May 2010 - Haskell-Cafe

currying combinators
by Günther Schmidt 28 May '10

28 May '10

Hi all, I've posted some code on hpaste http://www.hpaste.org/fastcgi/hpaste.fcgi/view?id=25694 in which I attempt to develop a "currying combinator" library. I'm stuck at some point and would appreciate any help. Günther

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Google Summer of Code: BlazeHTML RFC
by Jasper Van der Jeugt 28 May '10

28 May '10

Dear all, BlazeHtml started out on ZuriHac 2010. Now, Jasper Van der Jeugt is working on it as a student to Google Summer of Code for haskell.org. His mentors are Simon Meier and Johan Tibell. The goal is to create a high-performance HTML generation library. In the past few weeks, we have been exploring the performance and design of different drafts of this library. Now, the time has come to ask some questions to the Haskell community — more specifically the future users of BlazeHtml as well as current users of other HTML generation libraries. We have written an RFC to gather feedback from the community: HTML version: http://jaspervdj.be/posts/2010-05-27-blazehtml-rfc.html Plain version: http://github.com/jaspervdj/BlazeHtml/raw/develop/doc/RFC.lhs The easiest way of sending us feedback, comments or criticism is replying to the haskell-cafe thread here. Alternatively, drop a comment at the bottom of the HTML version or at reddit. Looking forward to your feedback, Kind regards, Simon Meier Jasper Van der Jeugt

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Steven S. Skiena of "The Algorithm Design Manual", Second Edition, 2008 has sent me a message that if there is a Haskell page of algorithms he will link to it.
by Casey Hawthorne 28 May '10

28 May '10

Hi: Steven S. Skiena of "The Algorithm Design Manual", Second Edition, 2008 has sent me a message that if there is a Haskell page of algorithms he will link to it. So, is there such a page and/or is there some collection(s) of algorithms and data structures some where that I can massage into the shape of his book? :) -- Regards, Casey

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Re: [Haskell] Re: [Haskell-cafe] Work on Video Games in Haskell
by Ketil Malde 28 May '10

28 May '10

<bf3(a)telenet.be> writes: > Or maybe this would be a nice research topic: how to generate C code > that looks like it’s human written… Nah, that's too easy: just add a sprinkling of buffer overflows, undefined behavior, and off-by one index errors. -k -- If I haven't seen further, it is by standing in the footprints of giants

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ANNOUNCE: Haskell Communities and Activities Report (18th ed., May 2010)
by Janis Voigtländer 28 May '10

28 May '10

On behalf of the many, many contributors, I am pleased to announce that the Haskell Communities and Activities Report (18th edition, May 2010) is now available in PDF and HTML formats: http://haskell.org/communities/05-2010/report.pdf http://haskell.org/communities/05-2010/html/report.html Many thanks go to all the people that contributed to this report, both directly, by sending in descriptions, and indirectly, by doing all the interesting things that are reported. I hope you will find it as interesting a read as I did. If you have not encountered the Haskell Communities and Activities Reports before, you may like to know that the first of these reports was published in November 2001. Their goal is to improve the communication between the increasingly diverse groups, projects, and individuals working on, with, or inspired by Haskell. The idea behind these reports is simple: Every six months, a call goes out to all of you enjoying Haskell to contribute brief summaries of your own area of work. Many of you respond (eagerly, unprompted, and sometimes in time for the actual deadline ;-) to the call. The editor collects all the contributions into a single report and feeds that back to the community. When I try for the next update, six months from now, you might want to report on your own work, project, research area or group as well. So, please put the following into your diaries now: ---------------------------------------- End of October 2010: target deadline for contributions to the November 2010 edition of the HC&A Report ---------------------------------------- Unfortunately, many Haskellers working on interesting projects are so busy with their work that they seem to have lost the time to follow the Haskell related mailing lists and newsgroups, and have trouble even finding time to report on their work. If you are a member, user or friend of a project so burdened, please find someone willing to make time to report and ask them to "register" with the editor for a simple e-mail reminder in October (you could point me to them as well, and I can then politely ask if they want to contribute, but it might work better if you do the initial asking). Of course, they will still have to find the ten to fifteen minutes to draw up their report, but maybe we can increase our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! Janis Voigtlaender <hcar at haskell.org>

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Optimizations and constant unboxed values
by Pierre-Etienne Meunier 28 May '10

28 May '10

Hi Cafe, Profiling a function that I thought ultra simple revealed that it consumed more than half the execution time of my code. After noticing that GHC did not unbox all I thought it did, I rewrote it with primitive types, and it did a little better, but not much. Then, examining the core (with of course -O3 on) revealed things like : (GHC.Prim.*## (GHC.Prim.-## 1.0 (GHC.Prim.**## 2.0 -53.0)) (GHC.Prim.**## 2.0 1024.0)) or case GHC.Prim.<## x_aB9 (GHC.Prim.**## 2.0 -1021.0) of _ {... Then I wondered if this was really the last stage of GHC's optimizations, as constants are not yet propagated. Or maybe GHC does not propagate constants, in which case I'd really like to write my 1-2^53 and 2^-1021 once and for all in my program. But since unsafeCoerce# does not work between doubles and words ( there is a trac ticket about it : http://hackage.haskell.org/trac/ghc/ticket/4092 ), I do not even think this is possible (and of course, specifying a double in decimal notation with ## is not precise enough for this program). Any clue about how to do it ? Thanks, PE

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Turn off verbose template haskell output
by Michael Snoyman 28 May '10

28 May '10

Hi all, Is there a GHC flag to turn off all of the "Loading package..." messages from Template Haskell? Thanks, Michael

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Chuch encoding of data structures in Haskell
by Günther Schmidt 28 May '10

28 May '10

Hi all, I'm exploring the use of church encodings of algebraic data types in Haskell. Since it's hard to imagine being the first to do so I wonder if folks here could point me to some references on the subject. I'm looking for examples of church encodings in Haskell a little bit beyond Church Booleans and Church Numerals. Günther

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Re[2]: [Haskell-cafe] Re: Unicode vs. System.Directory
by Bulat Ziganshin 28 May '10

28 May '10

Hello Andy, Friday, May 28, 2010, 1:05:59 AM, you wrote: > Looks my file-manager: > http://farm5.static.flickr.com/4027/4584389024_782b1e09ee_o.png can you please share windows and linux executables and source code? > I have finish all necessary GIO APIs at > http://patch-tag.com/r/AndyStewart/gio-branch/home > I will try to merge those APIs to next release version of gtk2hs when i > have spare time. it seems that i can just merge these sources into my program for a while. but what is the license? believe it or not, but i have commercial project on the march -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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Announce : New haskell-llvm mailing list.
by Erik de Castro Lopo 27 May '10

27 May '10

Hi all, I have set up a mailing list for discussion of haskell and LLVM related topics. All discussion on using Haskell with LLVM is relevant. That includes the haskell-llvm bindings on Hackage, custom LLVM bindings and directly generating LLVM IR code from haskell and passing that through the LLVM tools. In particular, this list is a place to share code, information, techniques and user experiences. The subscription page is here: http://projects.haskell.org/cgi-bin/mailman/listinfo/haskell-llvm Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

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