{-# LANGUAGE MultiParamTypeClasses
,FunctionalDependencies
,FlexibleInstances
#-}
{-
This file is part of funsat.
funsat is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
funsat is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with funsat. If not, see .
Copyright 2008 Denis Bueno
-}
-- | Idea from
module Control.Monad.MonadST where
import Control.Monad.ST
import Data.STRef
-- | A type class for monads that are able to perform `ST' actions.
class (Monad m) => MonadST s m | m -> s where
liftST :: ST s a -> m a
instance MonadST s (Control.Monad.ST.ST s) where
liftST = id
readSTRef :: MonadST s m => STRef s a -> m a
readSTRef = liftST . Data.STRef.readSTRef
writeSTRef :: MonadST s m => STRef s a -> a -> m ()
writeSTRef r x = liftST (Data.STRef.writeSTRef r x)
newSTRef :: MonadST s m => a -> m (STRef s a)
newSTRef = liftST . Data.STRef.newSTRef
modifySTRef :: MonadST s m => STRef s a -> (a -> a) -> m ()
modifySTRef r f = liftST (Data.STRef.modifySTRef r f)