March 2005 - Haskell - Haskell.org

ANNOUNCE: The GHC Survey 2005
by Simon Marlow 04 Mar '05

04 Mar '05

Just ahead of the 6.4 release, we've put together a GHC user survey. The idea is to help us get a better understanding of who uses GHC, what for, what aspects of GHC they consider most valuable, and what they would most like to see improved. The survey is anonymous (if you wish), and should take about 5 minutes to complete. We will use the information to help guide what we do in future, and to help justify what to do. Have your say! We'll also be publishing lots of cool stats once we have enough responses. Here's the link: http://www.haskell.org/ghc/survey/start.cgi Many thanks to Tomasz Zielonka for putting together the survey, which is implemented using WASH on GHC (of course). Simon M, on behalf of the GHC Team

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RE: [Haskell] sugar for extensible types (was: class associated types, via GADTs.)
by Simon Marlow 03 Mar '05

03 Mar '05

On 16 February 2005 08:08, Ralf Laemmel wrote: > Assoc types and GADTs are great but > I am still too fond of encoding extensible datatypes with (open) > classes. > I contributed to some related discussion at comp.compilers a while > ago [1]. The Haskell code samples are worth sharing (because they are > sooooo simple): > > http://homepages.cwi.nl/~ralf/OOHaskell/src/interpreter/nonextensible.hs > http://homepages.cwi.nl/~ralf/OOHaskell/src/interpreter/extensible.hs > (Note: *no* OOHaskell idioms used.) I wish we'd done exceptions like this. An extensible exception type is entirely possible, and using it is not hard either - see the attached file implemented in terms of the existing Control.Exception. For example: test = do x `catch` (\(IOException e) -> print e) `catch` (\(ArithException e) -> print e) and I make a new type into an exception like this: data T = ... deriving (Typeable, Show) instance Exception T this can replace DynExceptions and the strange catchJust/tryJust stuff in Control.Exception. Perhaps we can figure out a reasonable migration path that wouldn't break too much code in one go? Cheers, Simon

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integration of functional and imperative programming concepts
by Derek Elkins 03 Mar '05

03 Mar '05

> for my diploma thesis, I need to find information about integration of > functional and imperative programming concepts. Could somebody of you > point me to good websites, papers, etc. about this topic? You haven't been too specific about what kinds of things you are looking for. One thing that you might find useful is, http://www.mm.informatik.tu-darmstadt.de/~kuehne/fps/. Also there are plenty of functional-object-oriented languages. Checking the paper listings of FOOL conferences should provide many other papers.

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RE: [Haskell] Re: help with some basic code that doesn't work
by Simon Peyton-Jones 03 Mar '05

03 Mar '05

Happily, with GHC 6.4, your code works fine, both with 'deriving' and with a hand-written instance. It works because 6.4 can build recursive dictionaries. Simon | -----Original Message----- | From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of Shin-Cheng | Mu | Sent: 14 February 2005 05:32 | To: haskell(a)haskell.org | Cc: Malcolm.Wallace(a)cs.york.ac.uk | Subject: [Haskell] Re: help with some basic code that doesn't work | | 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 | | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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integration of functional and imperative programming concepts
by Wolfgang Jeltsch 03 Mar '05

03 Mar '05

Hello, for my diploma thesis, I need to find information about integration of functional and imperative programming concepts. Could somebody of you point me to good websites, papers, etc. about this topic? Thanks a lot. Best wishes, Wolfgang

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How to import user's modules with hs-plugins
by Javier García-Vivó Albors 02 Mar '05

02 Mar '05

Hello everybody. I'm using the hs-plugins function "eval" in my source code and I need to import a Haskell module at runtime. Do you know if it's possible? I've seen many examples of hs-plugins and never had a user's module import in the "eval" call. Thanks for your time ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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Summer School on Reliable Computing: Call for Participation
by Steve Zdancewic 02 Mar '05

02 Mar '05

Call for Participation Summer School on Reliable Computing July 20-29, 2005 University of Oregon Eugene, Oregon USA Registration Deadline: March 31, 2005. http://www.cs.uoregon.edu/research/summerschool/summer05/index.html e-mail: summer-school-security(a)cs.uoregon.edu Program ------- This Summer School will cover current research in reliability of software systems ranging from foundational materials on type systems, program analyses, and model checking to advanced applications of the techniques in practice. Material will be presented at a tutorial level that will help graduate students and researchers from academia or industry understand the critical issues and open problems confronting the field. The course is open to anyone interested. Prerequisites are an elementary knowledge of logic and mathematics that is usually covered in undergraduate classes on discrete mathematics. Some knowledge of programming languages at the level provided by an undergraduate survey course will also be expected. Our primary target group is PhD students. We also expect attendance by faculty members who would like to conduct research on this topic or introduce new courses at their universities. The program consists of more than twenty-five 80-minute lectures presented by internationally recognized leaders in programming languages, model checking, and software reliability research. Speakers and their topics include: * Counterexample-driven Refinement Thomas Ball Microsoft Research * Specifying and Checking Stateful Software Interfaces Manuel Fahndrich Microsoft Research * Checking Software Properties with Contracts Robby Findler University of Chicago * Domain-Specific Languages: For Fun and Profit Kathleen Fisher AT&T Research * Domain-Specific Languages: For Fun and Profit Kathleen Fisher AT&T Research * Improving Software Quality with Type Qualifiers Jeff Foster University of Maryland * Lightweight Analyses for Reliable Concurrency Stephen Freund Williams College * Type Systems: A Foundation for Reliable Computing Robert Harper Carnegie Mellon University * Program Verification by Lazy Abstraction Ranjit Jhala University of California at San Diego * An Introduction to Model Checking Orna Kupferman Hebrew University, Jerusalem Venue ----- The summer school will be held at the University of Oregon, located in the southern Willamette Valley city of Eugene, close to some of the world's most spectacular beaches, mountains, lakes and forests. On the weekend, students will have the option of participating in a group activity in Oregon's countryside. Housing ------- The school will provide on-campus housing and meals. To share a room with another student attending the school, the cost is $450.00 (USD) per person. Housing rates are based on check-in Tuesday, July 19 and check-out before noon on Saturday, July 30. Some single rooms may be available for an additional fee of $130.00 (USD). If you'd like a single room, please indicate your choice and we will try to accommodate you on a first-come/first-served basis. Registration ------------ The cost for registration is $175.00 (USD) for graduate students, and $300.00 (USD) for other participants. There are a limited number of grants available to fund part of the cost of student participation. The registration deadline is March 31, 2005. Additional information about the program, registration, venue, and housing options is available on the web site. Or, you may request more information by e-mailing summer-school-security(a)cs.uoregon.edu. Organizers ---------- Zena Ariola, University of Oregon David Walker, Princeton University Steve Zdancewic, University of Pennsylvania

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Deadlines Extended: CALL FOR PAPERS IN THREE SYMPOSIUMS
by Dr. M. Sarfraz 02 Mar '05

02 Mar '05

Deadlines Extended ==================================== CALL FOR PAPERS IN THREE SYMPOSIUMS ==================================== Symposium - 1 International Symposium of Graphical Models and Imaging (IV2005-GMAI) http://www.graphicslink.demon.co.uk/IV05/GMAI.htm IN The 9th IEEE International Conference on INFORMATION VISUALISATION 06- 07 - 08 July 2005 * LONDON * ENGLAND * IMPORTANT - PLEASE NOTE THAT: 1- The deadline for the paper submission is extended to: 21 March 2005. 2- The main conference IV05 details are available from: http://www.graphicslink.demon.co.uk/IV05/ ==================================== Symposium - 2 International Symposium of Computer Aided Geometric Design & Graphics (CGIV2005-CAGDAG) http://www.graphicslink.demon.co.uk/cgiv05/CAGDAG.htm IN The 2nd International Conference INFORMATION VISUALISATION 26 - 27 - 28 - 29 July 2005 * Xi jiao Hotel?* Beijing * China IMPORTANT - PLEASE NOTE THAT: 1- The deadline for the paper submission is extended to: 15 March 2005. 2- The main conference CGIV05 details are available from: http://www.graphicslink.demon.co.uk/cgiv05 ==================================== Symposium - 3 International Symposium of Computer Aided Geometric Design & Graphics (CGIV2005-CAGDAG) http://www.graphicslink.demon.co.uk/cgiv05/IRTAST.htm IN The 2nd International Conference INFORMATION VISUALISATION 26 - 27 - 28 - 29 July 2005 * Xi jiao Hotel?* Beijing * China IMPORTANT - PLEASE NOTE THAT: 1- The deadline for the paper submission is extended to: 15 March 2005. 2- The main conference CGIV05 details are available from: http://www.graphicslink.demon.co.uk/cgiv05 ==================================== CONTACT: All submissions should be addressed to: Dr Muhammad Sarfraz (Chair) Department of Information and Computer Science King Fahd University of Petroleum and Minerals KFUPM # 1510, Dhahran 31261 Saudi Arabia. Tel: +966-3-860-2763 Fax: +966-3-860-2763 Email: sarfraz(a)kfupm.edu.sa WWW: http://www.ccse.kfupm.edu.sa/~sarfraz/

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linear implicit parameters
by Immanuel Litzroth 02 Mar '05

02 Mar '05

Has anybody got a good example of how to use linear implicit parameters? I seem to be unable to understand the description in the ghc manual and I couldn't find a paper on the web. Immanuel *************************************************************************** I can, I can't. Tubbs Tattsyrup -- Immanuel Litzroth Software Development Engineer Enfocus Software Antwerpsesteenweg 41-45 9000 Gent Belgium Voice: +32 9 269 23 90 Fax : +32 9 269 16 91 Email: Immanuell(a)enfocus.be web : www.enfocus.be ***************************************************************************

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FACS'05 Call for Papers
by Luis Barbosa 02 Mar '05

02 Mar '05

[apologies if you receive multiple copies] --------------------------------------------- CALL FOR PAPERS FACS'05 II International Workshop on Formal Aspects of Component Software Macao October 24-25, 2005 www.iist.unu.edu/facs05/ --------------------------------------------- IMPORTANT DATES: Submission: Jul 15, 2005 Notification: Sep 15, 2005 Final Version: Sep 30, 2005 Workshop: Oct 24-25, 2005 INVITED SPEAKERS: * Farhad Arbab (CWI and LIACS, Leiden University) * Paolo Ciancarini (Università di Bologna) * Edmund Clarke (Carnegie Mellon University) AIMS AND SCOPE The objective of FACS'2005 is to bring together researchers in the areas of component software and formal methods to promote a deep understanding of this paradigm and its applications. The Workshop will also be interested in defining the common aspects of components and component-based development. It is expected that formal paper presentations be followed by lively debate in a stimulating atmosphere. Possible topics include, but are not limited to: * formal models for software components and component interaction * design and verification methods for component software * component composition and deployment: models, calculi, languages * component testing * specification of extra-functional properties in component software * certification of components and software architectures * component software vs object orientation * components for real-time, safety-critical, secure and/or embedded systems * experience reports and case studies in component software Further information is available at the web site: www.iist.unu.edu/facs05/ BACKGROUND: Component-based software emerged as a promising paradigm to deal with the ever increasing need for mastering systems' complexity, their evolution and reuse, and driving software engineering into sound production and engineering standards. Soon, however, it became a popular technology long before consensual definitions and principles, let alone formal foundations, have been put forward. Issues like mathematical models for components, their interaction and composition, or rigourous approaches to verification, deployment, testing and certification remain open research questions and challenging opportunities for formal methods. Moreover, new challenges are raised by applications to non conventional areas, such as safety-critical, mobile, and/or embedded systems. FACS'05 is the second in a series of workshops, founded by the International Institute for Software Technology of the United Nations University. The first FACS workshop was held in Pisa, Italy, in September 2003, collocated with FM'03. ORGANIZATION: UNU-IIST (Macao) PROGRAM COMMITTEE: Farhad Arbab (CWI, The Netherlands) Luis Barbosa (PC Chair, Universidade do Minho, Portugal) Marcello Bonsangue (LIACS-Leiden University, The Netherlands) Christiano Braga (Universidade Federal Fluminense, Brazil) Manfred Broy (Technical University of Munich, Germany) Calos Canal (Universidad de Malaga, Spain) João Faria (Universidade do Porto, Portugal) Jose Fiadeiro (University of Leicester, United Kingdom) Susanne Graf (VERIMAG, France) Mathai Joseph (Tata Consultancy Services Limited, India) Atsushi Igarashi (Kyoto University, Japan) Kung-Kiu Lau (The University of Manchester, United Kingdom) Zhiming Liu (PC Chair, UNU-IIST, Macao) Antónia Lopes (University of Lisbon, Portugal) Markus Lumpe (Iowa State University, USA) Tom Maibaum (McMaster University, Canada) Sun Meng (National University of Singapore, Singapore) Ugo Montanari (University of Pisa, Italy) David Naumann (Stevens Institute of Technology, USA) Anders Ravn (Aalborg University, Denmark) Bernhard Schätz (Technical University of Munich, Germany) Carolyn Talcott (SRI International, USA) ORGANISING COMMITTEE: He Jifeng, UNU-IIST, Macao (OC chair) Antonio Cerone, UNU-IIST, Macao Bernhard Aichernig, UNU-IIST, Macao Chan Iok Sam , UNU-IIST, Macao Xiaoshan Li, Univ. Macao RELATED EVENTS: ICTAC'05 will be held in Hanoi, Vietnam, the week before. SUBMISSION AND PUBLICATION: Submissions to the workshop will be judged on the basis of originality, relevance, technical soundness and presentation quality. Papers should be written in English and not exceed 15 pages in ENTCS format. Publication of the workshop proceedings in Electronic Notes in Theoretical Computer Science, Elsevier, is anticipated.

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