X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Control%2FConcurrent%2FQSem.hs;h=22f6c0c8f6be1eba665998fd90ef377536e7771f;hb=41e8fba828acbae1751628af50849f5352b27873;hp=c009aafe01e19b6a6f661bf5db6a619ff97505eb;hpb=1127922b72ce9f2e57dd4e77e303be6804ae9c3a;p=ghc-base.git

diff --git a/Control/Concurrent/QSem.hs b/Control/Concurrent/QSem.hs
index c009aaf..22f6c0c 100644
--- a/Control/Concurrent/QSem.hs
+++ b/Control/Concurrent/QSem.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Control.Concurrent.QSem
@@ -22,7 +24,7 @@ module Control.Concurrent.QSem
 
 import Prelude
 import Control.Concurrent.MVar
-import Control.Exception ( block )
+import Control.Exception ( mask_ )
 import Data.Typeable
 
 #include "Typeable.h"
@@ -36,7 +38,7 @@ import Data.Typeable
 
 -- |A 'QSem' is a simple quantity semaphore, in which the available
 -- \"quantity\" is always dealt with in units of one.
-newtype QSem = QSem (MVar (Int, [MVar ()]))
+newtype QSem = QSem (MVar (Int, [MVar ()])) deriving Eq
 
 INSTANCE_TYPEABLE0(QSem,qSemTc,"QSem")
 
@@ -51,7 +53,7 @@ newQSem initial =
 
 -- |Wait for a unit to become available
 waitQSem :: QSem -> IO ()
-waitQSem (QSem sem) = block $ do
+waitQSem (QSem sem) = mask_ $ do
    (avail,blocked) <- takeMVar sem  -- gain ex. access
    if avail > 0 then
      let avail' = avail-1
@@ -72,7 +74,7 @@ waitQSem (QSem sem) = block $ do
 
 -- |Signal that a unit of the 'QSem' is available
 signalQSem :: QSem -> IO ()
-signalQSem (QSem sem) = block $ do
+signalQSem (QSem sem) = mask_ $ do
    (avail,blocked) <- takeMVar sem
    case blocked of
      [] -> let avail' = avail+1