#ifdef __GLASGOW_HASKELL__
import Foreign.C.String
+#else
+import System.IO (hPutStrLn,stderr)
#endif
-- | 'putTraceMsg' function outputs the trace message from IO monad.
--- Usually the output stream is 'stderr' but if the function is called
+-- Usually the output stream is 'System.IO.stderr' but if the function is called
-- from Windows GUI application then the output will be directed to the Windows
-- debug console.
putTraceMsg :: String -> IO ()
putTraceMsg msg = do
#ifndef __GLASGOW_HASKELL__
- hPutStr handle msg
- hPutChar handle '\n'
+ hPutStrLn stderr msg
#else
withCString "%s\n" $ \cfmt ->
withCString msg $ \cmsg ->
debugBelch cfmt cmsg
-foreign import ccall unsafe debugBelch :: CString -> CString -> IO ()
+foreign import ccall unsafe "RtsMessages.h debugBelch"
+ debugBelch :: CString -> CString -> IO ()
#endif
{-# NOINLINE trace #-}
trace string expr = unsafePerformIO $ do
putTraceMsg string
return expr
+
+{-|
+Like 'trace', but uses 'show' on the argument to convert it to a 'String'.
+
+> traceShow = trace . show
+-}
+traceShow :: (Show a) => a -> b -> b
+traceShow = trace . show