X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=System%2FExit.hs;h=6de82c33aa9dee9dca5411f69aa39d7bf2b3c2a0;hb=ca4fc090b0ad583d07017a69430227ce32684ac0;hp=1dab14f732ae8fbc5e8116ad375ee13a982fb6d1;hpb=dbe5ad2718b2133d8c4205589905cf14acd73dcf;p=ghc-base.git

diff --git a/System/Exit.hs b/System/Exit.hs
index 1dab14f..6de82c3 100644
--- a/System/Exit.hs
+++ b/System/Exit.hs
@@ -13,21 +13,23 @@
 -----------------------------------------------------------------------------
 
 module System.Exit
-    ( 
+    (
       ExitCode(ExitSuccess,ExitFailure)
     , exitWith      -- :: ExitCode -> IO a
     , exitFailure   -- :: IO a
+    , exitSuccess   -- :: IO a
   ) where
 
 import Prelude
 
 #ifdef __GLASGOW_HASKELL__
-import GHC.IOBase
+import GHC.IO
+import GHC.IO.Exception
 #endif
 
 #ifdef __HUGS__
-import Hugs.Prelude
-import Hugs.Exception
+import Hugs.Prelude (ExitCode(..))
+import Control.Exception.Base
 #endif
 
 #ifdef __NHC__
@@ -40,7 +42,7 @@ import System
 -- ---------------------------------------------------------------------------
 -- exitWith
 
--- | Computation 'exitWith' @code@ throws 'ExitException' @code@.
+-- | Computation 'exitWith' @code@ throws 'ExitCode' @code@.
 -- Normally this terminates the program, returning @code@ to the
 -- program's caller.  Before the program terminates, any open or
 -- semi-closed handles are first closed.
@@ -50,20 +52,25 @@ import System
 -- A program that terminates successfully without calling 'exitWith'
 -- explicitly is treated as it it had called 'exitWith' 'ExitSuccess'.
 --
--- As an 'ExitException' is not an 'IOError', 'exitWith' bypasses
+-- As an 'ExitCode' is not an 'IOError', 'exitWith' bypasses
 -- the error handling in the 'IO' monad and cannot be intercepted by
--- 'catch' from the "Prelude".  However it is an 'Exception', and can
+-- 'catch' from the "Prelude".  However it is a 'SomeException', and can
 -- be caught using the functions of "Control.Exception".  This means
 -- that cleanup computations added with 'Control.Exception.bracket'
 -- (from "Control.Exception") are also executed properly on 'exitWith'.
-
+--
+-- Note: in GHC, 'exitWith' should be called from the main program
+-- thread in order to exit the process.  When called from another
+-- thread, 'exitWith' will throw an 'ExitException' as normal, but the
+-- exception will not cause the process itself to exit.
+--
 #ifndef __NHC__
 exitWith :: ExitCode -> IO a
-exitWith ExitSuccess = throwIO (ExitException ExitSuccess)
+exitWith ExitSuccess = throwIO ExitSuccess
 exitWith code@(ExitFailure n)
-  | n /= 0 = throwIO (ExitException code)
+  | n /= 0 = throwIO code
 #ifdef __GLASGOW_HASKELL__
-  | otherwise = ioError (IOError Nothing InvalidArgument "exitWith" "ExitFailure 0" Nothing)
+  | otherwise = ioError (IOError Nothing InvalidArgument "exitWith" "ExitFailure 0" Nothing Nothing)
 #endif
 #endif  /* ! __NHC__ */
 
@@ -72,3 +79,9 @@ exitWith code@(ExitFailure n)
 -- where /exitfail/ is implementation-dependent.
 exitFailure :: IO a
 exitFailure = exitWith (ExitFailure 1)
+
+-- | The computation 'exitSuccess' is equivalent to
+-- 'exitWith' 'ExitSuccess', It terminates the program
+-- sucessfully.
+exitSuccess :: IO a
+exitSuccess = exitWith ExitSuccess