base: Add forkOSWithUnmask

Fixes #8010, according to the specified libraries proposal. [1]

Also, some minor wordsmithing.

  [1] http://thread.gmane.org/gmane.comp.lang.haskell.libraries/22709

Signed-off-by: Austin Seipp <austin@well-typed.com>

libraries/base/Control/Concurrent.hs

@@ -3,6 +3,7 @@
            , MagicHash
            , UnboxedTuples
            , ScopedTypeVariables
+           , RankNTypes
   #-}
 {-# OPTIONS_GHC -fno-warn-deprecations #-}
 -- kludge for the Control.Concurrent.QSem, Control.Concurrent.QSemN
@@ -73,6 +74,7 @@ module Control.Concurrent (
         -- $boundthreads
         rtsSupportsBoundThreads,
         forkOS,
+        forkOSWithUnmask,
         isCurrentThreadBound,
         runInBoundThread,
         runInUnboundThread,
@@ -180,7 +182,7 @@ attribute will block all other threads.
 
 -}
 
--- | fork a thread and call the supplied function when the thread is about
+-- | Fork a thread and call the supplied function when the thread is about
 -- to terminate, with an exception or a returned value.  The function is
 -- called with asynchronous exceptions masked.
 --
@@ -316,6 +318,11 @@ forkOS action0
         return tid
     | otherwise = failNonThreaded
 
+-- | Like 'forkIOWithUnmask', but the child thread is a bound thread,
+-- as with 'forkOS'.
+forkOSWithUnmask :: ((forall a . IO a -> IO a) -> IO ()) -> IO ThreadId
+forkOSWithUnmask io = forkOS (io unsafeUnmask)
+
 -- | Returns 'True' if the calling thread is /bound/, that is, if it is
 -- safe to use foreign libraries that rely on thread-local state from the
 -- calling thread.

libraries/base/changelog.md

@@ -67,7 +67,11 @@
     unlifted types (#10868)
 
   * Keep `shift{L,R}` on `Integer` with negative shift-arguments from
-	segfaulting (#10571)
+    segfaulting (#10571)
+
+  * Add `forkOSWithUnmask` to `Control.Concurrent`, which is like
+    `forkIOWithUnmask`, but the child is run in a bound thread.
+
 
 ## 4.8.1.0  *Jul 2015*