September 2003 - Haskell

CfP: SNPD'03 Workshop on High-Level Approaches to Parallel and Distributed Computing
by Clemens Grelck 08 Jul '04

08 Jul '04

Please apologize in case you receive multiple copies of this information. ========================================================================== CALL FOR PAPERS Workshop on High-Level Approaches to Parallel and Distributed Computing held in the context of the Fourth ACIS International Conference on Software Engineering, Artificial Intelligence, Networking, and Parallel/Distributed Computing (SNPD'03) October 16th - 18th, 2003 Luebeck, Germany http://www.isp.uni-luebeck.de/snpd03/Workshop/ws02/index.htm ========================================================================== Scope and Topics: ================== Today parallel and distributed computing systems are readily available and provide a continuously improving price/performance ratio. However, this technological breakthrough in hardware is not accompanied by similar progress in software technology. Parallel and distributed programming is still dominated by low-level techniques such as explicit message passing. This low level of abstraction makes programming these systems exceedingly difficult, time-consuming, and error-prone. Hence, parallel and distributed computing requires new programming models which liberate programmers from low-level concerns and increase programming productivity while maintaining reasonable trade-offs between level of abstraction and runtime performance. Topics of interest include, but are not limited to - methodologies for high-level parallel programming, - parallel programming languages, - high-level libraries for parallel computing, - compilers and runtime systems for parallel computing, - implementation aspects of high-level parallel programming environments, - compiler-based optimization and parallelization, - experience with high-level parallel programming environments, - support for debugging and performance analysis, - concurrent array programming, - programming concepts for the grid. This workshop provides a forum for researchers and practitioners interested in the design, implementation, and evaluation of high-level parallel programming concepts. It aims at creating some focus within the otherwise broad spectrum of the SNPD'03 conference. Workshop Chair and Organizer: ============================== Clemens Grelck University of Luebeck Institute of Software Technology and Programming Languages Seelandstr. 1A 23569 Luebeck, Germany E-Mail: grelck(a)isp.uni-luebeck.de Papers and Publication: ======================== Original, unpublished papers in English not exceeding 8 pages in ACIS double column format are solicited. For detailed formatting instructions see the SNPD'03 conference web site at http://www.isp.uni-luebeck.de/snpd03/index.htm Please send your papers as PDF documents by electronic mail directly to the workshop chair: grelck(a)isp.uni-luebeck.de Please indicate your paper submission by the subject SNPD03 WORKSHOP SUBMISSION Accepted papers will be published in the conference proceedings with ISBN. A selection of excellent papers presented at the conference including its workshops will be published in a special issue of the International Journal of Computer and Information Science. Important Deadlines: ===================== Full paper submission due: August, 30th Notification of acceptance: September, 10th Camera-ready papers due: September, 24th

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RE: How overload operator in Haskell?
by Hal Daume 06 Nov '03

06 Nov '03

What you want to do is make your Vector an instance of the Num(eric) type class. For instance: instance Num Vector where (+) v1 v2 = zipWith (+) v1 v2 (-) v1 v2 = zipWith (-) v1 v2 negate v1 = map negate v1 abs v1 = map abs v1 (*) v1 v2 = ... fromInteger i = ... signum v1 = ... I've left the last three blank because it's unclear what should go there. Since (*) has type Vector->Vector->Vector (in this instance), you can't use dot product or something like that. signum :: Vector->Vector could be written and just return [-1], [0] or [1], I suppose. fromInteger :: Integer->Vector is a little harder. Perhaps just 'fromInteger i = [fromInteger i]' would be acceptable. Or you could leave these undefined. -- Hal Daume III | hdaume(a)isi.edu "Arrest this man, he talks in maths." | www.isi.edu/~hdaume > -----Original Message----- > From: haskell-admin(a)haskell.org > [mailto:haskell-admin@haskell.org] On Behalf Of Liu Junfeng > Sent: Wednesday, July 09, 2003 7:25 AM > To: haskell(a)haskell.org > Subject: How overload operator in Haskell? > > > I've learned haskell months, but I still can't understand the > type system very well. > I can only write: > ----------------------------------- > type Vector = [Double] > vadd,vsub :: Vector->Vector->Vector > v1 `vadd` v2 = zipWith (+) v1 v2 > v1 `vsub` v2 = zipWith (-) v1 v2 > svmul :: Double->Vector->Vector > s `svmul` v = map (s*) v > ------------------------------------ > Tough it works, it is not convenient to use. How to create a > Vector type and overload > mathematical operators? > Thanks for your help. > > Liu Junfeng > liujf(a)softhome.net > > > > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell >

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Enum on Float/Double
by George Russell 23 Oct '03

23 Oct '03

The situation with Enum on Ratio is pretty bad but at least it's not hopeless, since rational numbers are at least exact. But for Float/Double it seems to be a total disaster area. Since it seems to be impossible to abolish Enum Float/Double altogether, would it at least be possible to make it rather more useful, by making succ x return the next representable float after x (or x if x is non-finite) and pred x the previous representable float. This would (a) be useful; (b) make mathematical sense; (c) is tricky to implement with the existing primitives. Before someone else points it out, this is of course unimplementable should someone in the future implement infinite-precision reals in Haskell, but as (barring a solution to the halting problem) Eq would be as well, that does not bother me. My preference would be for succ (+-0) to return the smallest positive real, since then you could define succ x to be the unique y with x < y and forall z . z < y => not (x < z), where such a y exists, and I'm not sure if the Haskell standard knows about signed zeros. Feri wrote > Everybody working with floats should know their quirks While in an ideal world, everyone who represented a mouse position or anything else as a float should have a PhD in numerical analysis, in practice they do not. Indeed I think the Haskell Library Report contains quite a few examples of floating point code which a numerical analyst would have written rather better. So I don't think it's good enough to treat every Float/Double operation as if it had an implicit "UNSAFE" flag indicating that the compiler was entitled to wierd behaviour only comprehensible to experts, as seems to be the case with floating enumerations now.

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RE: Library Infrastructure Proposal & Home Page
by Simon Marlow 05 Oct '03

05 Oct '03

I think the proposal is great. Here's some random comments: It might be worth saying earlier on that the library infrastructure is expected to be a layer underneath the platform's native package support (if such support exists). For example, I've never used Python's Distutils, but I have a bunch of Python packages on my system that were installed using the native package system on top of Distutils (I presume). FreeBSD's ports is both a source and binary package system. A FreeBSD system functions perfectly well using only binary packages. To a certain extent Gentoo is the same, although they place far less emphasis on binary packages. FreeBSD (in source or binary mode), and Gentoo, have no support for recompiling packages when something they depend on has changed. This is the biggest failing of these systems IMHO. The 3rd paragraph of 2.1 therefore isn't correct - there's still a big problem for source-based distributions. However, this is not *our* problem, it's theirs - when a dependency is updated, everything that depends on it should be recompiled. ./Setup.lhs bdist: wouldn't it be better to create a source RPM than a binary RPM? Once you have a source RPM the RPM tools can be used to build a binary RPM. Similarly for FreeBSD and Gentoo - I'd expect Setup.lhs to produce a port skeleton/ebuild for me, not a binary package. The PackageConfig file: I'd leave out 'provides' and 'isDefault' unless we have a convincing example which needs them. Possibly add: 'haddock_html_root :: String' and 'haddock_interface :: String' for documentation. I'm thinking about removing 'extra_ghc_opts' - it's highly dodgy when combined with 'auto'. I agree with Ross's comments about data vs. code. Let's abstract as much as possible as data. Cheers, Simon

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RE: "interact" behaves oddly if used interactively
by Simon Marlow 01 Oct '03

01 Oct '03

> For GHC (6.0.1) > > "main=interact id" basically echoes every line of my input, whereas > "main=interact show" correctly waits for EOF before > outputting something. Which of these are you claiming is wrong? This is the behaviour I'd expect in both cases (although I'd have to go and carefully review the code for 'show :: String -> String' in the report to be able to tell whether it was supposed to be that strict or not). > Furthermore the buffering mode must be "LineBuffering". The buffering mode of a Handle attached to a terminal is LineBuffering by default. > If I explicitely set the buffering to "NoBuffering" I'm not able to > enter EOF by typing "ctrl-d". This is a consequence of Unixy terminal semantics. Unix does line buffering on terminals in the kernel as part of the terminal processing, unless you turn it off. However, the Ctrl-D processing is also part of the terminal processing which gets turned off when the kernel line buffering is disabled. So GHC tries its best to get NoBuffering semantics by turning off the kernel line buffering, but as a result you lose Ctrl-D. C'est la vie. I've added this to the FAQ. > Furthermore my terminal seems > to remain in > the buffering mode set by the previously called ghc-haskell program > (because it effects programs that do not "hSetBuffering".) This is a bug, recently fixed. > What should a student think about "interact" in the Prelude? (It's ok > for pipes only, I guess.) Well, combining laziness with I/O is always going to be problematic. I'd say steer clear of introducing students to interact. Cheers, Simon

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"interact" behaves oddly if used interactively
by Christian Maeder 01 Oct '03

01 Oct '03

Hi, For GHC (6.0.1) "main=interact id" basically echoes every line of my input, whereas "main=interact show" correctly waits for EOF before outputting something. Furthermore the buffering mode must be "LineBuffering". If I explicitely set the buffering to "NoBuffering" I'm not able to enter EOF by typing "ctrl-d". Furthermore my terminal seems to remain in the buffering mode set by the previously called ghc-haskell program (because it effects programs that do not "hSetBuffering".) With "runhugs" (Nov 2002) there is no premature output for "interact id", the buffering mode does not matter, but "ctrl-d" is not recognized as EOF. NHC98 does not even wait for a line break before outputting the result (and echoes "\EOT" for "ctrl-d"). What should a student think about "interact" in the Prelude? (It's ok for pipes only, I guess.) Christian module Main where import System.IO main = do hSetBuffering stdin NoBuffering interact id -- maeder@turing:~/haskell/examples> bash --version GNU bash, version 2.05b.0(1)-release (i586-suse-linux) Copyright (C) 2002 Free Software Foundation, Inc. maeder@turing:~/haskell/examples> ghc --version The Glorious Glasgow Haskell Compilation System, version 6.0.1 maeder@turing:~/haskell/examples> ghc --make Interact.hs -o interact Chasing modules from: Interact.hs Compiling Main ( Interact.hs, ./Interact.o ) Linking ... maeder@turing:~/haskell/examples> ./interact 1 1 2 2 3 3 ^D^D^D ccc interact: interrupted

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type class problem
by Dean Herington 01 Oct '03

01 Oct '03

Can someone explain why the following doesn't work? Is there some other way to achieve the same effect (declaring a set of instances for pair-like types in one go)? Thanks. Dean swan(108)% cat Test1.hs {-# OPTIONS -fglasgow-exts #-} class R r where rId :: r -> String class (R r) => RT r t where rtId :: r -> t -> String data (R r1, R r2) => RPair r1 r2 = RPair r1 r2 instance (R r1, R r2) => R (RPair r1 r2) where rId (RPair r1 r2) = "RPair " ++ rId r1 ++ " " ++ rId r2 class TPair t t1 t2 where prj :: t -> (t1,t2) inj :: (t1,t2) -> t instance (RT r1 t1, RT r2 t2, TPair t t1 t2) => RT (RPair r1 r2) t where rtId (RPair r1 r2) t = "RT (RPair " ++ rtId r1 t1 ++ " " ++ rtId r2 t2 ++ ")" where (t1,t2) = prj t main = return () swan(109)% ghci Test1.hs ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 5.04.3, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \____/\/ /_/\____/|_| Type :? for help. Loading package base ... linking ... done. Loading package haskell98 ... linking ... done. Compiling Main ( Test1.hs, interpreted ) Test1.hs:19: Could not deduce (RT r2 t21, RT r1 t11) from the context (RT (RPair r1 r2) t, RT r1 t1, RT r2 t2, TPair t t1 t2, R (RPair r1 r2)) Probable fix: Add (RT r2 t21, RT r1 t11) to the class or instance method `rtId' arising from use of `rtId' at Test1.hs:19 In the first argument of `(++)', namely `rtId r2 t2' In the second argument of `(++)', namely `(rtId r2 t2) ++ ")"' Test1.hs:20: Could not deduce (TPair t t11 t21) from the context (RT (RPair r1 r2) t, RT r1 t1, RT r2 t2, TPair t t1 t2, R (RPair r1 r2)) Probable fix: Add (TPair t t11 t21) to the class or instance method `rtId' arising from use of `prj' at Test1.hs:20 In a pattern binding: prj t Failed, modules loaded: none. Prelude>

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Re: Interfaces Greencard // Postgres DB
by Gottfried F. Zojer 30 Sep '03

30 Sep '03

Thanks fro the reply Well the installment fails . He more infos : Thats the error : error: failed dependencies: haskell is needed by greencard-2.05-1 Thats in my /etc/profile.local : PATH=$PATH:/home/hugs98-Dec2001/bin/export PATH Thats when I type hugs in a bash : Hugs session for: /home/hugs98-Dec2001/share/hugs/lib/Prelude.hs Type :? for help Prelude> :version -- Hugs Version December 2001 Alastair Reid <alastair(a)reid-consulting-uk.ltd.uk> schrieb am 29.09.03 19:11:42: > > > > Maybe I have a OT question .All is running fine with Hugs98 but I have > > headache to work with Greencard . It will not run (binary and also source > > .rpm fails )on SUSE 8.2 Pro > > Can you give me a bit more information about what is going wrong? > Does the install fail? > Does the install succeed but the binary won't run? > Does the binary run but the generated code won't compile? > > Also, what error messages are produced or, if none, what does happen? > > -- > Alastair Reid >

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Call for Papers: ICFP 2004
by Kathleen Fisher 29 Sep '03

29 Sep '03

Ninth Annual ACM SIGPLAN International Conference on Functional Programming Call for Papers ICFP 2004 September 20-22, 2004 Snowbird, Utah * Important Dates ----------------- Submission deadline 23:00 01 April, 2004 Apia, Samoan time (Thursday) Author review period 23:00 17 May to 23:00 19 May, 2004, Apia, Samoan time Author notification 26 May, 2004 Final paper due 07 July, 2004 Conference 20-22 September, 2004 * Scope ------- ICFP 2004 seeks original papers on the full spectrum of the art, science, and practice of functional programming. The conference invites submissions on all topics ranging from principles to practice, from foundations to features, and from abstraction to application. The scope covers all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages that support objects and concurrency. Topics of interest include, but are not limited to, the following: Foundations Formal semantics, lambda calculus, type theory, monads, continuations, control, state, effects. Design Algorithms and data structures, modules and type systems, concurrency and distribution, components and composition, relations to object-oriented and logic programming, multiparadigm programming. Implementation Abstract machines, compile-time and run-time optimization, just-in-time compilers, memory management. Interfaces to foreign functions, services, components and low-level machine resources. Transformation and analysis Abstract interpretation, partial evaluation, program transformation, theorem proving, specification and verification. Software development techniques for functional programming Design patterns, specification, verification and validation, debugging, test generation, tracing and profiling. Applications and domain-specific languages Systems programming, scientific and numerical computing, symbolic computing and artificial intelligence, systems programming, databases, graphical user interfaces, multimedia programming, application scripting, system administration, distributed-systems construction, web programming, XML and related languages. Practice and experience Functional programming in education and industry, ramifications on other paradigms and computing disciplines. Functional pearls Elegant, instructive examples of functional programming. Papers in the latter three categories need not necessarily report original research results; they may instead, for example, report practical experience that will be useful to others, re-usable programming idioms, or elegant new ways of approaching a problem. The key criterion for such a paper is that it makes a contribution from which other practitioners can benefit. It is not enough simply to describe a program! * Submission guidelines ----------------------- Due date & time: Submissions must be filed at the web site by 23:00 Thursday, 01 April, Apia, Samoa time. Some equivalents to this time are: * New York: 5:00 AM = 5h00 (02 April) * San Francisco: 2:00 AM = 2h00 (02 April) * Chicago: 4:00 AM = 4h00 (02 April) * Paris: Noon (02 April) * Hong Kong: 6:00 PM = 18h00 (02 April) * UTC: 10:00 AM (02 April) Submission URL: http://icfp.acm.org (Available after March 1, 2004). Authors should submit a 100-200 word abstract and a full paper by 23:00 Apia, Samoa Time on Thursday, 01 April, 2004. Submissions should be no more than 12 pages (including bibliography) in standard ACM conference format: two columns, nine-point font on a ten-point baseline, with pages 20pc (3.33in) wide and 54pc (9in) tall, with a column gutter of 2pc (0.33in). Detailed formatting guidelines are available at http://www.acm.org/sigs/pubs/proceed/template.html, along with formatting templates or style files for LaTeX, Word Perfect, and Word. You don't need to include categories, keywords, etc., though you are welcome to do so. Also, note that the ACM copyright notice is not required of submissions, only of accepted papers. Authors wishing to supply additional material to the reviewers beyond the 12-page limit can do so in clearly marked appendices, on the understanding that reviewers are not required to read the appendices. Submissions that do not meet these guidelines will not be considered. The submission deadline and length limitations are firm. Submissions will be carried out electronically via the Web, at the URL given above. Papers must be submitted in either PDF format or as PostScript documents that are interpretable by Ghostscript. They must be printable on US Letter sized paper. Individuals for which this requirement is a hardship should contact the program chair at least one week before the deadline. Submitted papers must adhere to SIGPLAN's republication policy. Each paper should explain its contributions in both general and technical terms, clearly identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. Authors should strive to make the technical content of their papers understandable to a broad audience. Authors will be given a 48-hour period (23:00 17 May to 23:00 19 May 2004 Apia, Samoa time) to read and respond to the reviews for their papers before the PC meeting. Authors of submitted papers will receive more details from the submission site. Authors of accepted papers will be required to sign the ACM copyright form. Proceedings will be published by ACM Press. * Conference Chair ------------------ Chris Okasaki U.S. Military Academy, West Point * Program Chair --------------- Kathleen Fisher AT&T Labs Shannon Laboratory 189 Park Ave., E244 Florham Park, NJ, USA kfisher at research.att.com Phone: +1 973 360.8675 Fax: +1 973 360.8077 Program Committee ----------------- * Lennart Augustsson (Sandburst Inc.) * Hans-J. Boehm (HP Laboratories) * Koen Claessen (Chalmers University) * Adriana Compagnoni (Stevens Institute of Technology) * Matthias Felleisen (Northeastern) * Zhenjiang Hu (University of Tokyo) * Erik Meijer (Microsoft SQLServer/WebData) * Manuel Serrano (INRIA Sophia Antipolis) * Peter Sewell (University of Cambridge) * Jérôme Siméon (Bell Laboratories) * Christopher A. Stone (Harvey Mudd College) * Martin Sulzmann (National University of Singapore) * David Walker (Princeton University) * Elena Zucca (Università di Genova) This document can be obtained in the following formats: HTML http://www.cs.indiana.edu/icfp04/cfp.html PostScript http://www.cs.indiana.edu/icfp04/cfp.ps PDF http://www.cs.indiana.edu/icfp04/cfp.pdf Plain text http://www.cs.indiana.edu/icfp04/cfp.txt

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Interfaces Greencard // Postgres DB
by Gottfried F. Zojer 29 Sep '03

29 Sep '03

Hello to all, I m new to Haskell but not to functional programming . Maybe I have a OT question .All is running fine with Hugs98 but I have headache to work with Greencard . It will not run (binary and also source .rpm fails )on SUSE 8.2 Pro Any hint is welcomed . Gottried F. Zojer P.s. Is somebody using Haskell in combination with PostgreSQL via C/or C++ interface.

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