- Haskell-Cafe - Haskell.org

whatever happened to sendFile?
by Jason Dusek 16 Aug '08

16 Aug '08

I found an old lib for it: http://www.haskell.org/ghc/docs/6.0/html/unix/System.Sendfile.html Hoogle turns up nothing, though. -- _jsn

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Pretty Print, text or ++?
by Paul Keir 15 Aug '08

15 Aug '08

Hi there, I'm writing a pretty printer using the Text.PrettyPrint library, and there's a pattern I'm coming across quite often. Does anyone know whether, text (a ++ b ++ c ++ d) or text a <+> text b <+> text c <+> text d runs quicker? Cheers, Paul

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"Prompt" Monad
by Martin Hofmann 15 Aug '08

15 Aug '08

I just came across last year's thread about Ryan Ingram's "Prompt" monad ( http://www.mail-archive.com/haskell-cafe@haskell.org/msg33040.html ) and wondered if it might be useful for debugging and program analysis purposes. In particular, I thought about enforcing program decisions interactively. Consider for example modifying the heuristic function of a search algorithm at specific breakpoints. Is this possible with the "Prompt" monad? Furthermore, could somebody post the full code of it (and maybe a short example how to use it if at hand)? I was not able to run the code from the previous posts and the referring links are dead. Thanks a lot, Martin

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Re: [Haskell-cafe] Re: Is www.haskell.org down?
by Donn Cave 15 Aug '08

15 Aug '08

Quoth "Thomas Schilling" <nominolo(a)googlemail.com>: | ... Haskell can learn from | O'Caml, O'Caml can learn from Haskell. I also think that most users | of either language actually know that. I'd like to start with a name for it. - Objective CAML (name of the language) - ocaml (name of the compiler) - OCaml (expedient name for language) I'm always a little piqued by "O'Caml", since I was so fond of O'Haskell. Now, there was a real Irishman. Donn

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Re: [Haskell-cafe] GHC Error: "FATAL:Symbol _XJv_srt already defined."
by Ron Alford 15 Aug '08

15 Aug '08

I reopened the bug, since I found slight changes to the file were able to reproduce the bug in recent versions of ghc-6.9. I also can't get the -S compilation step to work with the new file, unless I'm missing a step. -Ron Alford On Mon, Jul 21, 2008 at 3:32 AM, Ron Alford <ronwalf(a)volus.net> wrote: > Oops, already posted the bug: > http://hackage.haskell.org/trac/ghc/ticket/2456 > > On Mon, Jul 21, 2008 at 3:29 AM, Austin Seipp <mad.one(a)gmail.com> wrote: >> Status update: after checking out the latest HEAD and building it, the >> above error does not occur: >> >> $ ~/ghc-head/bin/ghc --version >> The Glorious Glasgow Haskell Compilation System, version 6.9.20080720 >> $ ~/ghc-head/bin/ghc --make DerivingError.hs >> >> <no location info>: >> Warning: -fallow-overlapping-instances is deprecated: Use the >> OverlappingInstances language instead >> [1 of 1] Compiling DerivingError ( DerivingError.hs, DerivingError.o ) >> $ >> >> However, this doesn't exactly help your immediate problem, and it >> likely won't until 6.10.1 is released, as 6.8.3 is going to be the >> last release of the 6.8 branch. >> >> Truly sorry I couldn't have helped you more. >> >> Austin >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> >

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cabal on ubuntu
by Martin DeMello 15 Aug '08

15 Aug '08

I'm running Ubuntu 8 (Hardy Heron), and while trying to install cabal ran into this bug: https://bugs.launchpad.net/ubuntu/+source/haskell-cabal/+bug/231099 I finally had to install cabal manually, but it took me a lot of googling to be sure that was the right thing to do. Could someone who knows more than me put a howto in the ubuntu wiki https://wiki.ubuntu.com/MOTU/Teams/UncommonProgrammingLanguages/Haskell and/or the haskell one http://www.haskell.org/haskellwiki/GNU/Linux#Ubuntu ? martin

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Re: Is www.haskell.org down?
by Don Stewart 15 Aug '08

15 Aug '08

By the way, for those wondering why Jon Harrop would say such an unusual thing on the Haskell list, have a look at his contributions over on the OCaml list, http://article.gmane.org/gmane.comp.lang.caml.general/43430 Some choice quotes: "almost all of the examples of Haskell's use in industry are fakes" "nobody has ever done anything significant using Haskell" Jon's the primary source of FUD against Haskell and its community, as he goes around promoting his site in other functional programming communities. This kind of behaviour's been going on for a few years now, sadly. It's all rather disappointing. -- Don

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searchmonkey for haskell apis
by brad clawsie 15 Aug '08

15 Aug '08

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 i've been looking into the possibility of creating some xslt to expose haskell apis to yahoo search via searchmonkey. if you see the java api search plugin, you can see some possibilities. i was wondering if anyone maintaining any the official api docs had considered looking at searchmonkey. from a site owner's perspective, some rdf metadata can be inlined with the api docs which yahoo will automatically crawl to build up a search corpus, which could then be rendered into a display using the searchmonkey tools. this approach would be superior to the xslt approach i suggest above, since it exposes industry standard metadata that any search engine can use. the xslt approach is an option yahoo offers to let third-parties "scrape" sites they want put in ysearch. since two parties approaches might conflict, i thought i would send out a note. thanks. brad -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEARECAAYFAkigzvsACgkQxRg3RkRK91MwiACeJ66+jYgPfKvoYCDNYsUulnTo 308An3NrwfkGAgfWJud4MaggHf0Zh9vw =n/9o -----END PGP SIGNATURE-----

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Is www.haskell.org down?
by Sean Leather 15 Aug '08

15 Aug '08

I can't reach www.haskell.org , and I'm having withdrawal issues. Sean

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haskell.org is down
by Benjamin L.Russell 15 Aug '08

15 Aug '08

I tried posting a message to the haskell-beginners mailing list about a half-hour ago, but it seems that all of haskell.org has been down for at least the past half-hour. If anybody on this mailing list responsible for server maintenance receives this message, could you please check into this matter? I would like to be able to post messages on the haskell-related mailing lists, but I can't even get the list of mailing lists to come up, much less post. -- Benjamin L. Russell

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Re: [Haskell-cafe] Bug with QuickCheck 1.1 and GHC 6.8.2
by Patrick Perry 15 Aug '08

15 Aug '08

The bug is in the "variant" function in QuickCheck. I replaced variant :: Int -> Gen a -> Gen a variant v (Gen m) = Gen (\n r -> m n (rands r !! (v+1)) where rands r0 = r1 : rands r2 where (r1, r2) = split r0 with variant :: Int -> Gen a -> Gen a variant v (Gen m) = Gen (\n r -> m n (rands r !! v')) where v' = abs (v+1) `mod` 10000 rands r0 = r1 : rands r2 where (r1, r2) = split r0 and now everything works fine. "10000" seems like a reasonable value here, but one could hard-code a lower or higher value as well. Can someone make sure this gets fixed in the next version of QuickCheck? I'm not sure who the maintainer is. Patrick

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Fwd: ANN: Initial release of Language.C
by Benedikt Huber 15 Aug '08

15 Aug '08

Hello, I'm forwarding this to cafe, in case some of you are interested in this as well but not subscribed to libraries. Again, feedback is most welcome. I've almost finished integrating Language.C with c2hs too (fixing a few bugs along the way), so there will be a quite complex example available soon. Thanks for your interest. Begin forwarded message to libraries(a)haskell.org: > From: Benedikt Huber <benjovi(a)gmx.net> > Date: 13. August 2008 15:45:50 GMT+02:00 I'm pleased to announce the first release of Language.C, a library for analysing and generating C code. This release features * A reasonably well tested parser handling and recording all of C99 and most GNU extensions, most notably gcc's attribute syntax. * A pretty printer generating source code from the AST, covering the same language subset as the parser. * A preview of the analysis framework, including functionality for dissecting C's cruel type and variable declarations. Places: * The project's homepage is located at http://www.sivity.net/projects/language.c (Getting Started, Bug Tracker) * The package is available via hackage (language-c-0.3) * darcs repo: http://code.haskell.org/language-c * API docs: http://code.haskell.org/~bhuber/docs/language-c-latest/ The library originated from the C-related code in c2hs (http://www.cse.unsw.edu.au/~chak/haskell/c2hs/ ), and is the topic of my SoC project, mentored by Iavor Diatchki. (Iavor, Don Steward and Duncan Coutts provided great support, thank you) Feedback and suggestions in any form are most welcome, especially because there is a large range of features which could be implemented. The current status and a few ideas for the next releases are summarized at http://www.sivity.net/projects/language.c/wiki/ ProjectPlan. best regards, benedikt

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Haskell equivalent toPerl stat function
by A Smith 15 Aug '08

15 Aug '08

Hi I'm new to Haskell, so correct me if this is the wrong list or the wrong question. I'm looking for a function similar to the Perl stat to provide me with the last modify time of a file. I've been poring over source code entries referencing hfileSize but can't find the specific bit which reads the directory entry, so I could copy the code. Any advice would be welcome. -- Andrew in Edinburgh,Scotland

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Bug with QuickCheck 1.1 and GHC 6.8.2
by Patrick Perry 14 Aug '08

14 Aug '08

I'm running into problems with generating an arbitrary function of type Double -> Double. Specifically, the following code: {-# LANGUAGE PatternSignatures #-} import Test.QuickCheck import Text.Show.Functions prop_ok (f :: Double -> Double) = f (-5.5) `seq` True prop_bug (f :: Double -> Double) = f (-5.6) `seq` True main = do putStr "prop_ok:\t" >> quickCheck prop_ok putStr "prop_bug:\t" >> quickCheck prop_bug On an Intel Core 2 Duo running Mac OS 10.5.4 with GHC 6.8.2 the output I get is prop_ok: OK, passed 100 tests. prop_bug: Test: Prelude.(!!): negative index On Intel Xeon running RedHat with GHC 6.8.2 both tests hang. Has anyone seen this before? Is it fixed in QuickCheck2? Thanks, Patrick

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Haskell Weekly News: Issue 81 - August 13, 2008
by Brent Yorgey 13 Aug '08

13 Aug '08

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20080813 Issue 81 - August 13, 2008 --------------------------------------------------------------------------- Welcome to issue 81 of HWN, a newsletter covering developments in the [1]Haskell community. This week saw some interesting talks at [2]AngloHaskell, and some cool new packages to hit Hackage, like [3]Language.C, [4]AERN-Real, [5]FTGL, and [6]Hoogle. What are you waiting for? Get out there and build something! Announcements Initial release of Language.C (language-c-0.3). Benedikt Huber [7]announced the [8]first release of [9]Language.C, a library for analysing and generating C code. This release features a reasonably well tested parser, a pretty printer, and a preview of the analysis framework. darcs roadmap. Jason Dagit [10]wrote to the list to thank everyone for their support for darcs, and to announce a webpage with a [11]roadmap for future darcs features. Darcs is alive and well! Anglo Haskell 2008 -- slides and audio. Matthew Sackman [12]announced that [13]slides and audio from Anglo Haskell 2008 are now available. BLAS bindings for haskell, version 0.5. Patrick Perry [14]announced a new release of the Haskell BLAS bindings, including a number of new features and improvements. Tutorial on information visualization and visual analytics in Haskell. Jefferson Heard [15]announced the [16]tutorial he will be presenting at DEFUN 2008, to give everyone a sneak peek at the long version of the tutorial before he's done with it. Comments and questions are welcome and encouraged. interval and polynomial enclosure arithmetics. Michal Konecny [17]announced the release of the [18]AERN-Real and [19]AERN-RnToRm packages, which model and reasonably efficiently implement exact real arithmetic. FTGL 1.0. Portable truetype font rendering in OpenGL. Jefferson Heard [20]announced the release of [21]Haskell bindings to FTGL, an easy to use library for portable rendering of TrueType fonts in OpenGL. Google Summer of Code Progress updates from participants in the 2008 [22]Google Summer of Code. GHC plugins. Max Bolingbroke is working on dynamically loaded plugins for GHC. [23]This week, he gave [24]a talk at AngloHaskell. Language.C. Benedikt Huber (visq) is [25]working on Language.C, a standalone parser/pretty printer library for C99. This week, he [26]announced the [27]first release of the [28]Language.C package. Hoogle 4. Neil Mitchell (ndm) is working on [29]Hoogle 4. [30]This week, he released several [31]command-line versions and a [32]web version of Hoogle 4, updated the manual, and gave [33]a talk at AngloHaskell. Next week, he plans to work on generating better Hoogle databases, and some bug fixes. DPH physics engine. Roman Cheplyaka (Feuerbach) is working on a [34]physics engine using [35]Data Parallel Haskell. [36]This week, he added complete support for general polyhedra, and fixed some bugs in the collision handler. He also added support for bounding spheres, although the results so far are disappointing, due to delays in the GHC implementation of parallel arrays. Next week, he plans to implement static bodies and BSP trees. Generic tries. Jamie Brandon is working on a library for efficient maps using generalized tries. GHC API. Thomas Schilling (nominolo) is working on [37]improvements to the GHC API. Cabal dependency framework. Andrea Vezzosi (Saizan) is working on a [38]make-like dependency analysis framework for Cabal. Blog noise [39]Haskell news from the [40]blogosphere. * >>> Nicholas Lativy: [41]Haskell in less than five minutes. Nicholas refreshes his memory of Haskell. * Douglas M. Auclair (geophf): [42]Monoid use. * Roman Cheplyaka: [43]Status report: week 11-12. * Douglas M. Auclair (geophf): [44]Combinatory Birds as Types. * Douglas M. Auclair (geophf): [45]Getting Better, part ][. * Neil Mitchell: [46]GSoC Hoogle: Week 11. * Max Bolingbroke: [47]Compiler Plugins AngloHaskell Talk. * London Haskell Users Group: [48]Video: Paradise, a DSEL for Derivatives Pricing. * Roman Cheplyaka (Feuerbach): [49]Compiling GHC. Roman records his experiences building the latest development version of GHC. * Luke Palmer: [50]Mindfuck: The Reverse State Monad. * Dan Piponi (sigfpe): [51]Untangling with Continued Fractions: Part 0. * Joachim Breitner: [52]Xmonad on my mobile phone. * Luke Palmer: [53]Composable Input for Fruit. * >>> Louis: [54]A Gentle Introduction to Haskell. Louis is learning Haskell by working through the Gentle Introduction. * >>> Bryan St. Amour: [55]Some Project Euler. Bryan learns some Haskell the good old-fashioned way---by solving Project Euler problems. * Magnus Therning: [56]TagSoup, meet Parsec!. Magnus uses Parsec to parse streams of tags. * Thomas M. DuBuisson: [57]hsXenCtrl and pureMD5. * Alpheccar: [58]Haskell, iPhone and Biotech. * >>> codeflow: [59]About AI and neural networks. codeflow implements neural networks in Haskell for some soccer-playing AI software. * >>> Vincent Kriek: [60]And the winner is.... Vincent decides to stick with xmonad. * >>> Matthew Trinneer: [61]A New Paradigm - Haskell and HAppS. Quotes of the Week * Anatoly Yakovenko: theory doesn't scare me. i am using haskell after all, so i am used to reading long winded papers. * bwr: mapM_ putStrLn$reverse[(++)([1..y-30]>>" ")$concat$map([" "," /", " -", " \\"]!!)[(foldr(.)(scanl(+)1)([1..y]>>[scanl(+)0])[2..]!!(2*(1+y)+x) )`mod`4|x<-[-y-2..59-y*2]]|y<-[30..61]] About the Haskell Weekly News New editions are posted to [62]the Haskell mailing list as well as to [63]the Haskell Sequence and [64]Planet Haskell. [65]RSS is also available, and headlines appear on [66]haskell.org. To help create new editions of this newsletter, please see the information on [67]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [68]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://www.wellquite.org/anglohaskell2008/ 3. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/language%2Dc 4. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real 5. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/FTGL 6. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hoogle 7. http://article.gmane.org/gmane.comp.lang.haskell.libraries/9809 8. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/language%2Dc 9. http://www.sivity.net/projects/language.c 10. http://www.haskell.org//pipermail/haskell-cafe/2008-August/045959.html 11. http://wiki.darcs.net/DarcsWiki/Roadmap 12. http://www.haskell.org//pipermail/haskell-cafe/2008-August/045986.html 13. http://www.wellquite.org/anglohaskell2008/ 14. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43036 15. http://article.gmane.org/gmane.comp.lang.haskell.cafe/42994 16. http://bluheron.europa.renci.org/docs/BeautifulCode.pdf 17. http://article.gmane.org/gmane.comp.lang.haskell.general/16368 18. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real 19. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-RnToRm 20. http://article.gmane.org/gmane.comp.lang.haskell.cafe/42955 21. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/FTGL 22. http://hackage.haskell.org/trac/summer-of-code/wiki/SoC2008 23. http://blog.omega-prime.co.uk/2008/08/11/compiler-plugins-anglohaskell-talk/ 24. http://www.wellquite.org/anglohaskell2008/ 25. http://www.sivity.net/projects/language.c/wiki/ 26. http://article.gmane.org/gmane.comp.lang.haskell.libraries/9809 27. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/language%2Dc 28. http://www.sivity.net/projects/language.c 29. http://code.haskell.org/hoogle/ 30. http://neilmitchell.blogspot.com/2008/08/gsoc-hoogle-week-11.html 31. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hoogle 32. http://haskell.org/hoogle/beta/ 33. http://www.wellquite.org/anglohaskell2008/ 34. http://haskell.org/haskellwiki/Hpysics 35. http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell 36. http://physics-dph.blogspot.com/2008/08/status-report-week-11-12.html 37. http://hackage.haskell.org/trac/ghc/wiki/GhcApiStatus 38. http://code.haskell.org/~Saizan/cabal 39. http://planet.haskell.org/ 40. http://haskell.org/haskellwiki/Blog_articles 41. http://blog.lativy.org/2008/08/13/haskell-in-less-than-five-minutes/ 42. http://logicaltypes.blogspot.com/2008/05/monoid-use.html 43. http://physics-dph.blogspot.com/2008/08/status-report-week-11-12.html 44. http://logicaltypes.blogspot.com/2008/08/combinatory-birds-as-types.html 45. http://logicaltypes.blogspot.com/2008/08/getting-better-part.html 46. http://neilmitchell.blogspot.com/2008/08/gsoc-hoogle-week-11.html 47. http://blog.omega-prime.co.uk/2008/08/11/compiler-plugins-anglohaskell-talk/ 48. http://www.londonhug.net/2008/08/11/video-paradise-a-dsel-for-derivatives-p… 49. http://ro-che.blogspot.com/2008/08/compiling-ghc.html 50. http://luqui.org/blog/archives/2008/08/10/mindfuck-the-reverse-state-monad/ 51. http://sigfpe.blogspot.com/2008/08/untangling-with-continued-fractions.html 52. https://www.joachim-breitner.de/blog/archives/300-Xmonad-on-my-mobile-phone… 53. http://luqui.org/blog/archives/2008/08/09/composable-input-for-fruit/ 54. http://lbks23.wordpress.com/2008/08/09/a-gentle-introduction-to-haskell/ 55. http://bryanstamour.com/?p=46 56. http://therning.org/magnus/archives/367 57. http://tommd.wordpress.com/2008/08/07/hsxenctrl-and-puremd5/ 58. http://www.alpheccar.org/en/posts/show/92 59. http://codeflow.wordpress.com/2008/08/03/about-ai-and-neural-networks/ 60. http://www.vincentkriek.nl/post/and-the-winner-is/ 61. http://thespohtexperiment.blogspot.com/2008/08/new-paradigm.html 62. http://www.haskell.org/mailman/listinfo/haskell 63. http://sequence.complete.org/ 64. http://planet.haskell.org/ 65. http://sequence.complete.org/node/feed 66. http://haskell.org/ 67. http://haskell.org/haskellwiki/HWN 68. http://code.haskell.org/~byorgey/code/hwn/

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Re: ``Orphan instances'' should be avoided anyway.
by Yitzchak Gale 13 Aug '08

13 Aug '08

<Moving from libraries to haskell-cafe...> I wrote: >> ...there must be some >> way to control the import and export of instances, just as we can >> now control the import and export of every other kind of symbol >> binding. Henning Thielemann wrote: > For me it's most often the case that an instance is missing. > If there is no way to change existing instance definitions, > then you must use 'newtype'. Yes, in that case newtype is a work-around, often messy. > Generalized newtype deriving simplifies to adapt the instances you want. That's only one part of it. Using a newtype can sometimes spew wreckage all over the place. But a more difficult case is when you need to use two libraries that already define conflicting instances. That requires a newtype plus however many adaptor functions you need, all inside a wrapper module. What a mess. These cases are likely to arise most often in large software projects. So there hasn't been a big enough demand yet for this feature to be implemented in any compiler, resulting in it being rejected from Haskell', unfortunately. But for large projects it has to work the other way around - the language features need to be there already for the language to be adopted for the project. Or to keep project managers from cursing themselves later on if they do choose Haskell. Anyway, I find the current behavior to be ugly and unintuitive. Why is it that when I say import Control.Monad.Error (throwError, runErrorT) there is no way to prevent also getting a surprising Monad Either instance? Never mind how things should have been named in Control.Monad.Error - that's the way it is right now. I need to be able to import the module without getting the instance. Regards, Yitz

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The Italian Haskellers Summer Meeting is Over: What Next?
by Titto Assini 13 Aug '08

13 Aug '08

E cosi' il primo incontro balnear/ricreativo degli Haskeller Italiani si e' felicemente concluso. Come da programma, rigidamente rispettato, abbiamo fatto il bagno e mangiato pizza e gelato ma soprattutto ci siamo conosciuti ed abbiamo discusso di tutto e di piu', prevalentemente Haskell (folds, arrows, happs, sviluppo web) ma non solo (democrazia elettronica, la crisi economica, mercato ed autosufficienza). Non si puo' dire che l'affluenza sia stata oceanica ma non dimentichiamo che con 3 persone si puo' fare una cellula rivoluzionaria e con una cellula rivoluzionaria si puo' cominciare a pensare a fare la rivoluzione :-) Insomma e' stato piacevole ed utile e lo riorganizzeremo certamente il prossimo anno. Ed adesso? E' evidente, dobbiamo organizzare un incontro invernale, sullo stile di AngloHaskell, per presentare e discutere progetti di sviluppo, idee per futuri progetti ed iniziative che possano servire a rafforzare ed estendere la comunita' Haskell Italiana. Interessati? Date uno sguardo a http://www.haskell.org/haskellwiki/ItaloHaskell Saluti, titto -- Pasqualino "Titto" Assini, Ph.D. 25 Heath Road - CO79PT Wivenhoe - Colchester - U.K.

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Dealing with heterogeneously-typed lists?
by Leif Warner 13 Aug '08

13 Aug '08

Hi all, I'm dealing with some datatype, say: data Invoice = Invoice { invoiceNum :: String, dollarAmt :: Currency, printDate :: Date, dueDate :: Date, vendorNum :: Int, vendorName :: String, isStock :: Bool, } that I want to put in or take out of rows in xml spreadsheets, databases, that sort of thing. The elements of the spreadsheet row want type annotations like "String", "Number, "DateTime", etc. Also, each data element is required to be formatted differently, e.g. (show dueDate) ++ "T00:00:00", because the spreadsheet format wants a time tacked on, too. I know in a language like Java or C++ I might do some sort of run-time type identification, which would detect the type of each element in the list, and output it appropriately. As it is, I'm tupling each accessor function with the the type the spreadsheet wants, as a string: e.g. [(invoiceNum, "String"), (dollarAmt, "Number"), (printDate, "DateTime"),...] Is there a better way of doing this? Maybe messing with the "show" function to precede the string representation with a few characters about the type it's supposed to be? Or would looking into something like this be a good idea? It looks a lil old... http://homepages.cwi.nl/~ralf/HList/<http://homepages.cwi.nl/%7Eralf/HList/> --Strongly typed heterogeneous collections Thanks! -Leif

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GLfloat on a Mac
by Conor McBride 13 Aug '08

13 Aug '08

Hi folks I thought I'd try a bit of OpenGL. Perhaps I should send this to the more specific list, but perhaps other people are, like me, trying out a variety of UI technology. I thought I'd give OpenGL a go, because I saw the name whizz by when I upgraded to 6.8.3. I found the tutorial and got copy-paste cracking. It was all going swimmingly while I did almost nothing, but then ghc started dying on me. I chopped down my failing code to this joyous specimen: HelloWorld.lhs contains ---------------------------------- > module Main where > import Graphics.Rendering.OpenGL > import Graphics.UI.GLUT > myFloat :: GLfloat > myFloat = 0.0 > main = return () ---------------------------------- $ ghc -package GLUT HelloWorld.lhs -o HelloWorld Illegal instruction I'm using ghc 6.8.3 on a Mac PowerBook G4. Googling "OpenGL illegal instruction" produced an unending choice of horror stories. What message am I not getting? Is there some crucial manual I'm not reading? Is there something which we should be being told on the relevant wiki page? Distressed Conor

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Re: [Haskell-cafe] Recommended Haskell Books
by haskell＠kudling.de 12 Aug '08

12 Aug '08

Also the Beta Version of "Real World Haskell" looks promising: http://book.realworldhaskell.org/beta/index.html >On Sun, Aug 10, 2008 at 1:29 PM, Warren Aldred <warren(a)live.com> wrote: >> I'm new to Haskell and looking for recommendations on introductory Haskell >> books. Online or offline. Any suggestions? > >I like >_Programming in Haskell_ (Hutton) >_The Haskell School of Expression_ (Hudak) >_Real World Haskell_ (Goerzen, O'Sullivan, Stewart) > >I'd advise against _The Haskell Road to Logic, Maths, and Programming_ >until much later unless you're strongly mathematically inclined.

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my first post
by shoulders 12 Aug '08

12 Aug '08

Thanks -----邮件原件----- 发件人: haskell-cafe-bounces(a)haskell.org [mailto:haskell-cafe-bounces@haskell.org] 发送时间: 2008年8月11日 18:33 收件人: onlyforjob(a)163.com 主题: The results of your email commands The results of your email command are provided below. Attached is your original message. - Results: Ignoring non-text/plain MIME parts You can access your personal options via the following url: http://www.haskell.org/mailman/options/haskell-cafe/onlyforjob%40163.com help Help for Haskell-Cafe mailing list: This is email command help for version 2.1.5 of the "Mailman" list manager. The following describes commands you can send to get information about and control your subscription to Mailman lists at this site. A command can be in the subject line or in the body of the message. Note that much of the following can also be accomplished via the World Wide Web, at: http://www.haskell.org/mailman/listinfo/haskell-cafe In particular, you can use the Web site to have your password sent to your delivery address. List specific commands (subscribe, who, etc) should be sent to the *-request address for the particular list, e.g. for the 'mailman' list, use 'mailman-request@...'. About the descriptions - words in "<>"s signify REQUIRED items and words in "[]" denote OPTIONAL items. Do not include the "<>"s or "[]"s when you use the commands. The following commands are valid: confirm <confirmation-string> Confirm an action. The confirmation-string is required and should be supplied by a mailback confirmation notice. end Stop processing commands. Use this if your mail program automatically adds a signature file. help Print this help message. info Get information about this mailing list. lists See a list of the public mailing lists on this GNU Mailman server. password [<oldpassword> <newpassword>] [address=<address>] Retrieve or change your password. With no arguments, this returns your current password. With arguments <oldpassword> and <newpassword> you can change your password. If you're posting from an address other than your membership address, specify your membership address with `address=<address>' (no brackets around the email address, and no quotes!). Note that in this case the response is always sent to the subscribed address. set ... Set or view your membership options. Use `set help' (without the quotes) to get a more detailed list of the options you can change. Use `set show' (without the quotes) to view your current option settings. subscribe [password] [digest|nodigest] [address=<address>] Subscribe to this mailing list. Your password must be given to unsubscribe or change your options, but if you omit the password, one will be generated for you. You may be periodically reminded of your password. The next argument may be either: `nodigest' or `digest' (no quotes!). If you wish to subscribe an address other than the address you sent this request from, you may specify `address=<address>' (no brackets around the email address, and no quotes!) unsubscribe [password] [address=<address>] Unsubscribe from the mailing list. If given, your password must match your current password. If omitted, a confirmation email will be sent to the unsubscribing address. If you wish to unsubscribe an address other than the address you sent this request from, you may specify `address=<address>' (no brackets around the email address, and no quotes!) who password See everyone who is on this mailing list. The roster is limited to list administrators and moderators only; you must supply the list admin or moderator password to retrieve the roster. Commands should be sent to haskell-cafe-request(a)haskell.org Questions and concerns for the attention of a person should be sent to haskell-cafe-owner(a)haskell.org - Done.

1 0

ANN: BLAS bindings for haskell, version 0.5
by Patrick Perry 12 Aug '08

12 Aug '08

Hey everyone, I've put together a new release of the Haskell BLAS bindings, now available on hackage. Here are the new features: * Add Banded matrix data type, as well as Tri Banded and Herm Banded. * Add support for trapezoidal dense matrices (Tri Matrix (m,n) e, where m is not the same as n). Note that trapezoidal banded matrices are *NOT* supported. * Add Diag matrix data type for diagonal matrices. * Add Perm matrix data type, for permutation matrices. * Enhance the RMatrix and RSolve type classes with an API that allows specifying where to store the result of a computation. * Enhance the IMatrix, RMatrix, ISolve, and RSolve type classes to add "scale and multiply" operations. * Remove the scale parameter for Tri and Herm matrix data types. * Flatten the data types for DVector and DMatrix. * Some inlining and unpacking performance improvements. As far as what to expect in version 0.6, I plan to add support for operations in the ST monad. This is going to require a pretty big code reorganization and will cause quite a few API breakages, but I think it's worth the pain. The next release will also come with a tutorial and examples. After the big code reorganization, I'll get started on LAPACK bindings. Please let me know if you are using the library. I'm really interested in what people like and don't like. If you think that some functionality is missing, let me know. If you think the API is awkward in certain places, let me know that, too. Patrick Cross-posted to: http://quantile95.com/2008/08/11/ann-blas-bindings-for-haskell-version-05/

2 1

Thinking about an unlistN
by Michael Feathers 12 Aug '08

12 Aug '08

I wrote this function the other day, and I was wondering if I'm missing something.. whether there is already a function or idiom around to do this. unlist3 :: (a -> a -> a -> b) -> [a] -> b unlist3 f (x:y:z:xs) = f x y z I was also wondering whether the function can be generalized to N or whether this is just one of those edges in the type system that you can't abstract over. Thanks, Michael

6 6

best strategy for comparing comparisons
by Jason Dusek 12 Aug '08

12 Aug '08

I'd like to perform a micro-benchmark, pitting ByteString comparision against Word comparison. What I'd like to do is: . Generate a bunch of random Word32s. . Generate strict ByteStrings containing those Word32s. . Compare every Word32 with every other Word32 for equality, and see how long it takes. . Ditto with ByteStrings. The first two are easy and I'm done with them already. The latter two seem like they'll run afoul of laziness. I have two ideas about how to do them: . Do every comparison with a list comprehension, compressing the result as I go using `all`. . Do every comparison in a recursive IO procedure. Are there other ways? Will strictness annotations, for example, allow me to run comparisons on larger lists? -- _jsn

2 1

self-referential data
by brian 12 Aug '08

12 Aug '08

>From https://secure.wikimedia.org/wikipedia/en/wiki/Bencoding , I think I should code data BValue = BString String | BInteger Integer | BList [BValue] | BDictionary (M.Map BString BValue) but: Not in scope: type constructor or class `BString' The implementations I've found just implemented BDictionary's map key as String, but I think that's kind of wrong.

5 5

Anglo Haskell 2008
by Matthew Sackman 11 Aug '08

11 Aug '08

Anglo Haskell is a gathering of all people Haskell-related from beginners, to seasoned hackers to academic giants. All and more are welcomed by large fuzzy green lambdas. Anglo Haskell has happened for the last two years and we see no reason why it should not happen again this year. For the last two years they've tended to have talks on Fridays and then Other Things on the Saturday (including Punting and Group Hacking, some or more of which may have happened in Pubs). We're proposing the same general format this year. In contrast to the last two years which have been held at MSR Cambridge (UK), we're this year proposing to hold the event at Imperial College, London. London is probably easier to get to and from (though more tedious to get across) than Cambridge and we hope this will attract people who previously have not been able to get out to Cambridge. The proposed dates are Friday the 8th and Saturday the 9th of August. More details are available on the wikipage: http://www.haskell.org/haskellwiki/AngloHaskell/2008 Please feel free to add to this page. If you're at all interested in coming along then please add your name to the wikipage. If you're interested in giving a talk - on literally anything Haskell related: this is not a solely theory day or solely a practical day; anything goes which is Haskell related - then similarly add yourself to the list of speakers. Schedule and other details will be confirmed soon. Lodging, travel and all other related matters will be discussed on the irc channel (and will eventually migrate to the wikipage) #anglohaskell. If you're free that weekend then please come along! Also, if you'd really like to come but can't make those dates and there are many of you then please shout loudly and things could potentially be moved, though with the lack of time left before the event, we'd prefer to avoid this. Matthew

1 4

Lambdabot
by Thomas Davie 11 Aug '08

11 Aug '08

I've been trying to lambdabot running properly recently, and have consistently hit an error "fd:6: hClose: resource vanished (Broken pipe)" whenever I try to run anything that involves executing haskell (including but not limited to evaluating arbitrary expressions, the brainfuck module, unlambda). A quick google revealed that it's a very common error, but not potential solutions. Any ideas on what's up would be very useful. Bob

1 0

I want to upgrade to ghc 6.8.3
by Galchin, Vasili 11 Aug '08

11 Aug '08

Hello, I am building 6.8.3 from my "local" 6.8.2. However, I am getting errors in compiling one of the Main.hs. E.g. Main.hs:76:23: Ambiguous occurrence `flags' It could refer to either `Main.flags', defined at Main.hs:118:0 or `System.Posix.flags', imported from System.Posix at Main.hs:59:0-18 ...... I did a "find . -name Main.hs" and there are several Main.hs. I am not sure which one is causing trouble or why. ?? Kind regards, Vasili

1 0

help
by shoulders 11 Aug '08

11 Aug '08

--------------------------------- 雅虎邮箱，您的终生邮箱！

1 0

please help me to find errors from my first app
by Changying Li 11 Aug '08

11 Aug '08

Hi. I want to write a reverse proxy like perlbal to practive haskell. Now I just write a very simple script to forward any request to www.google.com. but it dosn't work. I run command ' runhaskell Proxy.hs' and 'wget http://localhost:8080/'. but wget just wait forever and runhaskkell can get request. when I break wget, the 'runhaskell' can print response returned from www.google.com. why? module Main where import System.Posix.Process import Network import Prelude hiding (putStr) import System.IO hiding (hGetContents, putStr) import Control.Concurrent import System.Posix.Signals import Data.ByteString.Lazy.Char8 (hGetContents, hPut, putStr,hGet,cons) listenPort = PortNumber 8080 connectToHost = "208.67.219.230" connectToPort = PortNumber 80 main :: IO () main = do hSetBuffering stdout NoBuffering socket <- listenOn listenPort let doLoop = do (hdl, _, _) <- accept socket forkIO $ processRequest hdl doLoop doLoop processRequest :: Handle -> IO () processRequest hRequest = do installHandler sigPIPE Ignore Nothing; hSetBuffering hRequest NoBuffering hSetBuffering stdout NoBuffering request <- hGetContents hRequest putStr $ '>' `cons` (' ' `cons` request) hResponse <- connectTo connectToHost connectToPort hSetBuffering hResponse NoBuffering hPut hResponse request response <- hGetContents hResponse putStr $ '<' `cons` (' ' `cons` response) hPut hRequest response hClose hRequest hClose hResponse -- Thanks & Regards Changying Li

2 2

heap lifetime question
by Galchin, Vasili 11 Aug '08

11 Aug '08

Hello, What is the lifetime of various heap objects ... e.g. created by allocaBytes, alloca, etc? Regards, Vasili

4 9

Re: ANN: interval and polynomial enclosure arithmetics
by Michal Konecny 11 Aug '08

11 Aug '08

Roman Cheplyaka <roma <at> ro-che.info> writes: > * Michal Konecny <mik <at> konecny.aow.cz> [2008-08-08 13:38:56+0100] > > and members of the KEG research group at Aston > > University have used it for reliably solving differential equations > > and numerical constraint satisfaction problems. > > This's very interesting. Do you have any published papers (or other > sources of information) about it? Unfortunately, there isn't much yet but more is on the way. Only the following two papers are available at the moment: http://www-users.aston.ac.uk/~konecnym/papers/cfv08.html is about using our polynomial enclosures to prove NCSPs that arise from floating-point software verification problems. http://www-users.aston.ac.uk/~konecnym/papers/wollic08.html analyses the convergence rate of an ODE solver that uses piecewise constant enclosures (which is rather inefficient). Best regards, Michal -- |o| Michal Konecny |o| http://www-users.aston.ac.uk/~konecnym/ |o| office: (+42) (0)121 204 3462 |o| PGP key http://www-users.aston.ac.uk/~konecnym/ki.aow

1 0

Last Reminder: The Italian Haskellers Summer Meeting takes place tomorrow at Monterosso, 5 Terre
by Titto Assini 10 Aug '08

10 Aug '08

Il titolo dice tutto, maggiori dettagli ad: http://www.haskell.org/haskellwiki/?title=ItaloHaskell/Summer_2008 A domani, titto -- Pasqualino "Titto" Assini, Ph.D. 25 Heath Road - CO79PT Wivenhoe - Colchester - U.K.

1 0

Future of Darcs: Thanks for the poll responses and increase in contributors
by Jason Dagit 10 Aug '08

10 Aug '08

Hello, I just wanted to thank everyone that has shown their support for darcs recently by either stopping by #darcs on freenode or joining in discussions on the darcs-user mailing list. I'm cross posting to haskell-cafe because I suspect many of you came from there. There has been a lot of enthusiasm from people, a lot of discussion about patch theory and excitement about fixing bugs and performance issues. Several people have taken an interest in making darcs work flawlessly on the GHC repository (yes, I know they have already commited to switching, but it gives a great test case to improve on). Eric Kow and myself have been working on a roadmap for future darcs improvements, and we plan to annouce an official version soon. The tentative one can be found here: http://wiki.darcs.net/DarcsWiki/Roadmap Mainly I just wanted to say, Thanks! We're considering the feedback we received from the poll and the future of darcs is not uncertain and we'll do a better job of communicating that message in the future. Now, back to hacking on darcs! Thanks, Jason

1 0

ANN: Haskore tutorial (programming music using Haskell)
by jinjing 10 Aug '08

10 Aug '08

Hi there, Here's the project link: http://github.com/nfjinjing/haskore-guide/tree/master/doc/index.markdown I found Haskore pretty fun :) so I'm documenting it while learning it. Please don't hesitate to give suggestions / corrections. Questions: * How much music theory should be there ? ( I'm gonna learn those anyway ) * What kind of examples would be cool ? regards, jinjing

4 5

ANN: interval and polynomial enclosure arithmetics
by Michal Konecny 09 Aug '08

09 Aug '08

Hello, I have recently released the following two Haskell packages, which model and reasonably efficiently implement exact real arithmetic: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-Real implements arbitrary-precision interval arithmetic for approximating real numbers http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AERN-RnToRm implements arbitrary-precision arithmetic of bounded-degree piecewise-polynomial enclosures for approximating functions of type R^n -> R^m The libraries are fairly stable and complete (AERN-Real more so than AERN-RnToRm) and members of the KEG research group at Aston University have used it for reliably solving differential equations and numerical constraint satisfaction problems. Also, the libraries are designed in multiple levels of abstraction that are clearly separated by type classes. Thanks to this it is very easy to switch between different implementations of the lower-levels, eg using a different floating point type or different representation of polynomials. There are many similarities between AERN-Real and Augustsson's numbers package. The main difference is in how the bit-size of arbitrary precision floating point numbers is determined. In numbers, the bit size is determined statically via types using a type-level encoding of natural numbers. In AERN-Real, the bit-size is part of the floating-point number, which slows the arithmetic down a bit but one can change precision dynamically. Best regards, Michal -- |-| Dr. Michal Konecny, Computer Science, Aston University |-| Room MB212D | Tel +44 121 204 3462 | Fax +44 121 204 3681 |-| http://www.aston.ac.uk/~konecnym |-| OpenPGP key http://www.aston.ac.uk/~konecnym/ki.aston

2 1

Currying function using values from array
by Sukit Tretriluxana 09 Aug '08

09 Aug '08

Dear Haskell experts, I am currently studying Groovy language. An experiment I did with its closure is to perform closure/function "curry" using an array containing the values for the parameter binding. See the sample below. int addThemUp(a,b,c,d,e) { a+b+c+d+e } def arrayCurry(arr, cls) { arr.inject(cls) { c, v -> c.curry(v) } } println addThemUp(1,2,3,4,5) println arrayCurry([1,2,3,4,5], this.&addThemUp)() println arrayCurry([1,2,3,4], this.&addThemUp)(5) The printouts from the above code are the same, verifying that the code works fine. Then I come to ask myself how I can do the same in Haskell. I'm not a Haskell expert so I couldn't figure it. I wonder if you guys could shed some light on this. Thanks, Ed

6 7

Building fastcgi from hackage on windows.
by Edward Ing 09 Aug '08

09 Aug '08

I am using the cabal system to build the hackage version of fastcgi. I get the below messages with the "runghc Setup.lhs build" command. Network\FastCGI.hsc:59:21: fcgiapp.h: No such file or directory Network\FastCGI.hsc: In function `main': Network\FastCGI.hsc:200:0: error: `FCGX_Request' undeclared (first use in this function) It looks like I need the fastcgi sources. Where does this source come from? I didn't get any dependency messages when I did the setup config. Edward Ing

3 5

Re: [Haskell-cafe] Phantoms
by Trevor Elliott 09 Aug '08

09 Aug '08

Hi Andrew, Here's an example that might help: > import Data.Typeable > > data Test a = Test Int > > instance Typeable a => Show (Test a) where > show t@(Test i) = "Test " ++ show (typeOf (ty t)) ++ " " ++ show i > where > ty :: Test a -> a, > ty = undefined and its use: *Main> show (Test 10 :: Test Int) "Test Int 10" *Main> show (Test 10 :: Test String) "Test [Char] 10" --trevor On Wed, 2008-08-06 at 19:09 +0100, Andrew Coppin wrote: > I just (re)discovered that I can do things like > > data Foo x = Foo Int Int > > Now "Foo Int" and "Foo Double" are, as far as the type checker cares, > two completely different types, even though in fact they are the same. > This is actually Quite Useful, in the particular case I'm working on. > > Here's the thing though... How do I get it so that "Foo Int" and "Foo > Double" produce slightly different strings when printed? > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe

1 0

Show me
by Andrew Coppin 09 Aug '08

09 Aug '08

Suppose we have the following: data Foo x list_foo :: [x] -> Foo x foo_list :: Foo x -> [x] What would be the best way to write a Show instance? The thing that I came up with is instance (Show x) => Show (Foo x) where show foo = "list_foo " ++ show (foo_list foo) But apparently you're supposed to use the strange "showsPrec" method that I don't understand. So can somebody show me a correct instance definition for this type please?

3 4

USB and serial port
by Maurício 09 Aug '08

09 Aug '08

Hi, What are the alternatives to read a USB port (actually, a COM serial port with an USB adapter) in Haskell, running in Linux? Thanks, Maurício

5 8

Last Call for the Italian Haskellers Summer Meeting
by Titto Assini 08 Aug '08

08 Aug '08

As usual we will now switch to Dante's "bella lingua". Ottimissimi, mancano pochi giorni al primo incontro estivo/balneare degli haskeller italiani. Per informazioni e registrarsi date uno sguardo a: http://www.haskell.org/haskellwiki/ItaloHaskell/Summer_2008 Oppure contattate il sottoscritto via email o per telefono al 0584 791669. A presto ragazzi, titto -- Pasqualino "Titto" Assini, Ph.D. 25 Heath Road - CO79PT Wivenhoe - Colchester - U.K.

4 3

adjunction of product and exponentiation
by Jason Dusek 08 Aug '08

08 Aug '08

The problem as stated is to find the unit for the adjunction: ((- x A), (-)^A x A) The latter functor takes an arrow f to (f . -) x id_A and does the obvious thing for objects. The co-unit diagram is given as: B^A x A ---- eval_AB ----> B ^ ^ | | | | curry(g) x id_A g : C x A -> B | | | | | | C x A --------------------+ This diagram is somewhat puzzling, because it seems the second functor has turned into (-)^A ! Continuing in with that, we get a unit diagram like this: C ---- magic ----> (C x A)^A | | | | | | curry(g) (g . -) | | | | | v +------------------> B^A So what is the magic? It is an arrow that takes a C to an arrow that takes an A and makes the product C x A. I want to write curry(C x A) but that is ridiculous looking. What's the right notation for this thing? -- _jsn

2 4

instance deduction and phantom types
by Jason Dagit 08 Aug '08

08 Aug '08

Hello, I recently had a problem where GHC couldn't deduce some type classes from my constraints. I would get error messages like: Could not deduce (Conflict (PatchInfoAnd p), Patchy (PatchInfoAnd p)) from the context (RepoPatch p) But, I had some instances like this (minus the function definitions): class (Patchy p, Effect p, FromPrims p, Conflict p) => RepoPatch p instance Effect p => Effect (PatchInfoAnd p) instance Conflict (p x y) => Conflict (PatchInfoAnd (p x y)) instance RepoPatch (p x y) => Patchy (PatchInfoAnd (p x y)) The x and y in the last two are just phantom types on p. When I noticed that the phantom types were missing from the instance definition of Effect (PatchInfoAnd p), I removed them from the last two definitions. This made the "Could not deduce..." error message disappear. Why do the phantom types not belong in the instance definition? I'd like to understand the problem more fully, but I'm not sure what the problem is or how to get started researching it, so if someone could point me in the right direction I'd be very happy! Thanks! Jason

2 3

ANN: FTGL 1.0. Portable truetype font rendering in OpenGL
by Jefferson Heard 08 Aug '08

08 Aug '08

Hi folks. I've just released some Haskell bindings to FTGL at http://hackage.haskell.org/cgi-bin/hackage-scripts/package/FTGL . FTGL is an easy to use library for portable rendering of TrueType fonts in OpenGL, with functions for creating bitmapped fonts, texture-mapped fonts, buffered fonts, polygonal 2D fonts, and extruded polygonal 3D fonts. The code works on Windows and Linux. I've not tested it yet on the Mac. To use FTGL in your programs, just import Graphics.Rendering.FTGL and use do font <- createTextureFont "font.ttf" setFontFaceSize font 24 72 renderFont font "some string" More documentation can be found at the FTGL homepage at http://ftgl.sourceforge.net -- Jeff

3 3

ANN: Haddock version 2.2.1
by David Waern 08 Aug '08

08 Aug '08

-------------------------------------------- -- Haddock 2.2.1 -------------------------------------------- A new version of Haddock, the Haskell documentation tool, is out. The homepage will be updated soon, containing a windows binary release. Please use the bug tracker to submit bug reports and feature requests. -------------------------------------------- -- Changes since version 2.1.0 -------------------------------------------- * Support for GHC 6.8.3 * The Hoogle backend is back * Show associated types in the documentation for class declarations * Show type family declarations * Show type equality predicates * Major bug fixes (#1 and #44) * It is no longer required to specify the path to GHC's lib dir * Remove unnecessary parenthesis in type signatures * Minor bug fixes -------------------------------------------- -- Links -------------------------------------------- Homepage: http://www.haskell.org/haddock Hackage page: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haddock-2.2.1 Bugtracker and wiki: http://trac.haskell.org/haddock Mailing list: haskelldoc(a)haskell.org Code repository: http://code.haskell.org/haddock -------------------------------------------- -- Details -------------------------------------------- This release contains experimental and incomplete support for GHC's Type Families extension. We have basic support for rendering of type family declarations and associated types in the documentation. Type/Data instances are not shown in the documentation at all, and associated types are not shown for class instances. Feedback is appreciated, especially for ideas of how to render type family instances. Use either the bugtracker, or send a mail to the mailing list. We have also got the Hoogle backend back, thanks to Neil Mitchell! The plan is to be compatible with the upcoming pre-release of Hoogle 4, which is being developed by Neil as a Summer of Code project. -------------------------------------------- -- Get Involved -------------------------------------------- Haddock is an important project, as it is part of the Haskell infrastructure core. The code base is gradually becoming easier to read, better documented and more stable, but more work is needed. To get involved, start by grabbing the code at http://code.haskell.org/haddock then take a look at the bug and feature tracker at http://trac.haskell.org/haddock for things to work on. David

4 7

Scripting COM Components from Haskell - GreenCard on Hackage
by Günther Schmidt 08 Aug '08

08 Aug '08

Hi, does anybody know if the Greencard package / lib is the same software that is mentioned in the paper "Scripting COM Components from Haskell"? http://research.microsoft.com/~simonpj/papers/com.ps.gz I managed to install the hackage Greencard package on XP with GHC 6.8.3 but it seems to be quite different from what the paper describes. Günther

4 3

Network.CGI Content header problem in Firefox.
by Edward Ing 08 Aug '08

08 Aug '08

Hi, I am doing some tests with Haskell to produce CGI programmes. I am running Microsoft IIS 5.0 as the weberver executing haskell compile executables that are cgi. If I set the header with a content type, Firefox always reports the content-type as application/octet-stream, and tries to initiate a download. IExplorer 6.0 does not report the type at all. It seems like the setHeader function does not result in sending headers. Has anyone seen this problem. Code snippet here ==== main :: IO() main = runCGI $ handleErrors cgiMain cgiMain :: CGI CGIResult cgiMain = do x <- getVars y <- getInputs prog <- progURI query <- queryURI request <- requestURI path <- pathInfo inputs <- getInputs setHeader("Content-type" "text/plain") setCookie (Cookie "bbb" "hello" Nothing Nothing Nothing False ) liftIO (putStr "asdfasdf") output $ (uris "prog" prog) ++ (uris "query" query) ++ (uris "request" request) ++ "\npath: " ++ path ++ "\n" ++ (varsToString inputs) ++(varsToString x) ++ "\n\nVars\n"++ (varsToString y)

1 0

the Haskell "with" "pattern"?
by Galchin, Vasili 07 Aug '08

07 Aug '08

Hello, 1) Is there a common assumed semantics across all of the Haskell "with" things? withString? withData? 2) If the answer to 1) is yes, then does this imply some kind of polymorphism? Couldn't "with" be "reduced" to a higher order function then ?? Kind regards, Vasili

7 10

DEFUN 2008 (Developer Tracks on Functional Programming): Call for participation
by Matthew Fluet (ICFP Publicity Chair) 07 Aug '08

07 Aug '08

ACM SIGPLAN 2008 Developer Tracks on Functional Programming http://www.deinprogramm.de/defun-2008/ Victoria, BC, Canada, 25, 27 September, 2008 Held in conjunction with ICFP 2008: http://www.icfpconference.org/icfp2008/ DEFUN 2008 is the event for developers using functional languages: Recognized experts on functional programming technologies share their knowledge and professional skills in talks and tutorials in 10 exciting tracks. Find out how to best make functional programming work in your development project! Acquire new development skills! Learn about other functional languages! The DEFUN program (attached) has tracks with the following types of presentations: - Half-day general language tutorials for specific functional languages, given by recognized experts for the respective languages. - Half-day tutorials on specific techniques or the use of specific technologies in functional programming. - 45-minute "how-to" talks that provide specific information on how to solve specific problems using functional programming. These talks focus on concrete examples, but provide useful information for developers working on different projects or in different contexts. The developer tracks are complementary to ICFP itself (which is for researchers). They are anchored by CUFP, the Haskell Symposium, and the Erlang workshop. Organizers Kathleen Fisher AT&T Labs Simon Peyton Jones Microsoft Research Mike Sperber (co-chair) DeinProgramm Don Stewart (co-chair) Galois PROGRAM: Note: The sessions of a given morning or afternoon are concurrent. The markers (M1, M2, A1, A2, etc.) mark a particular session, and correspond to the designations on the registration forms. Note that the talks M5 together constitute a session. DAY 1 - 25 SEPTEMBER, 2008 MORNING SESSION M1 (Tutorial): Practical Erlang Programming Francesco Cesarini Erlang Training and Consulting M2 (Tutorial): A Gentle Introduction to Functional Information Visualization Jefferson Heard Renaissance Computing Institute, University of North Carolina M3 (Tutorial): JavaScript: from basics to building custom frameworks Sameer Sundresh and Erik Hinterbichler University of Illinois Urbana-Champaign and Pattern Insight, Inc. AFTERNOON SESSION A1 (Tutorial): Erlang DBG and the Trace Biff Tamas Nagy Erlang Training and Consulting A2 (Tutorial): Erlang QuickCheck Tutorial Thomas Arts IT University of Gothenburg and Quviq A3 (Tutorial): Practical and Portable Programming in Scheme Donovan Kolbly TippingPoint Technologies DAY 2 - 27 SEPTEMBER 2008 MORNING SESSION M4 (Tutorial): Real World Haskell Bryan O'Sullivan M5 (Talks): Ten one-liners: handling power series in Haskell Doug McIlroy Dartmouth Incremental multi-level input processing with left-fold enumerator Oleg Kiselyov How we locate wild animals with a functional program Ryan Newton MIT AFTERNOON SESSION A4 (Tutorial): Using QuickCheck and HPC - Obtaining Quality Assurance for Haskell Code Andy Gill Kansas University Koen Claessen Chalmers A5 (Tutorial): Introduction to F# Don Syme and Chris Smith Microsoft Research

1 0