[project @ 1999-05-14 19:49:22 by sof]

Added (yield :: IO ()) - the underlying bits were already there, really.

ghc/lib/concurrent/Concurrent.lhs

@@ -29,6 +29,8 @@ module Concurrent (
 	, par  		-- :: a -> b -> b
 	, seq  		-- :: a -> b -> b
 	, fork  	-- :: a -> b -> b
+	, yield         -- :: IO ()
+
 	{-threadDelay, threadWaitRead, threadWaitWrite,-}
 
 	-- MVars

ghc/lib/std/PrelConc.lhs

@@ -18,6 +18,8 @@ module PrelConc
 	, raiseInThread -- :: ThreadId -> Exception -> IO ()
 	, par  		-- :: a -> b -> b
 	, seq  		-- :: a -> b -> b
+	, yield         -- :: IO ()
+
 	{-threadDelay, threadWaitRead, threadWaitWrite,-}
 
 	-- MVars
@@ -68,6 +70,10 @@ myThreadId :: IO ThreadId
 myThreadId = IO $ \s ->
    case (myThreadId# s) of (# s1, id #) -> (# s1, ThreadId id #)
 
+yield :: IO ()
+yield = IO $ \s -> 
+   case (yield# s) of s1 -> (# s1, () #)
+
 -- "seq" is defined a bit wierdly (see below)
 --
 -- The reason for the strange "0# -> parError" case is that