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Re: The madness of implicit parameters: cured?
by Ashley Yakeley 05 Aug '03

05 Aug '03

At 2003-08-03 14:09, Ben Rudiak-Gould wrote: >This reduction is incorrect. Auto-lifted parameters on the RHS of an >application get lifted out I am interpreting this as "Auto-lifted parameters on the RHS of an application get lifted out before {@x=y}-style 'beta'-reduction can be done". I think this is ambiguous: ((\a -> ((a,?x) {@x = 2})) ?x,?x) {@x = 1} ((\a -> ((a,\@x -> @x) {@x = 2})) (\@x -> @x),\@x -> @x) {@x = 1} 1. ((\@x -> @x,\@x -> @x) {@x = 2},\@x -> @x) {@x = 1} ((\@x -> (@x,@x)) {@x = 2},\@x -> @x) {@x = 1} ((2,2),\@x -> @x) {@x = 1} (\@x -> ((2,2),@x)) {@x = 1} ((2,2),1) 2. (\@x -> ((\a -> ((a,\@x -> @x) {@x = 2})) @x,@x)) {@x = 1} ((\a -> ((a,\@x -> @x) {@x = 2})) 1,1) (((1,\@x -> @x) {@x = 2}),1) (((\@x -> (1,@x)) {@x = 2}),1) ((1,2),1) A simpler query: what types can f have here? Which if any should the compiler infer? f a b = (a,b) {@x = 2} And given that type, which of these are valid? f ?x ?x f ?x 1 f 1 ?x f 1 1 -- Ashley Yakeley, Seattle WA

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haskell for educative games
by Andre W B Furtado 04 Aug '03

04 Aug '03

Does anyone know if Haskell is/was used to develop educative games? Do you recommend some papers on the subject? Thanks a lot, -- Andre Furtado

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ANNOUNCE: GHC version 6.0.1
by Simon Marlow 04 Aug '03

04 Aug '03

============================================================= The (Interactive) Glasgow Haskell Compiler -- version 6.0.1 ============================================================= We are pleased to announce a new patchlevel release of the Glasgow Haskell Compiler (GHC), version 6.0.1. This is a bug-fix release relative to 6.0. The most important bugfixes are: * Fixes to make GHC work with GCC 3.3 * Fix for the "GHC deletes source files" bug * :cd now unloads any loaded modules in GHCi. * -mk-dll should work better on Windows. in addition to various other bugfixes. The release notes lists the changes in the 6.0 line relative to 5.04: http://www.haskell.org/ghc/docs/latest/html/users_guide/release-6-0.html How to get it ~~~~~~~~~~~~~ The easy way is to go to the WWW page, which should be self-explanatory: http://www.haskell.org/ghc/ We supply binary builds in the native package format for various flavours of Linux and BSD, and in Windows Installer (MSI) form for Windows folks. Binary builds for other platforms are available as a .tar.gz which can be installed wherever you want. The source distribution is also available from the same place. Packages will appear as they are built - if the package for your system isn't available yet, please try again later. Background ~~~~~~~~~~ Haskell is a standard lazy functional programming language; the current language version is Haskell 98, agreed in December 1998, and revised in December 2002. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license. A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page (see below). On-line GHC-related resources ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Relevant URLs on the World-Wide Web: GHC home page http://www.haskell.org/ghc/ Haskell home page http://www.haskell.org/ comp.lang.functional FAQ http://www.cs.nott.ac.uk/~gmh/faq.html System requirements ~~~~~~~~~~~~~~~~~~~ To compile programs with GHC, you need a machine with 64+MB memory, GCC and perl. This release is known to work on the following platforms: * i386-unknown-{linux,*bsd,mingw32} * sparc-sun-solaris2 * alpha-dec-osf3 * powerpc-apple-darwin (Mac OS X) Ports to the following platforms should be relatively easy (for a wunderhacker), but haven't been tested due to lack of time/hardware: * hppa1.1-hp-hpux{9,10} * i386-unknown-solaris2 * mips-sgi-irix{5,6} * {rs6000,powerpc}-ibm-aix The builder's guide on the web site gives a complete run-down of what ports work; it can be found at http://www.haskell.org/ghc/docs/latest/html/building/building-guide.html Mailing lists ~~~~~~~~~~~~~ We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at http://www.haskell.org/mailman/listinfo/glasgow-haskell-users http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see http://www.haskell.org/mailman/listinfo/ Please report bugs using our SourceForge page at http://sourceforge.net/projects/ghc/ or send them to glasgow-haskell-bugs(a)haskell.org. GHC users hang out on glasgow-haskell-users(a)haskell.org. Bleeding edge CVS users party on cvs-ghc(a)haskell.org.

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Re: The madness of implicit parameters: cured?
by Ashley Yakeley 04 Aug '03

04 Aug '03

At 2003-08-03 14:09, Ben Rudiak-Gould wrote: >> ((let g = \_ _ -> \@x -> @x in ((g (\@x -> @x)) {@x = 2})) (\@x -> >> @x)){@x = 1} >> ((let g = \_ _ -> \@x -> @x in (g 2)) (\@x -> @x)){@x = 1} > >This reduction is incorrect. Auto-lifted parameters on the RHS of an >application get lifted out, so > > g (\@x -> @x) => (\@x -> g { @x = @x } @x) Hmm... I assume you mean specifically this: g (\@x -> @x) \@x -> (g { @x = @x } @x) Supposing you have this: g = \_ -> 3 then you have this reduction: g ?x g (\@x -> @x) \@x -> (g { @x = @x } @x) \@x -> ((\_ -> 3) { @x = @x } @x) error: can't apply (\_ -> 3) { @x = @x } Something else I haven't mentioned is that you shouldn't use (->) as such in the type signatures. This is because (->) is an ordinary type-constructor. For instance, if you define this: type Func = (->) then all these are the same type: Func a b (->) a b a -> b But in your scheme, (->) has been extended to allow certain pseudo-types in its first position. It might be better to use a different syntax rather than overload (->) with something that isn't a type-constructor. -- Ashley Yakeley, Seattle WA

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ANN: H98 FFI Addendum 1.0, Release Candidate 12
by Manuel M T Chakravarty 04 Aug '03

04 Aug '03

Dear Haskell Folks, Release Candidate 12 of the H98 FFI Addendum 1.0 is now available from http://www.cse.unsw.edu.au/~chak/haskell/ffi/ Since the release of RC 11 (12 June), there was only one small change (which was already under discussion before RC 11 was published). Hence, I consider Version 1.0 of the FFI Addendum to be completed; no changes except linguistic ones and plain error corrections will be accepted anymore for this version. Cheers, Manuel -=- Changes since RC11: * 5.5: Swapped argument order of `newForeignPtr' and `addForeignPtrFinalizer' Note to FFI people, there were at least three votes (Alastair, Sven, and me) for this change and none against.

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CFP: CLIMA IV - 4th Intl. Workshop on Computational Logic in Multi-Agent Systems
by João Alexandre Leite 03 Aug '03

03 Aug '03

========================================================================== SECOND CALL FOR PAPERS CLIMA IV Fourth International Workshop on Computational Logic in Multi-Agent Systems January 6-7, 2004, Fort Lauderdale, Florida, USA http://centria.di.fct.unl.pt/~jleite/climaIV/index.htm Post-Proceedings will be published in Springer Verlag LNAI Submission Deadline: September 19th Co-located with the 7th LPNMR and the 8th AIMATH =========================================================================== Over recent years, the notion of agency has claimed a major role in defining the trends of modern research. Influencing a broad spectrum of disciplines such as Sociology, Psychology, Philosophy and many more, the agent paradigm virtually invaded every sub-field of Computer Science, not least because of the Internet and Robotics. Multi-agent Systems (MAS) are communities of problem-solving entities that can perceive and act upon their environments to achieve their individual goals as well as joint goals. The work on such systems integrates many technologies and concepts in artificial intelligence and other areas of computing. There is a full spectrum of MAS applications that have been and are being developed; from search engines, educational aids to electronic commerce and trade. Although commonly implemented by means of imperative languages, mainly for reasons of efficiency, the agent concept has recently increased its influence in the research and development of computational logic based systems. Computational Logic, by virtue of its nature both in substance and method, provides a well-defined, general, and rigorous framework for systematically studying computation, be it syntax, semantics, procedures, or implementations, environments, tools, and standards. The purpose of this workshop is to discuss techniques, based on computational logic, for representing, programming and reasoning about multi-agent systems in a formal way. This is clearly a major challenge for computational logic, to deal with real world issues and applications. Following the workshop on Multi-Agent Systems in Logic Programming affiliated with ICLP'99, the first CLIMA workshop took place in London, UK, affiliated with CL'2000. The 2001 edition of CLIMA, took place in Paphos, Cyprus, affiliated with ICLP'01. CLIMA'02 took place in Copenhagen, Denmark, and was affiliated with ICLP'02 and part of FLOC'02. We solicit unpublished papers that address formal approaches to multi-agent systems. The approaches as well asbeing formal must make a significant contribution to the practice of multi-agent systems. Relevant techniques include, but are not limited to, the following: * Nonmonotonic reasoning in MAS * Planning under incomplete information in MAS * Logical foundations of MAS * Usage of abduction in MAS * Representation of knowledge and belief in MAS * Knowledge and belief updates in MAS * Temporal reasoning for MAS * Theory of argumentation for MAS * Negotiation and co-operation for MAS * Communication languages for MAS * Distributed constraint satisfaction in MAS * Modal logic approaches to MAS * Logic based programming languages for MAS * Distributed theorem proving for MAS * Logic based implementations of MAS * Decision theory for MAS * Logic based agents for the Internet SUBMISSION INSTRUCTIONS We welcome and encourage the submission of high quality, original papers, which are not simultaneously submitted for publication elsewhere. Please refer to the workshop web pages for further instructions concerning the submission procedures. IMPORTANT DATES * Submission: September 19th, 2003 * Notification of Acceptance: October 17th, 2003 * Final version due: November 13th, 2003 * CLIMA IV: January 6-7th, 2004 PROCEEDINGS Post-proceedings will be published by Springer-Verlag as a volume of the Lecture Notes on Artificial Intelligence (LNAI) series. Informal proceedings will be available at the workshop and online. PROGRAM COMMITTEE * Chitta Baral, Arizona State University, USA * Gerd Brewka, University of Leipzig, Germany * Jürgen Dix, The University of Manchester, UK * Thomas Eiter, Vienna University of Technology, Austria * Klaus Fischer, DFKI, Germany * Michael Fisher, University of Liverpool, UK * James Harland, Royal Melbourne Inst. of Tech., Australia * Katsumi Inoue, Kobe University, Japan * Gerhard Lakemeyer, Aachen Univ. of Technology, Germany * João Leite, New University of Lisbon, Portugal * Yves Lespérance, York University, Canada * John Jules Ch. Meyer, Univ. of Utrecht, The Netherlands * Leora Morgenstern, IBM, USA * Luís Moniz Pereira, New University of Lisbon, Portugal * Fariba Sadri, Imperial College, UK * Ken Satoh, National Institute of Informatics, Japan * Renate Schmidt, The University of Manchester, UK * Guillermo Simari, Universidad Nacional del Sur, Argentina * V. S. Subrahmanian, University of Maryland, USA * Francesca Toni, Imperial College, UK * Paolo Torroni, University of Bologna, Italy * Wiebe van der Hoek, University of Liverpool, UK * Cees Witteveen, Delft Univ. of Tech., The Netherlands WORKSHOP ORGANIZERS: * Jürgen Dix, The University of Manchester, UK (dix(a)cs.man.ac.uk) * João Leite, New University of Lisbon, Portugal (jleite(a)di.fct.unl.pt) INQUIRIES: Please send program suggestions and inquires to either of the organizers.

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Laziness
by Dominic Steinitz 02 Aug '03

02 Aug '03

Could someone explain to me why this doesn't work test l = hs where hs = map (\x -> [x]) [0..abs(l `div` hLen)] hLen = length $ head hs whereas this does test l = hs where hs = map (\x -> [x]) (0:[1..abs(l `div` hLen)]) hLen = length $ head hs I would have thought laziness would allow the compiler to know that hs would contain at least one element and therefore calculate hLen. Dominic.

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Haskell for educative games
by Andre W B Furtado 02 Aug '03

02 Aug '03

Does anyone know if Haskell is/was used to develop educative games? Do you recommend some papers on the subject? Thanks a lot, -- Andre Furtado

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Re: Libraries and hierarchies
by John Meacham 01 Aug '03

01 Aug '03

confluence! Inspired by some posts the other day I implemented an immutable GUID naming scheme for interfaces with Haskell. I thought it would require compiler support, but it turns out a good 90% solution can be done as a separate program quite nicely and there are not too tough workarounds for the other 10%. http://repetae.net/john/computer/haskell/hsguid/ This is not really the same as your proposal, but is somewhat related and addresses many of the same issues. (and might be a bit lighter weight) actually, they would probably mix well as your proposed system could just use the same GUID pragmas hsguid uses as input. Let me know what y'all think. library developers, add a GUID to your code. it's easy and takes no resources, but could save users of your library a lot of hassle. :) John -- --------------------------------------------------------------------------- John Meacham - California Institute of Technology, Alum. - john(a)foo.net ---------------------------------------------------------------------------

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CSMR 2004 - CALL FOR PAPERS
by csmr2004＠unisannio.it 01 Aug '03

01 Aug '03

8th European Conference on Software Maintenance and Reengineering March 24 - 26, 2004 Tampere, Finland Call for Papers The European Conference on Software Maintenance is the premier European conference on the theory and practice of evolution, maintenance and reengineering of software systems. Now approaching its eight edition, we invite you to contribute to the discussion on the issues of developing maintainable systems and evolving, migrating and reengineering existing ones. The theme of this year's conference will be "the maintenance and evolution of the software architecture". Although nowadays the importance of designing a robust software architecture is well-understood by the industry, the activities related to its maintenance and evolution are rather immature and unsystematic. We solicit contributions on this theme. The topics of interest include, but are not restricted to: Evolution, maintenance and reengineering Software architecture recovery and evolution Automated software maintenance Software metrics Economical aspects of software evolution Pattern languages for evolution, maintenance and reengineering Experience reports (successes and failures) Tools and enabling technologies for evolution, maintenance and reengineering tools Formal methods to support evolution, maintenance and reengineering System assessment for evolution, maintenance and reengineering Migration, wrapping and interfacing legacy systems Dealing with legacy systems towards new technologies Data reengineering Reverse engineering of embedded systems Web-site evolution, maintenance and reengineering Migration towards Web-services Evaluation and assessment of reverse engineering tools Maintenance of open source projects Product family migration and maintenance One of the basic intentions of this conference is to offer a European forum for discussion and exchange of experiences among researchers and practitioners. Therefore, besides academics, we kindly invite all those in companies developing maintenance tools, offering reengineering services or going through legacy systems migration experiences to contribute by submitting papers or presenting innovative tools, solutions or experience reports. This conference is not limited to European participants. Authors from outside Europe are also welcomed. SUBMISSIONS Two types of submissions will be accepted: full length papers (not exceeding 4000 words in length and including a 150-200 word abstract) and short papers (not exceeding 2000 words in length and including a 75-100 word abstract) The official langue is Enligh. Authors are requested to submit electronically a PostScript or PDF version of their papers. In addition, they should send a separate file containing the title of the paper, full names, affiliations, postal and e-mail addresses, fax and telephone numbers of all authors. IEEE Computer Society Press will publish the CSMR 2004 Proceedings. Full papers exceeding 10 pages (4 pages for short papers) will be charged for pages in excess. Authors of accepted papers must sign the IEEE copyright form. At least one author of each accepted submission must register and present the paper at the conference. The Program Committee will select the best paper of the conference and a prize will be awarded for the winner. The Program Committee will select the winner and a formal presentation of the winner will be made in Tampere at CSMR 2004. SPECIAL SESSIONS Sessions of special interest, workshops, and tool demonstrations are welcomed. Please send suggestions to the program chair before the submissions closing date. SUBMISSION METHOD For submission details please visit the conference website: http://www.cs.tut.fi/~csmr2004/. Papers can also be submitted via email to the program chair. FINAL FORMAT OF PAPERS Accepted papers must be revised to conform with IEEE style guidelines at http://www.computer.org/cspress/instruct.htm.

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