February 2011 - Haskell

LOPSTR 2011 - second call for papers
by German Vidal 15 Feb '11

15 Feb '11

============================================================ Call for papers 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) ============================================================ Objectives: 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. The 21st International Symposium on Logic-based Program Synthesis and Transformation (LOPSTR 2011) will be held in Odense, Denmark; previous symposia were held in Hagenberg, Coimbra, Valencia, Lyngby, Venice, London, Verona, Uppsala, Madrid, Paphos, London, Venice, Manchester, Leuven, Stockholm, Arnhem, Pisa, Louvain-la-Neuve, and Manchester (you might have a look at the contents of past LOPSTR symposia). LOPSTR 2011 will be co-located with PPDP 2011 (International ACM SIGPLAN Symposium on Principles and Practice of Declarative Programming). Topics: Topics of interest cover all aspects of logic-based program development, all stages of the software life cycle, and issues of both programming- in-the-small and programming-in-the-large. Papers describing applications in these areas are especially welcome. Contributions are welcome on all aspects of logic-based program development, including, but not limited to: - specification - synthesis - verification - transformation - analysis - optimisation - specialization - partial evaluation - inversion - composition - program/model manipulation - certification - security - transformational techniques in SE - applications and tools Survey papers, that present some aspect of the above topics from a new perspective, and application papers, that describe experience with industrial applications, are also welcome. Papers must describe original work, be written and presented in English, and must not substantially overlap with papers that have been published or that are simultaneously submitted to a journal or a conference with refereed proceedings. Work that already appeared in unpublished or informally published workshops proceedings may be submitted. Following past editions, the formal post-conference proceedings will be published by Springer in the Lecture Notes in Computer Science (LNCS) series. IMPORTANT DATES AND SUBMISSION GUIDELINES: - Paper submission: March 27, 2011 - Extended abstract submission: April 3, 2011 - Notification (for pre-proceedings): May 16, 2011 - Camera-ready (for pre-proceedings): June 12, 2011 - Symposium: July 18-20, 2011 Submissions can either be (short) extended abstracts or (full) papers whose length should not exceed 9 and 15 pages (including references), respectively. Submissions must be formatted in the Lecture Notes in Computer Science style (excluding well-marked appendices not intended for publication). Referees are not required to read the appendices, and thus papers should be intelligible without them. Short papers may describe work-in-progress or tool demonstrations. Both short and full papers can be accepted for presentation at the symposium and will then appear in the LOPSTR 2011 pre-proceedings. Full papers can also be immediately accepted for publication in the formal proceedings to be published by Springer in the LNCS series. In addition, after the symposium, the programme committee will select further short or full papers presented in LOPSTR 2011 to be considered for formal publication. These authors will be invited to revise and/or extend their submissions in the light of the feedback solicited at the symposium. Then after another round of reviewing, these revised papers can also be published in the formal proceedings. Program Committee: Elvira Albert (Complutense University of Madrid, Spain) Malgorzata Biernacka (University of Wroclaw , Poland) Manuel Carro (Technical University of Madrid, Spain) Michael Codish (Ben-Gurion University of the Negev, Israel) Danny De Schreye (K.U.Leuven, Belgium) Maribel Fernandez (King's College London, UK) Raul Gutierrez (University of Illinois at Urbana-Champaign, USA) Mark Harman (University College London, UK) Frank Huch (C.A.U. Kiel, Germany) Michael Leuschel (University of Dusseldorf, Germany) Yanhong Annie Liu (State University of New York at Stony Brook, USA) Kazutaka Matsuda (Tohoku University, Japan) Fred Mesnard (Universite de La Reunion, France) Ulrich Neumerkel (Technical University of Wien, Austria) Alberto Pettorossi (Universita' di Roma Tor Vergata, Italy) Carla Piazza (University of Udine, Italy) Peter Schneider-Kamp (University of Southern Denmark, Denmark) Hirohisa Seki (Nagoya Institute of Technology, Japan) Josep Silva (Technical University of Valencia, Spain) German Vidal (Technical University of Valencia, Spain) Jurgen Vinju (Centrum Wiskunde & Informatica, The Netherlands) Jianjun Zhao (Shanghai Jiao Tong University, Shanghai) Contacts Program Chair (contact him for additional information about papers and submissions): German Vidal Department of Computer Science (DSIC) Universitat Politecnica de Valencia Valencia, Spain Email: lopstr11(a)dsic.upv.es General Chair Peter Schneider-Kamp Dept. of Mathematics and Computer Science University of Southern Denmark Campusvej 55 DK-5230 Odense M, Denmark Email: petersk(a)imada.sdu.dk

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Problems with (projects|community).haskell.org
by Erik de Castro Lopo 14 Feb '11

14 Feb '11

Hi all, Still a couple of problems with these servers. Firstly, community.haskell.org shows the default Apache "It works" page. It would be nice to have something better there. Secondly the mailman web interface on projects.haskell.org [0] is giving a Service Temporarily Unavailable message (and has been for a couple of days). Cheers, Erik [0] http://projects.haskell.org/cgi-bin/mailman/admindb/haskell-llvm -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

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CALL FOR Workshop Proposals (ICFEM 2011)
by Huibiao Zhu 13 Feb '11

13 Feb '11

************************************************************ ICFEM 2011: 13th International Conference on Formal Engineering Methods CALL FOR Workshop Proposals 25-28 Oct 2011 Radisson BLU Hotel, Durham, UK URL: http://www.scm.tees.ac.uk/icfem2011 ************************************************************ Since 1997, ICFEM has provided a forum for those interested in the application of formal engineering methods to computer systems. Researchers and practitioners, from industry, academia, and government, are encouraged to attend, and to help advance the state of the art. In 2011 the 13th International Conference on Formal Engineering Methods (ICFEM 2011), which is being sponsored and organised by Teesside University, will be held at the Radisson BLU hotel in Durham, UK, from the 25th to 28th October 2011. The first day, 25 October 2011, will be dedicated to workshops and other satellite events, while the ICFEM 2011 conference proper will occupy the subsequent three days, 26-28 October 2011. The organizing committee of ICFEM 2011 therefore cordially invites proposals for one-day workshops in any area of formal methods and software engineering, but particularly in new or emerging fields of application of formal methods and on experience with practical application domains of formal methods. Submission of Proposals Proposals for workshops should contain * a title and brief description of the workshop topic; * the names and contact details of the potential organisers; * a brief justification of the topic and estimated size of audience * a description of any special technical requirements Proposals should be sent to ICFEM2011 Workshops Chair, Steve Dunne, at s.e.dunne(a)tees.ac.uk no later than 10 March 2011.

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ANNOUNCE: Save the date! Haskell hackathon in Philadelphia, July 29-31
by Brent Yorgey 12 Feb '11

12 Feb '11

I am very pleased to announce that Hac phi 3, third in an annual series of Haskell hackathons hosted at the University of Pennsylvania in Philadelphia, will take place from July 29-31. More details will be forthcoming, but put it on your calendar now. The past two years have been a blast -- you won't want to miss this one! Q: Do I have to already be a Haskell expert to attend? A: No! All are welcome. In fact, sitting in a room with a bunch of enthusiastic Haskell hackers is a great way to learn. Past attendees have included seasoned Haskell gurus and raw beginners alike. Q: What does one do at a Haskell hackathon? A: The goal is to create a fun, interactive, collaborative environment for writing Haskell code. You can work on a project of your own, or help someone else with theirs. Q: What will the cost be? A: We're still working out the details, but as in past years, registration will be free, and we hope to be able to provide some of the meals. You'll be on your own for transportation and lodging. The Hac Phi team: Chris Casinghino (ccasin) Daniel Wagner (dmwit) Brent Yorgey (byorgey)

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Beginner - Binary Search Tree Question
by htc2011 12 Feb '11

12 Feb '11

Hi All, I am learning Haskell and can't understand the following problem. Maybe somebody could advise me on a solution? Using GHCI, I have the following definition of a BST: data Ord a => BST a = EmptyBST | Node ( BST a ) a ( BST a ) deriving (Show) I want to determine the number of leaves that a tree using the above definition has: numLeaves :: Ord a => BST a -> Int numLeaves EmptyBST = 0 numLeaves (Node b a c) | b == EmptyBST = 1 + numLeaves c | c == EmptyBST = 1 + numLeaves b | otherwise = numLeaves b + numLeaves c However whenever I load my haskell file containing the above code into GHCI, I get the following error: Could not deduce (Eq (BST a)) from the context (Ord a) arising from a use of `==' at a8.hs:17:3-15 Possible fix: add (Eq (BST a)) to the context of the type signature for `numLeaves' or add an instance declaration for (Eq (BST a)) In the expression: b == EmptyBST In a stmt of a pattern guard for the definition of `numLeaves': b == EmptyBST In the definition of `numLeaves': numLeaves (Node b a c) | b == EmptyBST = 1 + numLeaves c | c == EmptyBST = 1 + numLeaves b | otherwise = numLeaves b + numLeaves c Could anybody explain to me what this means? / How to get around this? Thank you for your time! -- View this message in context: http://haskell.1045720.n5.nabble.com/Beginner-Binary-Search-Tree-Question-t… Sent from the Haskell - Haskell mailing list archive at Nabble.com.

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#haskell-game & Haskellers Game Interest Group
by Korcan Hussein 12 Feb '11

12 Feb '11

Some of us interested in Haskell GameDev have formed chat room & Haskellers Interest Group, you can out find more info here. Just spreading the word around.

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ANNOUNCE: hspec-0.1.0 (Behavior Driven Development for Haskell)
by trystan.s＠comcast.net 12 Feb '11

12 Feb '11

hspec - Behavior Driven Development for Haskell hspec ties together requirements and code that verifies the requirements are met. The verifying code can be a boolean expression, a QuickCheck property, or an explination of why it's pending. The requirements can then be turned into documentation of what the code does and what remains to be implemented. hspec verifies its own requirements as an example of how to use it. You can find the code on github: https://github.com/trystan/hspec There's also a cabal generated tar.gz: https://github.com/downloads/trystan/hspec/hspec-0.1.0.tar.gz I'll add it to hackageDB when I get a user name.... And here it is in action: Step 1, define some requirements ]> import Test.Hspec ]> ]> specs :: IO [Spec] ]> specs = describe "quantify" [ ]> it "returns the singular form of a word when given the number 1" ]> (quantify 1 "thing" == "1 thing"), ]> ]> it "returns the plural form of a word when given a number greater than 1" ]> (quantify 2 "thing" == "2 things"), ]> ]> it "returns the plural form of a word when given the number 0" ]> (quantify 0 "thing" == "0 things"), ]> ]> it "handles describing the plural of words that end with an 'x'" ]> (pending "no need for this yet") ]> ] Step 2, make it compile ]> quantify _ _ = "" Step 3, watch your requirements fail ]> hspec specs quantify x returns the singular form of a word when given the number 1 x returns the plural form of a word when given a number greater than 1 x returns the plural form of a word when given the number 0 - handles describing the plural of words that end with an 'x' # no need for this yet Finished in 0.001 seconds 4 examples, 3 failures Step 4, make it right ]> quantify :: Int -> String -> String ]> quantify 1 s = "1 " ++ s ]> quantify n s = show n ++ " " ++ s ++ "s" Step 5, watch your requirements pass ]> hspec specs quantify - returns the singular form of a word when given the number 1 - returns the plural form of a word when given a number greater than 1 - returns the plural form of a word when given the number 0 - handles describing the plural of words that end with an 'x' # no need for this yet Finished in 0.001 seconds 4 examples, 3 failures Any advice, comments, or questions are welcome. Trystan Spangler

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SICSA PhD Studentships in Scotland
by Kevin Hammond 11 Feb '11

11 Feb '11

Ph.D. Studentships, Scottish Universities The Scottish Informatics and Computer Science Alliance (http://www.sicsa.ac.uk) invites applications for up to 20 international prize studentships from outstanding PhD candidates to Scottish universities. The studentships are open to citizens and residents of any country. SICSA studentships cover living costs and fees at the UK/EU level and successful candidates may apply for further fee support. We will consider applicants in any area of computer science and informatics but may give preference to students who are working in SICSA theme areas: Students must have or must expect to be awarded a 1st class honours degree or an MSc with Distinction or equivalent GPA scores. Your degree must be in a discipline that is relevant to your proposed field of research. For more details of how to apply for a SICSA prize studentship, see the SICSA web pages (http://www.sicsa.ac.uk/graduate-academy/prize-studentships/applying-for-a-s…) The deadline for applications is 28th February 2011. Please contact me in the first instance if you are interested: our research usually comes either under the modelling and abstraction or complex systems engineering themes. Best Wishes, Kevin -------- Kevin Hammond, Professor of Computer Science, University of St Andrews T: +44-1334 463241 F: +44-1334-463278 W: http://www.cs.st-andrews.ac.uk/~kh In accordance with University policy on electronic mail, this email reflects the opinions of the individual concerned, may contain confidential or copyright information that should not be copied or distributed without permission, may be of a private or personal nature unless explicitly indicated otherwise, and should not under any circumstances be taken as an official statement of University policy or procedure (see http://www.st-and.ac.uk) The University of St Andrews is a charity registered in Scotland : No SC013532

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ANNOUNCE: darcs 2.5.1
by Ganesh Sittampalam 10 Feb '11

10 Feb '11

Hi, The darcs team is pleased to announce the release of darcs 2.5.1, a minor upgrade for the 2.5 release. The main focus of this release is support for the GHC 7.0 series and the upcoming February 2011 Haskell Platform, but the release also includes a few bug fixes and minor usability improvements. A detailed changelog is below. Installing ---------- The easiest way to install darcs 2.5.1 from source is by first installing the Haskell Platform (http://www.haskell.org/platform) If you have installed the Haskell Platform or cabal-install, you can install this release by doing: $ cabal update $ cabal install darcs-2.5.1 Alternatively, you can download the tarball from http://darcs.net/releases/darcs-2.5.1.tar.gz and build it by hand as explained in the README file. Versions of GHC from 6.10.x to 7.0.x are supported. The 2.5 branch is also available as a darcs repository from http://darcs.net/releases/branch-2.5 Binaries -------- These will be posted to http://wiki.darcs.net/Binaries as they become available. Reporting bugs -------------- If you have an issue with darcs 2.5.1, you can report it via the web on http://bugs.darcs.net/ . You can also report bugs by email to bugs at darcs.net. Changelog --------- * Include original text in conflict marks Conflicts are now marked up as v v v v v v v original text before any conflicting patch ============= conflicting result A ************* conflicting result B .... ^ ^ ^ ^ ^ ^ ^ The inclusion of the original text makes it much easier to understand what the changes on either side of the conflict were. This is only an incremental improvement to our conflict marking, which we understand is still hard to use. More substantial improvements are in the works. * Support GHC 7.0 and various recent library versions (http://bugs.darcs.net/issue2008, http://bugs.darcs.net/issue2019) This should mean that darcs 2.5.1 will work with the upcoming Feb 2011 Haskell Platform release. * Restrict the GHC version in the cabal file This means that cabal builds will explicitly fail if an unsupported GHC version is encountered, which should cause less user confusion. * Update warning message about old-fashioned repositories It now points to a wiki page explaining our deprecation plan (http://wiki.darcs.net/OF) * Guard against non-repository paths during get (http://bugs.darcs.net/issue2035) Darcs normally checks for paths that point outside the repository when applying patches, but this check was missing in the case of get. * Darcs library API: make the "program name" configurable This makes it easier for external users of the library API to reuse Darcs' framework for handling commands. * darcs send now prints the remote repository address up front Previously it would first read the remote repository, which made it hard to see what was happening when accessing the remote repository hung. * Informational message about --set-default is now disabled by explicit use of --no-set-default (http://bugs.darcs.net/issue2003) This allows users to silence the message by placing 'pull no-set-default', 'push no-set-default' and 'send no-set-default' in ~/.darcs/defaults or _darcs/prefs/defaults. * Handle _darcs/format correctly on get (http://bugs.darcs.net/issue1978) This is mainly a forwards compatibility issue as no existing version of darcs would create format files that are affected by this bug. * Fix linking with libdarcs on Windows (http://bugs.darcs.net/issue2015) This was a simple problem with a missing object file.

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ANN: iteratee-0.7.0.2 and 0.8.0.1 released
by John Lato 10 Feb '11

10 Feb '11

(Apologies for cross-posting) I have recently discovered a memory leak which affects all current versions of iteratee. I have released iteratee versions 0.7.0.2 and 0.8.0.1 which fixes the memory leak. I would strongly encourage all users of earlier versions to upgrade to one of these releases. Cheers, John Lato

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