/usr/lib/hugs/packages/stm/Control/Concurrent/STM/TArray.hs is in libhugs-stm-bundled 98.200609.21-5.3ubuntu1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 | {-# OPTIONS -fglasgow-exts #-}
-----------------------------------------------------------------------------
-- |
-- Module : Control.Concurrent.STM.TArray
-- Copyright : (c) The University of Glasgow 2005
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
-- Portability : non-portable (requires STM)
--
-- TArrays: transactional arrays, for use in the STM monad
--
-----------------------------------------------------------------------------
module Control.Concurrent.STM.TArray (
TArray
) where
import Control.Monad (replicateM)
import Data.Array (Array, bounds)
import Data.Array.Base (listArray, arrEleBottom, unsafeAt, MArray(..))
import Data.Ix (rangeSize)
import Control.Concurrent.STM.TVar (TVar, newTVar, readTVar, writeTVar)
import Control.Sequential.STM (STM)
-- |TArray is a transactional array, supporting the usual 'MArray'
-- interface for mutable arrays.
--
-- It is currently implemented as @Array ix (TVar e)@,
-- but it may be replaced by a more efficient implementation in the future
-- (the interface will remain the same, however).
--
newtype TArray i e = TArray (Array i (TVar e))
instance MArray TArray e STM where
getBounds (TArray a) = return (bounds a)
newArray b e = do
a <- replicateM (rangeSize b) (newTVar e)
return $ TArray (listArray b a)
newArray_ b = do
a <- replicateM (rangeSize b) (newTVar arrEleBottom)
return $ TArray (listArray b a)
unsafeRead (TArray a) i = readTVar $ unsafeAt a i
unsafeWrite (TArray a) i e = writeTVar (unsafeAt a i) e
|