-----------------------------------------------------------------------------
---
+-- |
-- Module : Control.Monad.ST.Lazy
-- Copyright : (c) The University of Glasgow 2001
--- License : BSD-style (see the file libraries/core/LICENSE)
+-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : non-portable (requires universal quantification for runST)
--
--- $Id: Lazy.hs,v 1.2 2001/07/03 11:37:49 simonmar Exp $
---
-- This module presents an identical interface to Control.Monad.ST,
-- but the underlying implementation of the state thread is lazy.
--
unsafeInterleaveST,
fixST,
- STRef.STRef,
- newSTRef, readSTRef, writeSTRef,
-
- STArray.STArray,
- newSTArray, readSTArray, writeSTArray, boundsSTArray,
- thawSTArray, freezeSTArray, unsafeFreezeSTArray,
-#ifdef __GLASGOW_HASKELL__
--- no 'good' reason, just doesn't support it right now.
- unsafeThawSTArray,
-#endif
-
ST.unsafeIOToST, ST.stToIO,
strictToLazyST, lazyToStrictST
import Prelude
-import qualified Data.STRef as STRef
-import Data.Array
-
#ifdef __GLASGOW_HASKELL__
import qualified Control.Monad.ST as ST
-import qualified GHC.Arr as STArray
import qualified GHC.ST
-import GHC.Base ( ($), ()(..) )
+import GHC.Base
import Control.Monad
-import Data.Ix
-import GHC.Prim
#endif
-#ifdef __HUGS__
-import qualified ST
-import Monad
-import Ix
-import Array
-import PrelPrim ( unST
- , mkST
- , PrimMutableArray
- , PrimArray
- , primNewArray
- , primReadArray
- , primWriteArray
- , primUnsafeFreezeArray
- , primSizeMutableArray
- , primSizeArray
- , primIndexArray
- )
-#endif
-
-
#ifdef __GLASGOW_HASKELL__
newtype ST s a = ST (State s -> (a, State s))
data State s = S# (State# s)
#endif
-#ifdef __HUGS__
-newtype ST s a = ST (s -> (a,s))
-#endif
-
instance Functor (ST s) where
fmap f m = ST $ \ s ->
let
{-# NOINLINE runST #-}
runST :: (forall s. ST s a) -> a
runST st = case st of ST the_st -> let (r,_) = the_st (S# realWorld#) in r
-#endif
-
-#ifdef __HUGS__
-runST :: (__forall s. ST s a) -> a
-runST st = case st of ST the_st -> let (r,_) = the_st realWorld in r
- where realWorld = error "runST: entered the RealWorld"
-#endif
fixST :: (a -> ST s a) -> ST s a
fixST m = ST (\ s ->
let
ST m_r = m r
- (r,s) = m_r s
+ (r,s') = m_r s
in
- (r,s))
-
--- ---------------------------------------------------------------------------
--- Variables
-
-newSTRef :: a -> ST s (STRef.STRef s a)
-readSTRef :: STRef.STRef s a -> ST s a
-writeSTRef :: STRef.STRef s a -> a -> ST s ()
-
-newSTRef = strictToLazyST . STRef.newSTRef
-readSTRef = strictToLazyST . STRef.readSTRef
-writeSTRef r a = strictToLazyST (STRef.writeSTRef r a)
-
--- --------------------------------------------------------------------------
--- Arrays
-
-newSTArray :: Ix ix => (ix,ix) -> elt -> ST s (STArray.STArray s ix elt)
-readSTArray :: Ix ix => STArray.STArray s ix elt -> ix -> ST s elt
-writeSTArray :: Ix ix => STArray.STArray s ix elt -> ix -> elt -> ST s ()
-boundsSTArray :: Ix ix => STArray.STArray s ix elt -> (ix, ix)
-thawSTArray :: Ix ix => Array ix elt -> ST s (STArray.STArray s ix elt)
-freezeSTArray :: Ix ix => STArray.STArray s ix elt -> ST s (Array ix elt)
-unsafeFreezeSTArray :: Ix ix => STArray.STArray s ix elt -> ST s (Array ix elt)
-
-#ifdef __GLASGOW_HASKELL__
-
-newSTArray ixs init = strictToLazyST (STArray.newSTArray ixs init)
-
-readSTArray arr ix = strictToLazyST (STArray.readSTArray arr ix)
-writeSTArray arr ix v = strictToLazyST (STArray.writeSTArray arr ix v)
-boundsSTArray arr = STArray.boundsSTArray arr
-thawSTArray arr = strictToLazyST (STArray.thawSTArray arr)
-freezeSTArray arr = strictToLazyST (STArray.freezeSTArray arr)
-unsafeFreezeSTArray arr = strictToLazyST (STArray.unsafeFreezeSTArray arr)
-unsafeThawSTArray arr = strictToLazyST (STArray.unsafeThawSTArray arr)
-#endif
-
-
-#ifdef __HUGS__
-newSTArray ixs elt = do
- { arr <- strictToLazyST (primNewArray (rangeSize ixs) elt)
- ; return (STArray ixs arr)
- }
-
-boundsSTArray (STArray ixs arr) = ixs
-readSTArray (STArray ixs arr) ix
- = strictToLazyST (primReadArray arr (index ixs ix))
-writeSTArray (STArray ixs arr) ix elt
- = strictToLazyST (primWriteArray arr (index ixs ix) elt)
-freezeSTArray (STArray ixs arr) = do
- { arr' <- strictToLazyST (primFreezeArray arr)
- ; return (Array ixs arr')
- }
-
-unsafeFreezeSTArray (STArray ixs arr) = do
- { arr' <- strictToLazyST (primUnsafeFreezeArray arr)
- ; return (Array ixs arr')
- }
-
-thawSTArray (Array ixs arr) = do
- { arr' <- strictToLazyST (primThawArray arr)
- ; return (STArray ixs arr')
- }
-
-primFreezeArray :: PrimMutableArray s a -> ST.ST s (PrimArray a)
-primFreezeArray arr = do
- { let n = primSizeMutableArray arr
- ; arr' <- primNewArray n arrEleBottom
- ; mapM_ (copy arr arr') [0..n-1]
- ; primUnsafeFreezeArray arr'
- }
- where
- copy arr arr' i = do { x <- primReadArray arr i; primWriteArray arr' i x }
- arrEleBottom = error "primFreezeArray: panic"
-
-primThawArray :: PrimArray a -> ST.ST s (PrimMutableArray s a)
-primThawArray arr = do
- { let n = primSizeArray arr
- ; arr' <- primNewArray n arrEleBottom
- ; mapM_ (copy arr arr') [0..n-1]
- ; return arr'
- }
- where
- copy arr arr' i = primWriteArray arr' i (primIndexArray arr i)
- arrEleBottom = error "primFreezeArray: panic"
+ (r,s'))
#endif
-- ---------------------------------------------------------------------------
case (m (S# s)) of (a, S# s') -> (# s', a #)
#endif
-#ifdef __HUGS__
-strictToLazyST :: ST.ST s a -> ST s a
-strictToLazyST m = ST $ \s ->
- let
- pr = unST m s
- r = fst pr
- s' = snd pr
- in
- (r, s')
-
-
-lazyToStrictST :: ST s a -> ST.ST s a
-lazyToStrictST (ST m) = mkST $ m
-#endif
-
unsafeInterleaveST :: ST s a -> ST s a
unsafeInterleaveST = strictToLazyST . ST.unsafeInterleaveST . lazyToStrictST
projects / ghc-base.git / blobdiff