- Haskell-Cafe - Haskell.org

FFI and heap memory usage limit
by Marcin Kosiba 29 Jun '09

29 Jun '09

Hello, Recently I've come across a certain GC/FFI-related problem. I've googled a bit, but didn't find anything specific. I'm running certain simulations, which tend to allocate a lot of garbage in memory. Since this causes the OOM-killer to kill my simulation at 98% completion, I used the -M switch, and all was well. But because my simulation results are fairly big, I needed to compress them with bz2 before sending them over the network. So I used bzlib. Now this took an odd turn, because the simulation started crashing with out-of-memory errors _after_ completing (during bz2 compression). I'm fairly certain this is a GC/FFI bug, because increasing the max heap didn't help. Moving the bz2 compression to a separate process provided a reasonable solution. What I think is happening is that after the simulation completes, almost all of the available memory (within the -M limit) is filled with garbage. Then I run bzlib which tries to allocate more memory (from behind FFI?) to compress the results, which in turn causes an out-of-memory error instead of triggering a GC collection. I'm writing to ask if this is a known/fixed issue. I'm using ghc 6.10.3, bzlib 0.5.0.0. If this is something new then I'll try to come up with a small program which demonstrates the problem. -- Marcin Kosiba

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Proper arrival of platform?
by Magnus Therning 29 Jun '09

29 Jun '09

When will the Haskell Platform arrive properly? With that I mean, when will GHC stop shipping with a set of base libraries (e.g. network)? /M -- Magnus Therning (OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe

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Haskell Weekly News: Issue 123 - June 29, 2009
by Brent Yorgey 29 Jun '09

29 Jun '09

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20090629 Issue 123 - June 29, 2009 --------------------------------------------------------------------------- Welcome to issue 123 of HWN, a newsletter covering developments in the [1]Haskell community. A bit late this week since over the weekend I was trying to get some unruly satellites to behave (with moderate success). Anyway, some fun stuff this week: Haskell on the iPhone; new libraries for 3D animation, web development, session types; new releases of haskell-src-exts and darcs; and more. Also, if it seems that there haven't been many quotes lately, it's because people haven't been @remembering very many in #haskell. I cannot telepathically sense (via the Haskell-force, hereafter known as the "Horce") when someone says something funny. Announcements Haskell Symposium call for participation. Stephanie Weirich [2]announced that [3]registration is now open for the [4]ACM SIGPLAN Haskell Symposium 2009, to be held on 3 September 2009 in Edinburgh, Scotland (co-located with ICFP). The purpose of the Haskell Symposium is to discuss experiences with Haskell and future developments for the language. The scope of the symposium includes all aspects of the design, semantics, theory, application, implementation, and teaching of Haskell. jhc 0.6.1. John Meacham [5]announced the release of [6]jhc 0.6.1, featuring a a much simplified cross-compilation mechanism. X Haskell Bindings 0.3. Antoine Latter [7]announced the 0.3.* series release of the [8]X Haskell Bindings. This release, like the prior 0.2.* series focuses on making the API prettier. happstack-0.3.2. Matthew Elder [9]announced the release of [10]happstack-0.3.2, with many changes, updates, and bug fixes. sendfile-0.1. Matthew Elder [11]announced the release of [12]sendfile, a library which exposes zero-copy sendfile functionality in a portable way. Right now it natively supports linux 2.6+ (maybe older too) and windows 2000+; on other platforms it will fall back seamlessly to a portable haskell implementation. Reusable Corecursive Queues via Continuations. Leon Smith [13]requested feedback on a draft of an upcoming article in Monad.Reader issue 14, "Lloyd Allison's Corecursive Queues: Why Continuations Matter", describing the implementation of the [14]control-monad-queue package. Haskell on the iPhone. Ryan Trinkle [15]announced that his company, iPwn Studios Inc., is currently preparing to release an open source patch to GHC that allows it to output binaries for iPhone OS. The patch will be released under a BSD license as soon as possible and hopefully integrated into the GHC main-line in the near future. Program to set the GNOME desktop background picture randomly. Colin Paul Adams [16]announced [17]gnome-desktop, a library which periodically picks a random picture from $HOME/Pictures, and sets it as the GNOME desktop background. loli: a minimal web dev DSL. Jinjing Wang [18]announced the release of [19]loli, a web development DSL built on top of [20]hack. It allows you to easily define routes, build your custom template backends through a simple Template interface, and integrate with other hack middleware. Cal3D animation library. Gregory D. Weber [21]announced the [22]Cal3D for Haskell project, which provides a partial binding to the [23]C++ Cal3D animation library, a platform- and graphics-API-independent C++ library for skeletal-based character animation. There are three packages available on hackage: [24]cal3d-0.1, a Haskell binding to the Cal3D library itself; as well as [25]cal3d-opengl-0.1 and [26]cal3d-examples-0.1. A Reader Monad Tutorial. Henry Laxen [27]announced a nice [28]Reader monad tutorial. full-sessions: yet another implementation of session types. Keigo Imai [29]announced the pre-release of [30]full-sessions, yet another implementation of session types in Haskell. Session types are used to statically check the safe and consistent use of communication channels according to protocols. A notable advantage of [31]this implementation is that it requires almost no type annotation or term annotations. and at the same time provides full functionality of session types including channel-generation and channel-passing. darcs 2.3 beta 1. Petr Rockai [32]announced the immediate availability of a first beta release of darcs 2.3. There are a number of improvements and bugfixes over the last stable release, 2.2 (see the announcement for a full list). Moreover, work has been done on performance of "darcs whatsnew" for large repositories. This has also introduced a slight risk of regressions, but please note that all of the disruptive changes are in read-only code paths: the new code will never touch your repository, so it is unable to cause permanent harm. The worst that could happen is that you get no or bad diff from "darcs whatsnew". Please help test it (cabal install [33]darcs-beta)! New release of ZeroTH. Robin Green [34]announced a new release (2009.6.23.3) of [35]ZeroTH, a tool for preprocessing Haskell code to run splices and remove Template Haskell dependencies. Major changes include support for more Haskell code via haskell-src-exts 1.0.0, better error messages, and librification. Emping-0.6 and Tests/Examples. Hans van Thiel [36]announced version 0.6 of [37]Emping, a (prototype) interactive tool for the discovery and analysis of (universal, not statistical) predictive rules in tables of nominal data. haskell-src-exts-1.0.0. Niklas Broberg [38]announced the first stable release of the [39]haskell-src-exts package, version 1.0.0! haskell-src-exts is a package for Haskell source code manipulation. In particular it defines an abstract syntax tree representation, and a parser and pretty-printer to convert between this representation and String. It handles (almost) all syntactic extensions to the Haskell 98 standard implemented by GHC, and the parsing can be parametrised on what extensions to recognise. HaRe (the Haskell Refactorer) in action - short screencast. Claus Reinke [40]linked to [41]a short video showing [42]HaRe, the Haskell refactorer, in action. HaRe still exists---but needs some love in the form of time and/or funding for maintenance and continued development. Trivial pivoting for the DSP lu decomposition. Fernan Bolando [43]announced the beginnings of a [44]simple circuit simulator using haskell, which uses a modified version of the haskell DSP library matrix, extended with a simple pivoting method. Discussion make some Applicative functions into methods, and split off Data.Functor. Ross Paterson [45]proposed moving several functions such as (<$), (*>), and so on into their respective classes with default definitions, to allow for specialized implementations. base library and GHC 6.12. Ian Lynagh began a [46]discussion about how to structure the base library in the future. Proposal: ExplicitForall. Niklas Broberg [47]proposed adding a new GHC extension, ExplicitForall, to be used for turning on explicit 'forall' syntax in types, and to help disentangle and simplify some existing extensions. Generic Graph Class. Ivan Lazar Miljenovic [48]proposed a generic graph class to serve as a common interface for the many Haskell libraries that deal with graph data structures. Type system trickery. Andrew Coppin [49]asked how to statically ensure certain properties of recursive data structures with the type system, generating varied suggestions involving GADTs. Blog noise [50]Haskell news from the [51]blogosphere. Blog posts from people new to the Haskell community are marked with >>>, be sure to welcome them! * Magnus Therning: [52]Making a choice from a list in Haskell, Vty (part 0). * The Gentoo Haskell Team: [53]Haskell in Gentoo. * Michael Snoyman: [54]Hack Introduction. * >>> Henry Laxen: [55]Reader Monad Confusion. * >>> Akshay: [56]Dynamic Programming in Haskell and why DP is useful. * David Amos: [57]Direct products revisited. * mightybyte: [58]Basic Happstack Blog App. * David Amos: [59]Some groups and some graphs. * Gergely Patai: [60]Short-term hp2any plans. * Isaac Dupree: [61]cross-package, Plan A. * >>> Oliver Reeves: [62]Data Crunching in Haskell. * Roman Cheplyaka: [63]Halting problem. * Petr Rockai: [64]darcs 2.3 beta 1. * Eric Kow (kowey): [65]Haskell syntax highlighting on Wikipedia and Wikibooks. * Greg Bacon: [66]Setting up a simple test with Cabal. * Isaac Dupree: [67]Cross-package documentation, part 1. * Sean Leather: [68]RFC: Extensible, typed scanf- and printf-like functions for Haskell. * >>> Akshay: [69]Foray Into Haskell. * >>> Ivan Uemlianin: [70]decorate-sort-undecorate in Haskell. * Isaac Dupree: [71]How To Navigate Your Code:. * Petr Rockai: [72]soc progress 5. * DEFUN 2009: [73]The tutorial schedule is now ready. * DEFUN 2009: [74]Last call for talk proposals!. * >>> Greg Bacon: [75]Setting up a simple test with Cabal. * The GHC Team: [76]New paper: Parallel Performance Tuning for Haskell. * Brandon Simmons: [77]Fun with Lazy Arrays: the LZ77 Algorithm. * >>> Keith: [78]Bird Tracks Through Math Land: Basic Matrix Ops. Quotes of the Week * gnuvince: Contributions to Hackage are measured in µConals. * DavidWheeler: Compatibility means deliberately repeating other people's mistakes. About the Haskell Weekly News New editions are posted to [79]the Haskell mailing list as well as to [80]the Haskell Sequence and [81]Planet Haskell. [82]RSS is also available, and headlines appear on [83]haskell.org. To help create new editions of this newsletter, please see the information on [84]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [85]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.general/17320 3. http://www.regmaster.com/conf/icfp2009.html 4. http://haskell.org/haskell-symposium/2009/ 5. http://www.haskell.org//pipermail/haskell/2009-June/021449.html 6. http://repetae.net/computer/jhc/ 7. http://www.haskell.org//pipermail/haskell/2009-June/021460.html 8. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xhb 9. http://article.gmane.org/gmane.comp.lang.haskell.general/17317 10. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/happstack 11. http://article.gmane.org/gmane.comp.lang.haskell.general/17316 12. http://hackage.haskell.org/package/sendfile 13. http://article.gmane.org/gmane.comp.lang.haskell.general/17311 14. http://hackage.haskell.org/package/control-monad-queue 15. http://article.gmane.org/gmane.comp.lang.haskell.general/17307 16. http://article.gmane.org/gmane.comp.lang.haskell.general/17304 17. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/gnome%2Ddesktop 18. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60675 19. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/loli 20. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hack 21. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60596 22. http://haskell.org/haskellwiki/Cal3d_animation 23. http://home.gna.org/cal3d/ 24. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cal3d 25. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cal3d%2Dopengl 26. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cal3d%2Dexamples 27. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60591 28. http://www.maztravel.com/haskell/readerMonad.html 29. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60511 30. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/full%2Dsessions 31. http://www.agusa.i.is.nagoya-u.ac.jp/person/sydney/full-sessions.html 32. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60465 33. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/darcs%2Dbeta 34. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60430 35. http://hackage.haskell.org/package/zeroth 36. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60411 37. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Emping 38. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60392 39. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskell%2Dsrc%2D… 40. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60388 41. http://www.youtube.com/watch?v=4I7VZV7elnY 42. http://www.cs.kent.ac.uk/projects/refactor-fp/ 43. http://article.gmane.org/gmane.comp.lang.haskell.cafe/60590 44. http://plan9.bell-labs.com/sources/contrib/fernan/escomma.tar.bz2 45. http://thread.gmane.org/gmane.comp.lang.haskell.libraries/11428 46. http://thread.gmane.org/gmane.comp.lang.haskell.libraries/11413 47. http://thread.gmane.org/gmane.comp.lang.haskell.glasgow.user/17137 48. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/60460 49. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/60277 50. http://planet.haskell.org/ 51. http://haskell.org/haskellwiki/Blog_articles 52. http://therning.org/magnus/archives/664 53. http://gentoohaskell.wordpress.com/?p=3 54. http://blog.snoyman.com/2009/06/28/hack-introduction/ 55. http://www.maztravel.com/haskell/readerMonad.html 56. http://www.akrish.net/2009/06/28/dynamic-programming-in-haskell-and-why-dp-… 57. http://haskellformaths.blogspot.com/2009/06/direct-products-revisited.html 58. http://softwaresimply.blogspot.com/2009/04/basic-happstack-blog-app.html 59. http://haskellformaths.blogspot.com/2009/06/some-groups-and-some-graphs.html 60. http://just-bottom.blogspot.com/2009/06/short-term-hp2any-plans.html 61. http://haddock2009.wordpress.com/2009/06/25/cross-package-plan-a/ 62. http://buffered.io/2009/06/25/data-crunching-in-haskell/ 63. http://ro-che.blogspot.com/2009/06/halting-problem.html 64. http://web.mornfall.net/blog/darcs_2.3_beta_1.html 65. http://koweycode.blogspot.com/2009/06/haskell-syntax-highlighting-on.html 66. http://feedproxy.google.com/~r/gbacon/~3/7rlf4Dd1JKU/setting-up-simple-test… 67. http://haddock2009.wordpress.com/2009/06/24/cross-package-documentation-par… 68. http://feedproxy.google.com/~r/splonderzoek/~3/vO9VuXrFTCg/rfc-extensible-t… 69. http://www.akrish.net/2009/06/24/foray-into-haskell/ 70. http://llaisdy.wordpress.com/2009/06/24/decorate-sort-undecorate-in-haskell/ 71. http://haddock2009.wordpress.com/2009/06/23/how-to-navigate-your-code/ 72. http://web.mornfall.net/blog/soc_progress_5.html 73. http://www.defun2009.info/blog/2009/06/the-tutorial-schedule-is-now-ready/ 74. http://www.defun2009.info/blog/2009/06/last-call-for-talk-proposals/ 75. http://gbacon.blogspot.com/2009/06/setting-up-simple-test-with-cabal.html 76. 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ANN: loli: a minimal web dev DSL
by Jinjing Wang 29 Jun '09

29 Jun '09

loli is a DSL built on hack. It allows you to easily define routes, build your custom template backends through a simple Template interface, and integrate with other hack middleware. * driver The simplest app looks like this import Network.Loli import Hack.Handler.Happstack main = run . loli $ get "/" (text "loli power") * route get "/hello" $ do text "hello" will route "/hello" to a controller that outputs hello. * middleware using a middleware is just as declaring middleware lambda * template the template interface is class Template a where interpolate :: a -> String -> Context -> IO String Context is just [(String, String)] After implementing your own template engine, you can use output $ your-engine-constructor "template-name" * demo I put the source of a dummy paste app on itself: <http://lolipaste.easymic.com/00000-lolipaste.haskell> loli is on hackage, lolipaste is in loli repo on github: * <http://github.com/nfjinjing/loli> happy hacking -- jinjing

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XMonad and NetworkManager?
by Ketil Malde 29 Jun '09

29 Jun '09

Hi, A bit off-topic, but this is the café, after all... Like many here, I run XMonad as my window manager on top of Linux. On - at least my brand of - Linux, networking is generally handled by NetworkManager, which really needs its associated applet (nm-applet) to work properly. While I discovered trayer, which at least let me run nm-applet without dragging in most of Gnome, it still drags in some of the bloat, and interacts a bit poorly with the rest of the system (temporarily locks up the screen, transparency doesn't work, positions itself awkwardly, needs gconfd at incovinient times..) So: has anybody tried better alternatives to NetworkManager and nm-applet? Wicd, say? Or something that can integrate with dzen? -k -- If I haven't seen further, it is by standing in the footprints of giants

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ANNOUNCE: X Haskell Bindings 0.3
by Antoine Latter 29 Jun '09

29 Jun '09

I'd like to announce the 0.3.* series release of the X Haskell Bindings. This release, like the prior 0.2.* series focuses on making the API prettier. This release is based on the XCB protocol descriptions version 1.5 This does mean that there's a good chance this is a breaking release for any code compiled against 0.2.*. The goal of XHB is to provide a Haskell implementation of the X11 wire protocol, similar in spirit to the X protocol C-language Binding (XCB). On Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xhb Source: darcs get http://community.haskell.org/~aslatter/code/xhb/ New this release: * In 0.2, a lot of the core protocol requests, events and replies were updated to use prettier Haskell datatypes for the various enums and bitmasks. Thanks to Peter Harris's work on the protocol description XML files, these niceties have extended out to all of the extension requests, events and replies and such. * Due to name clashes, I the type-names for events and errors now include an "Event" or "Error" suffix. For example, the type "Notify" has become "NotifyEvent". * Now based on the protocol description version 1.5, from 1.4. Related projects: X protocol C-language Binding: http://xcb.freedesktop.org/

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[patch] lhaskell.vim update
by Nicolas Wu 29 Jun '09

29 Jun '09

I have made some modifications to the lhaskell.vim (v1.04) file to add a feature, and fix up some bugs. I don't know if this is the right place to post for patches, but the file I have claims that the haskell-cafe is the maintainer. First, I made it so that \begin{spec} and \end{spec} environments are recognised. This helps those of us who use lhs2TeX to document files. Second, I've fixed up the highlighting where inline Haskell between bars "|" used to be mistaken for verbatim text. There's also a small fix to handle \begin{code} \end{code} tags better. The modified file is attached.

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Haskell Platform + gtk2hs
by John Van Enk 29 Jun '09

29 Jun '09

List, Has any one managed to install gtk2hs on a Windows box running the Haskell Platform? I've had no luck; it seems the gtk2hs installer is unable to find the GHC installation. /jve

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How to convert CPid to Word32?
by Magicloud Magiclouds 29 Jun '09

29 Jun '09

Hi, I am trying to use Data.Binary with ProcessID. Well, how to convert between CPid and Word32? Thanks. -- 竹密岂妨流水过山高哪阻野云飞

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parallel haskell
by Kevin Smith 29 Jun '09

29 Jun '09

I'm interested in doing some research with parallel programming using Haskell (both multi-core on one machine and clusters using multiple machines) but in going through the various resources on the web (looking at GPH and others), it is not clear to me what the current state is as many of the resources/projects have out of date information in them. Any pointers ? What parallel extensions are available in the current version 6.10.3 ? Which parallel extensions support clustered networks ? Where to start ? Thanks

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