[project @ 2005-01-28 23:33:57 by krasimir]

[ghc-base.git] / Control / Exception.hs

diff --git a/Control/Exception.hs b/Control/Exception.hs
index dd6b6fd..83f37cb 100644 (file)
--- a/Control/Exception.hs
+++ b/Control/Exception.hs
@@ -117,7 +117,7 @@ import GHC.Base             ( assert )
 import GHC.Exception   as ExceptionBase hiding (catch)
 import GHC.Conc                ( throwTo, ThreadId )
 import Data.IORef      ( IORef, newIORef, readIORef, writeIORef )
-import Foreign.C.String ( CString, withCStringLen )
+import Foreign.C.String ( CString, withCString )
 import System.IO       ( stdout, hFlush )
 #endif
 
@@ -169,10 +169,9 @@ INSTANCE_TYPEABLE0(AsyncException,asyncExceptionTc,"AsyncException")
 -- might be a 'ThreadKilled', for example).  In this case it is usually better
 -- to use 'catchJust' and select the kinds of exceptions to catch.
 --
--- Also note that the "Prelude" also exports a
--- function called 'Prelude.catch' which has the same type as
--- 'Control.Exception.catch', the difference being that the
--- "Prelude" version only catches the IO and user
+-- Also note that the "Prelude" also exports a function called
+-- 'Prelude.catch' with a similar type to 'Control.Exception.catch',
+-- except that the "Prelude" version only catches the IO and user
 -- families of exceptions (as required by Haskell 98).  We recommend
 -- either hiding the "Prelude" version of
 -- 'Prelude.catch' when importing
@@ -244,6 +243,11 @@ mapException f v = unsafePerformIO (catch (evaluate v)
 -- to re-throw the exception after performing whatever cleanup is needed.
 -- Otherwise, 'tryJust' is generally considered to be better.
 --
+-- Also note that "System.IO.Error" also exports a function called
+-- 'System.IO.Error.try' with a similar type to 'Control.Exception.try',
+-- except that it catches only the IO and user families of exceptions
+-- (as required by the Haskell 98 @IO@ module).
+
 try :: IO a -> IO (Either Exception a)
 try a = catch (a >>= \ v -> return (Right v)) (\e -> return (Left e))
 
@@ -506,10 +510,11 @@ uncaughtExceptionHandler = unsafePerformIO (newIORef defaultHandler)
                Deadlock    -> "no threads to run:  infinite loop or deadlock?"
                ErrorCall s -> s
                other       -> showsPrec 0 other "\n"
-         withCStringLen ("Fail: "++msg) $ \(cstr,len) -> writeErrString cstr len
-         
-foreign import ccall unsafe "writeErrString__"
-       writeErrString :: CString -> Int -> IO ()
+         withCString "%s" $ \cfmt ->
+          withCString msg $ \cmsg ->
+            errorBelch cfmt cmsg
+
+foreign import ccall unsafe errorBelch :: CString -> CString -> IO ()
 
 setUncaughtExceptionHandler :: (Exception -> IO ()) -> IO ()
 setUncaughtExceptionHandler = writeIORef uncaughtExceptionHandler