- Haskell - Haskell.org

Re: Counting Constructors
by Marcin 'Qrczak' Kowalczyk 18 Jul '01

18 Jul '01

Tue, 17 Jul 2001 12:08:51 +0200 (MEST), Tobias Haeberlein <T.Haeberlein(a)gmx.de> pisze: > show (Succ ( ... (Succ Zero)..)) = n > (where n is the number of Succ's) > and > > show (Succ ( ... (Succ x)..)) = show x > (when x != Zero) This is not possible in Haskell 98 - you can't overload an operation on "any type except this one". There are no "negative assertions" or "exceptions". It might be possible in Hugs run with -98 option (define "instance Count a" and "instance Count a => Count (Bind a)" and "instance Count a => Show (Bind a)", where class Count has a function of type a->Int), but I would not be surprised if it didn't work correctly in all cases, e.g. if the answer was too small sometimes. Overlapped instances is not a well behaved concept. -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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Dead code detection
by Pertti Kellomäki 18 Jul '01

18 Jul '01

I am working with a fairly rapidly changing code base, with another person besides me making changes. Can any of the Haskell compilers warn about unused function definitions, or does a similar standalone tool exist? I am fairly sure the code base includes redundant definitions that just clutter up the source, and I would like to be able to detect them easily. Thanks, -- pertti

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RE: Dead code detection
by Simon Peyton-Jones 18 Jul '01

18 Jul '01

GHC will report unused bindings (-fwarn-unused-binds) but only within a module. If it's exported, GHC doesn't help you. I'm sure GHC itself has plenty of dead code that only a global analysis can spot! GHC's interface file for a module reports all the imported things that the module depends on. So the raw material for a global analyser is in place. Simon | -----Original Message----- | From: Pertti Kellomäki [mailto:pk@cs.tut.fi] | Sent: 18 July 2001 11:43 | To: haskell(a)haskell.org | Subject: Dead code detection | | | I am working with a fairly rapidly changing code base, | with another person besides me making changes. Can any of | the Haskell compilers warn about unused function definitions, | or does a similar standalone tool exist? I am fairly sure the | code base includes redundant definitions that just clutter up | the source, and I would like to be able to detect them easily. | | Thanks, | -- | pertti | | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell |

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BABEL'01: Preliminary programme and Call for Participation
by Andrew Kennedy 17 Jul '01

17 Jul '01

Call for Participation BABEL 2001 First workshop on multi-language infrastructure and interoperability. Part of PLI 2001 Firenze, Italy. 8th September 2001. http://research.microsoft.com/~nick/babel01.htm Preliminary programme now available at http://research.microsoft.com/~nick/babel01prog.htm AIMS AND SCOPE Recent years have seen a resurgence of interest in multi-language tools and intermediate languages, and in interoperability between programs and components written in different programming languages. Shared infrastructure such as code generators, analysis tools and garbage collectors can greatly ease the task of producing a high-quality implementation of a new programming language, whilst being able to interoperate easily with code written in existing languages is essential for such an implementation to be useful in practice. This workshop aims to bring together researchers and developers working on multi-language integration. REGISTRATION http://www.regmaster.com/pli2001.html Note that the deadline for the early registration rate is JULY 25. PROGRAMME COMMITTEE Nick Benton (chair) Microsoft Research Fergus Henderson University of Melbourne Andrew Kennedy (organiser) Microsoft Research Greg Morrisett Cornell University Martin Odersky Ecole Polytechnique Fédérale de Lausanne John Reppy Bell Labs Andrew Tolmach Portland State University David Wakeling University of Exeter PRELIMINARY PROGRAMME http://research.microsoft.com/~nick/babel01prog.htm 9:00-10:00. Invited talk Towards a Principled Multi-Language Infrastructure Zhong Shao (Yale University) 10:30-12:30. Session 1 A framework for interoperability Kathleen Fisher (AT&T Labs, Research), Riccardo Pucella (Cornell University) and John Reppy (Lucent Technologies, Bell Labs) Alice in the Land of Oz - An Interoperability-based Implementation of a Functional Language on Top of a Relational Language Leif Kornstaedt (Universität des Saarlandes) No-Longer-Foreign: Teaching an ML compiler to speak C "natively" Matthias Blume (Lucent Technologies, Bell Labs) ILX: Extending the .NET Common IL for Functional Language Interoperability Don Syme (Microsoft Research, Cambridge) 14:00-15:30. Session 2 Compiling Mercury to the .NET Common Language Runtime Tyson Dowd, Fergus Henderson (University of Melbourne) and Peter Ross (Mission Critical, Belgium) Object-Oriented Style Overloading for Haskell Mark Shields and Simon Peyton Jones (Microsoft Research, Cambridge) Annotations for Portable Intermediate Languages Fermin Reig (University of Glasgow) 16:00-17:30. Session 3 Active Oberon for .NET: An Exercise in Object Model Mapping Jurg Gutknecht (ETH Zurich) Language-Agnostic Approaches to Mobile Code Peter Housel, Christian Stork, Vivek Haldar, Niall Dalton and Michael Franz (University of California, Irvine) Tail call elimination on the Java Virtual Machine Michel Schinz and Martin Odersky (Ecole Polytechnique Fédérale de Lausanne)

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Dealing with implementation differences
by Pertti Kellomäki 17 Jul '01

17 Jul '01

Hello all, How does one deal cleanly with implementation differences, e.g. things like isAscii being defined in Hugs but not in GHC? I'd hate to resort to Makefile trickery and preprocessing. Btw, the reason I want to run the same sources with Hugs and GHC is that I have a compiler whose parser is generated with Happy. Compiling the parser on a smallish computer takes ages and I don't need the efficiency at this stage anyway. On the other hand, I find the error messages given by GHC very good. If someone can suggest another compiler to try out or a way to reduce the time needed for compiling the parser, I'd be grateful. The parser is about 3500 lines of Haskell. -- Pertti

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Counting Constructors
by Tobias Haeberlein 17 Jul '01

17 Jul '01

I want a show - instance for that type: data Bind a = Zero | Succ a resp. for the types (Bind ( ... (Bind a)...)) showing the following: show (Succ ( ... (Succ Zero)..)) = n (where n is the number of Succ's) and show (Succ ( ... (Succ x)..)) = show x (when x != Zero) ------------------------------------------------ And - a very similar problem - i'd like to have a function 'count' which get something of type 'Bind' and returns a value of type (Either Int a): count ((Succ ( ... (Succ Zero)..)) = Left n (n = #succ's) and count (Succ ( ... (Succ x)..)) = Right x (x != Zero) ------------------------------------------------- Does anyone know, how to define those functions in haskell/hugs ?? (Are they defineable at all?) Thanks, -Tobi -- GMX - Die Kommunikationsplattform im Internet. http://www.gmx.net GMX Tipp: Machen Sie Ihr Hobby zu Geld bei unserem Partner 1&1! http://profiseller.de/info/index.php3?ac=OM.PS.PS003K00596T0409a

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Re: Dealing with implementation differences
by Wolfgang Lux 17 Jul '01

17 Jul '01

Hello, > How does one deal cleanly with implementation differences, e.g. things > like > isAscii being defined in Hugs but not in GHC? I'd hate to resort to > Makefile > trickery and preprocessing. You can try to use some special compatibility module where you collect all the workarounds for the implmentation differences. But in this particular you should better read the (library) report and simply import the Char module (from where isAscii should be exported -- Hugs still exports it from the Prelude though it shouldn't). Wolfgang -- Wolfgang Lux Phone: +49-251-83-38263 Institut fuer Wirtschaftinformatik FAX: +49-251-83-38259 Universitaet Muenster Email: wlux(a)uni-muenster.de

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RE: Dealing with implementation differences
by Simon Peyton-Jones 17 Jul '01

17 Jul '01

| How does one deal cleanly with implementation differences, | e.g. things like isAscii being defined in Hugs but not in | GHC? I'd hate to resort to Makefile trickery and preprocessing. isAscii is certainly defined in GHC. It's in module Char, like the language definition says. | Btw, the reason I want to run the same sources with Hugs and | GHC is that I have a compiler whose parser is generated with | Happy. Provided you stick to Haskell98, the same sources should run on both. | Compiling the parser on a smallish computer takes ages | and I don't need the efficiency at this stage anyway. On the | other hand, I find the error messages given by GHC very good. | If someone can suggest another compiler to try out or a way | to reduce the time needed for compiling the parser, I'd be | grateful. The parser is about 3500 lines of Haskell. Hugs compiles really fast. The interactive version of GHC compiles much slower, but much faster than the batch version. ghc --interactive. [GHC 5.02 at least.] Simon

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Haskell Report (again)
by Simon Peyton-Jones 17 Jul '01

17 Jul '01

Folks Apart from a recent hiatus over module qualified names, the revised Haskell report is done. I sent round a message about the module-name question, which elicited no complaints, so I have incorporated the changes (see the bugs page, items dated [July 2001]). As ever, the draft is at http://research.microsoft.com/~simonpj/haskell98-revised I'm really hoping this is the final version, but experience suggests that whenever I say that someone discovers an entirely new question! So I'm putting it out again for you to pick over. Comments please. If I hear nothing by end July I'll freeze it then. Simon

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FLOPS 2002, First Call for Papers
by Zhenjiang Hu 15 Jul '01

15 Jul '01

We apologize, if you receive this message more than once. ********************************************************************* * * * CALL FOR PAPERS * * * * Sixth International Symposium on Functional and Logic Programming * * (FLOPS 2002) * * (Co-located with ACM SIGPLAN Aisa-PEPM 2002) * * * * University of Aizu, Aizu, Japan * * September 15--17, 2002 * * * * http://www.ipl.t.u-tokyo.ac.jp/FLOPS2002/ * * * ********************************************************************* Background ========== The symposium is a forum for research on all issues concerning functional programming and logic programming. In particular, it wants to stimulate the cross-fertilization as well as integration of the two paradigms. The symposium takes place about every 1.5 years in Japan. Previous FLOPS meetings were held in Fuji Susuno (1995), Shonan Village (1996), Kyoto(1998), Tsukuba (1999), and Tokyo (2001). Topics ====== The Sixth International Symposium on Functional and Logic Programming (FLOPS 2002) solicits original papers in all areas of functional and logic programming, including (but not limited to): * Language issues: language design and constructs, programming methodology, integration of paradigms, interfacing with other languages, type systems, constraints, concurrency and distributed computing * Foundations: semantics, rewrite systems and narrowing, type theory, proof systems * Implementation: compilation techniques, memory management, program analysis and transformation, partial evaluation, parallelism * Applications: case studies, real-world applications, graphical user interfaces, internet applications, database connection, formal methods and model checking Submissions =========== Submissions must be unpublished and not submitted for publication elsewhere. Submissions should fall into one of the following two categories: 1. Regular research papers: they should describe new results and will be judged on originality, correctness and significance. 2. System descriptions: they should contain a link to a working system and will be judged on originality, usefulness and design. All submissions must be written in English. Regular research papers can be up to 15 proceedings pages long, system descriptions will be up to 4 pages long. 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 indicate the submission category. Regular research papers should be supported by proofs and/or experimental results. In case of lack of space, this supporting information should be made accesible otherwise (e.g. a link to a web page, or an appendix). Submission is Web-based. In order to submit a paper, authors should fill in the submission form available at http://www.ucm.es/info/flops2002/www/submit.html where more detailed instructions are given. If submission through the Web is not possible, five hard copies may be sent to Mario Rodriguez-Artalejo Universidad Complutense de Madrid Departamento de Sistemas Informaticos y Programacion Edificio Fac. Matematicas Av. Complutense s/n 28040 Madrid, Spain Publication and presentation of accepted contributions ====================================================== The Proceedings of FLOPS 2002 will be published by Springer Verlag in the LNCS series. They will be available at the conference. One author of each accepted contribution is expected to attend the Symposium in order to present it. Presentations of regular research papers will be scheduled for 30 minutes, including questions from the audience. System presentations will be scheduled for 15 minutes. Important Dates =============== Submission Deadline: March 1, 2002 Notification: May 21, 2002 Final Version: June 25, 2002 Symposium: September 15--17, 2002 Program Co-Chairs ================= Zhenjiang Hu University of Tokyo, Japan Mario Rodriguez-Artalejo Universidad Complutense, Madrid, Spain E-Mail: flops2002(a)ucm.es Program Committee ================= Maria Alpuente Technical University of Valencia, Spain Wei-Ngan Chin National University of Singapore, Singapore Pierre Deransart INRIA-Rocquencourt, France Moreno Falaschi University of Udine, Italy Michael Hanus University of Kiel, Germany Zhenjiang Hu (Co-Chair) University of Tokyo, Japan Jan Maluszynski Linkoeping University, Sweden Aart Middeldorp University of Tsukuba, Japan Gopalan Nadathur University of Minnesota, USA Susumu Nishimura Kyoto University, Japan Catuscia Palamidessi The Pennsylvania State University, USA Mario Rodriguez-Artalejo (Co-Chair) Universidad Complutense, Madrid, Spain Francesca Rossi University of Padova, Italy Harald Sondergaard The University of Melbourne, Australia Kazunori Ueda Waseda University, Japan Kwangkeun Yi KAIST, Korea Local Arrangements Chair ======================== Taro Suzuki University of Aizu, Japan Sponsors ======== Sponsored by: Japan Society of Software Science and Technology (JSSST), Special Interest Group on Principles of Programming. In cooperation with: Association for Logic Programming (ALP).

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