Further to my previous messages: http://www.haskell.org//pipermail/haskell/2004-February/013522.html http://www.haskell.org//pipermail/haskell/2004-February/013679.html I've come back to my stripped-down test case, and recreated the C test program SpawnEchoShiftLetters.c [1] in Haskell SpawnEchoShiftLetters.hs [2]. I've also added some diagnostic code. To recap: the C code demonstrates that that the Win32 API used by spawnProc.c [4] is working as expected, so the problem appears to be in the Haskell interface to it. My problem seems to be occurring about here: [[ spawn cmd = withCString cmd $ \ p_cmd -> withObject 0 $ \ p_wIn -> withObject 0 $ \ p_rOut -> withObject 0 $ \ p_rErr -> do rc <- spawnProc p_cmd p_wIn p_rOut p_rErr when (rc /= 0) (ioError (userError ("runProc: unable to spawn " ++ show cmd))) wIn <- peek p_wIn (-1-} trace ("wIn "++show wIn) $ return () {- : -} (-2-} hIn <- openFd (fromIntegral wIn) False WriteMode False (-3-} trace ("hIn "++show hIn) $ return () ]] -- http://www.ninebynine.org/Software/HaskellUtils/Win32/POpen.hs Specifically: + the trace at {-1-} displays the expected value (i.e. the same as a similar trace in the C version of the code [1], namely the value 3), + the trace at {-3-} is not displayed, indicating... + failure of the openFd call at {-2-}, also indicated by a Hugs error message, thus: [[ SpawnEchoShiftLetters> runTest wIn 3 Program error: openFd: does not exist (file does not exist) SpawnEchoShiftLetters> ]] Thus, it would appear that I'm misunderstanding how to use the openFd function that is part of the Hugs-supplied library code, declared as a primitive: [[ -- Creating a handle from a file descriptor/socket. -- primitive openFd :: Int -- file descriptor -> Bool -- True => it's a socket. -> IOMode -- what mode to open the handle in. -> Bool -- binary? -> IO Handle ]] -- http://cvs.haskell.org/cgi-bin/cvsweb.cgi/hugs98/libraries/Hugs/IO.hs?rev=1.9&content-type=text/x-cvsweb-markup Can anyone help me out here? My current experimental code is all visible at [4]. Thanks. #g -- [1] http://www.ninebynine.org/Software/HaskellUtils/Win32/SpawnEchoShiftLetters.... [2] http://www.ninebynine.org/Software/HaskellUtils/Win32/SpawnEchoShiftLetters.... [3] http://www.ninebynine.org/Software/HaskellUtils/Win32/spawnProc.c [4] http://www.ninebynine.org/Software/HaskellUtils/Win32/ ------------ Graham Klyne For email: http://www.ninebynine.org/#Contact