May 2010 - Haskell - Haskell.org

Modular type inference
by Simon Peyton-Jones 14 May '10

14 May '10

Friends Many of you will know that I've been muttering about re-engineering GHC's type inference engine for some time now. Dimitrios, Tom, Martin and I have just completed an epic paper describing the Glorious New Framework that forms the substance of the above mutterings: http://haskell.org/haskellwiki/Simonpj/Talk:OutsideIn We'd love comments and feedback. Dimitrios and I plan to roll up our sleeves and implement it in June. Simon Modular type inference with local assumptions: OutsideIn(X) Abstract. Advanced type system features, such as GADTs, type classes, and type families have have proven to be invaluable language extensions for ensuring data invariants and program correctness among others. Unfortunately, they pose a tough problem for type inference, because they introduce local type assumptions. In this article we present a novel constraint-based type inference approach for local type assumptions. Our system, called OutsideIn(X), is parameterised over the particular underlying constraint domain X, in the same way as HM(X). This stratification allows us to use a common metatheory and inference algorithm. Going beyond the general framework, we also give a particular constraint solver for X = type classes + GADTs + type families, a non-trivial challenge in its own right.

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Final Call for Papers: VSTTE workshops on Theory and on Experiments & Tools
by Gudmund Grov 14 May '10

14 May '10

------ Apologies for multiple copies ------ VSTTE 2010: Workshops on Theories, Tools and Experiments Edinburgh, Scotland, 19th August 2010 (*** only 1 week to go! *****) The Third International Conference on Verified Software: Theories, Tools, and Experiments (VSTTE) is part of the Verified Software Initiative (VSI), a fifteen-year, cooperative, international project directed at the scientific challenges of large-scale software verification. VSTTE will host two workshops: * VS-Theory focuses on theoretical foundations of software verification. Topics range from the difficult and essential study of soundness of delicate proof methods, to the discovery of new specification techniques and proof methods, to dramatic simplification or unification of existing methods, to as yet unknown breakthroughs. * VS-Tools & Experiments focuses on the development of verification tools and their experimental evaluation. Topics include interfaces between tools, tool integration platforms, and case studies. The workshops will provide a forum to present new, possibly unfinished work and will also give the opportunity to propose research challenges, which will help form a research agenda for the Verified Software Initiative. For further details, see the workshop web site: http://www.macs.hw.ac.uk/vstte10/Workshops.html Submissions Papers must be written in English using Springer LNCS style. The page limit is 10 pages for technical papers and 5 pages for proposals of verification challenges. The proceedings will be published as a technical report. Details on the submission process are available at http://www.macs.hw.ac.uk/vstte10/Workshops.html. Important Dates Submission: May 21, 2010 Notification: June 25, 2010 Final version: July 23, 2010 Workshops: August 19, 2010, 9am-1pm Chairs * VS-Theory is co-chaired by David Naumann, Stevens Institute of Technology, USA and Hongseok Yang, Queen Mary, University of London, UK * VS-Tools & Experiments is co-chaired by Tiziana Margaria, University of Potsdam, Germany and Rajeev Joshi, NASA/JPL Laboratory for Reliable Software, USA -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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Package removal
by Yang Zhang 14 May '10

14 May '10

How do ghc users on Linux (esp. Debian/Ubuntu) systems remove packages? AFAICT there's only cabal unregister, and no way to remove files but manually, which is tricky when these packages are interspersed with other files in /usr/local. I found some old mailing list threads mentioning that this is an open issue, but as I'm currently facing this, I'm wondering if there's been any news on this front. Thanks. -- Yang Zhang http://yz.mit.edu/

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Linking very resource intensive with GHC 6.12.1 on Ubuntu 10.04
by Yang Zhang 13 May '10

13 May '10

After upgrading from Ubuntu 9.10 to 10.04, my manually-installed (not the distribution package) GHC 6.12.1 has difficulty linking. This is the first time I've tried compiling something since the upgrade. Once cabal gets to Linking, I see a lot of swapping and increased load numbers on my system with 700MB memory and nothing much running, and even after leaving the linker running for 10 minutes, the software doesn't stop. Anybody else seen this? -- Yang Zhang http://yz.mit.edu/

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ANN: Monad.Reader Issue 16
by Brent Yorgey 13 May '10

13 May '10

I am very pleased to announce that Issue 16 of The Monad.Reader is now available [1]. Issue 16 consists of the following three articles: * "Demand More of Your Automata" by Aran Donohue * "Iteratee: Teaching an Old Fold New Tricks" by John W. Lato * "Playing with Priority Queues" by Louis Wasserman Feel free to browse the source files [2]. You can check out the entire repository using darcs: darcs get http://code.haskell.org/~byorgey/TMR/Issue16 If you'd like to write something for Issue 17, please get in touch. The deadline will likely be sometime in September; more details will be forthcoming. -Brent [1] http://themonadreader.files.wordpress.com/2010/05/issue16.pdf [2] http://code.haskell.org/~byorgey/TMR/Issue16

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ANNOUNCE: hsSDL-0.6
by Lemmih 13 May '10

13 May '10

Simple DirectMedia Layer is a cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer. It is used by MPEG playback software, emulators, and many popular games, including the award winning Linux port of "Civilization: Call To Power." hsSDL is a nigh one-to-one Haskell binding to libSDL (and a few auxiliary library such as SDL-image, SDL-mixer and SDL-ttf). This release contains no API changes but signifies a new era of even greater stability. Version 0.6 also contains a much improved guide for building and using hsSDL on Macs. My thanks goes out to Johannes Krause. Without his contribution of time and expertise, this release wouldn't have happened. http://hackage.haskell.org/package/SDL http://hackage.haskell.org/package/SDL-image http://hackage.haskell.org/package/SDL-mixer http://hackage.haskell.org/package/SDL-ttf http://hackage.haskell.org/package/SDL-gfx -- Cheers, Lemmih

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HEADS UP: bugs in GHC 6.12.2
by Simon Marlow 12 May '10

12 May '10

Hi folks, I'm sorry to say that in GHC 6.12.2, as a result of fixing a couple of bugs in 6.12.1, we (well, I) managed to introduce some more serious ones: http://hackage.haskell.org/trac/ghc/ticket/4038 http://hackage.haskell.org/trac/ghc/ticket/4041 The first causes gtk2hs programs to crash, and we have a report of it affecting hmatrix too. There's no workaround unfortunately: the problem is that we changed some data structures related to FFI calls, with the result that a nested callback (calling out to C, back to Haskell, out to C again and back to Haskell in the same thread) can result in a crash or a bogus result. The second causes lazy bytestring's hGetContents to block waiting for a full buffer, when it should just return the data already read. You can work around this by using bytestring-0.9.1.5 instead of the supplied 0.9.1.6. We'll put out 6.12.3 with fixes for these as soon as possible. In the meantime, if you are still on 6.12.1 and not encountering any problems, I don't recommend upgrading. Sorry for the inconvenience. Cheers, Simon

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CICLOPS-WLPE 2010 at FLoC: Call for Participation
by German Vidal 12 May '10

12 May '10

[Apologies for multiple copies of this announcement] ******************************************************************* Call For Participation CICLOPS-WLPE 2010 Joint Workshop on Implementation of Constraint Logic Programming Systems and Logic-based Methods in Programming Environments Edinburgh, Scotland, U.K. July 15, 2010 http://users.dsic.upv.es/~ciclops-wlpe10/ Satellite event of the 26th International Conference on Logic Programming (ICLP 2010) http://www.floc-conference.org/ICLP-home.html ******************************************************************* IMPORTANT DEADLINES: * early registration deadline: 17 May 2010 * standard registration: 18 May 2010 - 30 June 2010 * late registration: after 30 June 2010 Registration, accomodation, and travel/visa information for all FLoC conferences and workshops is on the FLoC 2010 web pages: http://www.floc-conference.org/ INVITED TALKS: Programming with Boolean Satisfaction Michael Codish, Ben-Gurion University of the Negev (Israel) Solving Constraint Satisfaction Problems by a SAT Solver Naoyuki Tamura, Kobe University (Japan) ACCEPTED PAPERS: - Peter Biener, François Degrave and Wim Vanhoof A Test Automation Framework for Mercury - Petra Hofstedt Realizing evaluation strategies by hierarchical graph rewriting - Nicos Angelopoulos and Paul Taylor An extensible web interface for databases and its application to storing biochemical data - Paulo Moura Meta-Predicate Semantics - Jan Wielemaker and Vítor Santos Costa Portability of Prolog programs: theory and case-studies - Dimitar Shterionov, Angelika Kimmig, Theofrastos Mantadelis and Gerda Janssens DNF Sampling for ProbLog Inference - Vasco Pedro and Salvador Abreu Distributed Work Stealing for Constraint Solving - Paulo André and Salvador Abreu Casting the WAM as an EAM Workshop organizers: German Vidal DSIC, Universidad Politecnica de Valencia Camino de Vera S/N, 46022 Valencia, Spain http://www.dsic.upv.es/~gvidal/ Neng-Fa Zhou Department of Computer and Information Science, Brooklyn College The City University of New York 2900 Bedford Avenue, Brooklyn, NY 11210-2889 http://www.sci.brooklyn.cuny.edu/~zhou/

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Tsuru Capital is hiring
by Simon Cranshaw 12 May '10

12 May '10

We are looking to hire a programmer that has experience programming in a functional language, and is familiar with Haskell. There is a wide range of tools and applications that we want to build over time, including graphical interfaces and profiling tools for our trading system, parsers for new market feeds, and algorithms for trading strategies. If you have experience in any one of these areas it's a definite bonus. You will be working with a small team of developers, and from time to time will be working along side Traders to assist in tool development. Annual compensation will be in the region of USD150k with potential for growth. The team is based in Tokyo but there are projects that could be done remotely so feel free to apply for this type of work also. http://tsurucapital.com/en/jobs.html#programmer

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CHR 2010: Call for Participation
by Leslie DE KONINCK 12 May '10

12 May '10

CALL FOR PARTICIPATION CHR 2010 7th International Workshop on Constraint Handling Rules associated with ICLP 2010 (part of FLoC 2010) Edinburgh, Scotland, 20 July 2010 http://dtai.cs.kuleuven.be/CHR/CHR2010/ HIGHLIGHTS * newcomers' welcome to CHR tutorial by Thom Frühwirth * invited talk on the JBoss Drools business rules platform by Mark Proctor * invited talk by Matt Lilley of SecuritEase, a leading stock broking system * tutorial on CHRiSM, a CHR-based probabilistic formalism, by Jon Sneyers * presentation of the six accepted papers + two demos INTRODUCTION The Constraint Handling Rules (CHR) language has become a major declarative specification formalism and implementation language for constraint reasoning algorithms and applications. Algorithms are often specified using inference rules, rewrite rules, sequents, proof rules, or logical axioms that can be directly written in CHR. Its clean semantics facilitates program design, analysis, and transformation. See the CHR website for more information: http://dtai.cs.kuleuven.be/CHR/ PROGRAM The CHR 2010 workshop offers a very attractive and varied program. Next to our accepted technical papers, we have two invited speakers: Mark Proctor from the JBoss Drools project, a major open-source business rule platform, and Matt Lilley from SecuritEase, a leading stock broking dealing and settlement system, and one of the most prominent industry users of Prolog and CHR. Other highlights are the first practical confluence checker for CHR, and several application-oriented presentations, including two demos by students from the University of Ulm on using CHR with a multi-touch interface: one for automated music generation, and one aimed at providing long-term routing for fully autonomous sailing boats (in cooperation with the Roboat project). Because many FLoC attendants will be new to CHR, we included two additional introductionary presentations: Thom Frühwirth will give a broad tutorial on CHR in general, and Jon Sneyers will introduce the recent CHR-based probabilistic formalism CHRiSM (also presented at the main ICLP conference). The full workshop's program is available at: http://dtai.cs.kuleuven.be/CHR/CHR2010/programme.shtml REGISTRATION Registration for the workshop can be done online at: http://www.floc-conference.org/registration.html Early registration ends 17 May. ORGANIZATION Program Committee: * Sebastian Brand, NICTA and University of Melbourne, Australia * Henning Christiansen, Roskilde University, Denmark * Verónica Dahl, Simon Fraser University, Canada * Leslie De Koninck, NICTA and University of Melbourne, Australia (co-chair) * Thom Frühwirth, Ulm University, Germany * Marco Gavanelli, University of Ferrara, Italy * Rémy Haemmerlé, Universidad Politécnica 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://people.cs.kuleuven.be/~peter.vanweert/ Leslie De Koninck National ICT Australia, Victoria Research Laboratory Dept of Computer Science and Software Engineering, University of Melbourne Melbourne, Australia

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