April 2009 - Haskell - Haskell.org

ANNOUNCE: OpenAL 1.3.1.2
by Sven Panne 28 Apr '09

28 Apr '09

A new version of the OpenAL package has been uploaded to Hackage. This is a bug fix only release: * Minor tweaks for recent Cabal versions * Removal of old GHC build system relics. * Use the correct calling convention on Windows. Cheers, S.

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ANNOUNCE: GLUT 2.1.2.0
by Sven Panne 28 Apr '09

28 Apr '09

A new version of the GLUT package has been uploaded to Hackage. This is a feature release, adding all the shiny new features of the upcoming freeglut 2.6.0 C library plus a few older bits and pieces which had been missing: * Minor tweaks for recent Cabal versions * Removal of old GHC build system relics. * Added support for OpenGL 3.x context creation (freeglut only) * Added support for getModeValues (freeglut extension) * Added freeglut-specific full screen API * Added freeglut-specific (de-)initialization API * Added support for multisampling with given samples per pixel (freeglut) * Added support for mouse wheel callback (freeglut) * Added support for window state callback (freeglut) * Added support for captionless/borderless windows (freeglut 2.6.0) * Handle special keys introduced by freeglut 2.6.0 The most important addition is the ability to create versioned context, so you can use forward compatible OpenGL 3.1 contexts. Death to the fixed function pipeline!! ;-) Cheers, S.

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ANNOUNCE: OpenGL 2.2.2.0
by Sven Panne 28 Apr '09

28 Apr '09

A new version of the OpenGL package has bee uploaded to Hackage. This is mainly a bug fix release, containing the following changes: * Minor tweaks for recent Cabal versions. * Removal of old GHC build system relics. * Handle "invalid framebuffer operation" error. * Terminate GLSL attribute names with NUL in various functions. * Access 3D texture functions via their core API names, improving portability (e.g. for MacOS X). * Added a workaround for a bug in the SGI tessellator. * Fixed marshalling of control points for evaluators. * Added mapBuffer/unmapBuffer and beginQuery/endQuery to exported API. Cheers, S.

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ANNOUNCE: Haskell File Manager
by Michael Dever 28 Apr '09

28 Apr '09

Hi, The first release of Haskell File Manager has been uploaded to http://code.haskell.org/haskellfm This is a program for viewing/managing the files on your computer. It has all the common functionality you would expect from your current file manager, copying, moving, deleting, renaming, opening and searching. It is a beta release, so you know what to expect there, and any bugs found can be filed at http://trac.haskell.org/haskellfm . Regards, Michael

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Announce: GraphViz: Change of Maintainer
by Matthew Sackman 28 Apr '09

28 Apr '09

I no longer have the time to continue development of the (apparently, judging from the number of emails I'm getting, rather popular) graphviz package. Fortunately, Ivan Lazar Miljenovic who has extended it himself and sent me patches (some of which I did get round to folding in) has agreed to take on the package. Please direct all further queries to him! Many thanks Ivan! Matthew

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LAST CALL: Haskell Communities and Activities Report
by voigt＠tcs.inf.tu-dresden.de 28 Apr '09

28 Apr '09

Dear Haskellers, It is not yet too late to contribute to the May 2009 edition of the Haskell Communities and Activities Report. If you haven't already, please write an entry for your new project, or update your old entry. Please mail your entries to hcar(a)haskell.org in LaTeX format. More information can be found in the original Call for Contributions at http://www.haskell.org/pipermail/haskell/2009-April/021180.html I look forward to receiving your contributions. Thanks a lot, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:voigt@tcs.inf.tu-dresden.de

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ANN: Bamse-0.9.4, a Windows Installer generator
by Sigbjorn Finne 26 Apr '09

26 Apr '09

Hi, a new version of Bamse has been uploaded to hackage, http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bamse Bamse is a package and application for letting you quickly put together Windows Installers for your software projects/products from within the comforts of Haskell. New in this release is the support for generating MSIs from your Cabal projects, having them either be built from source or just have them be installed and registered at install-time. i.e., one-click installation of Cabal packages. See examples/Cabal.hs for a worked example of how to bundle up Cabal packages. I've found this functionality a bit useful, hope others do too. The new version also adds support for handling .NET assemblies. enjoy --sigbjorn

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Haskell Weekly News: Issue 115 - April 25, 2009
by Brent Yorgey 25 Apr '09

25 Apr '09

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20090425 Issue 115 - April 25, 2009 --------------------------------------------------------------------------- Welcome to issue 115 of HWN, a newsletter covering developments in the [1]Haskell community. By all reports, the [2]5th Haskell Hackathon was a resounding success, with over 50 hackers present and many interesting Haskell projects worked on! Announcements darcs hacking sprint 2 and hac5 report. Eric Kow [3]sent out a link to a [4]report on the second darcs hacking sprint, held as part of the Haskell Hackathon. HPong-0.1.2: A simple OpenGL Pong game based on GLFW. R.A. Niemeijer [5]announced the release of [6]HPong, a simple Pong game implemented using OpenGL and GLFW. Hac5 roundup. Martijn van Steenbergen [7]reported on the 5th Haskell Hackathon. See the [8]wiki page for details, pictures, and links to blog posts. HTTP-4000.0.6. Sigbjorn Finne [9]announced a new release of the [10]HTTP package, which adds more robust handling of ill-formed cookies, and fixes a bug in normalization of certain proxy-bound requests. dataenc 0.12.1.0. Magnus Therning [11]announced version 0.12.1.0 of the [12]dataenc package. This version adds a bunch of new encodings, including xxencode, hexadecimal, quoted-printable, python escaping, and url encoding; and also fixed some bugs. list-tries-0.0 - first release. Matti Niemenmaa [13]announced the first public release of [14]list-tries, a library providing implementations of finite sets and maps for list keys using tries, both simple and of the Patricia kind. The data types are parametrized over the map type they use internally to store the child nodes: this allows extending them to support different kinds of key types or increasing efficiency. curl-1.3.5. Sigbjorn Finne [15]announced a new release of the [16]curl package, which provides Haskell bindings to libcurl. It works with ghc 6.10.2, taking into account the updated story on how to register Haskell-based finalizers. Runge-Kutta library -- solve ODEs. Uwe Hollerbach [17]announced a [18]Runge-Kutta library for numerically solving ordinary differential equations. funsat-0.6. Denis Bueno [19]announced version 0.6 of [20]funsat, a modern, DPLL-style SAT solver written in Haskell. Funsat solves formulas in conjunctive normal form and produces a total variable assignment for satisfiable problems. Version 0.6 adds a representation for logical circuits (and, or, not, onlyif, iff, if-then-else) supporting efficient conversion to CNF, and now uses the BSD3 license. control-monad-exception-0.1: Explicitly typed exceptions. Pepe Iborra [21]announced the [22]control-monad-exception package, which provides explicitly typed exceptions for Haskell. The type of a computation in the EM monad carries a list of the exceptions that the computation may throw. A exception is raised with 'throw', which in addition adds it to the type, and captured with 'catch', which correspondingly removes it from the type. Only safe computations (all exceptions handled) can escape from the monad. Haskell Implementers' Workshop 2009 (co-located with ICFP). Simon Marlow [23]issued a call for talks to be given at the ACM SIGPLAN [24]Haskell Implementers' Workshop, to be held on September 3 in Edinburgh, Scotland, in conjunction with [25]ICFP 2009. The proposal deadline in 15 June. The Haskell Implementers Workshop is a new workshop to be held alongside ICFP 2009 this year in Edinburgh, Scotland. There will be no proceedings; it is an informal gathering of people involved in the design and development of Haskell implementations, tools, libraries, and supporting infrastructure. persistent-map-0.0.0. Peter Robinson [26]announced the [27]persistent-map package, which provides a thread-safe (STM) frontend for finite map types together with a backend interface for persistent storage. A pragmatic Haskell .NET interop layer, 0.4.0. Sigbjorn Finne [28]announced a new release of [29]hs-dotnet, a Haskell .NET interop layer. It lets you access .NET functionality from Haskell and vice versa. The new version includes development done since the start of the year. Apart from rewriting the internals completely to put it all on a sounder footing, this release includes proper support for .NET generic types (classes and interfaces), mapping them naturally on to Haskell parameterized types. Utrecht Haskell Compiler (UHC) -- first release. atze [30]announced the first public release of the [31]Utrecht Haskell Compiler (UHC). UHC supports almost all Haskell98 features plus many experimental extensions. The compiler runs on MacOSX, Windows (cygwin), and various Unix flavors. Features include multiple backends, including a bytecode interpreter backend and a GRIN based, full program analysing backend; experimental language extensions, some of which have not been implemented before; implementation via attribute grammars and other high-level tools; and ease of experimentation with language variants, thanks to an aspect-oriented internal organisation. 6.10.3 plans. Ian Lynagh [32]announced plans for a 6.10.3 release of GHC, in order to fix the handling of ^C in ghci. 6.10.3 will also use haskeline instead of editline. A HERE Document syntax. Jason Dusek [33]proposed a lightweight syntax for HERE documents in Haskell. Discussion Functor and Haskell. Daryoush Mehrtash [34]asked about the link between functors in category theory and Haskell's Functor class; the resulting thread is a good introduction to the connections between Haskell and category theory for those just learning the latter. breaking too long lines. Christian Maeder [35]asked how to break long lines in Haskell source, leading to an interesting discussion of coding style. Jobs Haskell consultant wanted to develop small, Mac-based utility in Haskell or AppleScript. R J [36]announced an opportunity to develop a short program to annotate lists of words with their definitions. Blog noise [37]Haskell news from the [38]blogosphere. * Twan van Laarhoven: [39]Where do I get my non-regular types?. * Sebastian Fischer: [40]Reinventing Haskell Backtracking. * Darcs: [41]darcs hacking sprint #2 report. * Well-Typed.Com: [42]Platform progress and the Hackathon. * Roman Cheplyaka: [43]Hac5: the rest of the story (almost). * Twan van Laarhoven: [44]A non-regular data type challenge. * Magnus Therning: [45]dataenc 0.12.1.0 released. * Galois, Inc: [46]Portland Next Week: ICFP PC Functional Programming Workshop. * Christophe Poucet (vincenz): [47]Flattening Data.Map. * Roman Cheplyaka: [48]Hac5: second day. * Xmonad: [49]contribs review. * GHC / OpenSPARC Project: [50]Loose ends and register pairing. * Sean Leather: [51]Latest on the incremental fold and attributes. * >>> Matthew Podwysocki: [52]Functional Solution for the Shortest Path Problem . * Chris Smith: [53]Code for Manipulating Graphs in Haskell. * Austin Seipp: [54]A little fun with Haskabelle. Proving things about *existing* Haskell code in Isabelle. * Tupil: [55]Running Happstack applications with FastCGI. * Martijn van Steenbergen: [56]Hac5-Saturday. * beelsebob: [57]Bottoms. * Antoine Latter: [58]Using Haskeline. * Darcs: [59]darcs weekly news #26. * Martijn van Steenbergen: [60]Hacking GHC-What I've learned. * >>> Brandon Simmons: [61]Initial tests of Tries: Follow Up. * >>> Lab 49: [62]The Algebra of Data, and the Calculus of Mutation. * Martijn van Steenbergen: [63]Hac5-Friday. Pictures from the Hackathon. * >>> Matthew Podwysocki: [64]Haskell and Collective Intelligence . Quotes of the Week * Gracenotes: foldr chosen for its magical evil terminating powers * uninverted: Moving from lisp to haskell with respect to functions is like moving from c to perl with respect to strings. * Berengal: [On infinitely fast computers] The OS probably has a failsafe built in: If a program is running it's in an infinite loop and needs to be killed... * nikki93: After a bit more delving, I've come to see the power of haskell at last. You have to treat functions like crap, forget about the C idea that they're 'big things'. They're not. * Berengal: I was squashing a bug, got frustrated, and typed "fix error" in ghci... About the Haskell Weekly News New editions are posted to [65]the Haskell mailing list as well as to [66]the Haskell Sequence and [67]Planet Haskell. [68]RSS is also available, and headlines appear on [69]haskell.org. To help create new editions of this newsletter, please see the information on [70]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [71]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://www.haskell.org/haskellwiki/Hac5 3. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57551 4. http://blog.darcs.net/2009/04/darcs-hacking-sprint-2-report.html 5. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57493 6. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HPong 7. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57470 8. http://www.haskell.org/haskellwiki/Hac5 9. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57336 10. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HTTP 11. http://article.gmane.org/gmane.comp.lang.haskell.libraries/10945 12. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dataenc 13. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57311 14. http://iki.fi/matti.niemenmaa/list-tries/ 15. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57251 16. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/curl 17. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57160 18. http://www.korgwal.com/software/rk-1.0.0.tar.gz 19. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57101 20. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/funsat 21. http://article.gmane.org/gmane.comp.lang.haskell.general/17120 22. http://article.gmane.org/gmane.comp.lang.haskell.general/17120 23. http://article.gmane.org/gmane.comp.lang.haskell.general/17113 24. http://haskell.org/haskellwiki/HaskellImplementorsWorkshop 25. http://www.cs.nott.ac.uk/~gmh/icfp09.html 26. http://article.gmane.org/gmane.comp.lang.haskell.general/17106 27. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/persistent-map 28. http://article.gmane.org/gmane.comp.lang.haskell.general/17105 29. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hs%2Ddotnet 30. http://article.gmane.org/gmane.comp.lang.haskell.general/17103 31. http://www.cs.uu.nl/wiki/UHC 32. http://article.gmane.org/gmane.comp.lang.haskell.glasgow.user/16792 33. http://article.gmane.org/gmane.comp.lang.haskell.prime/2787 34. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/57324 35. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/57207 36. http://article.gmane.org/gmane.comp.lang.haskell.cafe/57568 37. http://planet.haskell.org/ 38. http://haskell.org/haskellwiki/Blog_articles 39. http://twan.home.fmf.nl/blog/haskell/non-regular2.details 40. http://www-ps.informatik.uni-kiel.de/~sebf/pub/atps09.html 41. http://blog.darcs.net/2009/04/darcs-hacking-sprint-2-report.html 42. http://blog.well-typed.com/2009/04/platform-progress-and-the-hackathon/ 43. http://ro-che.blogspot.com/2009/04/hac5-rest-of-story-almost.html 44. http://twan.home.fmf.nl/blog/haskell/non-regular1.details 45. http://therning.org/magnus/archives/568 46. http://www.galois.com/blog/2009/04/23/portland-next-week-icfp-pc-functional… 47. http://cpoucet.wordpress.com/2009/04/18/flattening-datamap/ 48. http://ro-che.blogspot.com/2009/04/hac5-second-day.html 49. http://xmonad.wordpress.com/2009/04/22/contribs-review/ 50. http://ghcsparc.blogspot.com/2009/04/loose-ends-and-register-pairing.html 51. http://feedproxy.google.com/~r/splonderzoek/~3/KWqNCgsK1ww/latest-on-increm… 52. http://codebetter.com/blogs/matthew.podwysocki/archive/2009/04/21/functiona… 53. http://cdsmith.wordpress.com/2009/04/20/code-for-manipulating-graphs-in-has… 54. http://www.jedi-ninja.net/2009/04/20/A-little-fun.html 55. http://blog.tupil.com/running-happstack-applications-with-fastcgi/ 56. http://martijn.van.steenbergen.nl/journal/2009/04/19/hac5-saturday/ 57. http://noordering.wordpress.com/2009/04/19/bottoms/ 58. http://panicsonic.blogspot.com/2009/04/using-haskeline.html 59. http://blog.darcs.net/2009/04/darcs-weekly-news-26.html 60. http://martijn.van.steenbergen.nl/journal/2009/04/18/hacking-ghc-what-ive-l… 61. http://coder.bsimmons.name/blog/2009/04/initial-tests-of-tries-follow-up/ 62. http://blog.lab49.com/archives/3011 63. http://martijn.van.steenbergen.nl/journal/2009/04/17/hac5-friday/ 64. http://codebetter.com/blogs/matthew.podwysocki/archive/2009/04/17/haskell-a… 65. http://www.haskell.org/mailman/listinfo/haskell 66. http://sequence.complete.org/ 67. http://planet.haskell.org/ 68. http://sequence.complete.org/node/feed 69. http://haskell.org/ 70. http://haskell.org/haskellwiki/HWN 71. http://code.haskell.org/~byorgey/code/hwn/

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ANN control-monad-exception-0.1: Explicitly typed exceptions
by Pepe Iborra 25 Apr '09

25 Apr '09

The control-monad-exception package [1] provides explicitly typed exceptions for Haskell. In other words, this is a perfect example of bundling in a Haskell library what for other programming languages is a native feature. The type of a computation in the EM monad carries a list of the exceptions that the computation may throw. A exception is raised with 'throw', which in addition adds it to the type, and captured with 'catch', which correspondingly removes it from the type. Only safe computations (all exceptions handled) can escape from the monad. The encoding used for the exception list is based on a phantom type variable carrying a @Throws@ constraint for every exception type. Catching an exception @e@ satifies the constraint @Throws e@ thus removing it from the type. It is possible to teach Throws about exception subtyping by manually inserting new instances declaring the subtyping relations between exceptions. I don't believe there is a better way to handle this, as the existential wrapper encoding used for Control.Exception.SomeException does not reveal the subtyping relations, but ideas are welcome. Example -------- GHCi infers the following types eval :: (Throws DivideByZero l, Throws SumOverflow l) => Expr -> EM l Double eval `catch` \ (e::DivideByZero) -> return (-1) :: Throws SumOverflow l => Expr -> EM l Double runEM (eval `catch` \ (e::SomeException) -> return (-1)) :: Expr -> Double for the code below. > import Control.Monad.Exception > import Data.Typeable > data Expr = Add Expr Expr | Div Expr Expr | Val Double > eval (Val x) = return x > eval (Add a1 a2) = do > v1 <- eval a1 > v2 <- eval a2 > let sum = v1 + v2 > if sum < v1 || sum < v2 then throw SumOverflow else return sum > eval (Div a1 a2) = do > v1 <- eval a1 > v2 <- eval a2 > if v2 == 0 then throw DivideByZero else return (v1 / v2) > data DivideByZero = DivideByZero deriving (Show, Typeable) > data SumOverflow = SumOverflow deriving (Show, Typeable) > instance Exception DivideByZero > instance Exception SumOverflow Comments and patches are welcome. Cheers, Pepe Iborra [1] - http://hackage.haskell.org/cgi-bin/hackage-scripts/package/control-monad-ex…

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Hac5 roundup
by Martijn van Steenbergen 23 Apr '09

23 Apr '09

Dear Haskell Hackers, Many thanks to all those who attended Hac5! We had a spectacular number of participants: over 50 hackers showed up, representing several countries. Many thanks also to the organising committee and sponsors! Those bagels on Sunday were delicious. :-) Please check out the updated wiki page [1] for: * a nice group photo of most attendants taken by Thomas Davie; * a list of blog posts/galleries/videos of the event; * a list of projects worked on and the progress that was made. Additionally, if you covered Hac5 in some way or contributed to any of the projects, please add your links or progress summary to the page. Thanks, Martijn. [1] http://www.haskell.org/haskellwiki/Hac5

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