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{-# LANGUAGE FlexibleInstances,MultiParamTypeClasses #-}
module Control.Throws where
import Control.Exception.Extensible
import Control.Monad.Identity
import Control.Monad.Reader
import Control.Monad.State
class Throws e m where
throwException :: e -> m a
instance Exception e => Throws e Identity where
throwException = throw
{-instance MonadError e m => Throws e m where
throwException = throwError-}
instance Throws e (Either e) where
throwException = Left
instance Exception e => Throws e IO where
throwException = throw
instance Throws e m => Throws e (StateT s m) where
throwException x = StateT (\s -> throwException x)
instance Throws e m => Throws e (ReaderT s m) where
throwException x = ReaderT (\s -> throwException x)
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