February 2005 - Haskell

Installation with yum.
by Manoj Kummini 16 Feb '05

16 Feb '05

Hi. I am trying to install haskell on FC3 following the instructions from http://www.haskell.org/fedora/ I copied the lines: root@blandings ~# cat /etc/yum.repos.d/haskell.repo [haskell-stable] name=Haskell Packages (stable) baseurl=http://haskell.org/fedora/haskell/$releasever/$basearch/RPMS.stable gpgcheck=1 installdir=/opt root@blandings ~# When I try to install it, nothing happens, and I get the following message: root@blandings ~# yum install haskell-stable Setting up Install Process Setting up Repo: base repomd.xml 100% |=========================| 1.1 kB 00:00 Setting up Repo: haskell-stable repomd.xml 100% |=========================| 951 B 00:00 Setting up Repo: updates-released repomd.xml 100% |=========================| 951 B 00:00 Reading repository metadata in from local files base : ################################################## 2622/2622 haskell-st: ################################################## 53/53 primary.xml.gz 100% |=========================| 292 kB 03:02 MD Read : ################################################## 684/684 updates-re: ################################################## 684/684 No Match for argument haskell-stable Nothing to do root@blandings ~# I am new to yum, and could not find much help on the web for using this. Could someone tell me what I am missing or point to a URL? Thanks Manoj. -- Manoj Kummini Graduate Student, Dept. of Mathematics, The Univ. of Kansas, Lawrence KS 66045 USA. 38 deg 55 min N, 95 deg 14 min W. http://www.math.ku.edu/~kummini/index.html

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Writer monad
by Emil Axelsson 16 Feb '05

16 Feb '05

Hello, I have a huge space leak in a program due to laziness in the writer monad. Now when I'm trying to examine the behaviour of writer I get a bit puzzled by the following program: foo :: MonadWriter [Int] m => Int -> m () foo n = do tell [n] foo $ n+1 test = (snd $ runWriter $ foo 0) !! 3 testT = (snd $ runIdentity $ runWriterT $ foo 0) !! 3 I would expect both test and testT to terminate with the value 3, due to the laziness that caused me problems. But here is the actual run results: Ok, modules loaded: Main. *Main> test 3 *Main> testT *** Exception: stack overflow *Main> Could someone please explain this to me? / Emil

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[Newbie] Data structure for Dijkstra's algorithm
by RCP-Software 14 Feb '05

14 Feb '05

Hi! I am new to functional Programming and need some advice. I want to implement Dijkstra's algorithm for the shortest path problem. The algorithm calculates the shortest path from a single vertex in a directed graph to any other connected vertex ( http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm ). For input and output I need an appropriate graph representation. It should be as simple to implement as possible - speed and memory consumption does not matter. The graph consists of vertices (including the source vertex) and weighted edges. I first thought of an adjacency matrix implemented with nested lists. Something like [[0,1,6,2] , [1,0,2,infinity] , [6,2,0,3] , [2,infinity,3,0]] where every sublist represents a vertex, and every entry represents the edge weight to another vertex (infinity means there is no direct connection, and 0 means it points to itself). My main problem is that this adjacency list is not so easy to process. For my output I need a tree like structure and I always need to keep track of the previous vertex and its distance etc. Other approaches e.g. structure-like tuples didn't really work - my C experience is worthless. Bottom line - I don't what to do. Any help is appreciated. TIA, Robert Potthast

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Re: help with some basic code that doesn't work
by Shin-Cheng Mu 14 Feb '05

14 Feb '05

Malcolm Wallace <Malcolm.Wallace(a)cs.york.ac.uk> wrote: > Just a comment, since a couple of people have made similar statements. > Haskell will derive Eq for arbitrarily complex types - there is no > restriction to "simple" types, whatever they might be. Now that this topic is brought up... Occasionally I would need to define recursive datatypes using an explicit fixed-point operator, such as: > data Fix f = In (f (Fix f)) deriving (Show, Eq) > data L a x = Nil | Cons a x deriving (Show, Eq) However, Haskell was not able to derive from Fix f any instances. The following is what happens in GHCi: *Main> In Nil == In Nil Context reduction stack overflow; size = 21 Use -fcontext-stack20 to increase stack size to (e.g.) 20 `Eq (L e (Fix (L e)))' arising from use of `==' at <interactive>:1 `Eq (Fix (L e))' arising from use of `==' at <interactive>:1 <<deleted>> *Main> In Nil Context reduction stack overflow; size = 21 Use -fcontext-stack20 to increase stack size to (e.g.) 20 `Show (L e (Fix (L e)))' arising from use of `print' at <interactive>:1 <<deleted>> Probably Malcolm meant that Haskell will derive standard instances for arbitrarily complex type **if they are definable manually**. If so Malcolm's statement is true -- indeed I cannot even declare the instances by hand. The following declaration is acceptable by GHC after using the option -fallow-undecidable-instances, but even though, I got the same error message as I try to print In Nil. > Instance Show (f (Fix f)) => Show (Fix f) where > showsPrec _ (In x) = ("In ("++) . showsPrec 1 x . (')':) This is rather unsatisfactory, because I would not be able to inspect values of type Fix f in the interpreter. Is there a way to get around this? sincerely, Shin

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Using hs-plugins with ghci
by Javier García-Vivó Albors 12 Feb '05

12 Feb '05

Hello everybody. I'm trying to use hs-plugins library with ghci and this is the result: >>> ghci -package plugins ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 6.2.1, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \____/\/ /_/\____/|_| Type :? for help. Loading package base ... linking ... done. Loading package altdata ... linking ... done. Loading package haskell98 ... linking ... done. Loading package hi ... linking ... done. Loading package unix ... linking ... done. Loading package lang ... linking ... done. Loading package posix ... linking ... done. Loading package haskell-src ... linking ... done. Loading package plugins ... linking ... /usr/local/lib/hs-plugins/HSplugins.o: unknown symbol `addDLL' ghc-6.2.1: panic! (the `impossible' happened, GHC version 6.2.1): can't load package `plugins' Please report it as a compiler bug to glasgow-haskell-bugs(a)haskell.org, or http://sourceforge.net/projects/ghc/. Does anybody know how to fix it?? I'm getting crazy with this problem!! Thanks a lot. ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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2nd CFP Coordination and Organisation (CoOrg05)
by L.W.N.van.der.Torre＠cwi.nl 11 Feb '05

11 Feb '05

Second Call for Papers Submission site is now open (strict deadline March 1): http://coorg05.di.unito.it/ 1st International Workshop on Coordination and Organisation (CoOrg 2005) CoOrg 2005 is a one day workshop affiliated with the Seventh International Conference on Coordination Models and Languages (COORDINATION 2005), Namur, Belgium, April 20-23, 2005. (http://www.coordination2005.org) Workshop goals Organizations embody a powerful way to coordinate complex behavior in human society. Different models of organisations exist, from bureaucratic systems based on norms to competitive systems based on markets. Moreover, organizational concepts allow to structure the behavior of complex entities in a hierarchy of encapsulated entities: departments structured in roles, organisations structured in departments, and interorganizational coordination structured in organizations. Organizations specify the interaction and communication possibilities of each of these entities, abstracting from the implementation of their behavior. Since these entities are autonomous, they can only be coordinated exogeneously. Organisational models have been popular in the last years in agent theory for modelling coordination in open systems, where departments and organisations are modelled as autonomous entities. This is also due to the need to ensure social order within MAS applications like Web Services, Grid Computing, and Ubiquitous Computing. In these settings, openness, heterogeneity, and scalability pose new challenges on traditional MAS organizational models. It becomes necessary to integrate organizational and individual perspectives and to promote the dynamic adaptation of models to organizational and environmental changes. Nowadays, practical applications of agents to organizational modeling are being widely developed. Moreover, organisational concepts are used frequently for coordination purposes in different areas of Computer Science. For example, roles are used in access control, conceptual modelling, programming languages and patterns. Contracts are used in design by contract, and services are used in web services and service level agreements. Message based communication is used in networking. Finally, coordination techniques are used in formal models of organisations to analyse or simulate them. In contrast, most coordination languages refer mostly to different kinds of metaphors, like blackboards, shared dataspaces, component composition and channels. Although coordination is usually said to be of a multidisciplinary nature, the links between organisations and coordination have never received proper attention at the coordination conferences. CoOrg 2005, as part of COORDINATION2005, will provide an excellent opportunity to meet researchers studying coordination and organisations in cognitive science, social sciences, agent theory, computer science, philosophy, etc., to discuss the current state of the art and identify potential future directions and research issues. Topics of interest The topics of this symposium include, but are not restricted to, the following: * organisational concepts and methods for coordination: o role based coordination o contract based coordination o coordination in normative multiagent systems o service oriented coordination * coordination techniques for organisations: o normative systems o markets o authority and power o trust * interorganisational coordination o control of autonomy in coordination o integration of organizations * applications of coordination and organisation: o multiagent social simulation models o organization based software engineering o organization oriented programming o organizational patterns Invited speaker Andrea Omicini, University of Bologna Proceedings The papers accepted for the symposium will be available at the workshop. Moreover, selected work will be published in a volume of ENTCS. Important Dates * March 1, 2005: Submissions deadline * March 15, 2005: Notification of authors * April 1, 2005: camera ready copies deadline * April 20-23, 2005: COORDINATION 2005 conference Submissions The length of each paper including figures and references must be between 10 and 15 ENTCS style pages. All papers must be submitted in PDF or postscript format. Papers are to be submitted through the following web address: http://coorg05.di.unito.it/. Submissions should explicitly state their contribution and their relevance to the theme of the workshop. Other criteria for selection will be originality, significance, correctness, and clarity. Simultaneous or similar submissions to other conferences or journals are allowed, when this is indicated on the first page of the submitted paper. Chairs Leon van der Torre, CWI Amsterdam, The Netherlands Guido Boella, Department of Computer Science, Universita' di Torino, Italy Program committee * Farhad Arbab - CWI Amsterdam and University Leiden * Frank de Boer - CWI Amsterdam and University Leiden * Guido Boella - Dipartimento di Informatica, Universita' di Torino (co-chair) * Olivier Boissier - Systemes Multi-Agents G2I, ENSM.SE Saint-Etienne * Cristiano Castelfranchi - Institute of Cognitive Sciences and Technologies (ISTC), Italy * Kevin Crowston - Syracuse University * Mehdi Dastani - University of Utrecht * Joris Hulstijn - Vrije Universiteit Amsterdam * Andrea Omicini - University of Bologna * Pierre-Yves Schobbens - Institut d'Informatique University of Namur * Carles Sierra - IIIA of the Spanish Research Council, Barcelona * Leon van der Torre - CWI Amsterdam (co-chair) On the web SYMPOSIUM WEBSITE: http://boid.info/CoOrg05 COORDINATION 2005 WEBSITE: http://www.coordination2005.org/

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Cfp: ICTCS'05 conference
by g. michele pinna 11 Feb '05

11 Feb '05

Ninth Italian Conference on Theoretical Computer Science (ICTCS'05) Certosa di Pontignano (Siena), Italy October 12 - 14, 2005 http://ictcs05.dsmi.unisi.it Call for Papers The Ninth Italian Conference on Theoretical Computer Science will take place at the Certosa di Pontignano (Siena), Italy. Papers presenting original contributions in any area of theoretical computer science are being sought. Topics include (but are not limited to): analysis and design of algorithms, computability, computational complexity, cryptography, formal languages and automata, foundations of programming languages and program analysis, foundations of artificial intelligence and knowledge representation, foundations of web programming natural computing paradigms (quantum computing, bioinformatics), parallel and distributed computation, program specification and verification, term rewriting, theory of concurrency, theory of data bases, theory of logical design and layout, type theory, security, symbolic and algebraic computation, Program Committee: Michele Bugliesi (Venezia), Mario Coppo (Torino, Co-Chair), Pierluigi Crescenzi (Firenze), Giulia Galbiati (Pavia) Luisa Gargano (Salerno), Giorgio Ghelli (Pisa), Roberto Grossi (Pisa), Benedetto Intrigila (L'Aquila), Nicola Leone (Cosenza), Elena Lodi (Siena, Co-Chair), Flaminia Luccio (Trieste), Andrea Masini (Verona), Giancarlo Mauri (Milano), Corrado Priami (Trento), Geppino Pucci (Padova), Davide Sangiorgi (Bologna). Organizing Committee: S. Brunetti (Siena), G. Michele Pinna (Cagliari - Siena, Chair), E.B.P. Tiezzi (Siena). Invited Speakers: Luca Cardelli (Microsoft Research, Cambridge, United Kingdom) Giuseppe Castagna (LIENS - École Normale Supérieure, Paris, France) Nicola Santoro (School of Computer Science, Carleton University, Ottawa, Canada) Dates and Deadlines: Submission Deadline: 15 April 2005 Acceptance Notification: 7 June 2005 Camera-ready deadline: 2 July 2005 Early registration deadline: 16 September 2005 Conference: 12-14 October 2005 Submissions: Authors are invited to submit electronically one copy of their draft paper, not exceeding fifteen pages. The paper should clearly indicate the results achieved, their significance, and their relation to other work in the area. Extended proofs can be placed in a clearly marked appendix. It is planned to publish the proceedings in the Springer Lecture Notes in Computer Science series. To uniform the submissions the authors are encouraged to use Latex and the Springer LNCS style (www.springer.de/comp/lncs) The web-based submission form is available at the page ictcs05.dsmi.unisi.it/submission.html. In case electronic submission is not possible, the authors should contact: Mario Coppo Dipartimento di Informatica, Universita' di Torino Corso Svizzera 185 I-10149 Torino, Italy email: coppo(a)di.unito.it Conference Page: This Call For Papers is available online at the conference web page ictcs05.dsmi.unisi.it Registration Details: The registration form will be reachable from the conference web page. A limited number of grants for students and young researchers covering the registration fees are available. Details for the applications are in the conference web page.

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Implicit parallel functional programming
by Satnam Singh 10 Feb '05

10 Feb '05

I'm trying to find out about existing work on implicit parallel functional programming. I see that the Glasgow Haskell compiler has a parallel mode which can be used with PVM and there is interesting work with pH at MIT. Does anyone know of any other work on implicitly parallelizing functional programs for fine grain parallel execution? The emergence of multi-core processors makes me think that we should look at implicit parallel functional programming in a new light. Cheers, Satnam ________________________________________ Satnam Singh Microsoft One Microsoft Way Redmond Washington 98052-6399 USA Email: satnams(a)microsoft.com Telephone: +1 425 705 8208 Cell: +1 408 718 2588 Pager: 4087182588(a)mobile.att.com

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ICLP 2005 Doctoral Consortium: Call for Applications
by ICLP 2005 09 Feb '05

09 Feb '05

International Conference on Logic Programming Doctoral Consortium Sitges (Barcelona), Spain October 2-5, 2005 http://www.cs.nmsu.edu/~epontell/DC2005 ----------- The ICLP Doctoral Consortium (DC) is the first ever doctoral consortium to be offered as part of the International Conference on Logic Programming. The DC will take place during ICLP 2005 in Sitges (Barcelona), Spain. The Doctoral Consortium is designed for doctoral students working in areas related to logic programming, who are planning to pursue a career in academia. The Doctoral Consortium aims to provide students with an opportunity to present and discuss their research directions and to obtain feedbacks from peers as well as world-renown experts in the field. The Doctoral Consortium will also offer invited speakers and panels discussions. ------------ The Doctoral Consortium is held the during the regular activities of the ICLP 2005 Conference. The aims of the Doctoral Consortium are: * To provide doctoral students working in the field of logic programming with a friendly and open forum to present their research ideas, listen to ongoing work from peer students, and receive constructive feedback * To provide students with relevant information about important issues for doctoral candidates and future academics * To develop a supportive community of scholars and a spirit of collaborative research. * To support a new generation of researchers with information and advice on academic, research, industrial, and non- traditional career paths. The Consortium is designed for students currently enrolled in a Ph.D. program, though we are also open to exceptions (e.g., students currently in a Masters program and interested in doctoral studies). The Consortium is for students at any stage of their doctoral studies are welcome to apply. Applicants are expected to be conducting research in the field of Logic Programming; topics of interest include (but are not limited to): * Theoretical Foundations of Logic and Constraint Logic Programming * Sequential and Parallel Implementation Technology * Static and Dynamic Analysis, Abstract Interpretation, Compilation Technology, Verification * Logic-based Paradigms (e.g., Answer Set Programming, Concurrent Logic Programming, Inductive Logic Programming) * Innovative Applications of Logic Programming The Consortium allows participants to interact with established researchers and with other students, through presentations, question- answer sessions, panel discussions, and invited presentations. The Doctoral Consortium will provide the possibility to reflect - through short activities, information sessions, and discussions - on the process and lessons of research and life in academia. Each participant will give a short, critiqued, research presentation. The Doctoral Consortium will be held on a date to be determined, in parallel with the regular activities of the ICLP 2005 conference; the ICLP conference will run from October 2nd to October 5th, 2005. Doctoral Consortium participants will be offered the opportunity to have their abstracts published in the ICLP 2005 conference proceedings. Discussants: Several renown faculty members and researchers in the field of Logic Programming will join in evaluating the submission packets and will participate in the Doctoral Consortium, providing feedback to the presenters. The list of the discussants will be published at a later date. -------- Detailed submission instructions can be found in the ICLP 2005 Doctoral Consortium web site, at: http://www.cs.nmsu.edu/~epontell/DC2005 -------- Important Dates Submission Deadline: June 1st, 2005 Acceptance Notification: July, 1st 2005 Last Date to Update Research Summary: July 15th, 2005 Doctoral Consortium: October 2-5, 2005 ICLP 2005 Conference: October 2-5, 2005 ------------ Doctoral Consortium Chair: Enrico Pontelli Department of Computer Science New Mexico State University MSC CS, Box 30001 Las Cruces, NM 88003, USA epontell _a_t_ cs.nmsu.edu

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(no subject)
by Javier García-Vivó Albors 09 Feb '05

09 Feb '05

Hi. I'm trying to use the hs-plugins with ghci for Windows. Do you know how to do it? I've tried several ways to install the and I haven't managed it. Thanks for your help ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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