April 2002 - Haskell - Haskell.org

ObjectIO moved (was: Re: ANNOUNCE: Object I/O released)
by Krasimir Angelov 10 Apr '02

10 Apr '02

See http://www.haskell.org/ObjectIO __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax http://taxes.yahoo.com/

1 0

Fwd: Re: Doubt of`the book "The Haskell School of Expression", Paul Hudak
by Eray Ozkural 09 Apr '02

09 Apr '02

Where else should I forward your message so you don't do this again? Maybe your instructor is not too stupid to miss this mailing list so that you don't try plagiarism in front of the whole Internet? ---------- Forwarded Message ---------- Subject: Re: Doubt of`the book "The Haskell School of Expression", Paul Hudak Date: Tue, 09 Apr 2002 16:21:00 GMT From: "Euler" <emarinho(a)iceb.ufop.br> To: Eray Ozkural <erayo(a)cs.bilkent.edu.tr> Certainly! -- Eray Ozkural <erayo(a)cs.bilkent.edu.tr> Comp. Sci. Dept., Bilkent University, Ankara www: http://www.cs.bilkent.edu.tr/~erayo GPG public key fingerprint: 360C 852F 88B0 A745 F31B EA0F 7C07 AE16 874D 539C

1 0

CFP: CLIMA'02 - Computational Logic in Multi-Agent Systems
by Jo�o Alexandre Leite 09 Apr '02

09 Apr '02

[We apologize if you receive multiple copies of this message.] ****************************************************************** Second Call for Papers Computational Logic in Multi-Agent Systems (CLIMA'02) Copenhagen, Denmark August 1, 2002 http://centria.di.fct.unl.pt/~jleite/clima02/ Affiliated with FLOC'2002 and ICLP'2002 Submission Deadline: April 30th, 2002 ****************************************************************** Multi-agent systems (MAS) have become an increasingly important area of research, not least because of the advances in the Internet and Robotics. However multi-agent systems can become very complicated, and, consequently, reasoning about the behaviour of such systems can become extremely difficult. Therefore, it is important to be able to formalise multi-agent systems and, to do so in such a way that allows automated reasoning about agents' behaviour. The purpose of this workshop is to present techniques, based on computational logic (CL), for multi-agent systems in a formal way. In 1999, the ICLP'99 Workshop on Multi-Agent Systems in Logic Programming was held and constituted the first in this series. It was followed by CLIMA'00 at CL2000 and CLIMA'01 at ICLP'01. In 2000, we announced a special issue of the Annals of Math and AI and we especially invited all accepted papers of CLIMA'00 for submission to this issue. We got over 20 submissions and the issue will appear early in 2002. We are planning to continue this series of workshops in the following years in order to foster interaction between the multi-agent and the computational logic communities. We solicit unpublished papers that address formal approaches to multi-agent systems. The approaches as well as being formal must make a significant contribution to the practice of multi-agent systems. Relevant techniques include the following: * Non-monotonic reasoning in multi-agent systems * Planning under incomplete information in multi-agent systems * Usage of abduction in multi-agent systems * Representation of knowledge and belief in multi-agent systems * Temporal reasoning for multi-agent systems * Theory of argumentation for multi-agent negotiation and co-operation * Communication languages for multi-agent systems * Distributed constraint satisfaction in multi-agent systems * Decision theory for multi-agents * Distributed theorem proving for multi-agent systems ------------------------------ SUBMISSION INSTRUCTIONS ------------------------------ Papers should be written in English, unpublished, and not simultaneously submitted for publication elsewhere. Papers should be formatted according to the Springer LNCS style and not exceed 12 pages including figures, references, etc. Please send your paper in PostScript (PS) or Portable Document Format (PDF) file format to jleite(a)di.fct.unl.pt. ------------------------------ IMPORTANT DATES ------------------------------ * Submission: April 30th, 2002 * Notification of Acceptance: May 31st, 2002 * Final version due: June 20th, 2002 * CLIMA'02: August 1st, 2002 ------------------------------ PROCEEDINGS ------------------------------ Informal workshop proceedings will be available. As in 2000, we are planning to have a special issue of the Annals of Math and AI on "Computational Logic and Multi-Agency". Authors of the best CLIMA'02 papers will be invited to submit extended drafts for the special issue as a part of the volume. Further details can be found at http://centria.di.fct.unl.pt/~jleite/amai03/. ------------------------------ PROGRAM COMMITTEE ------------------------------ * Thomas Eiter, Vienna University of Technology, Austria * Klaus Fischer, DFKI, Germany * Michael Fisher, University of Liverpool, UK * James Harland, Royal Melbourne Institute of Technology, Australia * Wiebe van der Hoek, Utrecht University, The Netherlands * Katsumi Inoue, Kobe University, Japan * Luís Moniz Pereira, New University of Lisbon, Portugal * V.S. Subrahmanian, University of Maryland, USA * Francesca Toni, Imperial College, UK * Paolo Torroni, University of Bologna, Italy ------------------------------ WORKSHOP ORGANIZERS: ------------------------------ * Jürgen Dix The University of Manchester UK dix(a)cs.man.ac.uk * João Alexandre Leite New University of Lisbon Portugal jleite(a)di.fct.unl.pt * Ken Satoh National Institute of Informatics, Japan ksatoh(a)nii.ac.jp ------------------------------ INQUIRIES: ------------------------------ Please send program suggestions and inquires to either of the organizers.

1 0

Re: Doubt of`the book "The Haskell School of Expression", Paul Hudak
by Euler 09 Apr '02

09 Apr '02

I´m a student of Computer Science of Federal University of Ouro Preto, Minas Gerais, Brazil. I need contact anybody which study the book "The Haskell School of Expression Paul Hudak" and implements the examples of chapter 15. Please, Help me. Euler Horta Marinho

2 1

RE: ANNOUNCE: Object I/O released
by Peter Achten 09 Apr '02

09 Apr '02

Hello Krasimir, I am very curious about your implementation of the Object I/O system, but unfortunately could not open the .zip files either (same symptoms as Arjan van IJzendoorn wrote). Could you check the formats of these files? Thanks in advance. Simon Peyton-Jones wrote: >Krasimir > >| The version that I release is based entirely on LS >| version. I think that it is more elegant and more >| useful for customer. > >I'm delighted and impressed that you have completed the Object I/O >port, but I don't think I agree with you about the MVar/LS issue. > > A note to other readers: the issue is whether it is better, from > the programmer's point of view, to use MVars to manipulate > state, or to use the state parameterisation that Clean uses. > This issue is discussed in the paper by Peter Achten and mself > http://research.microsoft.com/~simonpj/Papers/haskellobjectio.htm > >My defence of the MVar approach is not because I simply >think that MVars are best for everything! >It's because I have really struggled to understand the types in the >Clean I/O system, and they become *so* much simpler when the >state parameterisation is left out. And if I struggle, then I fear that >novice programmers may be in real difficulty. > >I think that even Peter Achten thought this too, having done it both >ways (but I should let him speak for himself). This issue was one of the key design issues Simon and I had to resolve when porting the Clean Object I/O system to Haskell. The arguments in the above mentioned paper are still valid. Briefly, one can summarise them as: MVar-s offer many significant advantages (simpler types, simpler implementation, more expressive power, programming style similar to handling of identifier values) but have one disadvantage (state management is done by the programmer). As it happens, I am about to spend a couple of weeks (re)designing/implementing/bug-fixing the Object I/O library, and this issue is high on my priority list. I think this is a delicate design decision that should be taken with care, as it has impact on all existing programs and all implementations :-). Regards, Peter Additional remarks to those of Simon: >To respond to your points: > >| 1) In the MVAR version each event handler must like >| this: >| >| eventHandler state = do >| st <- takeMVar state >| ... >| ... >| putMVAR state st' >| >| In LS version there isn't need of takeMVar/putMVAR and >| the handler is more easy. But the reverse case is also true: in the LS version, an event handler must modify local state. So a function that is really not interested in the local state is either polymorphic in the local state or uses the local state lifting function (noLS and noLS1). In the MVAR version one wouldn't be bothered with this. >| >| 2) In MVAR version the event handlers in the device >| definitions must be defined as curry functions >| >| Example MVAR: >| state <- newMVAR (0::Int) >| openWindow (Window NilLS [WindowClose (closeWin >| state)]) >| >| Example LS: >| openWindow (0::Int) (Window NilLS [WindowClose >| closeWin]) > >Both are true, but you can easily wrap up the state passing >if that is what you want: > > state <- newMVAR (0::Int) > openWindow (Window NilLS [WindowClose (handle state closeWin)]) > > handle :: MVar a -> (a -> IO a) -> IO () > handle m t = do { s <- getMVar m; r <- t s'; putMVar m s' } > >Now you can write closeWin :: WinState -> IO WinState >if you want. > >Of course the reference to the state is still explicit, but I do not >think that is a bad thing. It tells you where that MVar can be modified >(and where it can't!). There might be two pieces of state for one >component, >one modified by one set of events and one by another, and it would be >nice >to make that apparent. > > >| 3) Modification of local state doesn't mean >| modification of device behaviour. The behaviour of the >| device is described with both local state and internal >| device data. This means that direct access to the >| state isn't a good idea. In the LS version the local >| state is encapsulated in the device and I think that >| this is more OOP style. > >I don't understand this; you can encapsulate the MVars too, in just >the same way: > >windowDevice = do { s <- newMVar 0; > openWindow ... } > >No caller of WindowDevice can see the encapsulated MVar. The main point of 'LS advocates' is that encapsulation is guaranteed by construction, while it is a program property in the MVAR system. This is of course a GOOD thing. However, this characteristic of LS is also its weakness: one simply can't (partially) share local state between GUI components of different top-level parents (except of course on the highest level within the interactive process) even though in practice this would make a lot of sense. One also can't easily modify event handlers once a GUI structure has been created, even if one would `know' the proper local state type because of the strong encapsulation (you can do it, but this requires quite some overhead, using typed message passing). In short, we have the following: MVAR subsumes LS (we can write more programs), but the price to pay is at least: less static error checking and more proof obligations wrt. locality of state. Perhaps there is an interesting alternative that covers all GOOD points and has fewer BAD points.

4 6

Re: deriving over renamed types
by Ashley Yakeley 09 Apr '02

09 Apr '02

At 2002-04-08 12:45, Lennart Augustsson wrote: >I just just wanted to say that I agree with almost everything Conor said. >I find it a little odd that the extension to Haskell that allows explicit >forall >does not also allow you use explicit type application (and type lanbda). What did you have in mind? data Zero; data Succ n; type Add Zero b = b; type Add (Succ a) b = Succ (Add a b); type Mult Zero b = Zero; type Mult (Succ a) b = Add b (Mult a b); type Fact Zero = Zero; type Fact (Succ n) = Mult (Succ n) (Fact n); data Foo f = MkFoo (f ()); type Succ' = Succ; type Succ'' n = Succ n; -- which of these types are the same? f1 = MkFoo undefined :: Foo Succ; f2 = MkFoo undefined :: Foo Succ'; f3 = MkFoo undefined :: Foo Succ''; f4 = MkFoo undefined :: (Add (Succ Zero)); -- Ashley Yakeley, Seattle WA

4 3

docon-2.04 announcement
by Serge D. Mechveliani 09 Apr '02

09 Apr '02

Announcement ------------ The Algebraic Domain Constructor DoCon-2.04, a computer algebra program written in Haskell, is available at http://www.botik.ru/pub/local/Mechveliani/docon/2.04/ ftp.botik.ru/pub/local/Mechveliani/docon/2.04/ What is new ----------- * Performancec tests for comparison to popular Axiom and MuPAD computer algebra programs (`strict' and non-functional systems) are refreshed and extended (see manual.ps); * DoCon was tested under the releases of ghc-5.02.2, 5.02.3; * Manual has become more readable, and it is in Postscript format; * Manual explains the relation of DoCon to Aldor language and Axiom system. DoCon-2.04 is a program package written in what we call Haskell-2-pre - certain functional extension of Haskell-98. Haskell-2-pre includes the multiparametric classes, overlapping instances, other minor features. DoCon-2.04 was tested under ghc-5.02.2, 5.02.3. Probably, it can be ported (with some effort) to other implementations. ----------------- Serge Mechveliani mechvel(a)botik.ru

1 0

Call for papers: CLPSE'02
by Dr. Gopal Gupta 08 Apr '02

08 Apr '02

CALL FOR PAPERS!! CALL FOR PAPERS!! CLPSE'02: (Constraint) Logic Programming and Software Engineering '02 http://www.utdallas.edu/~gupta/clpse July 28, 2002 COPENHAGEN, DENMARK In Conjunction with Eighteenth International Conference on Logic Programming (Part of FLOC'02) http://floc02.diku.dk/ICLP/ The aim of this workshop is to explore applications of logic programming and constraint programming to the process of constructing reliable software and to programming-in-the-large. Papers and experience reports describing use of LP and CP techniques to various aspects of the software engineering process are invited. The workshop will be held on Saturday, July 28, 2002, in conjunction with 18th International Conference on Logic Programming in Copenhagen, Denmark (held Jul 29 - Aug 1) and is a continuation of the successful CLPSE'00 workshop held during CL2000 in London, England, in July 2000 (http://www.cs.nmsu.edu/~gupta/lpse2000) and CLPSE'01 workshop held during ICLP'01 in Paphos, Cyprus (http://www.cs.utdallas.edu/~gupta/clpse/clpse01.html) Topics of interest include (but are not limited to): o Rapid prototopying and System Modeling o Software Design Methodologies o Software Specification o Domain Specific Languages o Derivation of Efficient Implementations from Specifications o Automatic Software Generation o Testing and Debugging o Test Case Generation o Software Verification o Software Process Discovery o Software Reuse o Analysis of Software Systems/Software Process o Software Quality Assurance o Requirements Analysis o Security Issues Paper Submission deadline: May 31, 2002 Notification of acceptance/rejection: June 7th, 2002 Submission procedure: Electronically submit a postscript, pdf, or a word file to gupta(a)utdallas.edu. Papers should be a maximum of 15 pages. Proceedings will be made available during the workshop. Organizers: Gopal Gupta, University of Texas, Dallas, USA Kung-Ku Lau, Manchester University , UK Isidros Ramos, Universidad Politecnica de Valencia, Spain Roel Wuyts, University of Berne, Switzerland

1 0

Re: deriving over renamed types
by Ashley Yakeley 08 Apr '02

08 Apr '02

At 2002-04-04 05:57, C T McBride wrote: >> ...which would be very useful, but would probably have unpleasant >> consequences for type inference... > >To my mind, this is not a credible objection. The horse has already >bolted; there's no point in trying to shut the stable door. Perhaps I should say "type decidability". Currently Haskell can always calculate whether one type-constructor is a substitution-instance of another, and therefore whether two type-constructors are the same. This may not be possible if you have full type lambdas, as in general there is no way of calculating whether two functions are the same. -- Ashley Yakeley, Seattle WA

3 2

SAVE02 call for papers
by Sandro.Etalle＠cwi.nl 08 Apr '02

08 Apr '02

FloC 2002 workshop SAVE 2002 Workshop on Specification, Analysis and Validation for Emerging Technologies Copenhagen , Denmark, July 27, 2002 CALL FOR PAPERS SUBMISSION DEADLINE: APRIL 27, 2002 ^^^^^^^^^^^^^^ TOPICS * Specification languages and rapid prototyping: * Logic programming and its extensions * First-order, constructive, modal and temporal logic * Constraints * Type theory * Analysis: * Abstract interpretation * Program analysis and transformation * Validation: * Simulation and testing * Deductive methods * Model checking * Theorem proving The preferred issues include, but are not limited to: * Mobility: specification and verification of mobile code. * Security: e.g. specification and verification of security protocols. * Interaction, coordination, negotiation, communication and exchange on the Web. * Open and Parametrized Systems. PUBLICATION The proceedings of the workshop will be published as technical report. We are planning a journal special issue: a selection of the workshop papers will be invited for submitting a full version to it. MOTIVATIONS AND GOALS The huge increase in interconnectivity we have witnessed in the last decade has boosted the development of systems which are often large-scale, distributed, time-critical, and possibly acting in an unreliable or malicious environment. Furthermore, software and hardware components are often mobile, and have to interact with a potentially arbitrary number of other entities. These systems require solid formal techniques for their verification and analysis. In this respect, computational logic plays an increasingly important role, both providing formal methods for proving system's correctness and tools - e.g. using techniques like constraint programming and theorem proving - for verifying their properties. In addition, computational logic is gaining importance as tool for the specification of these systems. For instance, one can think at the specification, in a form of temporal logic, of a communication protocol. Such specification offers the advantage that one can reason about it using formal methods, and at the same time it is often easily executable by rewriting it into a logic-based programming language. The first edition of SAVE 2001 took place as a one-day satellite event of ICLP/CP 2001 in Paphos, Cyprus. The technical program consisted of an invited talk and seven paper presentations covering problems related to security, real time systems, simulation and performance evaluation, and general purpose verification techniques (all papers are available on line in the here). The aim of this new edition is to bring together researchers interested in the use of computational logic as a tool for the specification, analysis and validation of systems, with particular emphasis on (but not restricted to) emerging technologies like World Wide Web and e-commerce, (protocols for) smart cards and mobile telephony, wireless technology, control and real-time systems, open and distributed systems. IMPORTANT DATES * Deadline for submissions: April 27, 2002 * Notification: May 27, 2002 * Final papers due: June 24, 2002 * Workshop date: July 27, 2002 PROGRAM COMMITTEE Alessandro Armando DIST, University of Genova, Italy Radhia Cousot, Ecole Polytecnique, France Thierry Massart, U. Libre de Brussels, Belgium Catuscia Palamidessi, Penn State University, USA Frank Pfenning, Carnegie Mellon University, USA Andreas Podelski Max-Planck-Institut, Germany Sriram Rajamani, Microsoft Research, USA Jean-Francois Raskin, U. Libre Brussels, Belgium INSTRUCTION FOR AUTHORS Please send your submission as a (uuencoded, gzipped, if possible) Postscript or PDF file to: giorgio(a)disi.unige.it The paper must not exceed 15 pages, and must contain a cover page with: title, name and addresses of the authors, abstract and keywords. Please prepare the manuscript using LaTex article style, single column, 12.2cm x 19.3cm text area. The proceedings will be published in electronic format. A printed version will be distributed to all participants of the workshop. WORKSHOP ORGANISERS/PC CHAIRS * Giorgio Delzanno - Dipartimento di Informatica e Scienze * dell'Informazione - Universita' di Genova. e-mail: giorgio(a)disi.unige.it * Sandro Etalle - Department of Computer Science- University of Twente and CWI. e-mail: etalle(a)cwi.nl * Maurizio Gabbrielli - University of Bologna, Italy e-mail: gabbri(a)cs.unibo.it

1 0