July 2005 - Haskell - Haskell.org

ICLP 2005: Call for Participation
by ICLP 2005 18 Jul '05

18 Jul '05

Dear Colleague, Please note that ICLP 2005 registration is now open. In fact, the early registration deadline is not too far (July 31st). More details can be found at the ICLP 2005 website: http://www.iiia.csic.es/iclp2005/ Highlights include invited talks by Ian Horrocks, Peter Stuckey, Francesca Rossi, a tutorial on "Inductive Logic Programmng, Statistical Relational Learning and its applications" by Vitor Santos Costa, contributed papers, posters, programming competition, panels, conference workshops, and of course the Solar Eclipse that will take place during the conference and will be visible in Barcelona (time has been set aside during the conference to view the eclipse). We look forward to seeing all of you in Barcelona. Best wishes, Gopal Gupta and Maurizio Gabbrielli ---------------------------------------------------------------------- LIST OF ACCEPTED PAPERS: ---------------------- Full papers (26 papers) ----------------------- Use of Logic Programming for Complex Business Rules Walter Wilson Semantics of Framed Temporal Logic Programs Zhenhua Duan, Xiaoxiao Yang and Maciej Koutny. On the relation between Answer Set and SAT procedures (or, between smodels and cmodels) Enrico Giunchiglia and Marco Maratea. HYPROLOG: a new logic programming language with assumptions and abduction Henning Christiansen and Veronica Dahl. A Generator of Efficient Abstract Machine Implementations and its Application to Emulator Minimization Jose Morales, Manuel Carro, German Puebla and Manuel Hermenegildo. Nondeterminism Analysis of Functional Logic Programs Bernd Brabel and Michael Hanus. Testing for Termination with Size Change Graphs Michael Codish, Vitaly Lagoon and Peter Stuckey. Towards an Integration of Answer Set and Constraint Solving Sabrina Baselice, Piero A. Bonatti and Michael Gelfond. Symbolic Support Graph: A Space Efficient Data Structure For Incremental Tabled Evaluation Diptikalyan Saha and C. R. Ramakrishnan. Towards Implementations for Advanced Equivalence Checking in Answer-Set Programming Hans Tompits and Stefan Woltran. Hybrid Probabilistic Logic Programs With Non-monotonic Negation Emad Saad and Enrico Pontelli. Reducing Inductive Definitions to Propositional Satisfiability Nikolay Pelov and Eugenia Ternovska. A Comparison of CLP(FD) and ASP Solutions to NP-Complete Problems Agostino Dovier, Andrea Formisano and Enrico Pontelli. A Well-Founded Semantics with Disjunction Joao Alcantara, Carlos Damasio and Luis Moniz Pereira. An optimised Semantic Web query language implementation in Prolog Jan Wielemaker. Practical Higher-Order Pattern Unification via On-the-Fly Raising Gopalan Nadathur and Natalie Linnell. Dynamic Mixed-Strategy Evaluation of Tabled Logic Programs Ricardo Rocha, Fernando Silva and Vitor Santos Costa. Small proof witnesses for LF Susmit Sarkar, Brigitte Pientka and Karl Crary. Guard and Continuation Optimization for Occurrence Representations of CHR Jon Sneyers, Tom Schrijvers and Bart Demoen. Abduction of Linear Arithmetic Constraints Michael Maher. Coordination of Many Agents Joxan Jaffar, Roland Yap and Kenny Zhu. Parallelizing Union-Find in Constraint Handling Rules Using Confluence Thom Fruehwirth. Luca Bortolussi and Herbert Wiklicky. A Distributed and Probabilistic Concurrent Constraint Programming Language Deductive Multi-valued Model Checking Ajay Mallya. Techniques for Scaling Up Analyses Based on Pre-Interpretations John P. Gallagher, Kim Henriksen and Gourinath Banda. Polynomial Interpretations as a Basis for Termination An Manh Thang Nguyen and Danny De Schreye. ----------------------------- Accepted posters (18 posters) ----------------------------- Inconsistency-based Strategy For Clarifying Vague Software Requirements Kedian Mu, Zhi Jin and Ruqian Lu. A Type System for CHR Emmanuel Coquery and Francois Fages. Decision Support for Personalization on Mobile Devices Thomas Kleemann and Alex Sinner. Algorithms for FO(ID) model generation Maarten Marikn, Rudradeb Mitra and Marc Denecker. Abstract Interpretation with Specialized Definitions German Puebla, Elvira Albert and Manuel Hermenegildo. Induction of causal ramifications for action descriptions in ASP Ramon Otero. The need for Ancestor Resolution when answering queries in Horn Clause Logic Oliver Ray. Modeling Systems in CLP with Coinductive Tabling Joxan Jaffar, Andrew Edward Santosa and Razvan Voicu. A Sufficient Condition for Strong Equivalence under the Well-Founded Semantics Chistos Nomikos, Panos Rondogiannis and William Wadge. Analyses, Optimizations and Extensions of Constraint Handling Rules: Ph.D. Summary Tom Schrijvers. IMPACT: Innovative Models for Prolog with Advanced Control and Tabling Ricardo Rocha, Ricardo Lopes, Fernando Silva and Vitor Santos Costa. Using CLP to characterise linguistic lattice boundaries in a text mining process Alexandre Saidi. Hybridization of Genetic Algorithms and Constraint Propagation for the BACP Tony Lambert, Carlos Castro, Eric Monfroy, Maria Cristina Riff and Fridiric Saubion. The MYDDAS Project: Using a Deductive Database for Traffic Characterization Michel Ferreira. Open World Reasoning in Datalog Gergely Lukacsy and Zsolt Nagy. Optimizing Queries for Heterogeneous Information Sources Andras Gyvrgy Bikis. Denotational semantics using Horn Concurrent Transaction Logic Marcus Santos. Gentra4cp: a Generic Trace Format for Constraint Programming Ludovic Langevine and The OADymPPaC team.

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offside rule question
by Frederik Eaton 18 Jul '05

18 Jul '05

Compiling the following module (with ghc) fails with error message "parse error (possibly incorrect indentation)", pointing to the let statement. The error goes away when I indent the lines marked "--*". But I don't understand how what I've written could be ambiguous. If I am inside a parenthesized expression, then I can't possibly start another let-clause. The fact that the compiler won't acknowledge this fact ends up causing a lot of my code to be squished up against the right margin when it seems like it shouldn't have to be. module Main where main :: IO () main = do let a = (map (\x-> x+1) --* [0..9]) --* print a return () Is there a reason for this behavior or is it just a shortcoming of the compiler? Frederik

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Re: A MonadPlusT with fair operations and pruning
by oleg＠pobox.com 16 Jul '05

16 Jul '05

on Jun 22 Andrew Bromage wrote about the usefulness of soft-cuts and "don't care" non-determinism in non-deterministic computations in Haskell. > http://www.haskell.org/pipermail/haskell/2005-June/016037.html Thank you very much for your explanation, it was helpful indeed. You noted, > Some of the interesting examples in Prolog are moot in Haskell by virtue > of the fact that Haskell is "strongly moded" And hence was our quandary. Even the leanTAP theorem prover looked too simple in Haskell to serve as a good example of advanced non-determinism. Your Tic-Tac-Toe example is thus even more appreciated. We have extended your code to boards of arbitrary NxN size (with M consecutive marks needed for winning). There is also a function for a human to play against the machine. We added some limits on the breadth and the depth of the search -- to keep both the reasonable response time and the pride. All in all, playing on the 5x5 board (with 4 marks needed for winning) is fairly entertaining. The archive LogicT.tar.gz mentioned previously now contains the tic-tac-toe code. The paper has been updated with its description. BTW, > best p b ... > | otherwise > = ifte (once (do > m <- choose [1..9] > b' <- move m p b > guard (win p b) > return (Win, b'))) > return > return > (ifte (once (do > m <- choose [1..9] > b' <- move m (otherPlayer p) b > guard (win (otherPlayer p) b') > return m)) > (\m -> do > b' <- move m p b > (w,_) <- best (otherPlayer p) b' > return (w,b')) The last statement should probably be `return (otherState w,b')', right? on Jan 5 2005, Andrew Bromage wrote on Haskell-Cafe: > Logical if-then-else has this signature: > > mif :: LogicT m a -> (a -> LogicT m b) -> LogicT m b -> LogicT m b > > Intuitively, this takes three arguments: the "condition", the "then" > case and the "else" case. This obeys the "obvious" laws of if-then-else: > > mif (return a) t e = t a > mif (mzero) t e = e > mif (mif c t' e') t e = mif c (\x -> mif (t' x) t e) (mif e' t e) Chung-chieh Shan has pointed out a problem with the last law: Let us consider the following instance of that law. We use Prolog, which implements soft-cuts (aka mif aka ifte) natively. In Prolog, `mif test t e' is written as `test *-> t ; e' He chose t === true, e === true, e' === fail, t' === X = 1, c === (X=1 ; X=2) mif (mif c t' e') t e translates to ((X=1 ; X=2) *-> X=1 ; fail) *-> true; true. and gives one answer, 1. mif c (\x -> mif (t' x) t e) (mif e' t e) translates to (X=1 ; X=2) *-> ( X=1 *-> true ; true) ; (fail *-> true; true). and gives two answers, 1 and 2. So, it seems the law has to be formulated in a more complex way, mif (mif c t' e') t e = mif (once c) (const $ mif (c >>= t') t e) (mif e' t e) with a surprising occurrence of `once'. That formulation isn't particularly useful for a backtracking _transformer_. In any case, we haven't encountered a need to simplify "mif (mif c t' e') t e" algebraically. It is interesting to see when such a law may be required.

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Early registration: GPCE'05 -- Generative Programming and Component Engineering
by Eelco Visser 15 Jul '05

15 Jul '05

CALL for EARLY REGISTRATION (deadline July 29) ---------------------------------------------------------------------- 4th International Conference on Generative Programming and Component Engineering (GPCE'05) Sep 29 - Oct 1, 2005, Tallinn (Estonia) http://www.gpce.org/05 Sponsored by ACM SIGPLAN, in cooperation with ACM SIGSOFT co-located with ICFP'05 and TFP'05 ---------------------------------------------------------------------- Please consult http://www.gpce.org/05 for the UP-TO-DATE and DETAILED programme http://www.cs.ioc.ee/tfp-icfp-gpce05/ for the ON-LINE REGISTRATION, hotel and travel information ---------------------------------------------------------------------- IMPORTANT DATES * Jul 29, 2005: EARLY REGISTRATION DEADLINE (and hotel discount rates) * Sep 02, 2005: Late registration deadline * Sep 27-28, 2005: GPCE workshops and tutorials * Sep 29 - Oct 1, 2005: GPCE papers and demos ---------------------------------------------------------------------- SCOPE. Generative and component approaches have the potential to revolutionize software development in a similar way as automation and components revolutionized manufacturing. Generative Programming (developing programs that synthesize other programs), Component Engineering (raising the level of modularization and analysis in application design), and Domain-Specific Languages (elevating program specifications to compact domain-specific notations that are easier to write and maintain) are key technologies for automating program development. GPCE arose as a joint conference, merging the conference on Generative and Component-Based Software Engineering (GCSE) and the workshop on Semantics, Applications, and Implementation of Program Generation (SAIG). The goal of GPCE is to provide a meeting place for researchers and practitioners interested in cutting edge approaches to software development. We aim to foster further cross-fertilization between the software engineering research community and the programming languages community, in addition to supporting the original research goals of both the GCSE and the SAIG communities. ---------------------------------------------------------------------- 3 INVITED SPEAKERS: * Oscar Nierstrasz: Object-oriented Reengineering Patterns * Oege de Moor: The AspectBench Compiler for AspectJ * Bernd Fischer: Certifiable Program Generation 25 TECHNICAL PAPERS 2 DEMONSTRATIONS: * Developing Dynamic and Adaptable Applications with CAM/DAOP: a Virtual Office Application * Metamodeling made easy - MetaEdit+ 2 TUTORIALS T1: Multi-stage Programming in MetaOCaml (Presenters: W.Taha, C.Calcagno) T2: Implementing Domain-Specific Modelling Languages and Generators (Presenters: R.Pohjonen and J-P.Tolvanen) 3 WORKSHOPS W1: Seventh Young Researchers Workshop (Organizers: D.R.Dechow, D.Foetsch, S.Kiebusch, S.Perugini, M.J.Rutherford, D.Shestakov) W2: Second MetaOCaml Workshop (Organizers: K.Swadi, W.Taha) W3: Graph and Model Transformations Workshop (Organizers: G.Karsai, G.Taentzer) ---------------------------------------------------------------------- PROGRAM COMMITTEE Chairs: * Robert Glück (U. of Copenhagen) * Michael Lowry (NASA) Members: * Don Batory (U. of Texas, USA) * Ira Baxter (Semantic Designs) * Cristiano Calcagno (Imperial College) * Prem Devanbu (U. of California at Davis) * Ulrich Eisenecker (U. of Leipzig) * Tom Ellman (Vassar College) * Robert Filman (NASA) * Zhenjiang Hu (U. of Tokyo) * Patricia Johann (Rutgers U.) * John Launchbury (Galois) * Anne-Françoise Le Meur (U. of Sci. and Tech. Lille) * Hong Mei (Peking U.) * Nicolas Rouquette (NASA) * William Scherlis (CMU) * Yannis Smaragdakis (Georgia Inst. of Tech.) * Walid Taha (Rice U.) * Todd Veldhuizen (Chalmers U. of Tech.) ORGANIZING COMMITTEE General Chair * Eugenio Moggi (Genova U.) Publicity Chair: * Eelco Visser (U. Utrecht) Workshops and Tutorials Chairs * Jeff Gray (U. of Alabama at Birmingham) * Andrew Malton (Waterloo U.) Local Arrangements Chair * Tarmo Uustalu (Inst. of Cybernetics, Tallinn) ----------------------------------------------------------------------

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RE: [Haskell] writeFile for a looong string
by Simon Marlow 14 Jul '05

14 Jul '05

On 14 July 2005 10:08, Johannes Waldmann wrote: > I am writing a long string (several MByte) to a file, > with writeFile fname ( render d ) > where d :: Text.PrettyPrint.HughesPJ.Doc > > I wonder what happens internally > (when compiled with ghc -O, if that matters) > Will the string be in memory completely > before it is actually written? No, it should be streamed to the output in constant space, as long as the String can be evaluated lazilly. Cheers, Simon

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line-based interactive program
by mt 14 Jul '05

14 Jul '05

hi, i'd like to know how to write simply a line-based interactive program, that is one with which you have a 'talk'. a simple filter-like line-based program ca be written as: -- a filter program process an entire input to yield some output type FilterProgram = [Line] -> [Line] but i don't knwo how to handle input/output such that the output can be printed before all the input exists (the user enter some lines, the program writes a response based on those lines, and so on) what's the simplest/most elegant approach ? thanks, minh thu

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writeFile for a looong string
by Johannes Waldmann 14 Jul '05

14 Jul '05

Dear all, I am writing a long string (several MByte) to a file, with writeFile fname ( render d ) where d :: Text.PrettyPrint.HughesPJ.Doc I wonder what happens internally (when compiled with ghc -O, if that matters) Will the string be in memory completely before it is actually written? My d is in fact vcat xs, for a list xs that is generated item by item. Is there a way to get more efficient behaviour without too much rewriting the program? -- -- Johannes Waldmann -- Tel/Fax (0341) 3076 6479/80 -- ---- http://www.imn.htwk-leipzig.de/~waldmann/ -------

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Template id function
by Mads Lindstrøm 13 Jul '05

13 Jul '05

Hi I am trying to learn Meta Haskell. One thing I want to do is create an identity function. It should get a type constructor as input and return the same type constructor as output. It should be possible to do: $(idDecl data Foo = Foo Int) and it should "return": data Foo = Foo Int Is this possible? if yes, how does one do it? -- Mads Lindstrøm <mads_lindstroem(a)yahoo.dk>

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PADL'06 Call for Papers
by Logic Programming Rsrch Association 12 Jul '05

12 Jul '05

----------------------------------------------------------------------------- CALL FOR PAPERS!!! Eighth International Symposium on Practical Aspects of Declarative Languages 2006 (PADL '06) http://www.cs.brown.edu/people/pvh/PADL06.html Charleston Place Hotel Charleston, South Carolina January 9-10 Co-located with ACM POPL'06 Declarative languages build on sound theoretical bases to provide attractive frameworks for application development. These languages have been successfully applied to vastly different real-world situations, ranging from data base management to active networks to software engineering to decision support systems. New developments in theory and implementation have opened up new application areas. At the same time, applications of declarative languages to novel problems raises numerous interesting research issues. Well-known questions include designing for scalability, language extensions for application deployment, and programming environments. Thus, applications drive the progress in the theory and implementation of declarative systems, and benefit from this progress as well. PADL is a forum for researchers and practioners to present original work emphasizing novel applications and implementation techniques for all forms of declarative concepts, including, functional, logic, constraints, etc. Topics of interest include: * innovative applications of declarative languages; * declarative domain-specific languages and applications; * practical applications of theoretical results; * new language developments & their impact on applications; * evaluation of implementation techniques on practical applications; * novel uses of declarative languages in the classroom; and * practical experiences PADL 06 welcomes new ideas and approaches pertaining to applications and implementation of declarative languages, and is not limited to the scope of the past five PADL symposia. PADL 06 will be co-located with the ACM POPL. IMPORTANT DATES AND SUBMISSION GUIDELINES Paper Submission: August 20, 2005 Notification: September 30, 2005 Final Manuscript: October 20, 2005 Symposium: January 9-10, 2005 Authors should submit an electronic copy of the full paper (written in English) in Postscript (Level 2) or PDF. Papers must be no longer than 15 pages, written in 11-point font and with single spacing. Since the final proceedings will be published as Lecture Notes in Computer Science by Springer Verlag, authors are strongly encouraged to use the LNCS paper formatting guidelines for their submission. Each submission must include on its first page the paper title; authors and their affiliations; contact author's email and postal addresses, telephone and fax numbers, abstract, and three to four keywords. The keywords will be used to assist us in selecting appropriate reviewers for the paper. If electronic submission is impossible, please contact the program chair for information on how to submit hard copies. MOST PRACTICAL PAPER AWARD The Most Practical Paper award will be given to the submission that is judged by the programm committee to be the best in terms of practicality, originality, and clarity of presentation. The program committee may choose not to make an award; or may make multiple awards. PROGRAM COMMITTEE: Kenichi Asai Ochanomizu University, Japan Daniel Damien BRICS, Denmark Mireille Ducasse IRISA/INSA of Rennes, France Matthew Flatt University of Utah, US Gopal Gupta University at Texas at Dallas, US Manuel Hermenegildo UP Madrid, Spain Paul Hudak Yale University, US Narendra Jusien Ecole des Mines de Nantes, France Laurent Michel University of Connecticut, US Enrico Pontelli New Mexico State University Gopalan Nadathur U. of Minnesota, US Vitor Santos-Costa U. Federal do Rio de Janeiro, Brazil Christian Schulte Royal Institute of Technology, Sweden Peter Stuckey U. of Melbourne, Australia Pascal Van Hentenryck Brown University, US Peter van Roy U. of Louvain, Belgium David S. Warren SUNY at Stony Brook, US Roland Yap National U. of Singapore, Singapore Contacts: For information about papers and submissions, please contact the Program Chair: Pascal van Hentenryck PC Chair - PADL 2006 Department of Computer Science Brown University Providence, RI, U.S.A. Email: pvh(a)cs.brown.edu For other information about the conference and the summer school, please contact: Gopal Gupta Department of Computer Science University at Texas at Dallas Dallas, TX, U.S.A. Email: gupta(a)utdallas.edu Sponsored by COMPULOG Americas (http://www.cs.nmsu.edu/~complog)

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Using hs-plugins
by Thomas Davie 12 Jul '05

12 Jul '05

I've been trying to get hs-plugins working on a box, to use the Eval module, but the register script seems not to register the eval package, or the printf module, which judging by the readme: --- And to unregister (maybe as root). Note that the unistall order matters: $ ghc-pkg -r printf $ ghc-pkg -r eval $ ghc-pkg -r plugins $ ghc-pkg -r hi $ ghc-pkg -r altdata --- it should have registered. Have I missed something really obvious? Bob

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