X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FIORef.hs;h=1b4b11029374f999a41941bef109fe6e0009582e;hb=b00868d3e62b6f00af6a2d71cf1d35087c832b85;hp=527e20a9b46e54d019b57f60dc04ebd810029648;hpb=a5f7dcaa3ebb00c8e6237f62b08ad9c2f65cfda7;p=ghc-base.git

diff --git a/Data/IORef.hs b/Data/IORef.hs
index 527e20a..1b4b110 100644
--- a/Data/IORef.hs
+++ b/Data/IORef.hs
@@ -14,27 +14,27 @@
 
 module Data.IORef
   ( 
-	-- * IORefs
-	IORef,		      -- abstract, instance of: Eq, Typeable
-	newIORef,	      -- :: a -> IO (IORef a)
-        readIORef,	      -- :: IORef a -> IO a
-        writeIORef,	      -- :: IORef a -> a -> IO ()
-	modifyIORef,	      -- :: IORef a -> (a -> a) -> IO ()
-	atomicModifyIORef,    -- :: IORef a -> (a -> (a,b)) -> IO b
+        -- * IORefs
+        IORef,                -- abstract, instance of: Eq, Typeable
+        newIORef,             -- :: a -> IO (IORef a)
+        readIORef,            -- :: IORef a -> IO a
+        writeIORef,           -- :: IORef a -> a -> IO ()
+        modifyIORef,          -- :: IORef a -> (a -> a) -> IO ()
+        atomicModifyIORef,    -- :: IORef a -> (a -> (a,b)) -> IO b
 
 #if !defined(__PARALLEL_HASKELL__) && defined(__GLASGOW_HASKELL__)
-	mkWeakIORef,          -- :: IORef a -> IO () -> IO (Weak (IORef a))
+        mkWeakIORef,          -- :: IORef a -> IO () -> IO (Weak (IORef a))
 #endif
-	) where
+        ) where
 
-import Prelude
+import Prelude  -- Explicit dependency helps 'make depend' do the right thing
 
 #ifdef __HUGS__
 import Hugs.IORef
 #endif
 
 #ifdef __GLASGOW_HASKELL__
-import GHC.Base		( mkWeak#, atomicModifyMutVar# )
+import GHC.Base         ( mkWeak#, atomicModifyMutVar# )
 import GHC.STRef
 import GHC.IOBase
 #if !defined(__PARALLEL_HASKELL__)
@@ -48,13 +48,10 @@ import NHC.IOExtras
     , newIORef
     , readIORef
     , writeIORef
+    , excludeFinalisers
     )
 #endif
 
-#ifndef __NHC__
-import Data.Dynamic
-#endif
-
 #if defined(__GLASGOW_HASKELL__) && !defined(__PARALLEL_HASKELL__)
 -- |Make a 'Weak' pointer to an 'IORef'
 mkWeakIORef :: IORef a -> IO () -> IO (Weak (IORef a))
@@ -66,6 +63,7 @@ mkWeakIORef r@(IORef (STRef r#)) f = IO $ \s ->
 modifyIORef :: IORef a -> (a -> a) -> IO ()
 modifyIORef ref f = writeIORef ref . f =<< readIORef ref
 
+
 -- |Atomically modifies the contents of an 'IORef'.
 --
 -- This function is useful for using 'IORef' in a safe way in a multithreaded
@@ -74,19 +72,22 @@ modifyIORef ref f = writeIORef ref . f =<< readIORef ref
 --
 -- Extending the atomicity to multiple 'IORef's is problematic, so it
 -- is recommended that if you need to do anything more complicated
--- then using 'MVar' instead is a good idea.
+-- then using 'Control.Concurrent.MVar.MVar' instead is a good idea.
 --
 atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
 #if defined(__GLASGOW_HASKELL__)
 atomicModifyIORef (IORef (STRef r#)) f = IO $ \s -> atomicModifyMutVar# r# f s
+
 #elif defined(__HUGS__)
-atomicModifyIORef = plainModifyIORef	-- Hugs has no preemption
+atomicModifyIORef = plainModifyIORef    -- Hugs has no preemption
   where plainModifyIORef r f = do
-		a <- readIORef r
-		case f a of (a',b) -> writeIORef r a' >> return b
-#endif
-
-#ifndef __NHC__
-#include "Dynamic.h"
-INSTANCE_TYPEABLE1(IORef,ioRefTc,"IORef")
+                a <- readIORef r
+                case f a of (a',b) -> writeIORef r a' >> return b
+#elif defined(__NHC__)
+atomicModifyIORef r f =
+  excludeFinalisers $ do
+    a <- readIORef r
+    let (a',b) = f a
+    writeIORef r a'
+    return b
 #endif