October 2001 - Glasgow-haskell-users

RE: IO concurrency
by Simon Marlow 15 Oct '01

15 Oct '01

> Playing with GHC, I met some oddity. > Consider the example: > > > import IO > > import Concurrent > > import Posix > > import PosixIO > > > > main = do > > (fdIn, fdIn_send) <- createPipe > > hIn_send <- fdToHandle fdIn_send > > hIn <- fdToHandle fdIn > > -- The "waiter" is a simple tk/tcl script which > > -- prints "click" anytime I click a button. > > runProcess "./waiter" [] Nothing Nothing > > Nothing (Just hIn_send) Nothing > > -- hSetBuffering hIn LineBuffering {-2-} > > -- hSetBuffering stdin LineBuffering > > forkIO(interact stdin) > > -- forkIO(interact hIn) {-1-} > > main_cycle > > where > > interact hIn = do > > line <- hGetLine hIn > > numIn <- handleToInt {-made from handleToFd & fdToInt-} > > -- threadWaitRead numIn {-3-} > > putStrLn line > > interact hIn > > main_cycle = do > > putStrLn "tick" > > threadDelay 1000000 > > main_cycle > > > The example works OK. It prints "tick" once a second and dups my input > as I type it. But, when I uncomment the line {-1-} to handle > input from > child as well, everything is hanged on this read operation. > Uncommenting > the {-3-} line helps, but, first, I'm not sure it is a right way and, > second, the matter is still unclear - what is the reason of such > difference? > > Uncommenting the {-2-} lines doesn't help. I thing the reason is in > some inner properties of the handlers, but have no idea in which one. I tried this here on Linux/x86 with 5.02 and it seems to work fine. Instead of the tcl/tk script you mentioned I used a FIFO in /tmp/fifo and made the runProcess just call "cat /tmp/fifo". Which GHC version and platform is this on? Cheers, Simon

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RE: problems with ghc-5.02 Socket module (SunOS)
by Simon Marlow 15 Oct '01

15 Oct '01

> what am I doing wrong? it worked before ... this program > > module Main (main) where > import IO > import Socket > main = do > h <- connectTo "theopc.informatik.uni-leipzig.de" > ( PortNumber $ 9999 ) > putStrLn "connected" > hClose h > > results in > > Fail: invalid argument > Action: getSocketOption > Reason: Invalid argument > > even though there IS a listener on the socket > (other programs can connect to it). There are two bugs in SocketPrim.getSocketOption, which are causing connectTo to fail in the way you reported. The fix will be in 5.02.1. Cheers, Simon

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Errors using connectTo in Sockets
by Peter Logarn 15 Oct '01

15 Oct '01

Hi! Does anyone know why I can't use the connectTo function in the library Socket included with ghc? If I try to run the following code: Prelude> Socket.connectTo "193.237.240.100" (Socket.PortNumber 21) I get the following error: *** Exception: invalid argument Action: getSocketOption Reason: Invalid argument I'm trying to connect to a ftp-server. I can see on the server that a connection is made, but the haskell program crashes. I have also tried to connect to a webserver, but that generates the same error. Process> Socket.connectTo "hem.passagen.se" (Socket.Service "http") *** Exception: invalid argument Action: getSocketOption Reason: Invalid argument Thanks, Peter Logarn

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problems with ghc-5.02 Socket module (SunOS)
by Johannes Waldmann 15 Oct '01

15 Oct '01

what am I doing wrong? it worked before ... this program module Main (main) where import IO import Socket main = do h <- connectTo "theopc.informatik.uni-leipzig.de" ( PortNumber $ 9999 ) putStrLn "connected" hClose h results in Fail: invalid argument Action: getSocketOption Reason: Invalid argument even though there IS a listener on the socket (other programs can connect to it). I have ghc-5.02 (binary package for SunOS) Any hints appreciated. how to find out what is invalid? -- -- Johannes Waldmann ---- http://www.informatik.uni-leipzig.de/~joe/ -- -- joe(a)informatik.uni-leipzig.de -- phone/fax (+49) 341 9732 204/252 --

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RE: ghc-pkg
by Simon Marlow 15 Oct '01

15 Oct '01

> I would like to add a request to Thomas list of lacking features of > ghc --make: > > When caching information between the compilation of > different modules, > use weak pointers. > > With large projects, ghc runs out of heapspace because of too much > caching. I think it's more likely that GHC has some space leaks which cause it to hang on to too much memory between compilations. In theory, it only caches the contents of interface files (in a pre-processed state), but due to leakage it may end up hanging on to more stuff. This is high up on our list of things to investigate. I'm not sure what you have in mind w.r.t. weak pointers - could you elaborate? In GHC there isn't a kind of pointer that says "hold on this unless we run out of heap", which is perhaps what you were after. Cheers, Simon

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Re: Dumb Windows Question
by Reuben Thomas 15 Oct '01

15 Oct '01

> How do I actually use ghc in Windows (98)? When I installed Hugs, my .hs > files got associated with Hugs and if I left-click on a .hs file I have > various options to run with. We don't do this with GHC. > So do I open a DOS box and invoke ghc or ghci? If so how, what do I have > to change to get the path to point to ghc? I tried autoexec.bat but this > seemed to have no effect. You have to set PATH as usual (I presume that is in autoexec.bat on Windows '98). > Also, how do I tell ghci where to find packages? I suspect this problem has more to do with the bug in ghci.exe (see the fixed version posted by Sigbjorn; I'll be uploading a fixed InstallShield as soon as I can fix one or two other serious problems) than any error in your command line, which looks fine. -- http://sc3d.org/rrt/ | violence, n. bravery for cowards

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Re: Dumb Windows Question
by Sven Eric Panitz 15 Oct '01

15 Oct '01

From: "Steinitz, Dominic J" <Dominic.J.Steinitz(a)BritishAirways.com> Sender: glasgow-haskell-users-admin(a)haskell.org Date: 15 Oct 2001 08:47:47 Z [...] Also, how do I tell ghci where to find packages? C:\Program Files\Glasgow Haskell Compiler\ghc-5.02\bin>ghci -package lang C:\PROGRA~1\GLASGO~1\GHC-5.02\BIN\GHC.EXE: no input files Usage: For basic information, try the `--help' option. [...] Packages seem to be a problem on some windows system with ghci 5.02. At least I could not load them on NT (got the same message as you), but it works well on my windows 2000 installation. Sven Eric -- ______________________________________________________________ Sven Eric Panitz Uhlandstr. 12 D-64297 Darmstadt Software AG sep(a)softwareag.com (+49)6151-92-1426 --- when I cannot sing my heart, I can only speak my mind ---

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Dumb Windows Question
by Steinitz, Dominic J 15 Oct '01

15 Oct '01

How do I actually use ghc in Windows (98)? When I installed Hugs, my .hs files got associated with Hugs and if I left-click on a .hs file I have various options to run with. So do I open a DOS box and invoke ghc or ghci? If so how, what do I have to change to get the path to point to ghc? I tried autoexec.bat but this seemed to have no effect. Also, how do I tell ghci where to find packages? C:\Program Files\Glasgow Haskell Compiler\ghc-5.02\bin>ghci -package lang C:\PROGRA~1\GLASGO~1\GHC-5.02\BIN\GHC.EXE: no input files Usage: For basic information, try the `--help' option. I did look through the documentation. If I missed the relevant sections, perhaps someone could point me at them. Many thanks, Dominic. ------------------------------------------------------------------------------------------------- To receive our special fares directly by email, register at http://www.britishairways.com/registration

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Good Error Message
by Steinitz, Dominic J 15 Oct '01

15 Oct '01

Can I just say thank you for the good error message. I'm sure I have used compilers (not Haskell) which would tell you that you have a problem but leave you to find where the two defintions are. Dominic. Encode.hs:8: Ambiguous occurrence `Octet' It could refer to either `Encode.Octet', defined at Encode.hs:7 or `ASNBaseTypes.Octet', imported from ASNBaseTypes at E ncode.hs:5 (at ./ASNBaseTypes.hi:34) make: *** [Encode.o] Error 1 ------------------------------------------------------------------------------------------------- To receive our special fares directly by email, register at http://www.britishairways.com/registration

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hslibs/ObjectIO
by Mike Thomas 15 Oct '01

15 Oct '01

Hi all. I thought I would try compiling the GHC CVS ObjectIO library on NT with GHC 5.02. Following error messages passed out by the compiler I modified C_util12.lhs as follows (see attached file): - import MarshallAlloc - import Ptr instead of Addr - Change Addr to Ptr - AddrOff changed to Int and get the following error message in the fpeek function: $ make ghc -static -c ../../OSWindows/Cutil_12.hs -fglasgow-exts -syslib concurrent -syslib ang -cpp -i../../CleanStdEnv:../../OSWindows:../../ObjectIO:../../OSWindo ws/Windows_C_12 -I../../ObjectIO -DMVAR=1 ..\\..\\OSWindows\\Cutil_12.hs:34: Couldn't match `* -> *' against `Type bx' Expected kind: * -> * Inferred kind: Type bx When checking that `Ptr' is a type In the type: forall a. (Storable a) => Ptr -> IO a While checking the type signature for `fpeek' make: *** [../../OSWindows/Cutil_12.o] Error 1 I am stumped on this (I don't know what the stars mean). My best guess is that it is something to do with the monomorphism restriction. Any advice on how to clear this up? Are the changes I made in keeping with the intention of the original code? Cheers Mike Thomas

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