March 2007 - Glasgow-haskell-users

chr and ord not in standard prelude
by Colletta, Edward 10 Mar '07

10 Mar '07

When I try to use functions chr or ord, I get a not in scope error. If I ":browse Prelude" I do not see these functions. Is there another module I should load?

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Re: Distributing a GHC-compiled binary for Macs (x86)
by Christian Maeder 09 Mar '07

09 Mar '07

(move a discussion to glasgow-haskell-users) Macs that don't have GHC installed don't seem to have readline-5 installed, either. Therefore we've created that GNUreadline.framework (see below). However, the binary that one wants to distribute must be linked against that framework. We do this by adding linker options to ghc: -optl-F/home/maeder/Library/Frameworks -optl-framework -optlGNUreadline We have also created a binary distribution (for powerpc, though) that uses our GNUreadline.framework. For this we've changed libraries/readline/config.mk manually: LD=/usr/bin/ld -F/home/maeder/Library/Frameworks -framework GNUreadline SRC_HC_OPTS += -optc-I/home/maeder/Library/Frameworks/GNUreadline.framework/Headers -optl-F/home/maeder/Library/Frameworks -optl-framework -optlGNUreadline SRC_HSC2HS_OPTS += -I/home/maeder/Library/Frameworks/GNUreadline.framework/Headers The binary distribution is here: http://www.informatik.uni-bremen.de/agbkb/forschung/formal_methods/CoFI/het… We think, that such a GNUreadline.framework is more flexible and mac-like than installing readline-5 under /opt/local. The framework can reside under /System/Library/Frameworks but also under $HOME/Library/Frameworks. Maybe you could consider making such a distribution (that also doesn't need root permission) as well? The sources and the script to create the GNUreadline framework are included: http://www.informatik.uni-bremen.de/agbkb/forschung/formal_methods/CoFI/het… Cheers Christian Christian Maeder schrieb: > Arjun Guha schrieb: >> Hi, >> >> I compiled a binary using GHC 6.6 on my Mac (specifically, using ghc >> --make). This binary seems to depend on the GNU MP framework--I >> imagine GHC uses it to implement its numeric tower. >> >> However, Macs that don't have GHC installed don't seem to have GMP, so >> I'll guess that it was installed along with the GHC binary. Is there >> any way to get around this GMP dependency? I expect the binary to be >> used on Macs that don't have GHC installed. It would be acceptable if >> I instructed Mac-users to download a binary installer for GMP, but I >> haven't been able to find one. >> >> Any hints or suggestions would be appreciated. Thanks. > > We tell our users to install a GMP.framework and a GNUreadline.framework: > > http://www.informatik.uni-bremen.de/agbkb/forschung/formal_methods/CoFI/het… > > Cheers Christian

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Parsing GHC Core
by Neil Mitchell 09 Mar '07

09 Mar '07

Hi, I would like to parse GHC Core to an abstract syntax tree, as the old GHC Core library used to allow the user to do. I do not want to depend on the GHC API (too big), but don't mind depending on a small and separately available .cabal'd package. I also don't mind copying a few modules into my program. The types are of no interest to me, if that makes it any easier Does anyone have the code/library to do this sitting around? Thanks Neil

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local ByteArrays: performGC do any good?
by Peter Tanski 08 Mar '07

08 Mar '07

Hello Simon and Ian, Perhaps either of you may be able to answer this question easily: I am testing the replacement Integer library in Haskell and I wanted to copy arrays between the two--I can't do all of that in Haskell because the RTS allocation has a maximum alignment of 4 when I need 16 (sometimes--I might also realign things, as a last resort). In any case, the easy way to do it would be to grab the ByteArray# from the Integer (J# Int# ByteArray#), grab the Addr# with the primitive byteArrayContents#, turn that into a pointer and pass it to the foreign function. That would be a sketchy move--even for testing-- because Integer ByteArrays are local (not pinned). Do you think doing a performGC just before grabbing the Addr# would help? There doesn't seem to be another primitive for marshalling a pointer from a ByteArray. Cheers, Peter Tanski

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[HDirect] ihc and COM
by Fernand Lacas 08 Mar '07

08 Mar '07

Hi, I'm continuing to experiment with HDirect and the ihc compiler. Trying the "huge" type libraries from Office applications (Word, Excel...), I've met the following issue: some Haskell stubs do not compile out of the box, essentially because of type mismatch between the type signature generated by the ihc compiler and the stub's code. For instance: > Excel.hs:32:25: No instance for (Automation.Variant a0) arising from use of `Automation.outVariant' at Excel.hs:32:25-45 Possible fix: add (Automation.Variant a0) to the type signature(s) for `global_getActiveCell' The faulty declaration is indeed : global_getActiveCell :: Global a1 -> Prelude.IO a0 global_getActiveCell = Automation.propertyGet "ActiveCell" [] Automation.outVariant whereas the correct type is (Automation.Variant a0) => Global a1 -> Prelude.IO a0 There are also some cases where there is a type mismatch between "Int64" and "Automation.Date" type, but the essence of the error is the same : the type signature does not match the method's stub's code. I've looked for an option in the compiler that would help (for instance, I suppose that removing all type signatures from the haskell file would allow to compile it), but I haven't found one. NB : the ihc command line was "../src/ihc.exe --tlb -fautomation -fprefix-interface-name -fmaybe-optional-params -v XL5EN32.OLB (where the OLB file is Excel's type library). Did anyone experienced similar issue ? Thanks in advance, sL PS: the COM library (without Automation) works well. ___________________________________________________________________________ Découvrez une nouvelle façon d'obtenir des réponses à toutes vos questions ! Profitez des connaissances, des opinions et des expériences des internautes sur Yahoo! Questions/Réponses http://fr.answers.yahoo.com

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unsafePerformIO safety.
by David Brown 07 Mar '07

07 Mar '07

I've noticed quite a few pages referencing constructs such as: var :: MVar ([Foo]) var = unsafePerformIO (newMVar ([])) and the likes. Is there a danger of different uses of 'var' getting new MVars instead of all sharing one. Having a reliable way to create a piece of global state would be very convenient. Dave

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Duplicate instance declarations of a methodless class
by mm 07 Mar '07

07 Mar '07

Hello, I was thinking that it could maybe be useful to allow duplicate instance declarations, if the class has no methods. From my naive point of view, i can not see problems, scince there are no conflicting methods to choose from. But the following program fails to be compiled by ghc-6.6: > {-# OPTIONS -fglasgow-exts -fallow-undecidable-instances #-} > class GT a b > class Succ a b > data Zero > data One > data Two > data Three > instance Succ One Zero > instance Succ Two One > instance Succ Three Two > instance Succ a b => GT a b > instance (Succ a b, GT b c) => GT a c The former two lines lead to: test5.lhs:22:1: Duplicate instance declarations: instance (Succ a b) => GT a b -- Defined at test5.lhs:22:1 instance (Succ a b, GT b c) => GT a c -- Defined at test5.lhs:23:1

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Re : HDirect and GHC-6.6
by Fernand Lacas 07 Mar '07

07 Mar '07

Hi all, It's been a long time since I had the time to work with haskell, but I have some news about HDirect. I now succeed in compiling "ihc.exe" with the typelib support (see my previous posts on the subject), but I had to bypass the packages. That is, the second compilation stage is made using the object files from the "comlib" rather than the "com" package. I understand that it is rather ugly but I still hope that it may be useful to anyone needing COM support with ghc. If anyone is interested in the source files, feel free to ask me. Sincerely yours, sL ___________________________________________________________________________ Nouveau : téléphonez moins cher avec Yahoo! Messenger ! Découvez les tarifs exceptionnels pour appeler la France et l'international. Téléchargez sur http://fr.messenger.yahoo.com

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Code breaks with '-O', any ideas.
by David Brown 06 Mar '07

06 Mar '07

My program 'harchive' <http://www.davidb.org/darcs/harchive/> breaks if compiled with '-O'. Just wondering if anyone has suggestions on how to figure out what might be causing this. Is is possible to build some files with '-O' and others without? I'm not using unsafePerformIO. Thanks, David

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Query information about installed modules user or system only?
by Marc Weber 05 Mar '07

05 Mar '07

Is there a way to ask ghc-pkg to list all availible packages found in the user lib or system lib or lib given by path? If I have read the documentation corretly it says: no. Is there any reason for this restriction? Can I query ghc-pkg to list pgk-config files (user/ system)? mfg Marc

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