April 2003 - Haskell - Haskell.org

FIRST CALL for PAPERS -- FLOPS2004
by pjs＠cs.mu.oz.au 28 Apr '03

28 Apr '03

------- Blind-Carbon-Copy X-Mailer: exmh version 2.5 10/15/1999 with version: MH 6.8.4 #1[UCI] To: pjs(a)cs.mu.oz.au Subject: FIRST CALL for PAPERS -- FLOPS2004 From: pjs(a)cs.mu.oz.au Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 29 Apr 2003 09:05:08 +1000 Message-ID: <16046.1051571108(a)muldi.cs.mu.oz.au> Sender: pjs(a)muldi.cs.mu.oz.au Apologies if you recieve this mail more than once. - -------------------------------------------------- *********************************************************************** * * * CALL FOR PAPERS * * * * Seventh International Symposium on Functional and Logic Programming * * (FLOPS 2004) * * * * Nara-Ken New Public Hall, Nara, Japan * * April 7-9, 2004 * * * * (http://logic.is.tsukuba.ac.jp/FLOPS2004/) * * * *********************************************************************** Background ========== The symposium is a forum for research on all issues concerning functional programming and logic programming. In particular, it wants to stimulate the cross-fertilization as well as integration of the two paradigms. The symposium takes place about every 1.5 years in Japan. Previous FLOPS meetings were held in Fuji Susono (1995), Shonan Village (1996), Kyoto(1998), Tsukuba (1999), Tokyo (2001) and Aizu (2002). Topics ====== The Seventh International Symposium on Functional and Logic Programming (FLOPS 2004) solicits original papers in all areas of functional and logic programming, including (but not limited to): * Declarative Pearls: new and excellent declarative programs with illustrative applications * Language issues: language design and constructs, programming methodology, integration of paradigms, interfacing with other languages, type systems, constraints, concurrency and distributed computing * Foundations: logic and semantics, rewrite systems and narrowing, type theory, proof systems * Implementation issues: compilation techniques, memory management, program analysis and transformation, partial evaluation, parallelism * Applications: case studies, industrial applications, graphical user interfaces, internet applications, database connection, formal methods and model checking Invited Speakers ================ The following three distinguished researchers have accepted to give invited talks at FLOPS 2004. * Masami Hagiya University of Tokyo * Carsten Schuermann Yale University * Peter Selinger University of Ottawa Submissions =========== Submissions must be unpublished and not submitted for publication elsewhere. Work that already appeared in unpublished or informally published workshops proceedings may be submitted. Submissions should fall into one of the following categories: * Regular research papers: they should describe new results and will be judged on originality, correctness and significance. * System descriptions: they should contain a link to a working system and will be judged on originality, usefulness and design. All submissions must be written in English and can be up to 15 proceedings pages long. Authors are strongly encouraged to use LaTeX2e and the Springer llncs class file, available at http://www.springer.de/comp/lncs/authors.html Regular research papers should be supported by proofs and/or experimental results. In case of lack of space, this supporting information should be made accessible otherwise (e.g. a link to a web page, or an appendix). Submission is Web-based. In order to submit a paper, authors should fill in the submission form available at http://logic.is.tsukuba.ac.jp/FLOPS2004/submission.html where more detailed instructions are given. If submission through the Web is not possible, five hard copies may be sent to Yukiyoshi Kameyama Institute of Information Sciences and Electronics University of Tsukuba Tennodai 1-1-1, Tsukuba, 305-8573, JAPAN Publication and presentation of accepted contributions ====================================================== The Proceedings of FLOPS 2004 will be published by Springer Verlag in the Lecture Notes in Computer Science (LNCS) series. LNCS is published, in parallel to the printed books, in full-text electronic version and final versions of the papers will need to be provided electronically including the source files. Proceedings will be available at the conference. One author of each accepted contribution is expected to attend the Symposium in order to present it. Important Dates =============== Submission Deadline: October 1, 2003 Notification: December 15, 2003 Final Version: January 15, 2004 Symposium: April 7-9, 2004 Program Co-Chairs ================= Yukiyoshi Kameyama University of Tsukuba, Japan Peter J. Stuckey University of Melbourne, Australia E-Mail: flops(a)logic.is.tsukuba.ac.jp Program Committee ================= Francois Fages INRIA Rocquencourt Herman Geuvers Nijmegen University Michael Hanus University of Kiel Martin Hofmann University of Muenchen Haruo Hosoya Kyoto University Yukiyoshi Kameyama University of Tsukuba Naoki Kobayashi Tokyo Institute of Technology John Lloyd Australian National University Aart Middeldorp University of Tsukuba Atsushi Ohori JAIST German Puebla Technical University of Madrid Morten Rhiger IT-University of Copenhagen Amr Sabry Indiana University Peter J. Stuckey University of Melbourne Martin Sulzmann National University of Singapore Kazunori Ueda Waseda University Philip Wadler Avaya Labs Local Arrangements Chair ======================== Jacques Garrigue Kyoto University Sponsors ======== FLOPS2004 is supported by Japan Society of Software Science and Technology (JSSST), Association for Logic Programming (ALP), and Asian Association for Foundation of Software (AAFS) [planed]. ------- End of Blind-Carbon-Copy

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Online judge and Haskell?
by Steffen Mazanek 28 Apr '03

28 Apr '03

Hello, it's me again and I have a new mad idea. There are a lot of programming contests out there and unfortunately most (all?) of them do not allow Haskell code till now! I think, this is hard to accept. Why not ask the people which run acm.uva.es/problemset to provide their problem sets, input and output files and the basic judging software and install it at haskell.org? Alternatively this may be a nice project for a student. I think an adaption of this software to permit Haskell code can not be that difficult! Do you think there is a need for such a project? Maybe it could help Haskell to become a part of official programming contests and hence to gain more popularity. I'm sorry to say, that due to another project my free time is very limited so I can not get it going by only myself. Ciao, Steffen -- Haskell: that's where I just curry until fail, unwords any error, drop all undefined, maybe break, otherwise in sequence span isControl and take max $, id: (d:[])

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REMINDER - Contributions to HC&A Report (May 2003 edition)
by C.Reinke 28 Apr '03

28 Apr '03

Dear Haskeller, as you can see from the Report's topics page at http://www.haskell.org/communities/topics.html , both confirmations from well-known contributors and offers from new contributors are still a bit sparse at this stage (not to mention actual contributions:), although we're making progress. First, many thanks to those who simply write their reports and are done with it! But, if the call for contributions should have caught you in your extended Easter holidays, could you please let me know as soon as possible how long that will delay your contributions?-) I wouldn't want to extend the general target deadline by much, as people should really get going on their Haskell Workshop papers soon (hint!-), but we may be able to accomodate individual delays. Just keep in mind that this is really an informal exercise: it probably takes less time to sit down and write an update of your report than it takes to worry about delays and making time.. Otherwise, could everybody send in their individual reports ** by the end of THIS week ** ? Please?-) Thanks, Claus -- Haskell Communities and Activities Report (May 2003 edition) Contributions are due in by the end of THIS week! http://www.haskell.org/communities/ ======================= original call for contributions follows Dear Haskellers, following the early reminder in the preface of the last edition, you've probably been waiting already, contribution in hand, eager to send it in for the May edition of our report (hey, editors can have their dreams, too!-), so here it is: *your* invitation to contribute to the fourth edition of the Haskell Communities & Activities Report http://www.haskell.org/communities/ These bi-annual HC&A Reports should give a birds-eye view of Haskell development over the last 6 months, and perhaps an outlook over concrete plans for the next 6 months. The current plan is to get contributions in by the end of April, and to get the collective report out early next month (some of you will find this an excellent opportunity to collect your thoughts about what to submit to this year's Haskell Workshop, btw;-). The general idea is to update all existing summaries (these reports are really about recent/current activities), to drop any topics that haven't had any activity for two consecutive 6-month periods, and to add any new developments or topics for which no-one contributed summaries to the previous edition, while trying to keep the whole from blowing up (last time, we ended up with about 30 pages). New suggestions for current hot topics, activities, projects, .. are welcome - especially with names and addresses of potential contacts, but here is a non-exclusive list of likely topics: General Haskell developments; Haskell implementations; Haskell extensions; Standardization and documentation; Haskell tutorials, how-tos and wikis; Organisation of Haskell tool and library development; Haskell-related projects and publications; Feedback from specialist mailing lists to the Haskell community as a whole; Haskell libraries or tools; Applications of Haskell; Haskell announcements; .. all (recent) things Haskell Announcements: if you've announced anything new on the Haskell list over the last six months, you'll want to make sure that is reflected in this edition. Project pings: if you're maintaining a Haskell tool/library/.., you'll want to let everyone know that it is still alive and actively maintained, even if there may have been no new additions. Tutorials: if you've fought with some previously undocumented corner of Haskell, and have been kind enough to write down how you did manage to build that networking program, or if you've written a tutorial about some useful programming techniques/patterns, this is your opportunity to spread the word (btw, short, topic-specific, and hands-on tutorials that only show how to achieve a certain practical task would do a lot to make things easier for new Haskellers - Erlang and Perl folks seem to be good at this kind of thing, but why not have a similar effort for Haskell?) Applications: if you've been working quietly, using Haskell for some interesting project or application (commercial or otherwise), you might want to let others know about it, and about your experiences using the existing tools and libraries; are you using Haskell on your job? Feedback: if you're on one of the many specialist Haskell mailing lists, you'll want to report on whatever progress has been made there (GUI API discussions, library organisation, etc.) If you're unsure whether a contact for your area of work has come forward yet, have a look at the report's potential topics page, or get in touch with me. I've contacted last time's contributors, hoping they will volunteer to provide updates of their reports, and will update the contacts on the topics page fairly regularly. But where you don't yet see contacts listed for your own subject of interest, you are very welcome to volunteer, or to remind your local community/project team/mailing list/research group/etc. that they really ought to get their act together and let the Haskell community as a whole know about what they've been doing!-) A typical summary report about a tool/library/project/application/.. would be between 1 and 3 paragraphs of ASCII text (what's it about? major topics and results since the last report? current hot topics? major goals for the next six months?) plus pointers to material for further reading (typically to a home page, or to mailing list archives, specifications and drafts, implementations, meetings, minutes,..). Browsing through previous editions should give you a good idea. Looking forward to your contributions, Claus -- Haskell Communities and Activities Report (May 2003 edition) All contributions are due in by the end of April 2003! http://www.haskell.org/communities/ _______________________________________________ Haskell mailing list Haskell(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell

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Re: Polymorphic stanamically balanced binary trees
by Okasaki, C. DR EECS 28 Apr '03

28 Apr '03

oleg describes an implementation of AVL trees that have two main features: 1. The trees are heterogenous (elements within the same tree can have different types). 2. The balance condition is partially enforced by the type checker, and partially by run-time checks. For feature 1, you can take your favorite solution for heterogenous lists (existentials, type dynamic, ...) and extend it to trees. This problem is orthogonal to the balance problem, and I'll ignore it in the rest of this post. For feature 2, there are lots of interesting approaches to push this kind of check into the type checker. For example, Hongwei Xi has several variations that do this using dependent types. It can also be done entirely with nested types. I think I first saw this done for AVL trees by Ross Paterson in 1998. First, here's a type that for trees of height h, given types for trees of height h-1 (t1) and for trees of height h-2 (t2). data Node a t1 t2 = Left t1 a t2 | Even t1 a t1 | Right t2 a t1 Next, here's a type for trees of arbitrary height, given types for trees of height h-1 and h-2. data Tree a t1 t2 = Zero t2 | Succ (Tree a (Node a t1 t2) t1) To start things off, we set t2 to the type of trees of height 0 and t1 to the type of trees of height 1. type AVLTree a = Tree a a () For example, a tree like 1 / 2 would be encoded as Succ | Succ | Zero | Left(1) / \ Even(2) () / \ () () Using polymorphic recursion, you can then implement typical tree functions like insert and delete. The type checker will catch any attempt to build an unbalanced tree. Note that there are no run-time checks in this approach. That last statement is a little bit of a lie. There is no run-time typechecking going on, but there are run-time artifacts of this algorithm, namely the Zero and Succ nodes which encode the height of the tree. Zero and Succ are data constructors, not type constructors as they are in oleg's version, so you have to walk through them at run-time. -- Chris

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No more numeric-quest?
by Mike Fagan 27 Apr '03

27 Apr '03

Dear Haskell Guys, None of the www.numeric-quest.com pages are available. Has anyone mirrored that stuff elsewhere? Thanks, Mike Fagan

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RE: Super Haddock (was Re: Literate Programming)
by Simon Marlow 27 Apr '03

27 Apr '03

> This seems like a good way of transitioning from .lhs to > haddock'd .hs. In > the long run, I think we (meaning Simon :-) should to extend > haddock to > take the place of the .lhs style of documenting code. To generate .hs from .lhs, the right way is to use GHC: $ ghc -E Foo.lhs -o Foo.hs The great thing about this is that it goes through the same preprocessing stages that your source goes through in order to compile it. So for example if you use CPP on your source too, just say 'ghc -E -cpp' to get the preprocessed output. > I use haddock to document interfaces for modules and it works > wonderfully > for that (and it would be even better if I could use haddock comments > inside records and in between constructor arguments, hint, hint). > > But I find myself using it in comments within code > (especially within local > functions) too. Perhaps a haddock that had two modes (one > for interfaces, > one for implementation) would work. The interface mode would > work as it > does now. The implementation mode would produce a .html > version of the > entire module, using haddock comments to mark it up. > > Simon: how much work would this be? That's an interesting idea. It's not at all what Haddock was intended for, but that's not to say it couldn't be done! There are some issues to do with how you want the output to look: should it retain the indentation of the original source, or ident according to some fixed style? If you want the indentation from the original source then Haddock's front end will need some changes to support retaining that information. Throwing away the original indentation and generating output indented according to a fixed style would be rather easier. Cheers, Simon

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Subtyping
by Steffen Mazanek 27 Apr '03

27 Apr '03

Hello. Yet another question: Consider a type structure like in "Typing Haskell in Haskell" where types are curried, e.g. data Type = TAp Type Type | TCon Id Kind | TVar Id Kind This means, "(->) Int" is a valid type. In a subtype calculus you can say, that "a->b" is a subtype of "c->d" if "b" is a subtype of "d" and "c" is a subtype of "a", because "->" is contravariant in its first and covariant in its second argument. So far so good, how can be dealt with subtyping and "partial" types? E.g. is it acceptable to say that "(->) a" is a subtype of "(->) b" if "b" is a subtype of "a"? Any ideas? Or can someone point me to an online-resource which addresses this topic? Thanks in advance, Steffen -- Haskell: that's where I just curry until fail, unwords any error, drop all undefined, maybe break, otherwise in sequence span isControl and take max $, id: (d:[])

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[ANNOUNCE] Haskell on FreeBSD web site <URL:http://haskell.org/fr eebsd/>
by Oliver Braun 26 Apr '03

26 Apr '03

Hi, I have just uploaded a first approach for an "Haskell on FreeBSD" web site: http://haskell.org/freebsd/ Please feel free to give me feedback! Regards, Olli -- Oliver Braun :: <obraun(a)unsane.org> :: <obraun(a)FreeBSD.org>

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RE: problems invoking haddock
by Simon Marlow 26 Apr '03

26 Apr '03

> I was not able to make Haddock run... Invoking it for a > simple hello world example > > > module Main where > > > > main :: IO() > > main = putStrLn "Hello World" > > gives me the following errors: > > Warning: module not found: Prelude > Warning: Main: the following names could not be resolved: > IO Prelude.() > > Fail: does not exist > Action: openFile > Reason: No such file or directory > File: /usr/local/lib/haddock-0.4/haddock.css Sounds like Haddock isn't installed properly. What procedure did you use to build/install it? Cheers, Simon

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binary input of 2d and 3d arrays
by Andrew French 25 Apr '03

25 Apr '03

Can someone point me to information sources on how to input/output multidimensional binary arrays? I am quite new to Haskell, have read some of Hudak and Thompson, but cant seem to find out how to do this basic task. There must surely be examples posted, but I havent been able to find any. -Andrew French

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