November 2007 - Haskell

ANNOUNCE: Gtk2Hs version 0.9.12.1 released
by Duncan Coutts 08 Nov '07

08 Nov '07

Gtk2Hs - A GUI Library for Haskell based on Gtk+ Version 0.9.12.1 is now available from: http://haskell.org/gtk2hs/download/ The source tarball and an installer for Windows are available. Packages for various platforms should become available soon, hopefully including Debian, Fedora, Gentoo, FreeBSD and Darwin. Changes since 0.9.12.1: * builds with GHC 6.8.1 * updated SOE API to match that of the recent SOE release * added status icon binding * added text buffer clipboard functions * fix build issue with recent glib versions * a few minor bug fixes Gtk2Hs feature highlights: * automatic memory management * Unicode support * nearly full coverage of Gtk+ 2.8 API * support for several additional Gtk+/Gnome modules: * Glade visual GUI builder * cairo vector graphics library * SVG rendering for cairo * OpenGL extension (works with HOpenGL) * GConf, Gnome's system for storing app preferences * SourceView, code editor widget with syntax highlighting * the Mozilla browser rendering engine in a widget * an implementation of the Graphics.SOE API * extensive haddock API reference documentation * multi-platform support with native look * LGPL licence Platforms and requirements: * builds from source on Linux, Windows and Solaris * should also build from source on MacOS X and FreeBSD * builds with GHC 6.4.2 - 6.8.1 * works with Gtk+ version 2.0 through to 2.10 * SVG support requires librsvg version 2.16 or later Please report all problems to gtk2hs-devel(a)sourceforge.net or in our bug tracker http://hackage.haskell.org/trac/gtk2hs Contributions and feedback are also most welcome. Windows release notes: The installer expects GHC 6.8.1 or GHC 6.6.1. Duncan (on behalf of the Gtk2Hs team)

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Garbage collection problem
by Jinping Zhang 05 Nov '07

05 Nov '07

HI,can anybody help me with the following garbage collection problem ? I'm trying to develop a test tool which can generate test data systematically for Haskell program, I have finished most of the work so far, however,while testing, the process would be interrupted because of the garbage collection problem with the notice "ERROR - Garbage collection fails to reclaim sufficient space",what shall i do to solve this problem? so that the user may test the possible input of a infinite type all the time as long as he or she wants to. By the way, the interpreter I used was Hugs98. Thank you very much. Best regards Jinping Zhang

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package maintainers: updating your packages to work with GHC 6.8.1
by Duncan Coutts 05 Nov '07

05 Nov '07

If you maintain a Haskell package this is for you. So now that GHC 6.8.1 is out you'll want to test your package with it. We'd especially like maintainers of packages that are distributed on hackage.haskell.org to test their packages and update them as necessary. However we would appreciate it if your packages will still work with GHC 6.6.x, so read below for details on how to do that. You'll most likely find that your package fails to build with GHC 6.8.1 with an error message like this: Could not find module `Data.Map': it is a member of package containers-0.1.0.0, which is hidden. This is the first symptom of the change in the base library in GHC 6.8.1. Several parts of the old base library got split out into separate packages. For example Data.Map is now in the containers package. Unfortunately this means most packages need updating. Of course you'd also like to make your packages continue to work with GHC 6.6.x (and perhaps older). If you go and just add containers to your package's build-depends then it will no longer work with GHC 6.6.x or older. So the solution at the moment is to use Cabal configurations like so: flag splitBase description: Choose the new smaller, split-up base package. library if flag(splitBase) build-depends: base >= 3, containers else build-depends: base < 3 Since this uses a new Cabal feature you'll have to make your packages require Cabal-1.2 or later: cabal-version: >=1.2 This is ok since Cabal-1.2.x comes with ghc-6.8 and can also be installed from hackage for older ghc versions. For a bigger example see Cabal's own .cabal file: http://hackage.haskell.org/packages/archive/Cabal/1.2.2.0/Cabal.cabal The new Cabal syntax is explained in the Cabal user guide: http://haskell.org/cabal/release/rc/doc/users-guide/x30.html#configurations This is all explained in more detail on the wiki: http://haskell.org/haskellwiki/Upgrading_packages And the details of other api changes in the libraries are in the GHC 6.8.1 release notes: http://haskell.org/ghc/docs/6.8.1/html/users_guide/release-6-8-1.html A list of packages on hackage that currently fail to build with GHC 6.8.1 is here: http://www.haskell.org/pipermail/libraries/2007-November/008529.html We realise that this change is rather disruptive, requiring changes in each package. We've started a wiki page with ideas on how to avoid this in future when the base package is shrunk again. http://hackage.haskell.org/trac/ghc/wiki/PackageCompatibility Duncan (Cabal release manager)

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ANNOUNCE: GHC version 6.8.1
by Ian Lynagh 03 Nov '07

03 Nov '07

============================================================= The (Interactive) Glasgow Haskell Compiler -- version 6.8.1 ============================================================= The GHC Team is pleased to announce a new major release of GHC. There have been a number of significant changes since the last major release, including: * Haskell Program Coverage (hpc) support has been added to the compiler * GHCi now includes a debugger * The first phase of the base package split has been done * The code generator now uses pointer tagging (which should mean most code improves by 10-15%, and as a result the compiler is also faster). The full release notes are here: http://haskell.org/ghc/docs/6.8.1/html/users_guide/release-6-8-1.html How to get it ~~~~~~~~~~~~~ The easy way is to go to the web page, which should be self-explanatory: http://www.haskell.org/ghc/ We supply binary builds in the native package format for many platforms, and the source distribution is available from the same place. Packages will appear as they are built - if the package for your system isn't available yet, please try again later. Background ~~~~~~~~~~ Haskell is a standard lazy functional programming language; the current language version is Haskell 98, agreed in December 1998 and revised December 2002. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license. A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page (see below). On-line GHC-related resources ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Relevant URLs on the World-Wide Web: GHC home page http://www.haskell.org/ghc/ GHC developers' home page http://hackage.haskell.org/trac/ghc/ Haskell home page http://www.haskell.org/ Supported Platforms ~~~~~~~~~~~~~~~~~~~ The list of platforms we support, and the people responsible for them, is here: http://hackage.haskell.org/trac/ghc/wiki/Contributors Ports to other platforms are possible with varying degrees of difficulty. The Building Guide describes how to go about porting to a new platform: http://hackage.haskell.org/trac/ghc/wiki/Building Developers ~~~~~~~~~~ We welcome new contributors. Instructions on accessing our source code repository, and getting started with hacking on GHC, are available from the GHC's developer's site run by Trac: http://hackage.haskell.org/trac/ghc/ Mailing lists ~~~~~~~~~~~~~ We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at http://www.haskell.org/mailman/listinfo/glasgow-haskell-users http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see http://www.haskell.org/mailman/listinfo/ Some GHC developers hang out on #haskell on IRC, too: http://www.haskell.org/haskellwiki/IRC_channel Please report bugs using our bug tracking system. Instructions on reporting bugs can be found here: http://www.haskell.org/ghc/reportabug

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TYPES small workshop on Effects and Type Theory
by Tarmo Uustalu 02 Nov '07

02 Nov '07

In the frame of the extended EU FP6-funded TYPES project, we are organizing an ad hoc "small workshop" on integration of effects into type-theoretic programming/reasoning. This is an informal event and attendance is not confined to people involved in TYPES. On the contrary, attendance and contributions from outside the TYPES consortium are most welcome. The invited speakers are Paul Levy and Aleksandar Nanevski. --- Call for contibutions and participation Workshop on Effects and Type Theory, EffTT Tallinn, Estonia, 13-14 December 2007 http://cs.ioc.ee/efftt/ a "small workshop" of the TYPES project Background The syntax and semantics of impurities of computation known as effects have been an important challenge for functional programming. Today, we tend to employ categorically inspired tools such as monads, Lavwere theories and arrows, but also more pragmatic approaches such as uniqueness typing. Effects are an issue also for type-theoretic programming and reasoning, where a number of aspects make them specifically interesting. First, we do not yet know what the best dependently typed generalizations of our simply typed tools are, although we hope they would reinforce the dual utility of type-theoretic calculi as programming languages and logics. Second, this duality specifically forces that pure computations must terminate, so even nontermination is an impurity and potentially an effect. Third, is it not likely that the type-theoretic glasses can help us see more clearly the particularities of external-world effects such as true destructively updatable state and true interactive input-output? Thus, this workshop is exactly about effects and type theory. Topics of interest include * all kinds of dependent generalizations of monads and more * type-theoretic language design for effects * type-theoretic effectful programming methodology * time, nontermination and type theory * state and type theory, including combinations of Hoare-like logics and type theory * interactive input-output and type theory * theories of external-world effects * type theory and concurrency * type-theoretic descriptions of physical systems * and any further topics about effects and type theory Invited speakers Our invited speakers are Paul Levy (Birmingham) and Aleksandar Nanevski (Microsoft Research, Cambridge). Contributing a talk The rest of the programme will be based on contributed talks and discussions. If you would like to contribute a talk, send a title and abstract to efftt(at)cs.ioc.ee by 21 November 2007. Organizers The workshop organizers are Thorsten Altenkirch, Marino Miculan and Tarmo Uustalu. Venue The workshop will take place in the building of the Estonian Academy of Sciences on Tallinn's Dome Hill. The workshop dates are during the Tallinn Christmas market and the Christmas Jazz festival of Jazzkaar. Participating To register, please drop an email to efftt(at)cs.ioc.ee as soon as possible, but not later than 21 November 2007. Attendance is not confined to people involved in the TYPES project; the workshop is open to anyone interested.

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Image manipulation
by Björn Wikström 01 Nov '07

01 Nov '07

Hi! I have lots and lots of images (jpegs) that I would like to manipulate and shrink (in size). They are around 5 Mb big, so I thought this would be a good Haskell project since its a lazy evaluating language. The problem is that I cant find any libraries for image manipulation. Anyone who knows something that would interest me and maybe give me some advices? Best regards, Bjorn.

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