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Re: A simple problem
by Ashley Yakeley 18 Jan '01

18 Jan '01

At 2001-01-18 15:38, I wrote: >3 is not always an Integer. It's of type "(Num a) => a". Of course, it would be nice if 3 were an Integer, and Integer were a subtype of Real. I haven't come across a language that does this, where for instance 3.0 can be cast to Integer (because it is one) but 3.1 cannot be. -- Ashley Yakeley, Seattle WA

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Re: A simple problem
by Ashley Yakeley 18 Jan '01

18 Jan '01

At 2001-01-18 05:16, Saswat Anand wrote: >class C a where > fun :: a -> Integer > >instance C Integer where > fun x = x+ 1 > >with these definitons: > >fun 3 --gives error in Hugs >fun (3::Integer) -- OK > >I am a building an embedded language, so don't want user to cast. Is there a >solution? 3 is not always an Integer. It's of type "(Num a) => a". I couldn't find a way to say that every Num is a C. -- Ashley Yakeley, Seattle WA

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A simple problem
by Saswat Anand 18 Jan '01

18 Jan '01

class C a where fun :: a -> Integer instance C Integer where fun x = x+ 1 with these definitons: fun 3 --gives error in Hugs fun (3::Integer) -- OK I am a building an embedded language, so don't want user to cast. Is there a solution? Thanks, Saswat

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FLOPS 2001 - Call for Participation
by Herbert Kuchen 18 Jan '01

18 Jan '01

********************************************************************* * CALL FOR PARTICIPATION * * * * FLOPS 2001 * * Fifth International Symposium on Functional and Logic Programming * * * * Waseda University, Tokyo, Japan * * March 7-9, 2001 * * * * http://www.ueda.info.waseda.ac.jp/flops2001/ * ********************************************************************* The symposium is a forum for research on all issues concerning functional programming and logic programming. In particular, it aims to stimulate the cross-fertilization as well as integration of the two paradigms. This is the fifth in the series of FLOPS symposia held every 1.5 years in Japan. The symposium program will consist of 3 invited talks and 21 technical research talks. The proceedings will be published by Springer-Verlag in the Lecture Notes in Computer Science series. Invited Talks ============= Gopalan Nadathur (Univ. of Minnesota, USA) "The Metalanguage lambda-Prolog and Its Implementation" George C. Necula (Univ. of California, Berkeley, USA) "A Scalable Architecture for Proof-Carrying Code" Taisuke Sato (Tokyo Institute of Technology, Japan) "Parameterized Logic Programs where Computing Meets Learning" Important Dates =============== Early Registration Deadline: January 30, 2001 Symposium: March 7-9, 2001 Venue ===== The symposium will be held at the International Conference Center of Waseda University, which is located in central Tokyo and can be accessed easily. For details, please visit the FLOPS2001 Web page http://www.ueda.info.waseda.ac.jp/flops2001/ . Registration and Hotel Information ================================== Details of registration and hotel booking information are available on the FLOPS2001 Web page. Registration fees are as follows: Before Jan. 30 After Jan. 31 Regular 22,000 yen 32,000 yen Student 12,000 yen 22,000 yen The fees include participation, proceedings, banquet and refreshments for one person. Additional banquet tickets are available. The current exchange rate for Japanese yen is US$1 = 116 yen and 1 Euro = 109 yen. Detailed information on accommodations near the conference site, ranging from luxuary to inexpensive, is available on the FLOPS Web page. Accepted Papers =============== (A timetable will be available on the FLOPS2001 Web page shortly.) Proving Syntactic Properties of Exceptions in an Ordered Logical Framework Jeff Polakow and Kwangkeun Yi A Higher-Order Colon Translation Olivier Danvy and Lasse R. Nielsen Compiling Lazy Functional Programs Based on the Spineless Tagless G-machine for the Java Virtual Machine Kwanghoon Choi, Hyun-il Lim, and Taisook Han A Higher-Order Logic Programming Language with Constraints Javier Leach and Susana Nieva Specifying and Debugging Security Protocols via Hereditary Harrop Formulas and lambdaProlog - A Case-study Giorgio Delzanno An Effective Bottom-Up Semantics for First-Order Linear Logic Programs Marco Bozzano, Giorgio Delzanno, and Maurizio Martelli A Framework for Goal-Directed Bottom-Up Evaluation of Functional Logic Programs Jesus M. Almendros-Jimenez and Antonio Becerra-Teron Theoretical Foundations for the Declarative Debugging of Lazy Functional Logic Programs Rafael Caballero, Francisco J. Lopez-Fraguas, and Mario Rodriguez-Artalejo Adding Linear Constrains over Real Numbers to Curry Wolfgang Lux A Complete Selection Function for Lazy Conditional Narrowing Taro Suzuki and Aart Middeldorp An Abstract Machine Based System for a Lazy Narrowing Calculus Teresa Hortala-Gonzalez and Eva Ullan Incremental Learning of Functional Logic Programs Cesar Ferri-Ramirez, Jose Hernandez-Orallo, and Maria Jose Ramirez-Quintana A General Type Inference Framework for Hindley/Milner Style Systems Martin Sulzmann Monadic Encapsulation with Stack of Regions Koji Kagawa Well-Typed Logic Programs Are not Wrong Pierre Deransart and Jan-Georg Smaus A Framework for Analysis of Typed Logic Programs Vitaly Lagoon and Peter J. Stuckey Abstract Compilation for Sharing Analysis Gianluca Amato and Fausto Spoto A Practical Partial Evaluator for a Multi-Paradigm Declarative Language Elvira Albert, Michael Hanus, and German Vidal A Simple Take on Typed Abstract Syntax in ML-like Languages Olivier Danvy and Morten Rhiger A Simply Typed Context Calculus with First-Class Environments Masahiko Sato, Takafumi Sakurai, and Yukiyoshi Kameyama Refining the Barendregt Cube using Parameters Fairouz Kamareddine, Twan Laan, and Rob Nederpelt Symposium Organization ====================== Program Co-Chairs: Herbert Kuchen Univ. of Muenster, Germany Kazunori Ueda Waseda Univ., Tokyo, Japan Program Committee: Sergio Antoy Portland State Univ., USA Gopal Gupta New Mexico State Univ., USA Michael Hanus Univ. of Kiel, Germany Fergus Henderson Univ. of Melbourne, Australia Zhenjiang Hu Univ. of Tokyo, Japan Herbert Kuchen Univ. of Muenster, Germany Giorgio Levi Univ. of Pisa, Italy Michael Maher Griffith Univ., Brisbane, Australia Dale Miller Pennsylvania State Univ., USA I.V. Ramakrishnan State Univ. of New York at Stony Brook, USA Olivier Ridoux IRISA, France Mario Rodriguez-Artalejo Complutense Univ., Madrid, Spain Colin Runciman Univ. of York, UK Akihiko Takano Hitachi Ltd., Japan Peter Thiemann Freiburg Univ., Germany Yoshihito Toyama Tohoku Univ., Japan Kazunori Ueda Waseda Univ., Tokyo, Japan Local Arrangements Chair: Zhenjiang Hu Univ. of Tokyo, Japan Sponsors ======== FLOPS2001 is sponsored by Japan Society of Software Science and Technology (JSSST), Special Interest Group on Principles of Programming, and held in cooperation with Association for Logic Programming (ALP).

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WRS'2001 - First call for papers
by Salvador Lucas Alba 18 Jan '01

18 Jan '01

[Apologies for multiple copies of this announcement] ************************************************************** *************** first call for papers and participation **************** ************************************************************** International Workshop on Reduction Strategies in Rewriting and Programming (WRS 2001) http://www.logic.at/wrs01/ held in conjunction with RTA 2001 Utrecht, The Netherlands, May 26, 2001 -------------------------------------------------------------------------- BACKGROUND AND AIMS Reduction strategies in rewriting and programming have attracted an increasing attention within the last years. New types of reduction strategies have been invented and investigated, and new results on rewriting / computation under particular strategies have been obtained. Research in this field ranges from primarily theoretical questions about reduction strategies to very practical application and implementation issues. The need for a deeper understanding of reduction strategies in rewriting and programming, both in theory and practice, is obvious, since they bridge the gap between unrestricted general rewriting (computation) and (more deterministic) rewriting with particular strategies (programming). Moreover, reduction strategies provide a natural way to go from operational principles (e.g., graph and term rewriting, narrowing, lambda-calculus) and semantics (e.g., normalization, computation of values, infinitary normalization, head-normalization) to implementations of programming languages. Therefore any progress in this area is likely to be of interest not only to the rewriting community, but also to neighbouring fields like functional programming, functional-logic programming, and termination proofs of algorithms. The workshop wants to provide a forum for the presentation and discussion of new ideas and results, recent developments, new research directions, as well as of surveys on existing knowledge in this area. Furthermore we aim at fostering interaction and exchange between researchers and students actively working on such topics. The workshop will be held in conjunction with RTA 2001 in Utrecht (The Netherlands) on May 26, 2001. It will feature 2 invited talks, a panel discussion, and contributed presentations selected from the submissions, with ample time for discussion. The workshop is (co-)organized by U Utrecht, TU Valencia and TU Wien. TOPICS OF INTEREST Topics of interest include, but are not restricted to, - theoretical foundations for the definition and semantic description of reduction strategies - strategies in different frameworks (term rewriting, graph rewriting, infinitary rewriting, lambda calculi, higher order rewriting, conditional rewriting, rewriting with built-ins, narrowing, constraint solving, etc.) and their application in (equational, functional, functional-logic) programming (languages) - properties of reduction strategies / computations under strategies (e.g., completeness, computability, decidability, complexity, optimality, (hyper-)normalization, cofinality, fairness, perpetuality, context-freeness, neededness, lazyness, eagerness, strictness) - interrelations, combinations and applications of reduction under different strategies (e.g., equivalence conditions for fundamental properties like termination and confluence, applications in modularity analysis, connections between strategies of different frameworks, etc.) - program analysis and other semantics-based optimization techniques dealing with reduction strategies - rewrite systems / tools / implementations with flexible / programmable strategies as essential concept / ingredient - specification of reduction strategies in (real) languages - data structures and implementation techniques for reduction strategies. SUBMISSIONS We solicit papers on all aspects of reduction strategies in rewriting and programming. Submissions should describe unpublished work, except for survey papers which are explicitly welcome, too. Submissions should not exceed 10 pages (however, survey papers may be longer) and be sent in postscript format to the PC co-chairs (wrs01(a)logic.at) by March 1, 2001. Selection of papers by the PC will be based on originality, significance, and correctness. Accepted papers will be included in the workshop proceedings that will be available at the workshop, and electronically on the web. Depending on the number and quality of submissions, formal publication of the proceedings is envisaged. Researchers just interested in attending the workshop may send a corresponding email to wrs01(a)logic.at by March 1, 2001, preferably together with a brief position paper (up to two pages in postscript) describing their interest and/or work in the area. However, we will also consider late requests for attendance. INVITED TALKS Richard Kennaway (UEA Norwich, UK): (to be confirmed) Eelco Visser (U Utrecht, The Netherlands): A Survey of Strategies in Program Transformation Systems PANEL DISCUSSION on ``Hot Topics in Reduction Strategies'' with Michael Hanus U Kiel (Germany) Tetsuo Ida U Tsukuba (Japan) Paul Klint (to be confirmed) CWI & U Amsterdam (The Netherlands) PROGRAM COMMITTEE Maria Alpuente TU Valencia (Spain) Rachid Echahed IMAG Grenoble (France) Bernhard Gramlich (co-chair) TU Wien (Austria) Salvador Lucas (co-chair) TU Valencia (Spain) Vincent van Oostrom U Utrecht (The Netherlands) Rinus Plasmeijer KU Nijmegen (The Netherlands) Manfred Schmidt-Schauss U Frankfurt a.M. (Germany) Yoshihito Toyama U Tohoku (Japan) LOCAL ORGANIZATION Vincent van Oostrom U Utrecht (The Netherlands) IMPORTANT DATES Submission March 1, 2001 Notification March 31, 2001 Final version April 30, 2001 Workshop May 26, 2001 FURTHER INFORMATION workshop website http://www.logic.at/wrs01/ workshop email address wrs01(a)logic.at **************************************************************************

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PPDP 2001: Call for Papers (second call)
by Harald Sondergaard 17 Jan '01

17 Jan '01

(Apologies if you receive multiple copies of this announcement.) Third International Conference on PRINCIPLES AND PRACTICE OF DECLARATIVE PROGRAMMING Firenze, Italy, 5-7 September 2001 CALL FOR PAPERS PPDP 2001 aims to stimulate research on the use of declarative methods in programming and on the design, implementation and application of programming languages that support such methods. Topics of interest include any aspect related to understanding, integrating and extending programming paradigms such as those for functional, logic, constraint and object-oriented programming; concurrent extensions and mobile computing; type theory; support for modularity; use of logical methods in the design of program development tools; program analysis and verification; abstract interpretation; development of implementation methods; application of the relevant paradigms and associated methods in industry and education. This list is not exhaustive: submissions describing new and interesting ideas relating broadly to declarative programming are encouraged. The technical program of the conference will combine presentations of the accepted papers with invited talks and advanced tutorials. PPDP 2001 is part of a federation of colloquia known as Principles, Logics and Implementations of high-level programming languages (PLI 2001) which includes the ACM SIGPLAN International Conference on Functional Programming (ICFP 2001) and a large number of workshops devoted to aspects of programming languages. The colloquia will run from 2 to 8 September, 2001. The venue for the conference is Firenze (Florence), one of Europe's most attractive cities, famous for its churches, galleries and museums. More details can be found on the conference web site. Web Sites and Email Contact: PPDP 2001: http://music.dsi.unifi.it/pli01/ppdp PLI 2001: http://music.dsi.unifi.it/pli01 mailto:ppdp01@cs.mu.oz.au Important Dates: Submission 15 March 2001 Notification 7 May 2001 Final Version 11 June 2001 Conference Chair: Rocco De Nicola, Universita di Firenze http://www.dsi.unifi.it/~denicola/ mailto:denicola@dsi.unifi.it Program Chair: Harald Sondergaard, The University of Melbourne http://www.cs.mu.oz.au/~harald/ mailto:harald@cs.mu.oz.au Program Committee: Maria Alpuente, Univ. Politecnica de Valencia, ES Yves Caseau, Bouygues, FR Michael Codish, Ben-Gurion Univ. of the Negev, IL Saumya Debray, Univ. of Arizona, US Conal Elliott, Microsoft Research, US Sandro Etalle, Univ. Maastricht, NL Roberto Giacobazzi, Univ. di Verona, IT Michael Leuschel, Univ. of Southampton, GB John Lloyd, Australian National Univ., AU Torben Mogensen, Kobenhavns Univ., DK Alan Mycroft, Cambridge Univ., GB Gopalan Nadathur, Univ. of Minnesota, US Martin Odersky, Ecole Polyt. Fed. Lausanne, CH Catuscia Palamidessi, Penn State Univ., US Andreas Podelski, Max-Planck-Inst. Informatik, DE Kostis Sagonas, Uppsala Univ., SE Christian Schulte, Univ. des Saarlandes, DE Michael Schwartzbach, Aarhus Univ., DK Harald Sondergaard, Univ. of Melbourne, AU Peter J. Stuckey, Univ. of Melbourne, AU

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RE: Finding primes using a primes map with Haskell and Hugs98
by Simon Peyton-Jones 17 Jan '01

17 Jan '01

| Another way to do this is to compute the final array directly, | instead of computing successive versions of the array: | | import Array | primes n = [ i | i <- [2 ..n], not (primesMap ! i)] where | primesMap = accumArray (||) False (2,n) multList | multList = [(m,True) | j <- [2 .. n `div` 2], m <- | multiples j] | multiples j = takeWhile (n>=) [k*j | k <- [2..]] This style is definitely the way to go. Haskell does badly if you update an array one index at a time. Remember that arrays can be recursive. Here's a definition of Fibonacci for example; you can probably adapt it for primes fibs :: Int -> Array Int Int -- If a = fibs n, then a!i is fib(i), for i<=n. fibs n = a where a = array (1,n) ([(1,1),(2,1)] ++ [(i,a!(i-1) + a!(i-2) | i <- [3..n]]) -- Notice that a is recursive Simon

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Re: O'Haskell OOP Polymorphic Functions
by Ashley Yakeley 17 Jan '01

17 Jan '01

OK, I've figured it out. In this O'Haskell statement, > struct Derived < Base = > value :: Int ...Derived is not, in fact, a subtype of Base. Derived and Base are disjoint types, but an implicit map of type "Derived -> Base" has been defined. -- Ashley Yakeley, Seattle WA

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FME2001 Call for Participation
by Pamela Zave 17 Jan '01

17 Jan '01

To learn about Formal Methods Europe 2001, to be held in Berlin 12-16 March, please visit the symposium website at: www.informatik.hu-berlin.de/top/fme2001 Registration and hotel reservation are available on the website. The deadline for early registration is 9 February. Please register now so we can look forward to seeing you in Berlin!

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Research assistant positions in Bremen
by Till Mossakowski 17 Jan '01

17 Jan '01

The following two research assistant positions are available at the University of Bremen, Germany. The Bremen Institute of Safe Systems in the Center for Computing Technologies at the University of Bremen hosts the research projects "Multi-logic systems as a basis for heterogeneous specification and development" (MULTIPLE) and "Algebraic specification + functional programming = environment for formal software development" (HasCASL) funded by the Deutsche Forschungsgemeinschaft (DFG). Within the framework of each of these projects, one position in the working group of Prof. Dr. Krieg-Brückner is to be immediately filled for at least two years (additional option for another two years), subject to availability of funds: Research Assistant Verg. Gr. IIa BAT (full time) In addition to successful university studies in computer science, experience and skills in functional programming (e.g. Haskell, ML) are expected. Familiarity with at least one of formal specification methods (like CoFI/CASL), theorem proving or category theory is desirable. Applicants with a PhD are welcome. However, there will also be the oppurtunity to prepare a PhD thesis in connection with the research project. In case of essentially equal qualification in the subject and personal suitability, severely handicapped applicants will be preferred. The University of Bremen intends to increase the share of women in scientific activities and does therefore strongly encourage women to apply for these positions. More detailed information about the projects can be found under http://www.tzi.de/cofi/projects/multiple.html http://www.tzi.de/cofi/projects/hascasl.html Please address your application with the usual documents and the reference number A164/00 (MULTIPLE) resp. A165/00 (HasCASL) before 01.02.2001 to: UNIVERSITÄT BREMEN Prof. Dr. B. Krieg-Brückner Fachbereich 3 Postfach 33 04 40 28334 Bremen e-Mail: cofi(a)tzi.de -- Till Mossakowski Phone: +49-421-218-4683, monday: +49-4252-1859 Dept. of Computer Science Fax: +49-421-218-3054 University of Bremen EMail: till(a)tzi.de P.O.Box 330440, D-28334 Bremen WWW: http://www.tzi.de/~till

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