Update documentation.

Control/Concurrent/Barrier.hs

@@ -21,21 +21,23 @@ barrier' reset count = do
 
     maybe (return ()) takeMVar w
 
--- | Self-resetting barrier.  'barrier' blocks until 'count' threads hit
--- it, and then they are all allowed to run.  The barrier is then
--- reset so that a further 'count' threads can block on it.
--- Typical usage is:
+-- | Self-resetting barrier.  'barrier' blocks until a specified
+-- number of threads have reached it, and then they are all allowed to
+-- run.  The barrier is then reset so that a further 'count' threads
+-- can block on it.  Typical usage is:
 -- 
 -- > do b <- barrier 3
 -- >    forkIO $ b >> putStrLn "1"  -- blocked
 -- >    forkIO $ b >> putStrLn "2"  -- blocked
 -- >    forkIO $ b >> putStrLn "3"  -- all three threads run
-barrier :: Int -> IO (IO ())
+barrier :: Int -- ^ count - number of threads required before barrier is opened
+        -> IO (IO ())
 barrier = barrier' id
 
 -- | Latching barrier.  This is the same as 'barrier', except once the
 -- barrier has opened (the requisite number of threads has reached
 -- it), it remains open, allowing all subsequent threads through
 -- unblocked.
-latchBarrier :: Int -> IO (IO ())
-latchBarrier = barrier' (\_ -> 0)
+latchBarrier :: Int -- ^ count - number of threads required before barrier is opened
+             -> IO (IO ())
+latchBarrier = barrier' (const 0)