    {-# LANGUAGE Safe #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Data.STRef.Lazy
    -- Copyright   :  (c) The University of Glasgow 2001
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  experimental
    -- Portability :  non-portable (uses Control.Monad.ST.Lazy)
    --
    -- Mutable references in the lazy ST monad.
    --
    -----------------------------------------------------------------------------

    module Data.STRef.Lazy (
            -- * STRefs
            ST.STRef,       -- abstract
            newSTRef,
            readSTRef,
            writeSTRef,
            modifySTRef
     ) where

    import Control.Monad.ST.Lazy
    import qualified Data.STRef as ST

    newSTRef    :: a -> ST s (ST.STRef s a)
    readSTRef   :: ST.STRef s a -> ST s a
    writeSTRef  :: ST.STRef s a -> a -> ST s ()
    modifySTRef :: ST.STRef s a -> (a -> a) -> ST s ()

    newSTRef :: forall a s. a -> ST s (STRef s a)
    newSTRef        = ST s (STRef s a) -> ST s (STRef s a)
    forall s a. ST s a -> ST s a
    strictToLazyST (ST s (STRef s a) -> ST s (STRef s a))
    -> (a -> ST s (STRef s a)) -> a -> ST s (STRef s a)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . a -> ST s (STRef s a)
    forall a s. a -> ST s (STRef s a)
    ST.newSTRef
    readSTRef :: forall s a. STRef s a -> ST s a
    readSTRef       = ST s a -> ST s a
    forall s a. ST s a -> ST s a
    strictToLazyST (ST s a -> ST s a) -> (STRef s a -> ST s a) -> STRef s a -> ST s a
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . STRef s a -> ST s a
    forall s a. STRef s a -> ST s a
    ST.readSTRef
    writeSTRef :: forall s a. STRef s a -> a -> ST s ()
    writeSTRef  STRef s a
    r a
    a = ST s () -> ST s ()
    forall s a. ST s a -> ST s a
    strictToLazyST (STRef s a -> a -> ST s ()
    forall s a. STRef s a -> a -> ST s ()
    ST.writeSTRef STRef s a
    r a
    a)
    modifySTRef :: forall s a. STRef s a -> (a -> a) -> ST s ()
    modifySTRef STRef s a
    r a -> a
    f = ST s () -> ST s ()
    forall s a. ST s a -> ST s a
    strictToLazyST (STRef s a -> (a -> a) -> ST s ()
    forall s a. STRef s a -> (a -> a) -> ST s ()
    ST.modifySTRef STRef s a
    r a -> a
    f)