- Haskell-Cafe - Haskell.org

About return type
by ZhangXu 09 Jul '09

09 Jul '09

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Leaner Haskell.org frontpage
by haskell＠kudling.de 09 Jul '09

09 Jul '09

Hi, i find the current www.haskell.org frontpage quite overwhelming. Compare it for example with the home pages of other programming languages : http://caml.inria.fr/ http://factorcode.org/ http://sbcl.sourceforge.net/ http://www.ruby-lang.org/en/ http://www.falconpl.org/ Here is my sketch of a leaner, more structured Haskell front page: http://www.haskell.org/haskellwiki/User:Lenny222/Haskell Comments? Bye, Lenny

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ANN: darcs 2.3 beta 2
by Petr Rockai 09 Jul '09

09 Jul '09

Hello! Two weeks passed and it is about time to release darcs 2.3 beta 2 (it's already a day late, sorry about that). As with beta 1, there is only a single installation package for this release of darcs: cabalised source. (Please note that the final version with also come with the legacy autoconf-based buildsystem, for the last time.) You can either download a tarball from <http://repos.mornfall.net/darcs/darcs-2.2.98.2.tar.gz> and build manually (see the build instructions in README inside the tarball), or, alternatively, you can use cabal-install to obtain a copy (the beta release is now available on Hackage): $ cabal update $ cabal install darcs-beta This, if successful, will give you a darcs binary in `~/.cabal/bin` -- you should probably add that to your PATH. What's new since beta 1 ----------------------- There are basically two relatively intrusive changes since beta 1. First, I have added index upgrade functionality to hashed-storage and this is now used by darcs, so that any bad or incompatible indexes are recreated transparently by darcs. Moreover, the index format is now architecture-independent, meaning that repositories shared across multiple architectures should not suffer from excessive index rebuilding. Second, Ganesh has done further work on his gzip CRC correction code. There is a very slight risk of regressions, so if you have around any repositories with broken CRCs in them, please test this functionality. Moreover, there is now an option to limit the repair to current repository, avoiding changes in related branches or caches. Trent, Thorkil and Eric have done cleanup work and a number of minor fixes for this release, improving overall quality and polish. One bug in the new indexing code has been found and reported by Eric and Guillaume independently, and is fixed in hashed-storage 0.3.4 (which required by this beta). You can track the release plan and progress at our wiki: <http://wiki.darcs.net/development>. The question of GHC 6.8 ----------------------- Using GHC 6.10.3 or newer is *strongly recommended*. You may compile darcs with GHC 6.8, but there are several caveats. If you are using 6.8.2 or older, please disable mmap support (pass -f-mmap to cabal install or runghc Setup configure below). Note that the GHC 6.8.2 that ships with Debian Lenny is not affected and it should be safe to keep mmap enabled. It is also recommended to disable use of Hackage zlib when compiling with GHC 6.8.2 (including the Debian Lenny version): pass -f-zlib to cabal. When using zlib, we have seen occasional crashes with error messages like "openBinaryFile: file locked" -- this is a known GHC 6.8.2 bug (and is fixed in GHC 6.8.3). Last, if you are using a 64-bit system, darcs may hang when you exit a pager when compiled with GHC older than 6.10.3. Although this is harmless, it is quite inconvenient. Overall, the status of GHC 6.8 is "semi-supported": for many cases, things will work just fine, especially if you take a little extra caution with compilation flags. Yours, Petr. -- Petr Ročkai | http://web.mornfall.net A physicist is an atom's way of knowing about atoms. (George Wald)

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ANN: Hayoo! beta 0.4
by Timo B. Hübel 09 Jul '09

09 Jul '09

Hello! We are pleased to announce the next beta version 0.4 of Hayoo!, the Haskell API search engine with find-as-you-type and suggestions. Visit Hayoo! here: http://holumbus.fh-wedel.de/hayoo This release includes some major changes to the web interface: - The full description of a function can now be displayed upon request, using the small "+" symbol in front of the description text - The most common root modules for all functions found are shown as list, providing a shortcut for further restricting the current query - Some example queries on the start page for easier use of Hayoo! Additionally, we have again updated the search index. It contains all packages from Hackage as well as gtk2hs as of 06.07.2009, a total of 111.946 function and type definitions. Please let us know about any problems, hints and suggestions. Happy hacking, Timo

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Re: [Haskell-cafe] Where can I get GHC for Solaris?
by John Ky 09 Jul '09

09 Jul '09

Hi Aycan, This is the version of make I am using: joky@sun05:~ $ make -v GNU Make 3.81 Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. This program built for sparc-sun-solaris2.9 joky@sun05:~ $ uname -a SunOS sun05 5.9 Generic_118558-30 sun4u sparc SUNW,Sun-Fire-280R Thanks, -John On Wed, Jul 8, 2009 at 4:48 PM, Aycan iRiCAN <aycan.irican(a)core.gen.tr>wrote: > Çar, 2009-07-08 tarihinde 09:55 +1000 saatinde, John Ky yazdı: > > Hi, > > > > I had a go with the binary dist, and got this error message on the > > make install: > > > > /home/a-m/joky/.tools/ghc-6.8.2/lib/ghc-6.8.2"' > > -DPKG_DATADIR='"/export/home/a-m/joky/.tools/ghc-6.8.2/share/ghc-6.8.2"' > package.conf.in \ > > | grep -v '^#pragma GCC' \ > > | sed -e 's/""//g' -e 's/:[ ]*,/: /g' \ > > > > | /export/home/a-m/joky/ghc-6.8.2/utils/ghc-pkg/ghc-pkg.bin > > --global-conf > /export/home/a-m/joky/.tools/ghc-6.8.2/lib/ghc-6.8.2/package.conf update - > --force > > ld.so.1: ghc-pkg.bin: fatal: libm.so.2: version `SUNW_1.2' not found > > (required by > > file /export/home/a-m/joky/ghc-6.8.2/utils/ghc-pkg/ghc-pkg.bin) > > ld.so.1: ghc-pkg.bin: fatal: libm.so.2: open failed: No such file or > > directory > > Killed > > make[1]: *** [install] Error 137 > > make[1]: Leaving directory `/export/home/a-m/joky/ghc-6.8.2/rts' > > make: *** [install] Error 2 > > Are you using gmake? > > -- > aycan > >

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Haskell Platform on Ubuntu
by Rafael Gustavo da Cunha Pereira Pinto 08 Jul '09

08 Jul '09

Is there anyone working on a Haskell Platform package for Ubuntu? GHC in Ubuntu is a pain! Regards Rafael Gustavo da Cunha Pereira Pinto

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Re: [Haskell] Haskell Hack Day, Edinburgh, 30 August 2009
by Johan Tibell 08 Jul '09

08 Jul '09

On Wed, Jul 8, 2009 at 12:12 PM, Eric Kow <kowey(a)darcs.net> wrote: > Dear Haskellers, > > I am pleased to report that we will be having a Haskell Hack Day in > Edinburgh, on Sunday 30 August (before the ICFP begins). The day will > be held at the ICFP conference venue, the Royal College of Physicians. > > The Hack Day will be free and open to all. > Come join us; it'll be a lot of fun! My flight arrives too late for actually taking part in the hackathon but I would be up for some beers after if anyone is interested. -- Johan

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ANN: texmath 0.1.0.1 - conversion of LaTeX math to MathML
by John MacFarlane 08 Jul '09

08 Jul '09

I'm pleased to announce an early release of texmath, a Haskell library for converting LaTeX math formulas to MathML. Hackage: http://hackage.haskell.org/package/texmath-0.1.0.1 Github: http://github.com/jgm/texmath/tree/master The package includes a standalone test program, testTeXMathML, and a CGI script, texmath-cgi, that can be used in web apps. This script is used in the demos at http://johnmacfarlane.net/texmath.xhtml http://johnmacfarlane.net/texmath.html texmath supports most of basic LaTeX and AMS extensions, but I'm sure some things have been left out, so let me know if you try a formula that should work but doesn't. John

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simple state monad exercises? (besides labeling trees)
by Thomas Hartman 08 Jul '09

08 Jul '09

Can someone give some simple common scenarios where the state monad is useful, besides labeling trees? References to puzzles like those in project Euler or similar would be nice. Thanks!

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lazy data structure for best-first search
by Martin Hofmann 08 Jul '09

08 Jul '09

I am looking for a good (preferably lazy) way to implement some kind of best-first search. The problem is, the expansion of the 'best' node in the search space forces other 'inferior' nodes to expand too. So my function expand :: Node -> ([Node],(Node -> [Node])) does not only return some successor nodes, but also a function to expand other Nodes with certain characteristics. So in fact, after one expansion, I need to fold over my complete search space, maybe updating other nodes and recompute the value of the cost function for the affected nodes. At the moment I am using StateT monad transformers, and retrieving the affected Nodes from a map (to avoid going through whole space), but this is not very elegant and I doubt whether it is efficient, too. I have already read through Spivey's paper "Algebras for combinatorial search". Unfortunately, he only proposes the use of heuristics and best-first search in combination with his framework for future work. Does anybody now some further papers on this topic? Thanks a lot in advance, Martin

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