X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=GHC%2FException.lhs;h=073e7a97c9ed60a74615c259a93252fe69f14e2b;hb=1fd0b9560f30181af709c784f70017e36a97d4da;hp=04f732a886f6b8bb56196a125ab72862ecafcc13;hpb=19de173b1bd4fa8cf1854cfefa619565910137f3;p=haskell-directory.git

diff --git a/GHC/Exception.lhs b/GHC/Exception.lhs
index 04f732a..073e7a9 100644
--- a/GHC/Exception.lhs
+++ b/GHC/Exception.lhs
@@ -1,5 +1,5 @@
 \begin{code}
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.Exception
@@ -14,6 +14,7 @@
 -- 
 -----------------------------------------------------------------------------
 
+-- #hide
 module GHC.Exception 
 	( module GHC.Exception, 
 	  Exception(..), AsyncException(..), 
@@ -105,10 +106,12 @@ unblock (IO io) = IO $ unblockAsyncExceptions# io
 -- the 'IO' monad.  It can be used to order evaluation with respect to
 -- other 'IO' operations; its semantics are given by
 --
--- >   evaluate undefined `seq` return ()  ==> return ()
--- >   catch (evaluate undefined) (\e -> return ())  ==> return ()
+-- >   evaluate x `seq` y    ==>  y
+-- >   evaluate x `catch` f  ==>  (return $! x) `catch` f
+-- >   evaluate x >>= f      ==>  (return $! x) >>= f
 --
--- NOTE: @(evaluate a)@ is /not/ the same as @(a \`seq\` return a)@.
+-- /Note:/ the first equation implies that @(evaluate x)@ is /not/ the
+-- same as @(return $! x)@.
 evaluate :: a -> IO a
 evaluate a = IO $ \s -> case a `seq` () of () -> (# s, a #)
         -- NB. can't write