From 26a398441d6001960acfa0b42a4a19b015952919 Mon Sep 17 00:00:00 2001
From: malcolm <unknown>
Date: Fri, 18 Oct 2002 16:29:18 +0000
Subject: [PATCH] [project @ 2002-10-18 16:29:18 by malcolm] Implement
 atomicModifyIORef for nhc98.

---
 Data/IORef.hs |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Data/IORef.hs b/Data/IORef.hs
index af8ebda..9170faf 100644
--- a/Data/IORef.hs
+++ b/Data/IORef.hs
@@ -48,6 +48,7 @@ import NHC.IOExtras
     , newIORef
     , readIORef
     , writeIORef
+    , excludeFinalisers
     )
 #endif
 
@@ -86,4 +87,11 @@ 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
+#elif defined(__NHC__)
+atomicModifyIORef r f =
+  excludeFinalisers $ do
+    a <- readIORef r
+    let (a',b) = f a
+    writeIORef r a'
+    return b
 #endif
-- 
1.7.10.4