
instance MonadError1 I.IdentityT where
catchError1 = I.liftCatch catchError
instance MonadError1 L.ListT where
catchError1 = L.liftCatch catchError
instance MonadError1 M.MaybeT where
catchError1 = M.liftCatch catchError
instance MonadError1 (R.ReaderT r) where
catchError1 = R.liftCatch catchError
instance Monoid w => MonadError1 (RWS.Lazy.RWST r w s) where
catchError1 = RWS.Lazy.liftCatch catchError
instance Monoid w => MonadError1 (RWS.Strict.RWST r w s) where
catchError1 = RWS.Strict.liftCatch catchError
instance MonadError1 (S.Lazy.StateT s) where
catchError1 = S.Lazy.liftCatch catchError
instance MonadError1 (S.Strict.StateT s) where
catchError1 = S.Strict.liftCatch catchError
instance Monoid w => MonadError1 (W.Lazy.WriterT w) where
catchError1 = W.Lazy.liftCatch catchError
instance Monoid w => MonadError1 (W.Strict.WriterT w) where
catchError1 = W.Strict.liftCatch catchError