January 2002 - Haskell

Programming style question
by Adrian Hey 14 Jan '02

14 Jan '02

Hello, Here's something I've always wanted to know but have never dared ask until now (it seems so basic). If I have defined a function like this.. f <args> = <blah> <args> it could be re-written.. f = <blah> I had always assumed the internal representation of these 2 definitions would be identical (and should yield identical code), but it appears that isn't so (with ghc at least). So.. Is there a semantic difference between the two? Which form is likely to result in faster code? Thanks -- Adrian Hey

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Re: differentiation. Reply
by Ketil Z Malde 14 Jan '02

14 Jan '02

Alec <alec314159(a)yahoo.com> writes: > On Wednesday 09 January 2002 06:50 am, S.D.Mechveliani wrote: >> Zhe Fu <fuzhezheng(a)hotmail.com> writes >>> Is there any built-in functions in Haskell to implement >>> diffential operation and partial diffential operation? >>> Or can anyone give me some advices about how to implement them >>> with Haskell? Thanks. >> If you are going to implement differential operators, >> try first to implement, for example, polynomial multiplication. >> After this, differentiation would not look hard. >> But it depends on what one wants to differentiate, one has to >> formulate first what kind of expressions are supposed to be >> differentiated. > how about this: > diff f x = (f (x + epsilon) - f (x - epsilon)) / (2 * epsilon) > where epsilon = 0.00001 > every call to say "diff sin" will cost you about as much as every call to > "sin" I used to toy with these kinds (i.e. numerical differentiation, as opposed to what SDM is talking about ) of functions a bit. One improvement, IMHO, would be to make diff parametric in epsilon, i.e. diff e f x = (f (x+e) - f (x-e)) / (2 * e) the "diff" above would simply be diff' = diff 0.00001 You can also apply diff to itself, getting second derivatives and such, but numerical accuracy will quickly start to suffer unless you're careful. Jerzy Karczmarczuk has some interesting papers on his web site using a different approach to differentiation, maintaining, IIRC, a lazy list of all derivatives of functions. I don't have the URL ready, but a your favorite search engine should be able to help you out. -kzm -- If I haven't seen further, it is by standing in the footprints of giants

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RTA 2002 **** EXTENDED DEADLINE****
by Pierre Lescanne 14 Jan '02

14 Jan '02

RTA 2002 **** EXTENDED DEADLINE**** In response to multiple requests, the program committee of RTA 2002 has decided to extend the submission deadline until 27th January Authors are expected to submit a title and abstract by 15th January. *************************************************************************** RTA 2002 - Call for Papers The 13th International Conference on Rewriting Techniques and Applications RTA'02 will take place from July 22, 2002 to July 24, 2002 in Copenhagen, Denmark, as part of the Federated Logic Conference FLoC'02. Topics RTA is the major forum for the presentation of research on all aspects of rewriting. Typical areas include (but are not limited to): * Applications: case studies; rule-based programming; symbolic and algebraic computation; theorem proving; functional and logic programming; proof checking. * Foundations: matching and unification; completion techniques; strategies; constraint solving; explicit substitutions. * Frameworks: string, term, and graph rewriting; lambda-calculus and higher-order rewriting; conditional rewriting; proof nets; constrained rewriting and deduction; categorical and infinitary rewriting. * Implementation: compilation techniques; parallel execution; rewriting tools. * Semantics: equational logic; rewriting logic. Best Paper Award A prize of 500 EUR will be given to the best paper as judged by the program committee. The program committee may decline to make the award or may split it among several papers. Submissions Submissions must be original and not submitted for publication elsewhere. Submissions should fall into one of the following categories: 1. Regular research papers describing new results; they will be judged on correctness and significance. 2. Papers describing the experience of applying rewriting techniques in other areas; they will be judged on relevance and comparison with other approaches. 3. Problem sets that provide realistic and interesting challenges in the field of rewriting. 4. System descriptions; they should contain a link to a working system and will be judged on usefulness and design. All submissions will be judged on originality. Submissions in the first three categories can be up to 15 proceedings pages long, system descriptions 4 proceedings pages. Authors are strongly encouraged to use LaTeX2e and the Springer llncs class file, available at http://www.springer.de/comp/lncs/authors.html. The title page should include the submission category. Proofs of theorems should be provided in the paper, or, if space does not permit, should be made accessible otherwise (e.g., as an appendix to the submission or via the Web). Submission is by email: Send a self-contained postscript file to <rta2002(a)lifl.fr> Proceedings Accepted papers will be published in the proceedings of the symposium (Lecture Notes in Computer Science, Springer-Verlag). Simultaneous submission to other conferences with published proceedings is not allowed. Important dates * Sun January 27, 2002 - extended deadline for paper submission * Fri March 22, 2002 - author notification * Thu April 25, 2002 - camera-ready papers due Program Committee * chair: Sophie Tison <Sophie.Tison(a)lifl.fr> LIFL - Laboratoire d'Informatique Fondamentale de Lille URA CNRS 369 Universit=E9 de Lille 1 Cité Scientifique --- Bat. M3 59655 Villeneuve d'Ascq cedex, FRANCE +33 03 20 43 43 09 +33 03 20 43 47 24 (secretary) +33 03 20 43 45 66 (fax) * Andrea Corradini <andrea(a)di.unipi.it>, Pisa * Daniel J. Dougherty <ddougherty(a)wesleyan.edu>, Wesleyan * Jürgen Giesl <giesl(a)informatik.rwth-aachen.de>, Aachen U of Technology * Bernhard Gramlich <gramlich(a)logic.at>, Vienna U of Technology * Thérèse Hardin <Therese.Hardin(a)lip6.fr>, Paris VI * Christopher Lynch <clynch(a)clarkson.edu>, Clarkson * Jerzy Marcinkowski <jma(a)tcs.uni.wroc.pl>, Wroclaw * Aart Middeldorp <ami(a)is.tsukuba.ac.jp>, Tsukuba * Joachim Niehren <niehren(a)ps.uni-sb.de>, Saarland * Femke van Raamsdonk <femke(a)cs.vu.nl>, Vrije U of Amsterdam * Albert Rubio <albert(a)lsi.upc.es>, Technical U of Catalonia * Ralf Treinen <Ralf.Treinen(a)lri.fr>, Paris-Sud

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Re: Bug? Re: GHC version 5.02.2 is available - SuSE RPMs
by Jorge Adriano 12 Jan '02

12 Jan '02

> > > module Main where > > > main :: IO() > > > main = do > > > putStr "n:" > > > n <- readLn :: IO(Int) > > > print n > > > > Used to work fine with ghc 5.00.2, that is, it would print "n:", then > > wait for the input, and finaly print n. > > With Ghc 5.02.2 it only prints "n:" after reading the n. <snip> > > It's actually expected behaviour with the current IO implementation - > you have to explicitly flush stdout before reading from stdin (if stdout > is buffered, that is). > > FWIW, I don't think this is the Right behaviour either. Well it seems at least quite annoying, not to mention that lots of programs will 'break'. When was this behaviour changed? And why? J.A.

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GHC version 5.02.2 is available
by Julian Seward (Intl Vendor) 12 Jan '02

12 Jan '02

The (Interactive) Glasgow Haskell Compiler -- version 5.02.2 ============================================================== We are pleased to announce a new patchlevel release of the Glasgow Haskell Compiler (GHC), version 5.02.2. The source distribution is freely available via the World-Wide Web, under a BSD-style license. See below for download details. Pre-built packages for Linux, FreeBSD, Solaris, Alpha(OSF) and Win32 are also available, or will appear shortly. Haskell is a standard lazy functional programming language; the current language version is Haskell 98, agreed in December 1998. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, C++, whatever). A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page at http://www.haskell.org/ GHC's Web page lives at http://www.haskell.org/ghc/ What's new in 5.02.2 ====================== Some important bugfixes: - fix for the long-standing "oversize heap-check" bug - networking library fixes: now works on Windows again - GHC's memory requirements should be improved over 5.02.1, especially when using --make. and many other minor fixes. How to get it =============== The easy way is to go to the WWW page, which should be self-explanatory: http://www.haskell.org/ghc/ We supply binary builds in the native package format for various flavours of Linux and BSD, and in InstallShield form for Windows folks. Everybody else gets a .tar.gz which can be installed where you want. Once you have the distribution, please follow the pointers in the README file to find all of the documentation about this release. On-line GHC-related resources =============================== Relevant URLs on the World-Wide Web: GHC home page http://www.haskell.org/ghc/ Haskell home page http://www.haskell.org/ comp.lang.functional FAQ http://www.cs.nott.ac.uk/~gmh/faq.html System requirements ===================== To compile programs with GHC, you need a machine with 64+MB memory, GNU C and perl. This release is known to work on the following platforms: * i386-unknown-{linux,freebsd,mingw32} * sparc-sun-solaris2 * alpha-dec-osf3 Ports to the following platforms should be relatively easy (for a wunderhacker), but haven't been tested due to lack of time/hardware: * hppa1.1-hp-hpux{9,10} * i386-unknown-solaris2 * mips-sgi-irix{5,6} * {rs6000,powerpc}-ibm-aix The builder's guide included in distribution gives a complete run-down of what ports work; an on-line version can be found at http://www.haskell.org/ghc/docs/latest/building/building-guide.html Mailing lists =============== We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at http://www.haskell.org/mailman/listinfo/glasgow-haskell-users http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see http://www.haskell.org/mailman/listinfo/ Please report bugs using our SourceForge page at http://sourceforge.net/projects/ghc/ or send them to glasgow-haskell-bugs(a)haskell.org. GHC users hang out on glasgow-haskell-users(a)haskell.org. Bleeding edge CVS users party on cvs-ghc(a)haskell.org.

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To:haskell,泛微网络企业互联网应用服务
by contact＠weaver.com.cn 12 Jan '02

12 Jan '02

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A Haskell specific preprocessor
by Olaf Chitil 11 Jan '02

11 Jan '02

I faintly remember that there was once work on a Haskell specific preprocessor. Why was the work abandoned? cpp just annoyed me again. I wrote (/*) = something and cpp complained Test.hs:4: unterminated comment Ciao, Olaf -- OLAF CHITIL, Dept. of Computer Science, The University of York, York YO10 5DD, UK. URL: http://www.cs.york.ac.uk/~olaf/ Tel: +44 1904 434756; Fax: +44 1904 432767

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ANN: H98 FFI Addendum 1.0, Release Candidate 1
by Manuel M. T. Chakravarty 11 Jan '02

11 Jan '02

Dear Haskell Hackers, It is my pleasure to announce Release Candidate 1 of the Foreign Function Interface (FFI) Addendum to Haskell 98: http://www.cse.unsw.edu.au/~chak/haskell/ffi/ I like to invite comments on the specification, which is the outcome of a rather long development effort (including of course all the work on GreenCard, H/Direct etc) by a considerable number of people and much technical discussion on ffi(a)haskell.org (which you can review in the archive of the mailing list at haskell.org if you are interested in the gory details). I append a short description of the idea behind H98 Addenda. Cheers, Manuel -=- Haskell 98 Addenda -=- In line with the outcome of the discussion at the last Haskell Workshop, a number of conservative extensions to the base language Haskell 98 in the form of addenda to the language definition are under way. These extensions strive to complement the base language in areas that have not been covered during the design of Haskell 98, but which are perceived to be of crucial importance in some application areas. An effort is made to design these extensions to have minimal impact on existing Haskell 98 programs. The benefit of a H98 Addendum over any random language extension provided by some Haskell implementation is that a H98 Addendum is a standardised design, and programs coded against such an addendum can be expected to be portable across implementations that support this standard. Generally, implementations of H98 are not required to implement all H98 Addenda, but if such an implementation does provide a feature that is covered by an addendum, it is expected that this extension conforms to that addendum (in the same way as it is expected to abide by the H98 language definition).

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The Newest and Fastest gateway to London
by ukresorts＠yahoo.com 11 Jan '02

11 Jan '02

The Newest and Fastest gateway to London Property/Cars/Jobs/Classifieds/Dating Business Directory Services. WWW.ONLINE-LONDON.NET Is your Business listed ?

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Call for Papers: 7th ERCIM FMICS (Malaga, Spain) July 12-13, 2002
by Hubert Garavel 10 Jan '02

10 Jan '02

[ Apologies for multiple copies ] ****************************************************************************** * * --- CALL FOR PAPERS --- * * 7th International Workshop on Formal Methods for Industrial Critical Systems * (FMICS 02) * * University of Málaga (Spain) * July 12-13, 2002 * Colocated with the 29th ICALP conference * * http://www.inrialpes.fr/vasy/fmics/workshop-7 * ****************************************************************************** *** SCOPE OF THE WORKSHOP *** The aim of the FMICS workshops is to provide a forum for researchers who are interested in the development and application of formal methods in industry. In particular, these workshops should bring together scientists who are active in the area of formal methods and interested in exchanging their experiences in the industrial usage of these methods. They also aim at the promotion of research and development for the improvement of formal methods and tools for industrial applications. Topics include, but are not restricted to: - Tools for the design and development of formal descriptions - Verification and validation of complex, distributed, real-time systems and embedded systems - Verification and validation methods that aim at circumventing shortcomings of existing methods in respect to their industrial applicability - Formal methods based conformance, interoperability and performance testing - Case studies and project reports on formal methods related projects with industrial participation (e.g. safety critical systems, mobile systems, object-based distributed systems) - Application of formal methods in standardization and industrial forums Previous Workshops of the ERCIM working group on formal methods for Industrial Critical Systems were held in Oxford (March 1996), Cesena (July 1997), Amsterdam (May 1998),Trento (July 1999), Berlin (April 2000), and Paris (July 2001). The Seventh International Workshop on Formal Methods for Industrial Critical Systems (FMICS 02) will take place in Málaga on July 12-13, 2002, in co-location with the 29th ICALP conference. *** INVITED SPEAKERS *** Andrew Gordon (Microsoft Research Cambridge, UK) Wang Yi (Uppsala University, Sweden) *** PROGRAMME COMMITTEE *** T. Arts (Ericsson, S) M. Bernardo (Univ. of Urbino, I) R. Cleaveland (SUNY and Reactive Systems, USA), co-chair W.J. Fokkink (CWI, NL) H. Garavel (INRIA Rhone-Alpes, F), co-chair S. Gnesi (CNR/IEI Pisa, I) P. Godefroid (Bell Labs, USA) H. Hermanns (Univ. Twente, NL) T. Margaria (METAFrame Technologies, D) P. Merino Gómez (Univ. Málaga, E), organization chair I. Schieferdecker (GMD Berlin, D) S. Schneider (Royal Holloway, University of London, UK) M. Sighireanu (University of Paris-7 Jussieu, F) R. de Simone (INRIA Sophia Antipolis, F) U. Ultes-Nitsche (University of Southampton, UK) A. Valmari (Tampere University of Technology, Fi) W. Visser (RIACS/NASA Ames, USA) *** LOCAL ORGANISING COMMITTEE *** All the local organising committee members belong to the Software Engineering Group of the University of Málaga. M. del Mar Gallardo P. López J. Martínez P. Merino *** IMPORTANT DATES *** => Deadline for submission: April 21, 2002 => Accept/Reject notification: May 15, 2002 => Final manuscript: June 12, 2002 => Tool demo proposals: May 3, 2002 (contact Hubert.Garavel(a)inrialpes.fr) => Workshop: July 12-13, 2002 *** SUBMISSIONS *** Papers submitted to FMICS 02 must be in English, up to 16 pages long, with a clear abstract and list of keywords. They should be submitted by e-mail to fmics02(a)inrialpes.fr. The format should be either standard PostScript (printable by any PostScript device) or PDF (Adobe's Portable Document Format). The proceedings of the workshop will be published physically by the University of Málaga and will appear as a volume in the ENTCS series (Electronic Notes in Theoretical Computer Science). It is advised to follow the instructions for authors of papers in ENTCS volumes (http://math.tulane.edu/~entcs) In case of acceptance of a paper at least one author has to present the contribution at the workshop, otherwise it will be removed from the list of publications. As an established tradition, the best papers presented at FMICS workshops are selected to appear in special issues of scientific journals. Since 1998, six special issues related to FMICS have been published (or will appear) in prestigious journals such as Formal Aspects of Computing, Formal Methods in System Design, and Science of Computer Programming. *** FURTHER INFORMATION *** The workshop will take place at University of Málaga in co-location with the 29th ICALP conference. Participants should register in advance. A minimal registration fee is charged for participants proceedings, lunch and refreshments. Further information on FMICS 02 can be obtained at the workshop web site: http://www.inrialpes.fr/vasy/fmics/workshop-7 Please indicate your interest to receive actual news via email by sending your address to fmics02(a)inrialpes.fr.

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