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cabal install fail for happs-hsp-template
by Thomas Hartman 02 Jun '08

02 Jun '08

Can cabal install be made to work for this package? ***** thartman@thartman-laptop:~>sudo cabal install happs-hsp-template [sudo] password for thartman: cabal: internal error: could not construct a valid install plan. The proposed (invalid) plan contained the following problems: Package Cabal is required by several packages, but they require inconsistent versions: package ghc-6.8.2 requires Cabal-1.2.3.0 package plugins-1.2 requires Cabal-1.5.2 thartman@thartman-laptop:~>cabal --version cabal-install version 0.4.7 using version 1.3.11 of the Cabal library thartman@thartman-laptop:~>ghc --version The Glorious Glasgow Haskell Compilation System, version 6.8.2 thartman@thartman-laptop:~>ghc-pkg list | grep -i ghc /usr/local/lib/ghc-6.8.2/package.conf: (ghc-6.8.2), haskell-src-1.0.1.1, haskell98-1.0.1.0, hpc-0.5.0.0,

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Vancouver Haskell users meeting
by Jon Strait 02 Jun '08

02 Jun '08

Anyone else here from Vancouver (Canada)? I thought it would be great to have a little informal get-together at a local cafe and share how we're currently using Haskell, or really anything (problems, comparisons, useful software tools, etc.) in relation to Haskell. I'm scheduling a meeting for this Thursday, June 5th. for 7PM at <http://www.waazubee.com/content/directions.php> Waazubee Cafe - http://www.waazubee.com/content/directions.php (at Commercial Dr. and 1st Ave.) They have wireless internet access. I'll get a table near the back, bring my laptop, and will have a copy of Hudak's SOE book (the front cover is impossible to miss) out on the table. If anyone wants to meet, but this Thursday is not a good day for you, let me know what days are better and we'll move the meeting. If anyone is sure that they will come this Thursday, you might let me know, so I can have an idea about the resistance in changing the day, if needed. Thanks, Jon

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modelling C in Haskell ..
by Galchin, Vasili 02 Jun '08

02 Jun '08

Hello, I don't want to write kludgy Haskell code! typedef struct blah { int val1; union { int val2; struct { int val3; int val4; } } } C_type; question: in Haskell, can I embed definition of the "union" inside of the C typedef, i.e. recursion definition? Or must I have a separate definition for the "union" which I "instantiate" inside the Haskell "typedef", i.e. Haskell "data"? Kind regards, Vasili

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Damnit, we need a CPAN.
by Achim Schneider 02 Jun '08

02 Jun '08

No, wait, there's cabal-install. And it doesn't even depend on 20+ packages I'd have to install manually. My day, for now, is saved, at least if portage installs it without hesitation. Ah, there it is: >>> Compiling source >>> in /var/tmp/portage/dev-haskell/cabal-darcs-0/work/cabal-darcs-0 ... * Bootstrapping Cabal... <no location info>: can't find file: Setup.lhs * * ERROR: dev-haskell/cabal-darcs-0 failed. Ok, let's try it the other way 'round...: % wget \ http://hackage.haskell.org/packages/archive/cabal-install/0.4.0/cabal-insta… % tar xvzf cabal-install-0.4.0.tar.gz % cd cabal-install-0.4.0 % runhaskell Setup.lhs configure --prefix=/home/ksf/cabal-inst --user Configuring cabal-install-0.4.0... % runhaskell Setup.lhs install Installing: /home/ksf/cabal-inst/bin Setup.lhs: dist/build/cabal/cabal: copyFile: does not exist (No such file or directory) % runhaskell Setup.lhs build Preprocessing executables for cabal-install-0.4.0... Building cabal-install-0.4.0... [...] % runhaskell Setup.lhs install Installing: /home/ksf/cabal-inst/bin % cabal update % cabal install phooey [...] type 'make' to build wxhaskell. type 'make install' to install wxhaskell. type 'make help' to receive help on all other make targets Configure Succeeded. Indeed. It succeeded. Now what? Building and installing by hand, it seems. Building works, installing too, but registering fails: the Makefile does not seem to like --user: % runhaskell Setup.lhs register --user -=-= Cabal executing: make register=-=- cat config/wxcore.pkg | sed -e "s|\${wxhlibdir}|/home/ksf/cabal-inst/lib|" | ghc-pkg update - Reading package info from stdin ... done. WARNING: unversioned dependencies are deprecated, and will NOT be accepted by GHC 6.10: base haskell98 Unable to rename "/usr/lib64/ghc-6.8.2/package.conf" to "/usr/lib64/ghc-6.8.2/package.conf.old" Saving old package config file... ghc-pkg.bin: /usr/lib64/ghc-6.8.2/package.conf: renameFile: permission denied (Permission denied) Just a second... # emerge wxhaskell -pv These are the packages that would be merged, in order: Calculating dependencies... done! [ebuild UD] dev-lang/ghc-6.4.2 [6.8.2] USE="X%* doc opengl%* -binary -ghcbootstrap -openal% -test%(-bash-completion%)" 0 kB [0=>1] [ebuild N ] dev-haskell/wxhaskell-0.9.4 USE="doc" 0 kB In other words: No way. The only program that touches anything in /usr/ is portage. Well, at least ghc-pkg update works on a mangled wxcore.pkg. Rationale: We need a CPAN, a cabal that is smart enough to know what to to, even if building depends on make, grapefruit authors that commit to hackage, a cabal-inst that can install from darcs (or at least from a local directory), or maybe just a make-replacement for haskell, like java has with ant (which is really cool if you successfully do not notice the xml-syntax). I would already shut up if there were an ebuild generator, but then I'm not that egoistic ;) Anyway, three hours after wanting to try it out, grapefruit is up and running, and I did not even have to install its dependencies by hand. It seems like grapefruit could benefit from nestable cabal packages, though: It has one big script that installs many packages. You could also call them dependencies. I'm going to shut up now. -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited.

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Default definitions for associated type synonyms
by Dreixel 02 Jun '08

02 Jun '08

Hello, Does anyone know if it is possible to specify a default definition for an associated type synonym? When I tried: class A a where > type B a = a > GHC (version 6.9.20080309) told me: "Type declaration in a class must be a kind signature or synonym default". However, when I look at the parser I see no way to specify such synonym default. Is this possible? Thanks, Zé Pedro

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GHCi panic
by Andrew Coppin 02 Jun '08

02 Jun '08

I don't suppose this will surprise anybody greatly, but... Apparently if you write a Haskell module that is 400 KB in size and defines a single CAF consisting of a 45,000-element [String], GHCi panics when attempting to load it interpretted, and hits a stack overflow attempting to load it compiled. GHC also takes forever to compile it in the first place, and eventually spits out a 5 MB interface file later followed by a 16 MB object file. And attempting to compile a trivial module against it again causes a stack overflow. Presumably the designers of GHC just didn't expect anybody to try to do anything this weird? ;-) I was hoping that doing things this way round would be *more efficient*. But this is apparently not the case at all, so I'll just go back to reading the file at runtime instead... [Presumably if I was desparate I could convert the data into some kind of preinitialised C structure and manually link it in - if I was that determined.]

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Images and GUIs in Haskell
by Ronald Guida 02 Jun '08

02 Jun '08

Two questions: 1. In a Haskell program, if all I want to do is output an image, like a graph or chart, what is the simplest library to use? N.B. Simpler := easier to get minimal functionality. I really don't want to wade through a bunch of boilerplate or climb a steep learning curve just to be able to plot a few lines or circles. 2. Suppose I want interactivity. For example, I want to plot a line graph, and then let the user click and drag the data points. From what I understand about GUIs, I would need to track mouse buttons (up and down), mouse movements, and possibly keystrokes. (I know this is the complete opposite extreme from my first question) In this case, what would be the best (not necessarily simplest) library to use? What would you recommend?

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haskell compiler on NetBSD amd64
by Donn Cave 02 Jun '08

02 Jun '08

So here I am with 64 bit Athlon hardware, running amd64 NetBSD (a.k.a. x86_64), reasonably motivated to compile Haskell. From what I make of the porting instructions, my only hope is to install FreeBSD-amd64 on another partition and download the 6.6.1 ghc for that platform, use it to generate .hc files to build 6.6.1 on NetBSD, and then use 6.6.1 to build 6.8 or whatever the current version may be by the time I get there? -- Donn Cave <donn(a)avvanta.com>

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Ghc / cgi static linking
by Pieter Laeremans 02 Jun '08

02 Jun '08

Hello, I'm researching the use of Haskell to replace some perl scripts (in a web app). The app is deployed with a webhosting provider. CGI scripts can be executed => I can use Haskell. I've tried some hello world cgi scripts, compiled them on the same linux the hosting company uses and deployed them. It worked! But I would like to implement a search feature for the website. For Java/php/perl there 's lucene. For haskell there 's holumbus. Unfortunately, sqlite is a requirement for holumbus. It is not installed at the server of the hosting company. Is it possible to staticly link the sqlite3 library using ghc ? And are there other lucene like libs available like holumbus for haskell ? thanks in advance, Pieter -- Pieter Laeremans <pieter(a)laeremans.org>

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Re: [Haskell-cafe] hmatrix
by Thomas Hartman 01 Jun '08

01 Jun '08

what package do you install/import to get at Vector? 2008/5/31 Thomas Hartman <tphyahoo(a)gmail.com>: > what package do you install/import to get at Vector? > > 2008/5/31 Anatoly Yakovenko <aeyakovenko(a)gmail.com>: >> What is the most efficient way to update a position in a matrix or a >> vector? I came up with this: >> >> updateVector :: Vector Double -> Int -> Double -> Vector Double >> updateVector vec pos val = vec `add` v2 >> where >> v2 = fromList $ (replicate (pos) 0.0) ++ ((val - (vec @> >> pos)):(replicate ((dim vec)- pos - 1) 0.0)) >> >> but this seems pretty inefficient to me. >> >> thanks, >> Anatoly >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> >

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