March 2002 - Haskell - Haskell.org

Why is this function type-correct
by Rijk J. C. van Haaften 04 Mar '02

04 Mar '02

Hello, Recently, I wrote a function similar to x :: a x = x 42 which is type-correct (Hugs, Ghc, THIH). Still, from the expression it is clear that the type shoud have a function type. The definition x :: a -> b x = x 42 is equally well accepted, though I can't see why this type would be correct. (I'd expect it to be too general.)

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ANNOUNCE: Haven - A Functional Vector Graphics Library
by Antony Courtney 04 Mar '02

04 Mar '02

I am pleased to announce an experimental release of Haven, a library for scalable vector graphics in Haskell. Haven provides a wealth of features, including: - Data types for common geometric shapes such as rectangles, ellipses and Bezier curves. - Composition of arbitrary shapes from sequences of straight and curved segments. - Intersection tests and bounds calculations on shapes. - Cropping of any image by any shape. - Affine transformations on images and paths. - Calculation of precise rectangular bounds of shapes and images. - High quality, anti-aliased rendering. - Scalable outline fonts. - Smooth blending of colors (gradients) - Alpha blending (transparency). - Fine-grained control of stroke width, join rules and end caps. - Constructive Area Geometry (CAG) for composing shapes using simple set-theoretic operations. Haven presents a purely functional API, but is implemented using the Java2D renderer. For more information on Haven, including examples and download instructions, please visit the haven web page at: http://www.haskell.org/haven Please send suggestions and bug reports to: antony(a)apocalypse.org Enjoy! -------- News: Release 1.1 (03-March-2002): * Substantial improvements to configuration and build process. Unified Makefile structure for Linux and Windows using Cygwin and GNU make. -- Antony Courtney Grad. Student, Dept. of Computer Science, Yale University antony(a)apocalypse.org http://www.apocalypse.org/pub/u/antony

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Convite Especial
by Fernando Henrique de Oliveira 04 Mar '02

04 Mar '02

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Flocasa: 1st Call for Paper
by Jean-Marie JACQUET 04 Mar '02

04 Mar '02

[ Our apologies for multiple copies. ] ====================================================================== 1st International Workshop on Foundations of Coordination Languages and Software Architectures (Foclasa 2002) August 24, 2002, Brno, Czech Republic Workshop affiliated to CONCUR'2002, 20 - 23 August 2002. http://www.fi.muni.cz/concur2002/Foclasa ====================================================================== SCOPE AND TOPICS Modern information systems rely more and more on combining concurrent, distributed, mobile and heterogenous components. This move from old systems, typically conceived in isolation, induces the need for new languages and software architectures. In particular, coordination languages have been proposed to cleanly separate computational aspects and communication. On the other hand, software architects face the problem of specifying and reasoning on non-functional requirements. All these issues are widely perceived as fundamental to improve software productivity, enhance maintainability, advocate modularity, promote reusability, and lead to systems more tractable and more amenable to verification and global analysis. The aim of the workshop is to bring together researchers working on the foundations of component-based computing, coordination, and software architectures. Topics of interest include (but are not limited to): o Theoretical models for coordination (component composition, concurrency, dynamic aspects of coordination, semantics, expressiveness); o Specification, refinement, and analysis of software archi- tectures (patterns and styles, verification of functional and non-functional properties); o Coordination, architectural, and interface definition languages (implementation, interoperability, heterogeneity); o Agent-oriented languages (formal models for interacting agents); o Dynamic software architectures (mobile agents, configuration, reconfiguration); o Modeling of information systems (groupware, internet and the web, workflow management, CSCW and multimedia applications) o Coordination patterns (mobile computing, internet computing); o Tools and environments for the development of coordinated applications SUBMISSION GUIDELINES Papers describing original work are solicited as contributions to Foclasa. Submitted papers should be limited to 6 000 words, preferrably formatted according to the Fundamenta Informaticae style (available at http://fi.mimuw.edu.pl/submissions.html) They should be emailed as PostScript (PS) or Portable Document Format (PDF) files to jmj(a)info.fundp.ac.be. PROCEEDINGS The proceedings will be published as a technical report of the Institute of Informatics at the University of Namur, and will be available at the workshop. Selected papers will be published in a special issue of the Funda- menta Informaticae journal, with February 2003 as expected publi- cation time. IMPORTANT DATES: o May 25, 2002: Submission deadline. o June 30, 2002: Notification of acceptance. o August 1, 2002: Final version. o August 24, 2002: Meeting Date. LOCATION The workshop will be held in Brno in August 2002. It is a satellite workshop of CONCUR 2002. For venue and registration see the CONCUR web page at http://www.fi.muni.cz/concur2002/ WORKSHOP ORGANIZERS o Antonio Brogi (University of Pisa, Italy) o Jean-Marie Jacquet (University of Namur, Belgium) PROGRAMME COMITTEE: o Antonio Brogi (University of Pisa, Italy) - Co-chair o Rocco De Nicola (University of Firenze, Italy) o Jos Luiz Fiadeiro (University of Lisbon, Portugal) o Roberto Gorrieri (Univerity of Bologna, Italy) o Paola Inverardi (Univerity L'Aquila, Italy) o Jean-Marie Jacquet (University of Namur, Belgium) - Co-chair o Joost Kok (University of Leiden, The Netherlands) o Antonio Porto (New University of Lisbon, Portugal)

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Flocasa: 1st Call for Paper
by Jean-Marie JACQUET 04 Mar '02

04 Mar '02

[ Our apologies for multiple copies. ] ====================================================================== 1st International Workshop on Foundations of Coordination Languages and Software Architectures (Foclasa 2002) August 24, 2002, Brno, Czech Republic Workshop affiliated to CONCUR'2002, 20 - 23 August 2002. http://www.fi.muni.cz/concur2002/Foclasa ====================================================================== SCOPE AND TOPICS Modern information systems rely more and more on combining concurrent, distributed, mobile and heterogenous components. This move from old systems, typically conceived in isolation, induces the need for new languages and software architectures. In particular, coordination languages have been proposed to cleanly separate computational aspects and communication. On the other hand, software architects face the problem of specifying and reasoning on non-functional requirements. All these issues are widely perceived as fundamental to improve software productivity, enhance maintainability, advocate modularity, promote reusability, and lead to systems more tractable and more amenable to verification and global analysis. The aim of the workshop is to bring together researchers working on the foundations of component-based computing, coordination, and software architectures. Topics of interest include (but are not limited to): o Theoretical models for coordination (component composition, concurrency, dynamic aspects of coordination, semantics, expressiveness); o Specification, refinement, and analysis of software archi- tectures (patterns and styles, verification of functional and non-functional properties); o Coordination, architectural, and interface definition languages (implementation, interoperability, heterogeneity); o Agent-oriented languages (formal models for interacting agents); o Dynamic software architectures (mobile agents, configuration, reconfiguration); o Modeling of information systems (groupware, internet and the web, workflow management, CSCW and multimedia applications) o Coordination patterns (mobile computing, internet computing); o Tools and environments for the development of coordinated applications SUBMISSION GUIDELINES Papers describing original work are solicited as contributions to Foclasa. Submitted papers should be limited to 6 000 words, preferrably formatted according to the Fundamenta Informaticae style (available at http://fi.mimuw.edu.pl/submissions.html) They should be emailed as PostScript (PS) or Portable Document Format (PDF) files to jmj(a)info.fundp.ac.be. PROCEEDINGS The proceedings will be published as a technical report of the Institute of Informatics at the University of Namur, and will be available at the workshop. Selected papers will be published in a special issue of the Funda- menta Informaticae journal, with February 2003 as expected publi- cation time. IMPORTANT DATES: o May 25, 2002: Submission deadline. o June 30, 2002: Notification of acceptance. o August 1, 2002: Final version. o August 24, 2002: Meeting Date. LOCATION The workshop will be held in Brno in August 2002. It is a satellite workshop of CONCUR 2002. For venue and registration see the CONCUR web page at http://www.fi.muni.cz/concur2002/ WORKSHOP ORGANIZERS o Antonio Brogi (University of Pisa, Italy) o Jean-Marie Jacquet (University of Namur, Belgium) PROGRAMME COMITTEE: o Antonio Brogi (University of Pisa, Italy) - Co-chair o Rocco De Nicola (University of Firenze, Italy) o Jos Luiz Fiadeiro (University of Lisbon, Portugal) o Roberto Gorrieri (Univerity of Bologna, Italy) o Paola Inverardi (Univerity L'Aquila, Italy) o Jean-Marie Jacquet (University of Namur, Belgium) - Co-chair o Joost Kok (University of Leiden, The Netherlands) o Antonio Porto (New University of Lisbon, Portugal)

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2nd CFP: Unification in non-classical logics
by Manuel Ojeda Aciego 04 Mar '02

04 Mar '02

======================================================================= We apologize if you receive this more than once ======================================================================= Second call for papers Unification in Non-Classical Logics --co-located with ICALP 2002-- July, 12-13, 2002, Málaga, Spain http://www.satd.uma.es/aciego/icalp-ws.html ======================================================================= The workshop on Unification in Non-Classical Logics will be held in Málaga, as a workshop of the 29-th International Colloquium on Automata, Languages, and Programming (ICALP 2002), which is a very convenient forum for an open discussion of the subject of non-canonical unification, roughly depicted below. Aims and scope -------------- Unification in non-classical logics, with various approaches to handling generalised terms, has drawn more and more attention in recent years. It turns out to be among the most promising areas of research on non-classical logics and its applications. So far, most popular lines of research include fuzzy unification of (conventional) databases and the use of fuzzy concepts in information retrieval. Some international events based on these topics have been held so far, for instance, the 2nd Intl Workshop on Logic Programming and Soft Computing (LPSC'98), or the special session on Advances in Possibilistic Logic and Related Issues at the IFSA Congress in Vancouver, Canada (2001), have non-classical unification among their topics. This workshop at ICALP is conceived as a forum for the exchange of ideas relevant for the concept of unification in non-classical logics, including, but not limited to, the following topics (practical implementations and experiences as well as theoretical advances): * Unification in multiple-valued and fuzzy logic programming. * Unification based on similarities and fuzzy equivalence relations. * Categorical unification. * Practical use of non-classical unification, e.g. in expert systems and information retrieval. We expect potential participants from the following areas: multiple-valued logic, fuzzy logic, uncertainty in logic programming, categorical applications to computer science. The workshop will have a limited number of presentations and the organizers will apply a refereeing procedure accordingly. The format will be as a set of presentations followed by a round table discussion. As the number of participants is estimated not to be very large, time enough will be allocated for each presentation (between 30 and 40 minutes), thus helping to have a relaxed workshop atmosphere in which discussions are encouraged. Submission ---------- Authors are invited to submit an extended abstract of their papers, presenting original contributions to the workshop themes. The workshop proceedings will be published as an issue in the ENTCS series (Electronic Notes on Theoretical Computer Science). Submissions should be written in English and not exceed 15 pages using the ENTCS style, and sent to the organizers in either PS or PDF form, together with a text-only message containig: title, abstract and keywords, the author's full names, and address and e-mail for correspondence. Simultaneous submission to other meetings with published proceedings is not allowed. Important dates --------------- * 20.03.2002 Workshop paper submission deadline * 21.04.2002 Workshop paper acceptance notification * 10.05.2002 Workshop paper camera-ready deadline Organizing Committee -------------------- Patrik Eklund Manuel Ojeda-Aciego Dept. Computing Science Dept. Matematica Aplicada Umea University Universidad de Malaga mailto:peklund@cs.umu.se mailto:aciego@ctima.uma.es ----------------------------------------------------------

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Re: getProtocolByName
by Dominic Steinitz 03 Mar '02

03 Mar '02

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multiparameter generic classes
by Hal Daume III 03 Mar '02

03 Mar '02

are there any papers/webpages/implementations/etc. of using multiparameter classes in a generic framework, with or without dependencies? thanks! - hal -- Hal Daume III "Computer science is no more about computers | hdaume(a)isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

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getProtocolByName
by dominic.j.steinitz＠britishairways.com 03 Mar '02

03 Mar '02

Here's my test program. TCP is a valid protocol. But I get the following when I run it. I'm running under W98 by the way. I have two questions: 1) Why do I get an error? 2) Even if this is a valid error why doesn't the function tell me so that I can handle it rather than terminating? Dominic. C:\Dom\haskell\ping>main Fail: does not exist Action: getProtocolByName Reason: no such protocol entry C:\Dom\haskell\ping>version C:\Dom\haskell\ping>"c:\program files\glasgow haskell compiler\ghc-5.02\bin\ghc" --version The Glorious Glasgow Haskell Compilation System, version 5.02 module Main(main) where import BSD main = do protocolEntry <- getProtocolByName "TCP" {- The documentation gives no clue as to what constitutes an error condition. Looking at the C equivalent in http://www.opengroup.org/onlinepubs/7908799/xns/endprotoent.html, this gives a null pointer to the data structure. Assume for now that the Haskell equivalent returns a null protocol name. -} if protoName protocolEntry == "" then putStrLn "Error" else putStrLn ("Protocol name: " ++ (protoName protocolEntry))

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Research Opportunity: Refactoring Functional Programs (UKC)
by Claus Reinke 03 Mar '02

03 Mar '02

Job opportunity for postdoc / graduate Research Associate in Refactoring Functional Programs at University of Kent. Please bring to the attention of suitable candidates / forward as appropriate. ----------------------------------------------- ad follows Research Associate in Refactoring Functional Programs Applications are invited for a three year Research Associate position at the University of Kent at Canterbury, to work under the direction of Professor Simon Thompson and Dr Claus Reinke on an EPSRC funded project entitled "Refactoring Functional Programs". Applications are welcomed from candidates with a doctorate or a very good first degree; in the latter case a successful candidate will have the opportunity of registering to study for a PhD. Refactoring is the process of redesigning existing code without changing its functionality. In our project we will explore refactoring for functional programs and in particular we will construct a catalogue of functional refactorings, and build a prototype tool in Haskell to support refactoring of Haskell programs. Applicants should be able to demonstrate strong experience of programming in a functional programming language, preferably Haskell, and have good communication skills. The appointment will be made within the salary ranges of £17,278-£26,229 p.a. on the Research IA scale. Please telephone the Personnel Office for further particulars on 01227 827837 (24 hours) or email: Personnel(a)ukc.ac.uk, quoting the reference number R02/24. Text phone users please telephone 01227 823674. The closing date is Friday 22 March 2002. Informal enquires can be directed to either Simon or Claus: {S.J.Thompson,C.Reinke}@ukc.ac.uk. More details of the project and further particulars for the position can be found at: http://www.cs.ukc.ac.uk/people/staff/sjt/Refactor/ Simon and Claus

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