reference (empty) → 0.1

raw patch · 4 files changed

+102/−0 lines, 4 filesdep +basedep +stmsetup-changed

Dependencies added: base, stm

Files

• Data/Reference.hs +62/−0
• LICENSE +19/−0
• Setup.hs +2/−0
• reference.cabal +19/−0

@@ -0,0 +1,62 @@+{-# LANGUAGE MultiParamTypeClasses #-}+{- |+Module      : $Header$+Description : Class connecting mutable variables and monads they exists in.+Copyright   : (c) Maciej Piechotka+License     : MIT++Stability   : none+Portability : portable++Reference is class which generalizes references and monads they exists in. It means that IORef, STRef and others can be accessed by common interface.+-}+module Data.Reference+  (+    Reference(..),+  )+where+import Control.Concurrent.MVar+import Control.Concurrent.STM+import Control.Monad.ST+import Data.IORef+import Data.STRef++-- | Class connecting mutable variable and monad it exists in.+class Monad m => Reference r m where+    -- | Create new reference.+    newRef :: a -- ^ An initial value+           -> m (r a)+    -- | Reads a reference.+    readRef :: r a -- ^ Reference+            -> m a+    -- | Write to reference.+    writeRef :: r a -- ^ Reference+             -> a -- ^ New value+             -> m ()+    -- | Modify the reference. Default implementation is provided but it MUST+    -- be overloaded if the reference is atomic to provide an atomic write.+    modifyRef :: r a -- ^ Reference+              -> (a -> m (a, b)) -- ^ Computation+              -> m b -- ^ Result of computation+    modifyRef r f = readRef r >>= f >>= \(a, b) -> writeRef r a >> return b++instance Reference IORef IO where+    newRef = newIORef+    readRef = readIORef+    writeRef = writeIORef++instance Reference (STRef s) (ST s) where+    newRef = newSTRef+    readRef = readSTRef+    writeRef = writeSTRef++instance Reference MVar IO where+    newRef = newMVar+    readRef = readMVar+    writeRef = putMVar+    modifyRef = modifyMVar++instance Reference TVar STM where+    newRef = newTVar+    readRef = readTVar+    writeRef = writeTVar

@@ -0,0 +1,19 @@+Copyright (c) 2010 Maciej Piechotka++Permission is hereby granted, free of charge, to any person obtaining a copy+of this software and associated documentation files (the "Software"), to deal+in the Software without restriction, including without limitation the rights+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell+copies of the Software, and to permit persons to whom the Software is+furnished to do so, subject to the following conditions:++The above copyright notice and this permission notice shall be included in+all copies or substantial portions of the Software.++THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN+THE SOFTWARE.

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

@@ -0,0 +1,19 @@+Name:                reference+Version:             0.1+Synopsis:            A class for references in Haskell+Description:         Reference is class which generalizes references and monads                      they exists in. It means that IORef, STRef and others can+                     be accessed by common interface.+License:             MIT+License-file:        LICENSE+Author:              Maciej Piechotka+Maintainer:          uzytkownik2@gmail.com+Copyright:           2010 (c) Maciej Piechotka+Category:            Control, Data+Build-type:          Simple+Cabal-version:       >=1.4++Library+  Exposed-modules:   Data.Reference+  Build-depends:     base >= 4 && < 5,+                     stm+