X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Control%2FMonad%2FST.hs;h=008dafc0b9f749923a65dd1e3ac662fa1a07734f;hb=57e487c332d1f428ee5ff85dbb32730d25a58235;hp=02d8d15d76530ec9f2d85f4a6d2370db1e71d568;hpb=746ef6a7fd71bb1e9ebe3cd107c5f9f79f3b7a68;p=ghc-base.git

diff --git a/Control/Monad/ST.hs b/Control/Monad/ST.hs
index 02d8d15..008dafc 100644
--- a/Control/Monad/ST.hs
+++ b/Control/Monad/ST.hs
@@ -2,27 +2,32 @@
 -- |
 -- Module      :  Control.Monad.ST
 -- 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   :  experimental
 -- Portability :  non-portable (requires universal quantification for runST)
 --
--- The State Transformer Monad, ST
+-- This library provides support for /strict/ state threads, as
+-- described in the PLDI \'94 paper by John Launchbury and Simon Peyton
+-- Jones /Lazy State Threads/.
 --
 -----------------------------------------------------------------------------
 
 module Control.Monad.ST
-      (
-	ST                  -- abstract, instance of Functor, Monad, Typeable.
-      , runST		    -- :: (forall s. ST s a) -> a
-      , fixST		    -- :: (a -> ST s a) -> ST s a
-      , unsafeInterleaveST  -- :: ST s a -> ST s a
+  (
+	-- * The 'ST' Monad
+	ST,		-- abstract, instance of Functor, Monad, Typeable.
+	runST,		-- :: (forall s. ST s a) -> a
+	fixST,		-- :: (a -> ST s a) -> ST s a
 
-      , unsafeIOToST	    -- :: IO a -> ST s a
+	-- * Unsafe operations
+	unsafeInterleaveST,  	-- :: ST s a -> ST s a
+	unsafeIOToST,		-- :: IO a -> ST s a
 
-      , RealWorld	    -- abstract
-      , stToIO		    -- :: ST RealWorld a -> IO a
+	-- * Converting 'ST' to 'IO'
+	RealWorld,		-- abstract
+	stToIO			-- :: ST RealWorld a -> IO a
       ) where
 
 import Prelude
@@ -30,6 +35,18 @@ import Prelude
 import Control.Monad.Fix
 import Data.Dynamic
 
+#ifdef __HUGS__
+import Hugs.ST
+import qualified Hugs.LazyST as LazyST
+
+fixST :: (a -> ST s a) -> ST s a
+fixST f = LazyST.lazyToStrictST (LazyST.fixST (LazyST.strictToLazyST . f))
+
+unsafeInterleaveST :: ST s a -> ST s a
+unsafeInterleaveST =
+    LazyST.lazyToStrictST . LazyST.unsafeInterleaveST . LazyST.strictToLazyST
+#endif
+
 #ifdef __GLASGOW_HASKELL__
 import GHC.ST
 import GHC.Base		( unsafeCoerce#, RealWorld )