February 2010 - Haskell

Bug in opengl...
by Manuel Hernandez 18 Feb '10

18 Feb '10

Hi! This was so ugly...: ----- mh@dsktp:/media/VENUS/python$ ghc -package GLUT HelloWorld.hs -o HelloWorld Binary: Int64 truncated to fit in 32 bit Int ghc: panic! (the 'impossible' happened) (GHC version 6.10.4 for i386-unknown-linux): Prelude.chr: bad argument Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug ---- First program in: http://blog.mikael.johanssons.org/archive/2006/09/opengl-programming-in-has… Why, why? Warm regards, Manuel.

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ANN: concurrent-extra-0.1
by Roel van Dijk 17 Feb '10

17 Feb '10

Hello, We would like to announce the release of concurrent-extra [1]. A library which offers a few extra synchronization primitives. These primitives are found in the standard libraries of languages like Java and Python, but not in Haskell. Quick overview: * Lock: Enforce exclusive access to a resource. Also known as a mutex or a binary semaphore. * RLock: A lock which can be acquired multiple times by the same thread. Also known as a reentrant mutex. * Event: Wake multiple threads by signaling an event. Includes both pessimistic and optimistic versions. * ReadWriteLock: Multiple-reader, single-writer locks. Used to protect shared resources which may be concurrently read, but only sequentially written. * ReadWriteVar: Concurrent read, sequential write variables. Plug & Play: cabal install concurrent-extra Darcs: darcs get http://code.haskell.org/~roelvandijk/code/concurrent-extra/ Thanks to Neil Brown and Simon Marlow for an initial review. Comments are still more than welcome! Regards, Roel & Bas van Dijk [1] http://hackage.haskell.org/package/concurrent-extra

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Parsec operator issue
by Adam Crume 17 Feb '10

17 Feb '10

I have a parser with a prefix "-" and an infix "=". When I try to parse "x=-1", it fails. Does anyone know how to fix this? I stripped my code down as much as possible. It parses "x=1" and "-1", but fails for "x=-1". import Text.Parsec import qualified Text.Parsec.Expr as PE import qualified Text.Parsec.Language as L import qualified Text.Parsec.Token as T lexer = T.makeTokenParser L.emptyDef {T.reservedOpNames = ["=", "-"]} reservedOp = T.reservedOp lexer integer = T.integer lexer >> return "" symbol = T.identifier lexer expression = PE.buildExpressionParser table (integer <|> symbol) where table = [ [ PE.Prefix (reservedOp "-" >> return (\x-> "")) ], [ PE.Infix (reservedOp "=" >> return (\x-> \y->"")) PE.AssocRight ] ] input = do e <- expression eof return e testParse s = case (parse input "(unknown)" s) of Left f -> putStrLn $ s ++ "\n" ++ show f Right f -> putStrLn s main = do testParse "x=1" testParse "-1" testParse "x=-1" _________________________________________________________________ Hotmail: Free, trusted and rich email service. http://clk.atdmt.com/GBL/go/201469228/direct/01/

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CMCS 2010: Call for Short Submissions & Call for Participation
by Alexandra Silva 16 Feb '10

16 Feb '10

------------------------------------------------------------------------ CMCS 2010 Call for Short Submissions & Call for Participation ------------------------------------------------------------------------ The 10th International Workshop on Coalgebraic Methods in Computer Science 26-28 March 2010, Paphos, Cyprus (co-located with ETAPS 2010) <http://event.cwi.nl/cmcs10/> Aims and scope ------------------------- The aim of the workshop is to bring together researchers with a common interest in the theory of coalgebras and its applications. Over the last two decades, coalgebra has developed into a field of its own, presenting a mathematical foundation for various kinds of dynamical systems, infinite data structures, and logics. Coalgebra has an ever growing range of applications in and interactions with other fields such as reactive and interactive system theory, object oriented and concurrent programming, formal system specification, modal logic, dynamical systems, control systems, category theory, algebra, analysis, etc. The topics of the workshop include, but are not limited to: * the theory of coalgebras (including set theoretic and categorical approaches); * coalgebras as computational and semantical models (for programming languages, dynamical systems, etc.); * coalgebras in (functional, object-oriented, concurrent) programming; * coalgebras and data types; * (coinductive) definition and proof principles for coalgebras (with bisimulations or invariants); * coalgebras and algebras; * coalgebraic specification and verification; * coalgebras and (modal) logic; * coalgebra and control theory (notably of discrete event and hybrid systems). An anniversary: the 10th CMCS --------------------------------------------- CMCS took place for the first time when ETAPS started, in 1998. Since then, it has always been collocated with ETAPS, becoming bi-annual since the start of CALCO (Conference on Algebra and Coalgebra) in 2005. In 2010, we will celebrate the 10th edition of CMCS, by inviting a number of specialists in the field to present overviews of both obtained results and future challenges. Invited Speakers ------------------------- At this tenth meeting the following invited speakers will present overviews of important subareas. * Venanzio Capretta: Coalgebra in functional programming and type theory * Bartek Klin: Operational semantics coalgebraically * Dirk Pattinson: Logic and coalgebra * Ana Sokolova: Probabilistic systems coalgebraically Short contributions ----------------------------- Apart from the presentation of regular papers (see list below) and invited contributions, some time has been reserved for *short contributions* . These will not be published in the proceedings but will be bundled in a CWI technical report. They should be no more than two pages and may describe work in progress, summarise work submitted to a conference or workshop elsewhere, or in some other way appeal to the CMCS audience. The instructions for submitting short contributions can be found at: <http://event.cwi.nl/cmcs10/submission.html> Important dates ------------------- * 27 February 2010: strict submission deadline short contributions * 28 February 2010: deadline normal registration * 6 March 2010: notification short contributions * 26-28 March 2010: the workshop List of accepted regular papers --------------------------------------------- * Jan Komenda . Coinduction in concurrent timed systems * Jiri Adamek, Stefan Milius and Jiri Velebil . Recursive Program Schemes and Context-Free Monads * Bartek Klin . Structural operational semantics and modal logic, revisited * Hauhs Michael and Baltasar Tranc n y Widemann . Applications of Algebra and Coalgebra in Scientific Modelling: Illustrated with the Logistic Map * Kazuyuki Asada and Ichiro Hasuo . Categorifying Computations into Components via Arrows as Profunctors * Corina Cirstea . Generic Infinite Traces and Path-Based Coalgebraic Temporal Logics * Vincenzo Ciancia, Alexander Kurz and Ugo Montanari . Families of symmetries for the semantics of programming languages * Jiho Kim . Higher-order algebras and coalgebras from parameterized endofunctors * Bart Jacobs . From Coalgebraic to Monoidal Traces * Adriana Balan and Alexander Kurz . On coalgebras over algebras Programme Committee ---------------------------------- Jiri Adamek (Braunschweig) Alexandru Baltag (Oxford) Luis Barbosa (Braga) Marcello Bonsangue (Leiden) Corina Cirstea (Southampton) Robin Cockett (Calgary) Andrea Corradini (Pisa) Neil Ghani (Glasgow) Peter Gumm (Marburg) Furio Honsell (Udine) Bart Jacobs (Nijmegen, co-chair) Bartek Klin (Cambridge) Clemens Kupke (London) Alexander Kurz (Leicester) Marina Lenisa (Udine) Stefan Milius (Braunschweig) Ugo Montanari (Pisa) Larry Moss (Bloomington) Milad Niqui (Amsterdam) Dirk Pattinson (London) Dusko Pavlovic (Oxford) John Power (Edinburgh) Horst Reichel (Dresden) Grigore Rosu (Urbana) Jan Rutten (Amsterdam, co-chair) Davide Sangiorgi (Bologna) Lutz Schr der (Bremen) Alexandra Silva (Amsterdam) Hendrik Tews (Nijmegen) Tarmo Uustalu (Tallinn) Yde Venema (Amsterdam) Hiroshi Watanabe (Osaka) James Worrell (Oxford) Organising Committee -------------------------- Bart Jacobs, Milad Niqui (co-chair, CWI), Jan Rutten, Alexandra Silva (co-chair, CWI). Contact ---------- cmcs10(a)cwi.nl .

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ANN: vector 0.5
by Roman Leshchinskiy 15 Feb '10

15 Feb '10

Hi everyone, I am pleased to announce the release of version 0.5 of package vector, a high-performance Haskell array library with a powerful loop fusion framework. The main highlights compared to previous versions are: * DPH-style unboxed vectors (in Data.Vector.Unboxed) which use associated types to select the appropriate unboxed representation depending on the type of the elements. * A redesigned interface between mutable and immutable vectors. In particular, the popular unsafeFreeze primitive is now supported for all vector types. * Many new operations on both immutable and mutable vectors. * Significant performance improvements. The library comes with a fairly complete testsuite (mainly thanks to Max Bolingbroke) and is quite stable by now. Barring various disasters, I expect to release version 1.0 in the next 3 to 4 months. The release is accompanied by a new version of the NoSlow array benchmark suite. A few quite meaningless preliminary benchmarks are available at: http://unlines.wordpress.com/2010/02/15/vector-0-5-is-here-2 Both vector and NoSlow are on Hackage. Hackers can get the darcs repos from http://code.haskell.org/vector and http://code.haskell.org/NoSlow Enjoy! Roman

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CHR 2010: Second Call for Papers
by Van Weert Peter 15 Feb '10

15 Feb '10

========================================================================= Second Call for Papers Seventh International Workshop on Constraint Handling Rules CHR 2010 http://www.cs.kuleuven.be/~dtai/CHR/CHR2010/ Edinburgh (Scotland), July 20, 2010 (co-located with ICLP 2010, part of FLoC 2010) ========================================================================= News * Submission deadlines are about two weeks earlier than first announced! (due to FLoC 2010 requirements) * Invited speaker: We are privileged to announce a distinguished invited speaker this year: Mark Proctor, lead of the thriving, innovating JBoss Drools project (http://www.jboss.org/drools/) He will introduce the Drools Business Logic integration Platform, a fully featured business rule engine and management system that seamlessly integrates powerful Complex Event Processing and workflow capabilities. Introduction The CHR 2010 Workshop will be held July 20, 2010 in Edinburgh (Scotland) at the occasion of the 26th International Conference on Logic Programming (ICLP 2010), the premier international venue for presenting research in logic programming. This year, ICLP is held as part of the Fifth Federated Logic Conference (FLoC 2010). More information on the venue and co-located conferences can be found on the FLOC website (http://www.floc-conference.org/) The Constraint Handling Rules (CHR) language has become a major declara- tive specification formalism and implementation language for constraint reasoning algorithms and applications. Algorithms specified using infe- rence rules, rewrite rules, sequents, proof rules, or logical axioms can often be directly written in CHR. Its clean semantics facilitates pro- gram design, analysis, and transformation. For more information, please visit the CHR website (http://www.cs.kuleuven.be/~dtai/projects/CHR/) The aim of the CHR workshop series is to stimulate and promote interna- tional research and collaboration on topics related to the CHR language. The workshop is a lively, friendly forum for presenting and discussing new results, interesting applications, and work in progress. Previous Workshops on Constraint Handling Rules were organized in 2004 in Ulm (Germany), in 2005 in Sitges (Spain) at ICLP, in 2006 in Venice (Italy) at ICALP, in 2007 in Porto (Portgual) at ICLP, in 2008 in Hagen- berg (Austria) at RTA, and in 2009 in Pasadena (California, US) at ICLP. Topics of Interest The workshop calls for contributions on all aspects of CHR, including topics such as: - (Operational) semantics - Program analysis (confluence, termination, ...) - Comparisons with related approaches - Expressivity and complexity - Language extensions (negation, modules, ...) - Constraint solvers - Implementation and optimization - Concurrency & parallelism - Program transformation and generation - Programming environments (debugging, confluence checking, ...) - Programming pearls Application papers that describe experience with (industrial) applications, are especially welcome. Important dates - Abstract submission deadline: March 29, 2010 - Paper submission deadline: April 5, 2010 - Notification of acceptance: May 1, 2010 - Final version due: May 17, 2010 (tentative) - Workshop date: July 20, 2010 Submission Information The four broad categories for submissions are: 1. technical papers for describing technically sound, innovative ideas that can advance the state of the art of CHR 2. application papers, where the emphasis will be on the use of CHR in the application, on the impact on the application domain, and the lessons learned from this application 3. system and tool papers, empasising the novelty, practicality, usability and general availability of the systems and tools described 4. short papers, for ongoing work not yet ready for full publication and research project overviews. All papers must describe original, previously unpublished research, and must not simultaneously be submitted for publication elsewhere. They must be written in English. Technical papers must not exceed 15 pages. The limit for short papers is 7 pages, as is the standard page limit for application papers, and system and tool papers. However, particularly strong contributions in the latter two areas may be submitted as technical paper as well. All papers must be in the Springer LNCS format. General information about the Springer LNCS series and the LNCS authors' instructions are available at the Springer LNCS home page (http://www.springer.com/computer/lncs?SGWID=0-164-7-72376-0) Submissions must be made via the EasyChair submission system, available at http://www.easychair.org/conferences/?conf=chr10 Programme Committee - Sebastian Brand, National ICT Australia, and the University of Melbourne, Victoria, Australia - Henning Christiansen, Roskilde University, Denmark - Vernica Dahl, Simon Fraser University, Canada - Leslie De Koninck, Victoria Research Laboratory, NICTA, Australia (co-chair) - Thom Fruehwirth Ulm University, Germany - Marco Gavanelli, University of Ferrara, Italy - Remy Haemmerle, Universidad Politecnica de Madrid, Spain - Maria-Chiara Meo, "Gabriele d'Annunzio" University, Italy - Paolo Pilozzi K.U.Leuven, Belgium - Frank Raiser, Ulm University, Germany - Peter Van Weert, K.U.Leuven, Belgium (co-chair) - Jairson Vitorino, Federal University of Pernambuco, Brazil - Armin Wolf, Fraunhofer FIRST, Germany Workshop Coordinators Contact: chr2010(a)easychair.org Peter Van Weert Department of Computer Science, K.U.Leuven Leuven, Belgium http://www.cs.kuleuven.be/~petervw/ Leslie De Koninck Victoria Research Laboratory, NICTA Melbourne, Australia Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

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ANN: data-ordlist-0.4, now with mergeAll and unionAll
by Leon Smith 15 Feb '10

15 Feb '10

Data-Ordlist is a package of convenience functions for dealing with ordered lists. It's had it's second release in 7 days, with bugfixes, documentation improvements, and now two new functions. Big thanks to Omar Antolín Camarena, Topi Karvonen, Heinrich Apfelmus, and Dave Bayer for (knowingly or unknowingly) contributing to this release! http://hackage.haskell.org/package/data-ordlist Version 0.4: (2010-02-15) * The "CHANGES" file was added to document the changes between releases. * Documentation Improvements * A rough first pass at a test suite * The functions `mergeAll` and `unionAll` were added. They operate on a possibly infinite list of possibly infinite ordered lists; assuming the heads of the lists are ordered. Thanks goes to Omar Antolín Camarena, Heinrich Apfelmus, and Dave Bayer. Omar Antolín Camarena suggested the addition, located the article used as the basis for the implementation, and was quite helpful with testing and debugging. Heinrich Apfelmus wrote his "Implicit Heaps" article, where he simplified an algorithm by Dave Bayer. It is this article that forms the basis of our implementation. <http://apfelmus.nfshost.com/articles/implicit-heaps.html> Dave Bayer posted his 'venturi' implementation to the haskell-cafe mailing list on 2007 Jul 22. It also appears as "BayerPrimes.hs" inside of Melissa O'Neill's "haskell-primes.zip": <http://www.mail-archive.com/haskell-cafe@haskell.org/msg27612.html> <http://www.cs.hmc.edu/~oneill/code/haskell-primes.zip> Version 0.2: (2010-02-07) * The module name was changed from `Data.OrdList` to `Data.List.Ordered` * Fixed bugs in `insertSetBy`, `insertBagBy`, and `nub`. The insertion functions assumed reversed lists, while `nub` failed to remove duplicates. Thanks to Topi Karvonen for reporting the first issue! * Changed semantics of `insertSetBy` slightly: the new version replaces an element if it is already there. If the old semantics turns out to be important, a new function can be added at a later date. * Changed semantics of `nubBy`: the new version negates the binary relation, so that `new_nubBy f == old_nubBy (not . f)`. It is now in better keeping with the spirit of the rest of the library, and mades the bug in `nub` more obvious. * Better documentation, I hope. At the very least, the process of documenting `nubBy` revealed the bug in `nub`.

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Call for Copy: Monad.Reader Issue 16
by Brent Yorgey 12 Feb '10

12 Feb '10

Call for Copy: The Monad.Reader - Issue 16 ------------------------------------------ Whether you're an established academic or have only just started learning Haskell, if you have something to say, please consider writing an article for The Monad.Reader! The submission deadline for Issue 16 will be: **Friday, April 16, 2010** The Monad.Reader ~~~~~~~~~~~~~~~~ The Monad.Reader is a electronic magazine about all things Haskell. It is less formal than journal, but somehow more enduring than a wiki- page. There have been a wide variety of articles: exciting code fragments, intriguing puzzles, book reviews, tutorials, and even half-baked research ideas. Submission Details ~~~~~~~~~~~~~~~~~~ Get in touch with me if you intend to submit something -- the sooner you let me know what you're up to, the better. Please submit articles for the next issue to me by e-mail (byorgey at cis.upenn.edu) Articles should be written according to the guidelines available from http://themonadreader.wordpress.com/contributing/ Please submit your article in PDF, together with any source files you used. The sources will be released together with the magazine under a BSD license. If you would like to submit an article, but have trouble with LaTeX please let me know and we'll work something out.

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CFP: APNOC 2010 - 2nd Int. Workshop on Abstractions for Petri Nets and Other Models of Concurrency
by Serebrenik, A. 12 Feb '10

12 Feb '10

=============================================================== APNOC 2010 2nd International Workshop on Abstractions for Petri Nets and Other Models of Concurrency http://www.win.tue.nl/apnoc2010/ =============================================================== Braga, Portugal, June 21, 2010 a satellite event of Petri Nets 2010 31th International Conference on Application and Theory of Petri Nets and Other Models of Concurrency =============================================================== Selected papers from the workshop will be published in ToPNoC - "Transactions on Petri Nets and Other Models of Concurrency" - journal subline of Lecture Notes in Computer Science. =============================================================== Deadline for abstracts: March 13, 2010 Deadline for paper submission: March 20, 2010 =============================================================== APNOC is a forum for researchers interested in abstraction techniques and methodologies for modeling and verification of concurrent systems. The modeling language of particular interest is Petri nets; other formalisms such as process algebras, pi-calculus, B-method, etc., are also of great interest, since abstraction techniques are often formalism-independent and could be transferred from one formalism to another. Both academics and practitioners can contribute and learn from such a meeting. Contributions describing original research in topics related to the use of abstractions for Petri nets and other models of concurrency, as well as surveys addressing abstraction techniques and open problems and new applications of abstractions are being sought. Topics of interest include but are not limited to: * State space abstraction and aggregation * Abstract interpretation techniques * Abstractions for handling underspecified systems * Pattern-based abstractions * Abstractions for handling incomplete information * Abstraction for efficiency, explanation, anytime reasoning, * Methodologies for applying abstraction techniques in modelling * Case studies where abstraction plays a central role * Tools support for abstractions The programme committee invites submissions of full contributions (up to 15 pages) or short contributions (up to 7 pages). Papers should be submitted in electronic form (PDF) using the Springer LNCS-format (http://www.springer.de/comp/lncs/authors.html) Submissions should include title, author's address and email, and an abstract. Please use the online conference management system (see http://www.win.tue.nl/apnoc2010/) Accepted papers will be included in the workshop proceedings which will be available at the workshop. At least one of the authors of each accepted contribution should register and take part in the workshop to give the presentation. Selected papers from the workshop will be invited for publication in a volume of a journal subline of Lecture Notes in Computer Science entitled "Transactions on Petri Nets and Other Models of Concurrency" (ToPNoC). Important Dates: Abstract submission: 13 March, 2010 Submission deadline: 20 March, 2010 Start of reviews: 23 March, 2010 Start of discussion phase: 23 April, 2010 Notification of acceptance: 1 May, 2010 Final version: 22 May, 2010 PROGRAMME COMMITTEE: Josep Carmona (Spain) Radhia Cousot (France) Philippe Darondeau (France) Jörg Desel (Germany) Wan Fokkink (The Netherlands) Pierre Ganty (Belgium) Serge Haddad (France) Olga Kouchnarenko (France) Maciej Koutny (UK) Laure Petrucci (France) Olivier H. Roux (France) Alexander Serebrenik (The Netherlands) (co-chair) Natalia Sidorova (The Netherlands) (co-chair) Martin Steffen (Norway) Walter Vogler (Germany) ================================================

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ANN: hledger 0.8 released
by Simon Michael 12 Feb '10

12 Feb '10

hledger 0.8 is out! http://hledger.org http://hledger.org/MANUAL.html#installing Bug fixes, refactoring and Hi-Res Graphical Charts. (See Roman Cheplyaka's blog: http://www.reddit.com/r/haskell/comments/b0w0q/using_the_hledger_package_to…) Best - Simon Release notes: ...................... * parsing: in date=date2, use first date's year as a default for the second * add: ctrl-d doesn't work on windows, suggest ctrl-c instead * add: --no-new-accounts option disallows new accounts (Roman Cheplyaka) * add: re-use the previous transaction's date as default (Roman Cheplyaka) * add: a command-line argument now filters by account during history matching (Roman Cheplyaka) * chart: new command, generates balances pie chart (requires - fchart flag, gtk2hs) (Roman Cheplyaka, Simon Michael) * register: make reporting intervals honour a display expression (#18) * web: fix help link * web: use today as default when adding with a blank date * web: re-enable account/period fields, they seem to be fixed, along with file re-reading (#16) * web: get static files from the cabal data dir, or the current dir when using make (#13) * web: preserve encoding during add, assuming it's utf-8 (#15) * fix some non-utf8-aware file handling (#15) * filter ledger again for each command, not just once at program start * refactoring, clearer data types Stats: 62 days since last release, 2 contributors, 76 commits, 3464 lines of non-test code, 97 tests, 53% test coverage

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