May 2011 - Haskell - Haskell.org

ANNOUNCE: CamHac: Haskell Hackathon in Cambridge, UK, 12-14 August 2011
by Simon Marlow 26 May '11

26 May '11

CamHac is happening - come and spend a long weekend in Cambridge hacking Haskell code in great surroundings with fantastic company! Full details on the wiki page: http://www.haskell.org/haskellwiki/CamHac When: Friday-Sunday 12-14 August 2011 Where: the Horobin Room of Homerton Conference Centre [1] Registration is free! See the wiki page above for details. We're limited to 50 people, and registration is on a first-come first-served basis, so sign up soon. Feel free to email me with any questions. Many thanks to Microsoft Research Cambridge for agreeing to sponsor the event! Cheers, Simon [1] http://www.homertonconference.com/Horobin.html

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LOPSTR 2011 - call for participation
by German Vidal 26 May '11

26 May '11

(our apologies if you receive multiple copies of this message) ============================================================ CALL FOR PARTICIPATION 21th International Symposium on Logic-Based Program Synthesis and Transformation LOPSTR 2011 http://users.dsic.upv.es/~lopstr11/ Odense, Denmark, July 18-20, 2011 (co-located with PPDP 2011, AAIP 2011 and WFLP 2011) ============================================================ ONLINE REGISTRATION IS OPEN: http://www.imada.sdu.dk/~petersk/OLP/registration.html EARLY REGISTRATION DEADLINE: May 30, 2011 (next Monday!) The aim of the LOPSTR series is to stimulate and promote international research and collaboration on logic-based program development. LOPSTR is open to contributions in logic-based program development in any language paradigm. LOPSTR has a reputation for being a lively, friendly forum for presenting and discussing work in progress. Formal proceedings are produced only after the symposium so that authors can incorporate this feedback in the published papers. SYMPOSIUM PROGRAM (tentative): Monday, July 18, 2011: 14:00 - 15:00: Session 1 * Thomas Stroeder, Peter Schneider-Kamp, Jürgen Giesl, Fabian Emmes and Carsten Fuhs. A Linear Operational Semantics for Termination and Complexity Analysis of ISO Prolog * Olivier Namet, Maribel Fernandez and Helene Kirchner. A Strategy Language for Graph Rewriting Coffee break 15:30 - 17:30: Session 2 * Paulo Moura. Meta-Predicate Semantics * Jose F. Morales, Manuel Hermenegildo and Rémy Haemmerlé. Modular Extensions for Modular (Logic) Languages * Nik Sultana. A prototype refactoring tool based on a mechanically-verified core * Céline Dandois and Wim Vanhoof. Clones in logic programs and how to detect them Tuesday, July 19, 2011: 09:00 - 10:00: LOPSTR Invited Talk * John Gallagher. <TBA> Coffee break 10:30 - 12:30: Session 3 * Wim Vanhoof. On the partial deduction of non-ground meta-interpreters * Fabio Fioravanti, Alberto Pettorossi, Maurizio Proietti and Valerio Senni. Using Real Relaxations During Program Specialization * Hirohisa Seki. Proving Properties of Co-logic Programs by Unfold/Fold Transformations * Rafael Caballero, Adrian Riesco, Alberto Verdejo and Narciso Marti- Oliet. Simplifying Questions in Maude Declarative Debugger by Transforming Proof Trees Lunch break 14:00 - 15:00: Session 4 * Giovanni Bacci, Marco Comini, Marco A. Feliú and Alicia Villanueva. Automatic Synthesis of Specifications for Curry Programs * Jesus Almendros-Jimenez, Rafael Caballero, Yolanda García-Ruiz and Fernando Saenz-Perez. A Declarative Embedding of XQuery in a Functional-Logic Language Coffee break 15:30 - 17:30: Session 5 * Elvira Albert, Miguel Gomez-Zamalloa and José Miguel Rojas Siles. Resource-driven CLP-based Test Case Generation * Soichiro Hidaka, Zhenjiang Hu, Kazuhiro Inaba, Hiroyuki Kato, Kazutaka Matsuda, Keisuke Nakano and Isao Sasano. Marker-directed optimization of UnCAL graph transformations * Sneyers and Daniel De Schreye. Probabilistic Termination of CHRiSM Programs * Paolo Pilozzi and Daniel De Schreye. Improved termination analysis of CHR using self-sustainability analysis Wednesday, July 20, 2011: 9:00 - 10:00: PPDP/LOPSTR Invited Talk * Fritz Henglein. <TBA> Coffee break 10:30 - 11:30: PPDP/LOPSTR Invited Talk * Vitaly Lagoon. The Challenges of Constraint-Based Test Generation Coffee break 11:30 - 12:30: Session 6: * Pedro Cabalar and Stephane Demri. Automata-based Computation of Temporal Equilibrium Models * Demeyer and Wim Vanhoof. Proper Granularity for Atomic Sections in Concurrent Programs Lunch and Excursion ============================================================

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Haskell Weekly News: Issue 183
by Daniel Santa Cruz 26 May '11

26 May '11

Welcome to issue 180 of the HWN, a newsletter covering developments in the Haskell community. This release covers the week of May 15 to 21, 2011. Announcements Janis Veigtlander announced that the 20th edition of the Haskell Communities and Activities reports is hot off the press! http://goo.gl/GRi7V Simon Marlow announced that he has put together a tutorial on Parallel and Concurrent programming in Haskell. http://goo.gl/LPst8 Quotes of the Week * Sergey Mironov:I looked further and found that 'Oleg already did it'. * monochrom: just say "yes" Top Reddit Stories * Wolfgang - A Wolfram Alpha clone in Haskell (under heavy load?) Domain: jabberwock.xs4all.nl, Score: 75, Comments: 10 On Reddit: http://goo.gl/okNC7 Original: http://goo.gl/7pSXA * Numeric Haskell: a tutorial about the multi-dimensional, parallel arrays package, Repa Domain: haskell.org, Score: 54, Comments: 7 On Reddit: http://goo.gl/ZRSn3 Original: http://goo.gl/InWB9 * Space leak zoo: a catalog of common space leaks in Haskell programs Domain: blog.ezyang.com, Score: 41, Comments: 7 On Reddit: http://goo.gl/npVLv Original: http://goo.gl/aMbo5 * Exercises in Optimization: A (soon to be) three-part series detailing an adventure in optimizing Haskell code. Domain: csks.wordpress.com, Score: 34, Comments: 0 On Reddit: http://goo.gl/cjWBX Original: http://goo.gl/wPqbl * Tutorial: Parallel and Concurrent Programming in Haskell :: PDF Domain: community.haskell.org, Score: 33, Comments: 7 On Reddit: http://goo.gl/CB1wt Original: http://goo.gl/yzTOU * Anatomy of a thunk leak: How to debug Haskell’s most famous space leak Domain: blog.ezyang.com, Score: 32, Comments: 3 On Reddit: http://goo.gl/f18jX Original: http://goo.gl/PiQ98 * Preview release of diagrams EDSL for declarative drawing Domain: haskell.org, Score: 31, Comments: 9 On Reddit: http://goo.gl/6sykO Original: http://goo.gl/uhbV1 * I/O is not a monad Domain: r6.ca, Score: 31, Comments: 23 On Reddit: http://goo.gl/zAra5 Original: http://goo.gl/mn49r * Eliza in 70 lines of Haskell Domain: github.com, Score: 28, Comments: 7 On Reddit: http://goo.gl/hjgNf Original: http://goo.gl/S7t9m * The "Whole Program" Fallacy Domain: lukepalmer.wordpress.com, Score: 26, Comments: 10 On Reddit: http://goo.gl/Efja3 Original: http://goo.gl/vzXVK Top StackOverflow Questions * What Haskell representation is recommended for 2D, unboxed pixel arrays with millions of pixels? votes: 48, answers: 3 Read on SO: http://goo.gl/gVpwB * Good introductory text about GHC implementation? votes: 24, answers: 2 Read on SO: http://goo.gl/6MZoh * Questions on a Haskell -> C# conversion votes: 13, answers: 3 Read on SO: http://goo.gl/0t3Gu * Can't perform I/O in foldr? votes: 12, answers: 4 Read on SO: http://goo.gl/d9Jg0 * What does "this function will fuse" mean? votes: 11, answers: 3 Read on SO: http://goo.gl/tMdlR * Haskell function type question votes: 10, answers: 3 Read on SO: http://goo.gl/gyTns * Is this always true: fmap (foldr f z) . sequenceA = foldr (liftA2 f) (pure z) votes: 10, answers: 1 Read on SO: http://goo.gl/emKmg * Difference between hsc2hs and c2hs? votes: 8, answers: 2 Read on SO: http://goo.gl/1wnhC * Is it possible to create PHP extensions in Haskell? votes: 8, answers: 2 Read on SO: http://goo.gl/QwkpK * How can configuration tools like sdl-config be used with a cabalized project? votes: 8, answers: 2 Read on SO: http://goo.gl/vHCOu About the Haskell Weekly News To help create new editions of this newsletter, please send stories to dstcruz(a)gmail.com. Until next time, Daniel Santa Cruz

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ANNOUNCE: regex-genex-0.2.0
by 唐鳳 25 May '11

25 May '11

Hi all, I've just released regex-genex 0.2.0 to Hackage: http://hackage.haskell.org/package/regex-genex-0.2.0 The main interface is this: genex :: [String] -> IO [String] Given a list of regular repressions, genex returns all possible strings that matches all of them. For example: Regex.Genex> genex ["\\d", "[123abc]"] ["2","3","1"] Currently it recognizes the same pattern syntax as regex-tdfa, with full support for word boundaries (\b) and backreferences (\1 through \9). The list is generated lazily, so this terminates quickly: Regex.Genex> fmap (take 10) (genex ["([abc]+)\\1"]) ["bb","cc","aa","bbbb","cccc","aaaa","bcbc","acac","baba","abab"] It uses the "sbv" SMT solver library, which requires the "yices" binary be present in PATH; yices2 can be downloaded from here: http://yices.csl.sri.com/download-yices2.shtml Suggestions and feedback are most welcome. :-) Cheers, Audrey

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ANNOUNCE: haskell-src-exts 1.11.1
by Niklas Broberg 25 May '11

25 May '11

Fellow Haskelleers, I'm pleased to announce the release of haskell-src-exts-1.11.1! * On hackage: http://hackage.haskell.org/package/haskell-src-exts * Via cabal: cabal install haskell-src-exts * Darcs repo: http://code.haskell.org/haskell-src-exts This major release fixes some long-standing bugs in the fixity handling. Many thanks for Lennart Augustsson for the patches! Changelog: 1.10.2 --> 1.11.1 =============== * API change: the fixities field in ParseMode is now of type Maybe [Fixity]. If the field is Nothing the parsing will not try to do any fixity resolution whatsoever, otherwise it behaves as before. * API change, bug fix: The Fixity type contains a QName rather than an Op to name the operator. The operator must match the given QName exactly (i.e., unqualified names only match unqualified names, and qualified names only match qualified names) for applyFixities to perform fixups. * Bug fix: End-of-file inside an OPTIONS pragma no longer loops. Cheers, /Niklas

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Second CFP: Continuation Workshop 2011
by oleg＠okmij.org 25 May '11

25 May '11

Submission deadline: June 25, 2011 Invited speakers: Mats Rooth (Cornell), Noam Zeilberger (Universite' Paris 7) There will be a tutorial session in the evening before the workshop. ACM SIGPLAN Continuation Workshop 2011 http://logic.cs.tsukuba.ac.jp/cw2011/ co-located with ICFP 2011, Tokyo, Japan Saturday, September 24, 2011 Call for Contributions Continuations have been discovered many times, which highlights their many applications in programming language semantics and program analysis, linguistics, logic, parallel processing, compilation and web programming. Recently, there has been a surge of interest specifically in delimited continuations: new implementations (in Scala, Ruby, OCaml, Haskell), new applications (to probabilistic programming, event-driven distributed processing), substructural and constructive logics, natural language semantics. The goal of the Continuation Workshop is to make continuations more accessible and useful -- to practitioners and to researchers in various areas of computer science and outside computer science. We wish to promote communication among the implementors and users in many fields. We would like to publicize the applications of continuations in academic (logic, linguistics) and practical fields and various programming languages (OCaml, Haskell, Scala, Ruby, Scheme, etc). Continuation Workshop 2011 will be informal. We aim at accessible presentations of exciting if not fully polished research, and of interesting academic, industrial and open-source applications that are new or unfamiliar. The workshop will have no published proceedings; submissions of short abstracts are preferred. Invited speakers ---------------- Mats Rooth, Director of Computational Linguistics Lab, Cornell University, USA http://conf.ling.cornell.edu/mr249/ Noam Zeilberger, Universite' Paris 7 http://www.pps.jussieu.fr/~noam/ Tutorials --------- In the evening before the workshop, there will be a tutorial session on delimited continuations and their main applications. Tutorial date and time: Friday, September 23, 2011, 19:00-21:00 Tutorial place: IIJ (next to NII, the place of the ICFP conference) Tutorial speakers: Kenichi Asai and Oleg Kiselyov Important dates --------------- Submission: June 25, 2011 Notification: August 8, 2011 Tutorials: September 23, 2011 Workshop: September 24, 2011 Format ------ The workshop will consist of presentations by the participants, selected from submitted abstracts. Participants are invited to submit working drafts, source code, and/or extended abstracts for distribution on the workshop homepage and to the attendees, but as the workshop will have no formal proceedings, any contributions may be submitted for publication to other venues. (See the SIGPLAN republication policy for more details.) Scope ----- We seek several types of presentations on topics related to continuations. We especially encourage presentations that describe work in progress, outline a future research agenda, or encourage lively discussion. Research presentations on: - implementations of continuations - semantics - type systems and logics - meta-theory and its mechanization - code generation with continuations or effects - distributed programming - systems programming and security - pearls Research presentations must be broadly accessible and should describe new ideas, experimental results, significant advances in the theory or application of continuations, or informed positions regarding new control operators. Application presentations, or status reports These broadly accessible presentations should describe interesting applications of continuations in research, industry or open source. We encourage presentations of applications from areas outside of programming language research -- such as linguistics, logics, AI, computer graphics, operating systems, etc. These presentations need not present original research, but should deliver information that is new or that is unfamiliar to the general ICFP audience. (A broadly accessible version of research presented elsewhere, with the most recent results and more discussion of future work may be acceptable as a CW 2011 status report.) The abstract submission should justify, to a general reader, why an application is interesting. Demos and work-in-progress reports Live demonstrations or presentations of preliminary results are intended to show new developments, interesting prototypes, or work in progress. In the abstract submission (which need only be about half a page), describe the demo and its technical content, and be sure to include the demo's title, authors, collaborators, references, and acknowledgments. A demonstration should take 10-15 minutes, and a work-in-progress report should take about 5 minutes. The exact time per demo will be decided based on the number of accepted submissions. (Presenters will have to bring all the software and hardware for their demonstration; the workshop organizers are only able to provide a projector.) Submission Guidelines and Instructions -------------------------------------- Unlike the previous Continuation Workshops, we do not require the submission of complete research papers. We will select presentations based on submitted abstracts, up to 2 (A4 or US letter) pages long in the PDF format (with the optional supplementary material, up to 8 PDF pages). Persons for whom this poses a hardship should contact the program chair. Submissions longer than a half a page should include a paragraph synopsis suitable for inclusion in the workshop program. Email submissions to cw2011-submit(a)logic.cs.tsukuba.ac.jp Organizers ---------- Yukiyoshi Kameyama, University of Tsukuba Chung-chieh Shan, Rutgers University Oleg Kiselyov Program Committee ----------------- Kenichi Asai, Ochanomizu University, Japan Malgorzata Biernacka, University of Wroclaw, Poland Hugo Herbelin, PPS - pi.r2, INRIA, France Oleg Kiselyov Julia Lawall, University of Copenhagen, Denmark Tiark Rompf, EPFL, Switzerland Chung-chieh Shan, Rutgers University (Chair) Hayo Thielecke, University of Birmingham, UK

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ANNOUNCE: time-recurrence-0.2
by Chris Heller 25 May '11

25 May '11

Hot on the heels of the 0.1 release of time-recurrence: http://hackage.haskell.org/package/time-recurrence comes your favorite recurring time library: time-recurrence-0.2. At this point the library can generate many of the examples given in section 3.8.5.3 of the iCalendar RFC. The interface has been reworked to make things more concise, an example: > -- Generate every 10 days, 5 occurrences > startDate = utcGregorianWithTime 1997 9 2 14 0 0 -- Y M D HH MM SS > map moment $ take 5 $ recurBy 10 [] $ Daily startDate > [1997-09-02 14:00:00 UTC > ,1997-09-12 14:00:00 UTC > ,1997-09-22 14:00:00 UTC > ,1997-10-02 14:00:00 UTC > ,1997-10-12 14:00:00 UTC] I'm still tweaking the main data structures so things are very unstable right now. There is no support for operators like the iCalendar BYSETPOS, which would allow you to generate "the 30th of the month in June if it is a Week Day otherwise the last Week Day in June". For the future I also am looking at how to enforce some of the more esoteric iCalendar rules, such as using BYMONTHDAY in a MONTHLY frequency when also using BYDAY. Since I am not being strict I can simply punt on the matter, but it would be interesting to support such dependencies. As always I encourage all feedback, suggestions and pull requests. -Chris

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Call for Participation: PPDP 2011
by mh＠informatik.uni-kiel.de 23 May '11

23 May '11

====================================================================== CALL FOR PARTICIPATION PPDP 2011 13th International ACM SIGPLAN Symposium on Principles and Practice of Declarative Programming http://www-ps.informatik.uni-kiel.de/ppdp11/ July 20-22, 2011, Odense, Denmark In cooperation with ACM SIGPLAN Co-located with LOPSTR 2011, WFLP 2011, and AAIP 2011 ====================================================================== ONLINE REGISTRATION IS OPEN, EARLY REGISTRATION DEADLINE: May 30, 2011 PPDP 2011 aims to provide a forum that brings together researchers from the declarative programming communities, including those working in the logic, constraint and functional programming paradigms, but also embracing a variety of other paradigms such as visual programming, executable specification languages, database languages, AI languages and knowledge representation languages used, for example, in the semantic web. The goal is to stimulate research in the use of logical formalisms and methods for specifying, performing, and analyzing computations, including mechanisms for mobility, modularity, concurrency, object-orientation, security, and static analysis. SYMPOSIUM PROGRAM (preliminary): Wednesday, July 20, 2011: 9:00 - 10:00: PPDP/LOPSTR Invited Talk * Fritz Henglein. <TBA> Coffee break 10:30 - 11:30: PPDP/LOPSTR Invited Talk * Vitaly Lagoon. The Challenges of Constraint-Based Test Generation Coffee break 11:30 - 12:30: Session 1: Verification and Specification * Felix Schernhammer and Jose Meseguer. Incremental Checking of Well-Founded Recursive Specifications Modulo Axioms * Kazuhiro Inaba, Soichiro Hidaka, Zhenjiang Hu, Hiroyuki Kato and Keisuke Nakano. Graph-Transformation Verification using Monadic Second-Order Logic Lunch and Excursion Thursday, July 21, 2011: 9:00 - 10:00: Session 2: Declarative Languages * Robert Giegerich, Stefan Janssen and Georg Sauthoff. Bellman's GAP - A Declarative Language for Dynamic Programming * Rafael Del Vado Vírseda and Fernando Pérez Morente. A Modular Semantics for Higher-Order Declarative Programming with Constraints Coffee break 10:30 - 12:30: Session 3: Analysis * Jan Christiansen and Daniel Seidel. Minimally Strict Polymorphic Functions * Santiago Escobar, Deepak Kapur, Christopher Lynch, Catherine Meadows, Jose Meseguer, Paliath Narendran and Ralf Sasse. Protocol Analysis in Maude-NPA Using Unification Modulo Homomorphic Encryption * Tony Bourdier and Horatiu Cirstea. Symbolic analysis of network security policies using rewrite systems * Dario Colazzo and Carlo Sartiani. Precision and Complexity of XQuery Type Inference Lunch break 14:00 - 15:00: Session 4: Concurrency * David Sabel and Manfred Schmidt-Schauss. A Contextual Semantics for Concurrent Haskell with Futures * Jasmin Christian Blanchette, Tjark Weber, Mark Batty, Scott Owens, Susmit Sarkar. Nitpicking C++ Concurrency Coffee break 15:30 - 16:30: Session 5: Logic Programming and Constraints * Vivek Nigam, Limin Jia, Boon Thau Loo and Andre Scedrov. Maintaining Distributed Logic Programs Incrementally * Rémy Haemmerlé, Pedro Lòopez-Garcìa and Manuel V. Hermenegildo. CLP Projection for Constraint Handling Rules Friday, July 22, 2011: 9:00 - 10:00: PPDP Invited Talk * Andrey Rybalchenko. Towards Automatic Synthesis of Software Verification Tools Coffee break 10:30 - 12:30: Session 6: Types and Lambda Calculus * Malgorzata Biernacka, Dariusz Biernacki and Serguei Lenglet. Typing Control Operators in the CPS Hierarchy * Bernardo Toninho, Luis Caires and Frank Pfenning. Dependent Session Types via Intuitionistic Linear Type Theory * Sandra Alves, Maribel Fernandez, Mário Florido and Ian Mackie. Recursion in a linear typed lambda-calculus * Nicolas Guenot. Nested Proof Search as Reduction in the lambda-calculus Lunch break and Closing ----------------------------------------------------------------------

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ANNOUNCE: wl-pprint-text 1.0.0.0
by Ivan Lazar Miljenovic 22 May '11

22 May '11

And lo, the people of Haskell hath declared that the text [1] library was to be the One True Way of dealing with textual data (unless, of course, you're annoyed about it using UTF-16 instead of UTF-8). And yet there was much sadness in the land, for there was no pretty-printing library available to produce said Text values, meaning that it was difficult for supplicants to produce the formatting their form of praise required. A voice then spake: make ye a new pretty-printing library aimed specifically for Text values. But thou shall not use the API from pretty [2], as it is rather limited. Instead, the design of wl-pprint [3] looks Real Good! It has more combinators available, can neatly deal with wrapping lists, and also has support for producing output for both humans and the machines that serve us so well! Thus were mighty energies aimed at producing such a library. Many were the hour at which toil was spent on this task, but at long last the task was completed. Yet great evil (i.e. programmer laziness) befell the great task, and it lay hidden for many a moon. However, with much effort the project was recovered, and is now available for all! [4] Some changes were regrettably required to achieve this task. The most important of which was that it was discovered that wl-pprint may not be as perfect as all that, in that documents of no content were treated poorly. However, spects of the pretty package were able to redeem themselves by supplying the necessary functionality. However, the great task was able to extend upon that which was there before, by invoking the almighty powers of the Monad. TL;DR: wl-pprint-text is a pretty-printing package for lazy Text values based upon the API of wl-pprint. It however deals with the nil document better than wl-pprint does, and also has a version where all the comibnators are lifted into a Monad, primarily so that it can be used within a State Monad. [1]: http://hackage.haskell.org/package/text [2]: http://hackage.haskell.org/package/pretty [3]: http://hackage.haskell.org/package/wl-pprint [4]: http://hackage.haskell.org/package/wl-pprint-text -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com IvanMiljenovic.wordpress.com

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ANNOUNCE: time-recurrence-0.1
by Chris Heller 21 May '11

21 May '11

I'm happy to announce the initial release of time-recurrence: http://github.com/hellertime/time-recurrence A library for generating and inspecting recurring times. This first release is a proof of concept which I am using to find a workable API. There are many features missing at the moment, but since it is my first Haskell library, I was both excited to let it out into the wild and hoping to solicit some feedback on its design. The general direction is to have something that works much like the RRULE portion of the iCalendar (RFC 5545) specification. I have decided avoid strict RFC compliance at this time. Currently the library works like this: > import Data.Time.Recurrence (toUTCTime, withRules, recur, yearly, byMonth, June, July) > take 4 . map toUTCTime $ withRules [byMonth [June, July]] $ recur yearly Which would produce the following (the library defaults to the UTC Epoch as a start date): > [1858-06-17 00:00:00 UTC > ,1858-07-17 00:00:00 UTC > ,1859-06-17 00:00:00 UTC > ,1859-07-17 00:00:00 UTC] In the future I plan to increase the number of rules, and add functions to test if a time is a valid occurrence of a given rule. I encourage your feedback, suggestions and patches. -Chris

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