diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,26 @@ +Copyright (c) Henning Thielemann +All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions +are met: +1. Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. +2. Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in the + documentation and/or other materials provided with the distribution. +3. Neither the name of the University nor the names of its contributors + may be used to endorse or promote products derived from this software + without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +SUCH DAMAGE. diff --git a/Setup.lhs b/Setup.lhs new file mode 100644 --- /dev/null +++ b/Setup.lhs @@ -0,0 +1,3 @@ +#! /usr/bin/env runhaskell +> import Distribution.Simple +> main = defaultMain diff --git a/data-ref.cabal b/data-ref.cabal new file mode 100644 --- /dev/null +++ b/data-ref.cabal @@ -0,0 +1,41 @@ +Name: data-ref +Version: 0.0 +License: BSD3 +License-File: LICENSE +Author: Henning Thielemann +Maintainer: Henning Thielemann +Category: Data +Homepage: http://www.haskell.org/haskellwiki/Mutable_variable +Synopsis: Unify STRef and IORef in plain Haskell 98 +Description: + This package provides a unique interface to both STRef and IORef. + The advantage is that it is plain Haskell 98, + the disadvantage is that we cannot use STRef and IORef as they are. + . + Our approach works with Haskell 98 single parameter type classes + because we use an explicit dictionary, + and we do not pass the references around but their accessors. + . + Similar packages: @reference@, @ref-mtl@, @ref-fd@, @ref-tf@. +Tested-With: GHC==7.4.2 +Cabal-Version: >=1.6 +Build-Type: Simple +Source-Repository head + type: darcs + location: http://code.haskell.org/~thielema/data-ref/ + +Source-Repository this + type: darcs + location: http://code.haskell.org/~thielema/data-ref/ + tag: 0.0 + +Library + Build-Depends: + transformers >=0.2 && <0.4, + stm >=2.2 && <2.4, + base >=2 && <5 + + GHC-Options: -Wall + Hs-Source-Dirs: src + Exposed-Modules: + Data.Ref diff --git a/src/Data/Ref.hs b/src/Data/Ref.hs new file mode 100644 --- /dev/null +++ b/src/Data/Ref.hs @@ -0,0 +1,84 @@ +{- +Following an idea by Dominique Devriese: + +-} +module Data.Ref where + +import Data.IORef (newIORef, readIORef, writeIORef, ) +import Data.STRef (newSTRef, readSTRef, writeSTRef, ) +import Control.Concurrent.STM.TVar (newTVar, readTVar, writeTVar, ) +import Control.Concurrent.STM (STM, ) +import Control.Monad.ST (ST) +import Control.Monad (liftM) + +import qualified Control.Monad.Trans.Class as MT +import qualified Control.Monad.IO.Class as MIO + +import qualified Control.Monad.Trans.RWS.Lazy as MRWSL +import qualified Control.Monad.Trans.RWS.Strict as MRWSS +import qualified Control.Monad.Trans.State.Lazy as MSL +import qualified Control.Monad.Trans.State.Strict as MSS +import qualified Control.Monad.Trans.Writer.Lazy as MWL +import qualified Control.Monad.Trans.Writer.Strict as MWS +import qualified Control.Monad.Trans.Cont as MC +import qualified Control.Monad.Trans.Error as ME +import qualified Control.Monad.Trans.Maybe as MM +import qualified Control.Monad.Trans.Reader as MR +import qualified Control.Monad.Trans.Identity as MI +import Data.Monoid (Monoid) + +import Prelude hiding (read) + + +data T m a = Cons { write :: a -> m (), read :: m a } + +modify :: C m => T m a -> (a -> a) -> m () +modify ref f = write ref . f =<< read ref + +newCons :: C m => + (a -> m ref) -> (ref -> a -> m ()) -> (ref -> m a) -> + a -> m (T m a) +newCons nw wr rd = liftM (\r -> Cons (wr r) (rd r)) . nw + + +class Monad m => C m where + new :: a -> m (T m a) + +instance C IO where + new = newCons newIORef writeIORef readIORef + +instance C (ST s) where + new = newCons newSTRef writeSTRef readSTRef + +instance C STM where + new = newCons newTVar writeTVar readTVar + + +{- +mapMonad :: (Monad m, Monad n) => (forall b. m b -> n b) -> T m a -> T n a +mapMonad lft (Cons wr rd) = Cons (lft . wr) (lft rd) +-} + +lift :: (Monad m, MT.MonadTrans t) => T m a -> T (t m) a +lift (Cons wr rd) = Cons (MT.lift .wr) (MT.lift rd) + +liftIO :: (MIO.MonadIO m) => T IO a -> T m a +liftIO (Cons wr rd) = Cons (MIO.liftIO .wr) (MIO.liftIO rd) + +newLifted :: (C m, MT.MonadTrans t) => a -> t m (T (t m) a) +newLifted = MT.lift . liftM lift . new + + +instance C m => C (MI.IdentityT m) where new = newLifted + +instance C m => C (MM.MaybeT m) where new = newLifted +instance (ME.Error e, C m) => C (ME.ErrorT e m) where new = newLifted + +instance C m => C (MC.ContT r m) where new = newLifted +instance C m => C (MR.ReaderT r m) where new = newLifted +instance C m => C (MSS.StateT s m) where new = newLifted +instance C m => C (MSL.StateT s m) where new = newLifted +instance (Monoid w, C m) => C (MWS.WriterT w m) where new = newLifted +instance (Monoid w, C m) => C (MWL.WriterT w m) where new = newLifted +instance (Monoid w, C m) => C (MRWSS.RWST r w s m) where new = newLifted +instance (Monoid w, C m) => C (MRWSL.RWST r w s m) where new = newLifted