- Haskell - Haskell.org

Overloading and Literal Numerics
by Alain Cremieux 27 Jun '02

27 Jun '02

Hi, I am trying to create an overloaded function "à la Java" to be able to call it either with a string or a number. Ex : definePort "http" definePort 80 but I have problem with restrictions in Haskell's type system (or with my lack of experience with it). The program : data PolyType = MkPolyLeft String | MkPolyRight (String, String) | MkPolyNum Int deriving Show class Poly a where poly :: a -> PolyType instance Poly String where poly s = MkPolyLeft s instance Poly (String, String) where poly p = MkPolyRight p instance Poly Int where poly i = MkPolyNum i po :: (Poly a) => a -> PolyType po = poly tpo1, tpo2, tpo3 :: PolyType tpo1 = po "35" tpo2 = po ("36", "37") tpo3 = po 39 gives the following result with ghc (5.03 & -fglasgow-exts) : cl.hs:21: Ambiguous type variable(s) `a' in the constraint `Poly a' arising from use of `po' at cl.hs:21 In the definition of `tpo3': po 39 cl.hs:21: Ambiguous type variable(s) `a' in the constraint `Num a' arising from the literal `39' at cl.hs:21 In the first argument of `po', namely `39' In the definition of `tpo3': po 39 I think I need the "closed" extension of the 'class' clause to do that (but it does not seem to be implemented yet). Is there a better solution ? Thank you, Alain

4 4

Advance Notice of Possible Research Opening
by Kevin Hammond 26 Jun '02

26 Jun '02

Dear friends, Although final confirmation is awaited, Kevin Hammond and Steve Linton expect shortly to be in a position to advertise a three year post-doctoral fellowship to work on a research project entitled: "Computational Algebra for Commodity Parallel Machines". The goal of this project is to develop and experiment with flexible and robust parallel implementations of some key computational group theory algorithms, using Glasgow Parallel Haskell and link these to GAP as a high-performance back-end, with the possibility of closer integration including calls back from Haskell to GAP. A copy of the Case for Support outlining the programme of research can be seen on the World Wide Web at: http://www-circa.dcs.st-and.ac.uk/~sal/parallel.pdf We will be looking for a Research Assistant with the following qualities: A Programming experience: 1. They must be an experienced Programmer 2. Preferably, they should have experience of functional languages, preferably Haskell 3. Ideally they would have experience of functional language implementation, preferably the Glasgow Haskell compiler and ideally the GUM parallel runtime B Mathematics 1. They must have taken at least some university level discrete mathematics course (this may however have been taken in e.g. a computer science department) 2. Preferably they should have studied group theory and/or computer algebra 3. Ideally they would have a good knowledge of computational group theory and experience with GAP Assuming the funding is confirmed, a formal advertisement will appear on the School of Computer Science and University of St Andrews Web sites, on www.jobs.ac.uk and in the press, and will be circulated. In the meantime, feel free to make informal enquiries directly to us: Kevin Hammond (kh(a)dcs.st-and.ac.uk) Steve Linton (sal(a)dcs.st-and.ac.uk)

1 0

Weird profiling behaviour
by ketil＠ii.uib.no 26 Jun '02

26 Jun '02

Hi, I have what I think is a really strange problem. I have a fair sized problem, which involves sorting a data set, first on labels (which are Strings) and then on scores (which are Ints). The strange thing is that string sorting is *vastly* faster than int scoring! Now, I've tried modifying the sorting routinges, moving them into the same module, and so on, to no avail. Is there any likely explanation? The pipeline is basically sortBy int_cmp . compound_equal . sortBy string_cmp I hesitate to post the code, since it's part of a rather large program, and in the hope that somebody will pop up and say that oh, yes, it's a well know feature of 'sortBy'. Or that it's an artifact of profiling. Or something like that. Any, and I mean any, suggestions really, really welcome. -kzm -- If I haven't seen further, it is by standing in the footprints of giants

4 7

Papers on strictness annotations
by Robert Ennals 26 Jun '02

26 Jun '02

I know this is slightly off topic but... Does anyone know if there are any papers published anywhere on strictness annotations? It seems that it would be nice to be able to cite a paper on the concept, but, as far as I can tell, no such paper exists. -Rob

4 5

TLDI'03 Call for Papers
by Zhong Shao 25 Jun '02

25 Jun '02

CALL FOR PAPERS TLDI'03 The ACM SIGPLAN Workshop on Types in Language Design and Implementation (Formerly called TIC, The International Workshop on Types in Compilation) http://www.cs.cmu.edu/~petel/tldi03/ January 18, 2003 New Orleans, Louisiana Co-located with POPL'03 The role of types and proofs in all aspects of language design, compiler construction, and software development has expanded greatly in recent years. Type systems, type analyses, and formal deduction have led to new concepts in compilation techniques for modern programming languages, verification of safety and security properties of programs, program transformation and optimization, and many other areas. In recognition of this expanding role, the ACM SIGPLAN Workshop on Types in Language Design and Implementation (TLDI'03) expands on the previous three International Workshops on Types in Compilation (TIC'97, TIC'98 and TIC'00), to bring together researchers to share new ideas and results in this area. This year, TLDI'03 will be sponsored by ACM SIGPLAN and colocated with POPL'03. Submissions for this event are invited on all interactions of types with language design, implementation, and programming. This includes both practical applications and theoretical aspects. TLDI'03 specifically encourages papers from a broad field of programming language and compiler researchers, including those working in object-oriented, dynamically-typed, late-binding, and mobile-code paradigms, as well as traditional fully-static type systems. Topics of interest include: - Proof-carrying code and certifying compilation - Typed intermediate languages and type-directed compilation - Type-based language support for safety and security - Types for interoperability - Type safety and security of system programming languages - Type-based program analysis, transformation, and optimization - Dependent types and type-based proof assistants - Types for security protocols, concurrency, and distributed computing - Type inference and type reconstruction - Type-based specifications of data structures and program invariants - Type-based memory management This is not meant to be an exhaustive list; papers on novel utilizations of type information are welcome. Authors concerned about the suitability of a topic are encouraged to inquire via electronic mail to the program chair prior to submission. HOW TO SUBMIT A PAPER We solicit submissions on original research not published or submitted for publication elsewhere. Technical summaries, in English and not to exceed 5000 words (approximately 10 pages), should be submitted to the program chair by FRIDAY, SEPTEMBER 27, 2002. Because of hard constraints imposed for the publication of the proceedings, this is a hard deadline. WE WILL BE UNABLE TO ACCEPT FOR REVIEW ANY LATE SUBMISSIONS. To submit a paper, authors should complete the following two steps by the submission deadline: 1) Send an e-mail message to petel(a)cs.cmu.edu containing the title, authors' contact information, and an abstract (not to exceed 200 words) in ASCII. 2) Send the technical summary itself. The summary should also be sent electronically to petel(a)cs.cmu.edu. (Persons to whom electronic submission poses a hardship may make individual arrangements with the program chair.) Adobe Portable Document Format (PDF) is strongly preferred for all submissions. Authors should be sure to use full font inclusion to ensure portability. All papers must be formatted for US Letter (8.5"x11") paper. Postscript (PS) format submissions will also be accepted, provided that they preview and print properly using Ghostscript with standard fonts. All submissions must include a return postal address and an electronic mail address. Receipt of the submissions will be acknowledged by e-mail within 2 days. The proceedings for the workshop will be published by the ACM Press. IMPORTANT DATES Please note: Due to the short time from submission to publication of the proceedings, the submission deadlines given above are firm. - 5:00 PM EDT (= 21:00 UTC), September 27, 2002 Deadline for submission of papers - Friday, Nov. 8, 2002 Notification of acceptance - Monday, Dec. 2, 2002 Camera-ready copy due - Saturday, Jan. 18, 2003 TLDI'03 in New Orleans PROGRAM CHAIR Peter Lee School of Computer Science 5000 Forbes Avenue Carnegie Mellon University Pittsburgh, Pennsylvanie 15213-3891 E-mail: petel(a)cs.cmu.edu Tel.: +1-412-268-3049 Fax: +1-412-268-5577 GENERAL CHAIR Zhong Shao Department of Computer Science 51 Prospect Street Yale University New Haven, Connecticut 06520-8285 E-mail: shao(a)cs.yale.edu Tel: +1-203-432-6828 Fax:+1-203-432-0593 PROGRAM COMMITTEE Alex Aiken, University of California, Berkeley Andrew Appel, Princeton University David F. Bacon, IBM T.J. Watson Research Center Manuel Fahndrich, Microsoft Research Matthew Flatt, University of Utah Atsushi Igarashi, Kyoto University Peter Lee, Carnegie Mellon University Xavier Leroy, INRIA Christine Paulin-Mohring, University of Paris South Scott Smith, The Johns Hopkins University Philip Wadler, Avaya Labs

1 0

�� ChinaWp ��ؿ�
by �� 24 Jun '02

24 Jun '02

您好，亲爱的朋友您的朋友华商网―ChinaWp 给您寄来了一封精美的贺卡！现在保存在"卡秀 Cardshow " (将保存30天）。请点击以下地址观看您的贺卡： http://www17.kaxiu.com/usercard00/10248829932110970135085XP_0.htm 愿您今天有份愉快的好心情！ *************************************************************** 心灵互动，卡秀沟通！ http://www.kaxiu.com/ *************************************************************** Hi,亲爱的朋友 This is a nice E-greeting from your friend 华商网―ChinaWp ! Go and pick it up at: http://www17.kaxiu.com/usercard00/10248829932110970135085XP_0.htm This personal greeting will be available for 30 days. Hope you enjoy it and have fun! *************************************************************** Free E-greeting at Cardshow ---- http://www.kaxiu.com *************************************************************** 使用极星邮件群发，无须通过邮件服务器，直达对方邮箱，速度绝对一流！下载网址：http://www.lovexin.com，更多免费的超酷软件等你来下…… ---------------------------------------------------- INFORMATION This message has been sent using a trial-run version of the TSmtpRelayServer Delphi Component. ----------------------------------------------------

1 0

Register before July 12: Advanced Functional Programming Summer School
by Johan Jeuring 24 Jun '02

24 Jun '02

Last registration date July 12. About 10 places left. -- Johan Jeuring Summer School and Workshop on Advanced Functional Programming St Anne's College, Oxford, UK 19th to 24th August 2002 http://www.functional-programming.org/afp/afp4 In conjunction with Summer School and Workshop on Generic Programming Call for participation This is the fourth school in a series on schools on Advanced Functional Programming. Previous schools were held in Baastad, Sweden (1995, LNCS 925), Olympia, Washington (LNCS 1129), and Braga, Portugal (LNCS 1608). We have recruited a group of excellent lecturers on advanced technologies in Functional Programming. ************ Lecturers ************ * Richard Bird (University of Oxford) and Jeremy Gibbons (University of Oxford): Arithmetic Coding with Folds and Unfolds * Manuel Chakravarty (University of New South Wales): Fast Arrays in Haskell * Matthias Felleisen (Northeastern University): Developing Interactive Web Programs in DrScheme * Cedric Fournet (Microsoft Research) and Fabrice Le Fessant (INRIA Rocquencourt): Jocaml3, a Language for Concurrent, Distributed and Mobile Programming * Paul Hudak (Yale University): Robots, Arrows and Functional Reactive Programming * Koen Claessen (Chalmers University of Tecnology) and Colin Runciman (University of York): Testing and Tracing Lazy Functional Programs * Philip Wadler (Avaya Labs): XQuery: A Typed Functional Language for Querying XML In addition, on the afternoon of Monday 19th August there will be a half-day Introduction to Functional Programming, presented by Graham Hutton (University of Nottingham). ************ Deadlines ************ For registration: 12th July 2002 ************ Organizers ************ Johan Jeuring (Utrecht University) Simon Peyton Jones (Microsoft Research) ************ Further information ************ Web: http://www.functional-programming.org/afp/afp4/info.html PDF poster: http://www.functional-programming.org/afp/afp4/afp-poster.pdf Email: afp-info(a)functional-programming.org Post: AFP, c/o Jane Ellory, Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, United Kingdom. Fax: +44 1865 273839; mark "fao SSAFP (Jane Ellory)"

1 0

Re: HaXml Help
by D.J.Steinitz 23 Jun '02

23 Jun '02

I've now managed to write a program to generate the relevant instances. So I don't get the error messages I reported. However, ghc is taking an enormous amount of time compiling. It's now at the desugaring stage ( I've run it with -v2). Dominic.

1 0

Biz Kurduk Ordan Biliyoruz
by �leti... 22 Jun '02

22 Jun '02

1 0

��ֻҪ80Ԫ��Ż�!!!!
by ��ȷ� 22 Jun '02

22 Jun '02

�𾴵Ŀͻ�� ã��˾��רҵ��ṩ�̡��Żݵļ۸񼰸��ȶ��Ӯ��˹��ͻ��Ŀ϶�� 80Ԫ �� 300Ԫ 200M(��HTML)�͹��ֻ��150Ԫ 60M(asp,access)��ֻ��236Ԫ 200M(asp,access)��ֻ��336Ԫ ��......��http://www.ondns.com ��ȫ��Żݶ�ࡣ ��QQ��1761020 MAIL��web@ondns.com��ȡ��۸�� ˳ף ��w�� æ�д��б�Ǹ��粻��յ��ʼ��ţ�help@ondns.com ============================================ �ͻ�רԱ��Ф�� 绰��0592-5557491��5557492 QQ:1761020 ��棺0592-5557491 http://www.ondns.com mail:web@ondns.com ============================================ ʹ�ü��ʼ�Ⱥ��ͨ��ʼ��ֱ��Է��䣬�ٶȾ��һ�� ַ��http://www.lovexin.com��ѵĳ��¡�� ---------------------------------------------------- INFORMATION This message has been sent using a trial-run version of the TSmtpRelayServer Delphi Component. ----------------------------------------------------

1 0