- Glasgow-haskell-users

strace breaks cabal - how to find the problem?
by Robin Green 25 Mar '09

25 Mar '09

On my obscure configuration (GHC 6.10.1, with pkgenv activated, on Fedora Linux rawhide running on a VirtualBox x86 VM with hardware virtualisation enabled), running strace on cabal causes it to misbehave, as described below. I don't know whether this is due to a bug in cabal, the GHC runtime, strace, the Linux kernel, VirtualBox, or my processor's virtualization support. Not sure how to proceed to debug this. Perhaps someone else could try this, on their configuration, and report what they find? This command is ran in an untarred copy of hs-bibutils 0.1 (not that it matters): strace -f -e trace=file cabal install --extra-include-dirs=../bibutils_4.1/lib/ 2>&1|cat >cabal.strace Cabal fails to determine the version of ghc-pkg (or sometimes ghc), and stops, complaining that it can't verify that the version of ghc(-pkg) is the required one. ghc-pkg is execve'd, but something goes wrong - not sure what. -- Robin

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ANNOUNCE: GHC 6.10.2 Release Candidate 1
by Ian Lynagh 25 Mar '09

25 Mar '09

We are pleased to announce the first release candidate for GHC 6.10.2: http://www.haskell.org/ghc/dist/6.10.2-rc1/ This includes two source bundles: ghc-6.10.1.20090314-src.tar.bz2 ghc-6.10.1.20090314-src-extralibs.tar.bz2 Only the first of these is necessary. The "extralibs" package contains various extra packages that we normally supply with GHC - unpack the extralibs tarball on top of the source tree to add them, and they will be included in the build automatically. There are also installers for Windows (i386) and OS X (i386), and binary distributions for x86_64/Linux and i386/Linux. More may appear later. Please test as much as possible; bugs are much cheaper if we find them before the release! Thanks Ian, on behalf of the GHC team

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Re: [Haskell-cafe] GHC 6.10.2 - PCap package - affected by the change of Finalizers?
by Bulat Ziganshin 24 Mar '09

24 Mar '09

Hello Neil, Tuesday, March 24, 2009, 9:08:08 PM, you wrote: one more case > Looks like pcap package needs a little tweek for 6.10.2 - programs > compiled with it bomb out with > ......error: a C finalizer called back into Haskell. > use Foreign.Concurrent.newForeignPtr for Haskell finalizers. > Is my interpretation of this error message correct? > Cheers > Neil > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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Puzzling (to me) type error message
by Colin Adams 24 Mar '09

24 Mar '09

I'm trying out concurrent haskell (never mind that the code isn't actually very concurrent - I'm just trying to get things to compile first). So with the following code, I get: play_move :: IORef Game_state -> IO () play_move game_state_ior = do (_, state, _) <- readIORef game_state_ior putStr "Playing AI: " start_time <- getCurrentTime ai_in_channel <- newChan ai_out_channel <- newChan writeChan ai_in_channel state ai_thread_id <- forkIO (run_ai ai_in_channel ai_out_channel) move <- readChan ai_out_channel end_time <- move `seq` (modifyIORef game_state_ior $! update_interactive_from_move move) >> getCurrentTime putStrLn $ show $ (diffUTCTime end_time start_time) run_ai :: Chan Non_interactive_state -> Chan Move.Move -> IO () run_ai in_channel out_channel = do state <- readChan in_channel let move = recommended_move state writeChan out_channel move UI.hs:625:45: Not in scope: type constructor or class `Move.Move' If I then comment-out the type signature for run_ai, it compiles fine with the following warning message: UI.hs:626:0: Warning: Definition but no type signature for `run_ai' Inferred type: run_ai :: Chan Non_interactive_state -> Chan Move.Move -> IO () Ghc 6.10.1 on Mac OS X. What is going on?

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Loading plugin with ghc api
by John O'Donnell 23 Mar '09

23 Mar '09

Hi, I would like to use the API for ghc, so that a running program can load a module (Foo.o) and use a function defined in that module. From the documentation available, it seems like thatś possible, but I can´t figure out how to do it. There is an example on the wiki, but the explanation just says the code is equivalent to ghc --make. That example does indeed work, but there is no hint as to whether the running program can then access anything defined in the module it has just loaded. Is there any available documentation on how to load a plugin, or any working example somewhere? Thanks in advance, John O´Donnell

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mkIfThenElse
by Colin Paul Adams 22 Mar '09

22 Mar '09

This function has disappeard from CoreUtils in recent release(s). I am portfing some code which uses this function (just once). What should I be looking to use instead? -- Colin Adams Preston Lancashire

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How do I add new dependencies and source files into the build system?
by Colin Paul Adams 22 Mar '09

22 Mar '09

I have added a subdirectory named verify to the compiler directory, and made a change to simplCore to call functions from it. I have managed to get it to compile by editing ghc.cabal in the compiler directory (after some problems with cabal which are now sorted). But I think this is not the correct way to do it, as ./configure rebuilds this file, it seems. Where should I be doing this? -- Colin Adams Preston Lancashire

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Can't find parsec
by Colin Paul Adams 21 Mar '09

21 Mar '09

I am trying to incorporate Dana Xu's static contract checking code into ghc 6.11. I've run into a problem that puzzles me. I am getting the following error message: verify/SimplIface.lhs:16:7: Could not find module `Text.ParserCombinators.Parsec.Language': Use -v to see a list of the files searched for. But a quick find command shows that ./utils/ext-core/Language/Core/ParsecParser.hs has this very same import, so I figure it must be usable within the compiler. What do I have to do to get it to find this module? -- Colin Adams Preston Lancashire

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Another victim of the state hack
by Jules Bean 20 Mar '09

20 Mar '09

I have the impression that it's useful to you to see how often the state hack trips people up, so I've added some more comments to http://hackage.haskell.org/trac/ghc/ticket/2284 ...about how it bit me. This is a real headache. To be frank, controlling lazy evaluation and sharing to get the right complexity for your code can be hard enough at the best of times, without the compiler sometimes ignoring the sharing you try to ask for...

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Adding DPH to HEAD
by Colin Paul Adams 20 Mar '09

20 Mar '09

I tried following the advice on the DPH wiki: ./sync-all --dph get This wouldn't run because of permissions, so I tried putting sh in front of the command. This produced a lot of error messages: ./sync-all: line 3: use: command not found ./sync-all: line 4: use: command not found ./sync-all: line 8: git: command not found ./sync-all: line 8: my: command not found ./sync-all: line 8: chomp: command not found ./sync-all: line 9: git: command not found ./sync-all: line 9: my: command not found ./sync-all: line 9: chomp: command not found ./sync-all: line 10: git: command not found ./sync-all: line 10: my: command not found ./sync-all: line 10: chomp: command not found ./sync-all: line 12: my: command not found ./sync-all: line 13: my: command not found ./sync-all: line 15: syntax error near unexpected token `{' ./sync-all: line 15: `if ($defaultrepo =~ /^...*:/) {' Following a suggestion from Simon Marlow, I instead tried: ./darcs-all --dph get which was more successful. Does the wiki page need updating? But when I then typed make I got: <snip> --constraint="Cabal == 1.7.0" Configuring installPackage-1.0... cabal-bin: The following installed packages are broken because other packages they depend on are missing. These broken packages must be rebuilt before they can be used. package Cabal-1.7.0 is broken due to missing package array-0.2.0.0, containers-0.2.0.0, process-1.0.1.0 make[2]: *** [with-bootstrapping-compiler] Error 1 make[2]: Leaving directory `/home/colin/ghc/utils/installPackage' make[1]: *** [with-bootstrapping-compiler.installPackage] Error 2 make[1]: Leaving directory `/home/colin/ghc/utils' make: *** [stage1] Error 2 What do I do in such circumstances? I tried a cabal install Cabal --rebuild which seemed to work OK, but when i type make again i get the same error as before. -- Colin Adams Preston Lancashire

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