June 2001 - Haskell - Haskell.org

Working Conference on Generic Programming: first call for papers
by Johan Jeuring 18 Jun '01

18 Jun '01

WCGP '02 IFIP TC2 Working Conference on GENERIC PROGRAMMING http://www.generic-programming.nl/wcgp/cfp.html Organised in conjunction with MPC'02 July 8 - July 13, 2002 Dagstuhl, Germany CALL FOR PAPERS Generic programming is about making programs more adaptable by making them more general. Generic programs often embody non-traditional kinds of polymorphism; ordinary programs are obtained from them by suitably instantiating their parameters. In contrast with normal programs, the parameters of a generic programs are often quite rich in structure. For example they may be other programs, types or type constructors, class hierarchies, or even programming paradigms. Generic programming techniques have always been of interest, both to practitioners and to theoreticians, but only recently have generic programming techniques become a specific focus of research in the functional and object-oriented programming language communities. This working conference will bring together leading researchers in generic programming from around the world, and feature papers capturing the state of the art in this important emerging area. We welcome contributions on all aspects, theoretical as well as practical, of generic programming, aspect-oriented programming, polytypic programming, adaptive object-oriented programming, generic components, and so on. SUBMISSION Full papers should be submitted in Postscript or pdf format by e-mail to reach Jeremy.Gibbons(a)comlab.ox.ac.uk by February 16, 2002. The details of the submission procedure can be found at http://www.generic-programming.nl/wcgp/submit.html Although there is no page limit, submissions should strive for brevity and clarity. IMPORTANT DATES Submission February 16, 2002 Notification April 12, 2002 Final version due May 24, 2002 PROGRAMME COMMITTEE Matt Austern Eerke Boiten Ulrich Eisenecker Jeremy Gibbons (co-chair) Ralf Hinze Johan Jeuring (co-chair) Gary Leavens Karl Lieberherr Lambert Meertens Eugenio Moggi Bernhard Moeller Oege de Moor David Musser Martin Odersky Ross Paterson Simon Peyton Jones Colin Runciman Doaitse Swierstra Stephanie Weirich LOCAL ORGANISATION Jeremy Gibbons Johan Jeuring Bernhard Moeller CORRESPONDENCE Jeremy Gibbons (Jeremy.Gibbons(a)comlab.ox.ac.uk) Johan Jeuring (johan(a)jeuring.net)

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RE: Eq instance for (a,b,c,d,e) and upwards
by Simon Peyton-Jones 18 Jun '01

18 Jun '01

Folks It seems that people are happy with the draft Haskell report (I'm glad to say). There seem to be two outstanding issues: * Tuples. I've decided to specify that tuples up to size 15 exist, along with all their Eq, Ord, etc instances up to that size. * The Prelude types of deleteBy deleteFirstsBy intersectBy Although these could be given more general types, it's an unforced change, and Fergus points out that the more general types could change error messages for the worse. I'm going to let sleeping dogs lie and make no change here. [Recall that no-change is the *strong* default.] The final version of everything is at http://research.microsoft.com/~simonpj/haskell98-revised I'm ready to call it a day, but of course I may have made some stupid error. Take a look please and let me know. I have not yet made PDF; there are issues I don't understand about how to get PDF to look right. Help sought! Simon

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PLI 2001 in Firenze
by Rocco De Nicola 15 Jun '01

15 Jun '01

CALL FOR PARTICIPATION AND EARLY REGISTRATION PLI 2001 Principles, Logics, and Implementations of high-level programming languages Firenze, ITALY September 2 - 8, 2001 http://music.dsi.unifi.it/pli01/ The colloquium on Principles, Logics, and Implementations of high- level programming languages is a collection of events aimed at the advancement of high-level programming languages. PLI 2001 includes the following conferences and workshops: ACM Sponsored Conferences: ICFP (September 3-5) Int. Conf. on Functional Programming General chair: Benjamin Pierce (Univ. Pennsylvania) Program chair: Xavier Leroy (INRIA Rocquencourt) Invited speakers: To be announced PPDP (September 5-7) Int. Conf. on Principles and Practice of Declarative Programming Conference chair: Rocco De Nicola (Univ. Firenze) Program chair: Harald Søndergaard (Univ. Melbourne) Invited speakers: J. Esparza, A. Gordon, and D.A. Schmidt. ACM Sponsored Workshops: · BABEL (Multi-language Infrastructure and Interoperability) · HASKELL · QAPL (Quantitative Aspects of Programming Languages) · RULE (Rule-Based Programming) · SAIG (Semantics, Applications, and Implementation of Program Generation) · SCHEME (Scheme and Functional Programming) · VCL (Verification and Computational Logic) Co-located Workshops: · ERLANG · FICS (Fixed Points in Computer Science) A detailed presentation of PLI2001, including schedule of events, travel and tourist information, is available at the WEB page http://music.dsi.unifi.it/pli01/. Registration and accommodation information and forms are available at http://music.dsi.unifi.it/pli01/registration/ Early registration rates apply until July 25. For informations about hotels please contact (mentioning PLI 2001) Giubbi Jet di Volo Viaggi Piazza San Jacopino, 34/r - 50144 Firenze Telephone: +39 055 3249074 - +39 055 350577 Fax: +39 055 366807 E-mail: incoming(a)voloviaggi.com For all other informations mail to pli-org(a)gdn.dsi.unifi.it ------------------------------------------------------------------- Firenze is packed in September; do book accommodation as soon as possible. ------------------------------------------------------------------- -- <><><><><><><><><><><><><><><><><><><><><><><><><><> Prof. Rocco De Nicola Dip. Sistemi e Informatica Univ. di Firenze Via C. Lombroso 6/17 I-50134 FIRENZE (ITALY) tel. +39 055 4796733 fax +39 055 4796730 Web Page: http://www.dsi.unifi.it/~denicola/ <><><><><><><><><><><><><><><><><><><><><><><><><><>

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Re: Why is there a space leak here?
by cwitty＠newtonlabs.com 11 Jun '01

11 Jun '01

"S. Alexander Jacobson" <alex(a)shop.com> writes: > On 6 Jun 2001, Carl R. Witty wrote: > > > "S. Alexander Jacobson" <alex(a)shop.com> writes: > > > > > For example w/ foldl: > > > > > > foldl + 0 [1..10000] > > > foldl (+) ((+) 0 1) [2..10000] > > > foldl (+) ((+) ((+) 0 1) 2) [3..10000] > > > > > > Can't the implementation notice that each iteration leads to a > > > larger closure and, if it is running out of space go ahead an just > > > evaluate (+) 0 1? > > > > It's complicated. You can't (in general) know whether application of > > a function will increase or decrease the space used. If you were > > running out of space, would you just search the whole unevaluated > > program graph for reductions which somehow seemed "likely" to reduce > > the space used? Would you add such reduction nodes to some global > > list at the time they were created? > > I'm not clear why you can't in general notice that you are using > more space after function application than before. I it hard to see why a > program couldn't do the analysis I just did on foldl. I wasn't worried about foldl; you assumed that (+) 0 1 got smaller if you carried out the application. Even for (+) on Integer, this is not guaranteed (for large integers, if something else happens to be holding on to the summands, evaluating the addition can increase total space usage). > You could accumulate statistics on funtions that increase/decrease space > used at runtime and evaluate those that do reduce space used... Right, that's the sort of thing I meant about "likely" above. But how do you find such function applications in the global program graph, if you seem to be running low on space? (And you also need to realize that some functions might usually have "small" outputs, and sometimes have "large" outputs.) > > One portable way to implement a memoizing function in Haskell (if the > > domain of the function is countable) is to lazily build a data > > structure that contains the results of the function on every possible > > argument. Then you evaluate the portions of the data structure that > > you need; the result on each argument is only evaluated once. This > > probably would count as a "growing expression", and it's certainly > > possible that the function on some arguments would be bottom. > > I don't think I understood this. Can you clarify? Let me know if JCAB's response wasn't enough here. Carl Witty

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Haskell 98 Report
by Simon Peyton-Jones 11 Jun '01

11 Jun '01

Folks I've finished what I hope is the final version of the Haskell 98 Language and Library Reports http://research.microsoft.com/~simonpj/haskell98-revised However, experience shows that bug fixes are often themselves buggy, so I urge you, once again, to take a look at your favourite passages and check they are correct. As ever, there's a complete list of changes at the above URL, with the ones I've made since the April release identified for your pleasure. Comments (hopefully vanishingly few) by 15 June please. Thanks very much Simon

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CFP ESSLLI02 (Trento, Italy)
by Claire Gardent 11 Jun '01

11 Jun '01

[An HTML version of the Call for Proposals is available via the FoLLI page <http://www.folli.uva.nl/Esslli/2002/cfp.txt>. Usual apologies apply if you receive multiple copies of this message.] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Fourteenth European Summer School in Logic, Language and Information ESSLLI-2002 August 4-17, 2002, Trento, Italy %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% CALL FOR COURSE and WORKSHOP PROPOSALS -------------------------------------- The main focus of the European Summer Schools in Logic, Language and Information is on the interface between linguistics, logic and computation. Foundational, introductory and advanced courses together with workshops cover a wide variety of topics within the three areas of interest: Language and Computation, Language and Logic, and Logic and Computation. Previous summer schools have been highly successful, attracting up to 500 students from Europe and elsewhere. The school has developed into an important meeting place and forum for discussion for students and researchers interested in the interdisciplinary study of Logic, Language and Information. ESSLLI-2002 is organised under the auspices of the European Association for Logic, Language and Information (FoLLI). The ESSLLI-2002 Programme Committee invites proposals for foundational, introductory, and advanced courses, and for workshops for the 14th annual Summer School on a wide range of topics in the following fields: LANGUAGE & COMPUTATION LANGUAGE & LOGIC LOGIC & COMPUTATION In addition to courses and workshops there will be a Student Session. A Call for Papers for the Student Session will be distributed separately. PROPOSAL SUBMISSION: Proposals should be submitted through a web form located at <http://www.folli.uva.nl/Esslli/2002/submission.html> All proposals should be submitted no later than July 22, 2001. Authors of proposals will be notified of the committee's decision no later than September 17, 2001. Proposers should follow the guidelines below while preparing their submissions; proposals that deviate can not be considered. GUIDELINES FOR SUBMISSION: Anyone interested in lecturing or organising a workshop during ESSLLI-2002, please read the following information carefully. ALL COURSES: Courses are taught by 1 or max. 2 lecturers. They typically consist of five sessions (a one-week course) or ten sessions (a two-week course). Each session lasts 90 minutes. Timetable for Course Proposal Submission: Jul 22, 2001: Proposal Submission Deadline Sep 17, 2001: Notification Nov 15, 2001: Deadline for receipt of title, abstract, lecturer(s) information, course description and prerequisites Jun 1, 2002: Deadline for receipt of camera-ready course material FOUNDATIONAL COURSES: These are really elementary courses not assuming any background knowledge. They are intended for people to get acquainted with the problems and techniques of areas new to them. Ideally, they should allow researchers from other fields to acquire the key competences of neighbouring disciplines, thus encouraging the development of a truly interdisciplinary research community. Foundational courses may presuppose some experience with scientific methods in general, so as to be able to concentrate on the issues that are germane to the area of the course. INTRODUCTORY COURSES: Introductory courses are central to the activities of the Summer School. They are intended to equip students and young researchers with a good understanding of a field's basic methods and techniques. Introductory courses in, for instance, Language and Computation, can build on some knowledge of the component fields; e.g., an introductory course in computational linguistics should address an audience which is familiar with the basics of linguistics and computation. Proposals for introductory courses should indicate the level of the course as compared to standard texts in the area. ADVANCED COURSES: Advanced courses should be pitched at an audience of advanced Masters or PhD students. Proposals for advanced courses should specify the prerequisites in some detail. WORKSHOPS: The aim of the workshops is to provide a forum for advanced Ph.D. students and other researchers to present and discuss their work. A workshop has a theme. At most one organiser is paid. The organisers should be specialists in the theme of the workshop and give a general introduction in the first session. They are also responsible for the programme of the workshop, i.e., for finding speakers. Each workshop organiser will be responsible for producing a Call for Papers for the workshop by November 15, 2001. The call must make it clear that the workshop is open to all members of the LLI community. It should also note that all workshop contributors must register for the Summer School. A workshop consists of five sessions (a one-week workshop) or ten sessions (a two-week workshop). Sessions are normally 90 minutes. Timetable for Workshop Proposal Submissions Jul 22, 2001: Proposal Submission Deadline Sep 15, 2001: Notification Nov 15, 2001: Deadline for receipt of Call for Papers Dec 1, 2001: Send out Call for Papers Mar 15, 2002: Deadline for Papers (suggested) May 1, 2002: Notification of Workshop Contributors (suggested) May 15, 2002: Deadline for Provisional Workshop Programme Jun 1, 2002: Deadline for receipt of camera-ready copy of Workshop notes Jun 1, 2002: Deadline for Final Workshop Programme FORMAT FOR PROPOSALS: The web-based form for submitting course and workshop proposals is accessible at <http://www.folli.uva.nl/Esslli/2002/submission.html>. You will be required to submit the following information: * Name (name(s) of proposed lecturer(s)/organiser) * Address (contact addresses of proposed lecturer(s)/organiser; where possible, please include phone and fax numbers) * Title (title of proposed course/workshop) * Type (is this a workshop, a foundational course, an introductory course, or an advanced course?) * Section (does your proposal fit in Language & Computation, Language & Logic or Logic & Computation? name only one) * Description (describe the proposed contents in at most 150 words) * External funding (will you be able to find external funding to help fund your travel and accommodation expenses? if so, how?) * Further particulars (any further information that is required by the above guidelines should be included here) FINANCIAL ASPECTS: Prospective lecturers and workshop organisers should be aware that all teaching and organising at the summer schools is done on a voluntary basis in order to keep the participants fees as low as possible. Lecturers and organisers are not paid for their contribution, but are reimbursed for travel and accommodation. Please note the following: In case a course is to be taught by two lecturers, a lump sum is paid to cover travel and accommodation expenses. The splitting of the sum is up to the lecturers. However, please note that the organisers highly appreciate it if, whenever possible, lecturers and workshop organisers find alternative funding to cover travel and accommodation expenses. Workshop speakers are required to register for the Summer School; however, workshop speakers will be able to register at a reduced rate to be determined by the Organising Committee. Finally, it should be stressed that while proposals from all over the world are welcomed, the Summer School can in general guarantee only to reimburse travel costs for travel from destinations within Europe to Trento. Exceptions will be made depending on the financial situation. PROGRAM COMMITTEE: Claire Gardent (chair) Attn: ESSLLI-2002 LORIA BP 239 Campus Scientifique 54506 Vandoeuvre-les-Nancy (France) Tel: +33-3-83-59-2039 Fax: +33-3-83-27-5652 Email: claire.gardent(a)loria.fr Local co-chair: Paolo Bouquet (bouquet(a)cs.unitn.it) Language & Computation: Hinrich Schuetze (me(a)hinrichschuetze.com) Gerry Altmann (g.altmann(a)psych.york.ac.uk) Language & Logic: Fabio Pianesi (pianesi(a)irst.itc.it) Steve Pulman (stephen.pulman(a)somerville.ox.ac.uk) Logic & Computation: Simon Parsons (S.D.Parsons(a)csc.liv.ac.uk ) Frank Wolter (wolter(a)jaist.ac.jp) ORGANISING COMMITTEE: Luciano Serafini (chair) Email: serafini(a)itc.it FURTHER INFORMATION: To obtain further information, visit the web site for ESSLLI-2002 <http://www.folli.uva.nl/Esslli/2002/esslli-2002.html>. For this year's summer school, please see the web site for ESSLLI-2001 <http://www.helsinki.fi/esslli>. http://www.loria.fr/~gardent

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re: Monomorphism Restriction
by Bernard James POPE 11 Jun '01

11 Jun '01

Ashley Yakeley, Seattle WA, writes: > Is there a point to the "monomorphism restriction" in GHC and Hugs? In > practice, all it seems to mean is "occasionally require unnecessary > explicit type signatures". I think the point is made clearly enough in section 4.5.5 of the Haskell 98 language report, you can find it at www.haskell.org. Whether you are satisified with this explanation is another matter. Regards Bernie.

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Monomorphism Restriction
by Ashley Yakeley 10 Jun '01

10 Jun '01

Is there a point to the "monomorphism restriction" in GHC and Hugs? In practice, all it seems to mean is "occasionally require unnecessary explicit type signatures". -- Ashley Yakeley, Seattle WA

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Re: Why is there a space leak here?
by cwitty＠newtonlabs.com 10 Jun '01

10 Jun '01

"S. Alexander Jacobson" <alex(a)shop.com> writes: > For example w/ foldl: > > foldl + 0 [1..10000] > foldl (+) ((+) 0 1) [2..10000] > foldl (+) ((+) ((+) 0 1) 2) [3..10000] > > Can't the implementation notice that each iteration leads to a > larger closure and, if it is running out of space go ahead an just > evaluate (+) 0 1? It's complicated. You can't (in general) know whether application of a function will increase or decrease the space used. If you were running out of space, would you just search the whole unevaluated program graph for reductions which somehow seemed "likely" to reduce the space used? Would you add such reduction nodes to some global list at the time they were created? > I realize that there is a risk of evaluating _|_ unnecessarily, but if you > are otherwise going to run out of memory, you might as well give it a > shot. > > In practice, how often do you expect to see growing expressions that cover > a _|_ that are not actually an error in any case? It's certainly possible. One portable way to implement a memoizing function in Haskell (if the domain of the function is countable) is to lazily build a data structure that contains the results of the function on every possible argument. Then you evaluate the portions of the data structure that you need; the result on each argument is only evaluated once. This probably would count as a "growing expression", and it's certainly possible that the function on some arguments would be bottom. > Hunting down memory leaks is already so obscure, that you might as well > take a shot at solving the problem automatically... > > Alternatively, is there some magical way of warning about leaky > expressions at compile time? You don't have to ban them, but it would be > nice if the programmer were aware of which parts of the code are likely to > grow... In general, this problem is uncomputable. It might be possible to come up with some useful approximation, but I bet that's a very difficult research problem. Carl Witty

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SAS'01: Early registration 15th June
by radhia＠lix.polytechnique.fr 09 Jun '01

09 Jun '01

___________________________________________________________________________ [We apologize for any inconvience caused by multiple copies] SAS'01 Eigth International Static Analysis Symposium La Sorbonne, Paris, 16-18 July, 2001 http://www.ens.fr/sas01/ Registration information is available on the SAS'01 website. Early registration ends soon (15th June). ___________________________________________________________________________

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