February 2005 - Haskell

RE: [Haskell] sugar for extensible types (was: class associated types, via GADTs.)
by Simon Marlow 04 Mar '05

04 Mar '05

On 16 February 2005 08:08, Ralf Laemmel wrote: > Assoc types and GADTs are great but > I am still too fond of encoding extensible datatypes with (open) > classes. > I contributed to some related discussion at comp.compilers a while > ago [1]. The Haskell code samples are worth sharing (because they are > sooooo simple): > > http://homepages.cwi.nl/~ralf/OOHaskell/src/interpreter/nonextensible.hs > http://homepages.cwi.nl/~ralf/OOHaskell/src/interpreter/extensible.hs > (Note: *no* OOHaskell idioms used.) I wish we'd done exceptions like this. An extensible exception type is entirely possible, and using it is not hard either - see the attached file implemented in terms of the existing Control.Exception. For example: test = do x `catch` (\(IOException e) -> print e) `catch` (\(ArithException e) -> print e) and I make a new type into an exception like this: data T = ... deriving (Typeable, Show) instance Exception T this can replace DynExceptions and the strange catchJust/tryJust stuff in Control.Exception. Perhaps we can figure out a reasonable migration path that wouldn't break too much code in one go? Cheers, Simon

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Type of y f = f . f
by Jim Apple 02 Mar '05

02 Mar '05

Is there a type we can give to y f = f . f y id y head y fst are all typeable? Jim Apple

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Building a dynamic loadable Parsec parser
by Adam Turoff 28 Feb '05

28 Feb '05

Hi, I've got a little parser written using Parsec that I want to link into some C code. I start by compiling the Haskell sources like so: ghc -ffi -fglasgow-exts -main-is My_Init -c parse.hs When linking parse.o and parse_stub.o against my (additional) glue code, I get the following errors: Main.o(.text+0xc): undefined reference to `__stginit_ZCMain' Main.o(.text+0x14): undefined reference to `__stginit_ZCMain' Main.o(.text+0x20): undefined reference to `ZCMain_main_closure' Main.o(.text+0x24): undefined reference to `ZCMain_main_closure' I'm trying to build a .so that I can load into another process (via Tcl, actually). If I define a main function in my C glue code, these errors go away. But I can't have a main function in this .so. So, two questions: - is it possible to compile and link these .o files into a .so (on Solaris, using ghc 6.2.2)? - what do I need to do to create an entry point for this Haskell code that _isn't_ called main()? Thanks, -- Adam

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postgresql foreign function call segfaults
by Edwin Eyan Moragas 28 Feb '05

28 Feb '05

Hi Group, i'm trying to complete an haskell pgsql interface. all compiles well when using ghc's generated executable but it segfaults when i do a pqexec. -- PGresult *PQexec(PGconn *conn, const char *query); foreign import ccall "libpq-fe.h PQexec" pqexec::X_PGconn->CString->IO X_PGresult here's the offending code: create conn=do putStrLn "creating table products" putStrLn ("\t"++screate) q<- newCString screate -- segmentation fault here! rs<- pqexec conn q stat<- pqcmdstatus rs stats<-peekCString stat putStrLn ("\tstatus is: "++ show stats) ra<- pqcmdtuples rs ras<-peekCString ra putStrLn ("\trows affected is: "++ show ras) screate= "CREATE TABLE products (" ++ "product_no integer," ++ "name text," ++ "price numeric" ++")" i'm using pgsql 7.4, gcc 3.3.4, ghc 6.2.2 i tried compiling with -fvia-C and it doesn't finish compiling. i'm asking this question in the fear that i have done something wrong. i have posted my code the code, makefile and generated .hc file here: http://www.eyan.org/haskell/ -- kind regards, eyan http://www.eyan.org

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Call for Tutorials - ICTAC05
by Bernhard K. Aichernig 28 Feb '05

28 Feb '05

Call for Tutorials - ICTAC05 INTERNATIONAL COLLOQUIUM ON THEORETICAL ASPECTS OF COMPUTING Hanoi, Vietnam - 17--21 October, 2005 http://www.iist.unu.edu/ictac05 ===================== BACKGROUND AND OBJECTIVES ICTAC is an International Colloquium on Theoretical Aspects of Computing founded by the International Institute for Software Technology of the United Nations University (UNU-IIST). The aim of the colloquium is to bring together practitioners and researchers from academia, industry and government to present research results, and exchange experience, ideas, and solutions for their problems in theoretical aspects of computing.The colloquium is aimed particularly, but not exclusively, at participants from developing countries. We believe that this will help developing countries to strengthen their research, teaching and development in computer science and engineering, improve the links between developing countries and developed countries, and establish collaboration in research and education. The first ICTAC (ICTAC'04) was held in Guiyang, China and its proceedings were published as "ICTAC 2004: Theoretical Aspects of Computing", LNCS 3407. ICTAC'05 will have a technical program for five days including two days for tutorials and three days for a conference, and a training school for 5 days. The topics of the conference include, but are not limited to: - automata theory and formal languages - principles and semantics of programming languages - logics and their applications - software architectures and their description languages - software specification, refinement, and verification - model checking and theorem proving - formal techniques in software testing - models of object and component systems - coordination and feature interaction - integration of formal and engineering methods - service-oriented development - document-driven development - models of concurrency, security, and mobility - theory of parallel, distributed, and internet-based (grid) computing - real-time and embedded systems - type and category theory in computer science SPONSORS AND ORGANISATION ICTAC'05 will be organised jointly between the Institute of Information Technology of the Vietnamese Academy of Sciences and Technology (IoIT), the University of Technology of the Vietnam National University in Hanoi (UoT-VNU) and UNU-IIST. UNU-IIST, IoIT and UoT-VNU are also sponsors of ICTAC'05. There will be an one-week training school during 10--14 October 2005 before the conference. TUTORIAL SUBMISSION You are welcome to submit a proposal for a tutorial on any subject related to the topics listed above. All tutorial proposal submissions should have a detailed description of the tutorial contents, the time duration, and an extended abstract written in English. The extended abstract should not not exceed 5 pages in LNCS format (see http://www.springer.de/comp/lncs/authors.html for details). The extended abstract of the accepted tutorials will be published in the proceedings of the ICTAC05 conference which will be published by Springer in the Lecture Notes in Computer Science series. All queries and tutorial proposals should be sent to the program committee co-chairs Dang Van Hung, e-mail: dvh(a)iist.unu.edu, or Martin Wirsing, e-mail: wirsing(a)informatik.uni-muenchen.de. The deadline for tutorial proposal submission is 11 July 2005, and the notification of tutorial proposal acceptance is 25 July 2005. The date for tutorials is 17-18 October, 2005. ADVISORY COMMITTEE Dines Bjorner, Singapore Manfred Broy, Germany Jifeng He, UNU-IIST Mathai Joseph, India Shaoying Liu, Japan Zhiming Liu, UNU-IIST Jim Woodcock, UK Jose Luiz Fiadeiro, UK Tobias Nipkow, Germany PUBLICITY CHAIR Bernhard K. Aichernig, UNU-IIST ORGANISING COMMITTEE Le Hai Khoi, IoIT (co-chair) Ho Si Dam, UoT-VNU (co-chair) Nguyen Tue, UoT-VNU Bui The Duy, UoT-VNU Nguyen Viet Ha, UoT-VNU Vu Duc Thi, IoIT Le Quoc Hung, IoIT Do Nang Toan, IoIT Ngo Quoc Tao, IoIT PROGRAM COMMITTEE Marc Aiguier, France Keijiro Araki, Japan J.O.A. Ayeni, Nigeria Jay Bagga, USA Hubert Baumeister, Germany Michel Bidoit, France Jonathan Bowen, UK Victor A. Braberman, Argentina Cristian S. Calude, New Zealand Ana Cavalcanti, UK Yifeng Chen, UK Dang Van Hung, UNU-IIST (co-chair) Jim Davies, UK Janos Demetrovics, Hungary Jin Song Dong, Singapore Henning Dierks, Germany Do Long Van, Vietnam Marcelo F. Frias, Argentina Wan Fokkink, Netherlands Susanna Graf, France Valentin Goranko, South Africa Dimitar Guelev, Bulgaria Michael R. Hansen, Denmark Jozef Hooman, Netherlands Purush Iyer, USA Ryszard Janicki, Canada Takuya Katayama, Japan Maciej Koutny, UK Xuandong Li, China Antonia Lopes, Portugal Antoni Mazurkiewicz, Poland Hrushikesha Mohanty, India Ngo Quang Hung, USA Nguyen Cat Ho, Vietnam Paritosh Pandya, India Jean-Eric Pin, France Narjes Ben Rajeb, Tunisia R. Ramanujam, India. Anders P. Ravn, Denmark Gianna Reggio, Italy Wolfgang Reif, Germany Riadh Robbana, Tunisia Mark Ryan, UK Zaidi Sahnoun, Algeria Augusto Sampaio, Brazil Don Sannella, UK Bernhard Schaetz, Germany Andrea Maggiolo-Schettini, Italy Carolyn Talcott, USA P. S. Thiagarajan, Singapore Ji Wang, China Martin Wirsing, Germany (co-chair) Mingsheng Ying, China Jian Zhang, China Hongjun Zheng, USA -- Bernhard Aichernig, Research Fellow of UNU-IIST www.iist.unu.edu/~bka ---------------------------------------------------------------------- SEFM 2005: 3rd IEEE International Conference on Software Engineering and Formal Methods, Koblenz, Germany, 7.- 9. Sept. 2005 http://sefm2005.uni-koblenz.de ICTAC 2005: International Colloquium on Theoretical Aspects of Computing, Hanoi, Vietnam, 17-21 October, 2005 http://www.iist.unu.edu/ictac05/

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Re: [Haskell] Compiling GHC on Panther using darwin ports
by Gregory Wright 27 Feb '05

27 Feb '05

Hi Chris, Excellent news. Thank you for helping to track down the bug in the port. Best Wishes, Greg On Feb 27, 2005, at 1:37 PM, Chris Brown wrote: > Greg, > > That appears to be working now! Thanks very much for your help! > > Kind regards, > > Chris. > > > On 27 Feb 2005, at 18:00, Gregory Wright wrote: > >> >> Hi Chris, >> >> Portfile revision 14 is in cvs and (I hope) does what you need. >> Let me know if you have problems. >> >> If you have trouble, just try installing dlcompat by hand (sudo port >> install dlcompat) >> and ghc should built. But let me know if you have to resort to this >> so I can fix the portfile. >> >> The ghc build is somewhat of a hairball. Thanks for helping find these >> bugs. >> >> Best Wishes, >> Greg >> >> >> On Feb 27, 2005, at 12:11 PM, Chris Brown wrote: >> >>> Hi Greg, >>> >>> Thanks very much for your help, however I am still getting exactly >>> the same error message. >>> >>> I have done a cvs update in the darwinports directly and tried to >>> install ghc again (after a make clean). I have checked the revision >>> number of the portfile for ghc and it says it is revision number 13. >>> >>> Hope you can help further... >>> >>> Thanks, >>> >>> Chris. >>> >>> >>> On 27 Feb 2005, at 16:15, Gregory Wright wrote: >>> >>>> >>>> Hi Chris, >>>> >>>> Forget about my last message. I had accidentally introduced a bug >>>> in my last revision. I have updated the portfile; update from cvs >>>> and >>>> you should be ready to go. >>>> >>>> (The bootstrap compiler still depends on the darwinports dlcompat >>>> library, which was not a dependency of the port. It is now. I >>>> hope to >>>> remove this constraint and use the system dlcompat when ghc 6.4 >>>> appears in a few weeks.) >>>> >>>> Best Wishes, >>>> Greg >>>> >>>> >>>> >>>> On Feb 27, 2005, at 6:12 AM, Chris Brown wrote: >>>> >>>>> Hi, >>>>> >>>>> I am trying to install GHC on Mac OS X (Panther) using Darwin >>>>> Ports. When i run >>>>> >>>>> sudo port install ghc >>>>> >>>>> I get the following error message shortly into the compilation: >>>>> >>>>> ------------------------------------------------------------------- >>>>> ----- >>>>> ==fptools== make boot - --no-print-directory -r; >>>>> in >>>>> /Users/chrisbrown/darwinports/dports/lang/ghc/work/ghc-6.2.2/ghc/ >>>>> utils/hasktags >>>>> ------------------------------------------------------------------- >>>>> ----- >>>>> /Users/chrisbrown/darwinports/dports/lang/ghc/work/ghc-bootstrap/ >>>>> bin/ghc -M -optdep-f -optdep.depend -osuf o -H16m -O >>>>> -I/opt/local/include -L/opt/local/lib HaskTags.hs >>>>> dyld: >>>>> /Users/chrisbrown/darwinports/dports/lang/ghc/work/ghc-bootstrap/ >>>>> lib/ghc-6.2.2/ghc-6.2.2 can't open library: >>>>> /opt/local/lib/libdl.1.dylib (No such file or directory, errno = >>>>> 2) >>>>> make[3]: *** [depend] Trace/BPT trap >>>>> make[2]: *** [boot] Error 1 >>>>> make[1]: *** [boot] Error 1 >>>>> make: *** [build] Error 1 >>>>> >>>>> >>>>> I remember on Tiger this was because the portfile which tells >>>>> darwin ports what to do has a condition in it to compile the >>>>> bootstrap differently for panther or jaguar (and obviously not >>>>> tiger). >>>>> >>>>> Could anyone please help me to fix this compilation error? >>>>> >>>>> Thanks, >>>>> >>>>> Chris Brown. >>>>> >>>>> _______________________________________________ >>>>> Haskell mailing list >>>>> Haskell(a)haskell.org >>>>> http://www.haskell.org/mailman/listinfo/haskell >>>>> >>>> >>> >> >

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Encode module library
by Otakar Smrz 27 Feb '05

27 Feb '05

I might be wrong, but it seems there is no module library in Haskell that would provide a unified interface for converting strings from one encoding into another, be it Unicode Transformation Formats, the numerous 8-bit encodings, or some user-defined transliterations or transcriptions. Inspired by the Encode module in Perl, I have sketched an architecture of such an interface for Haskell. Let me give links to the proto-implementation and its documentation: http://ckl.mff.cuni.cz/smrz/Encode-0.01.zip http://ckl.mff.cuni.cz/smrz/Encode/doc/index.html There, I further discuss and illustrate how extending the library with new encodings would be done, and what the common data representation type might be. I would be happy for your comments and suggestions. Thank you, Otakar Smrz

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RE: [Haskell] par and forkIO
by Simon Peyton-Jones 25 Feb '05

25 Feb '05

Essentially not at present; but it's high on our list. Because of the fun we've been having with Software Transactional Memory (STM), which will be in GHC 6.4, and because of the multi-core machines that are coming right now, Simon and I are starting to think much more about genuine hardware concurrency, esp on multi-cores. We have not actually done anything yet, but I think we will soon. STM is described in a PPoPP paper on my home page http://research.microsoft.com/%7Esimonpj/papers/stm/index.htm Simon | -----Original Message----- | From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of S. Alexander | Jacobson | Sent: 24 February 2005 15:55 | To: Haskell Mailing List | Subject: [Haskell] par and forkIO | | Multicore and multi-cpu machines are getting more and more common. | | e.g. http://www.anandtech.com/systems/showdoc.aspx?i=2354&p=2 | and | http://www.electronicsweekly.com/articles/article.asp?liArticleID=38887& liArticleTypeID=1&liCategory | ID=1&liChannelID=114&liFlavourID=1&sSearch=&nPage=1 | | Do the current implementations of par and forkIO in e.g. GHC take | advantage multiple CPUs/cores or is special plumbing needed (GPH?)? | | -Alex- | | ______________________________________________________________ | S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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Call for participation WWV'05
by Santiago Escobar 25 Feb '05

25 Feb '05

-- We apologize for multiple copies -- ****************************************************************** ****************** Call for participation ****************** ****************************************************************** 1st International Workshop on Automated Specification and Verification of Web Sites (WWV'05) March 14-15 2005, Valencia, SPAIN http://www.dsic.upv.es/workshops/wwv05 ******************************************************************* WWV'05 will be held in Valencia, Spain at the Technical University of Valencia (Universidad Politecnica de Valencia): Universidad Politecnica de Valencia "Rectorado" Building - ground floor Congress Room number 1 Camino de Vera S/N 46022 Valencia (Spain) SCOPE The increased complexity of Web sites and the explosive growth of Web-based applications has turned their design and construction into a challenging problem. Nowadays, many companies have diverted their Web sites into interactive, completely-automated, Web-based applications (such as Amazon, on-line banking, or travel agencies) with a high complexity that requires appropriate specification and verification techniques and tools. Systematic, formal approaches to the analysis and verification can address the problems of this particular domain with automated and reliable tools that also incorporate semantic aspects. WWV'05 provides a forum for researchers from the communities of Rule-based programming, Automated Software Engineering, and Web-oriented research to facilitate the cross-fertilization and the advancement of hybrid methods that combine the three areas. The WWV'05 programme includes works on formal methods and techniques applied to Web sites, Web services or Web-based applications such as: * rule-based approaches to Web site analysis, certification, specification, verification, and optimization * formal models for describing and reasoning about Web sites * model-checking, synthesis and debugging of Web sites * abstract interpretation and program transformation applied to the semantic Web REGISTRATION Registration is web-based via the secure link: http://www.dsic.upv.es/workshops/wwv05/registration The deadline for early registration is March, 4th. ACCOMODATION The organization of the conference has blocked rooms for the days of the workshop in some conveniently located hotels in Valencia and in a university dormitory. These rooms will be blocked until March, 4th. After this day, we are not responsible for the accomodation. For further information, follow the link: http://www.dsic.upv.es/workshops/wwv05/valencia/accomodation.html FALLAS FESTIVAL The workshop coincides with the famous Valencia Fallas Festival (March 15 - 19) which is one of the biggest festivals in Spain. So make your reservations as soon as possible. INVITED SPEAKERS Shriram Krishnamurthi Brown University, USA Anthony Finkelstein University College London, UK PROGRAM CO-CHAIRS Maria Alpuente Technical University of Valencia, Spain Moreno Falaschi University of Siena, Italy WORKSHOP CHAIR Santiago Escobar Technical University of Valencia, Spain PROGRAM COMMITTEE Maria Alpuente Technical University of Valencia, Spain Sarat Babu CDAC, India Demis Ballis University of Udine, Italy Gilles Barthe INRIA Sophia-Antipolis, France Thierry Despeyroux INRIA Sophia-Antipolis, France Wolfgang Emmerich University College London, UK Santiago Escobar Technical University of Valencia, Spain Moreno Falaschi University of Siena, Italy Maria del Mar Gallardo Technical University of Malaga, Spain Furio Honsell University of Udine, Italy Giorgio Levi University of Pisa, Italy Jan Maluszynski LinkÃ¶ping University, Sweden Massimo Marchiori MIT Lab for Computer Science, USA Tiziana Margaria University of GÃ¶ttingen, Germany ACCEPTED PAPERS Regular Contributions - Gianluca Amato, Massimo Coppola, Stefania Gnesi, Francesca Scozzari and Laura Semini. Modeling Web Applications by the Multiple Levels of Integrity Policy. - Gregorio Diaz Descalzo, Juan Jose Pardo Mateo, M. Emilia Cambronero Piqueras, Valentin Valero Ruiz and Fernando Cuartero Gomez. Verification of Web Services with Timed Automata. - Bo Hu, Florian Lauck and Jan Scheffczyk. How Recent is a Web Document? - Javier Jesus Gutierrez Rodriguez, Maria Jose Escalona Cuaresma, Manuel Mejia Risoto and Jesus Torres Valderrama. Testing web applications in practice. - Martin Karusseit and Tiziana Margaria. Feature-based Modelling of a Complex, Online-Reconfigurable Decision Support Service. - Claude Kirchner, Helene Kirchner and Anderson Santana. Anchoring modularity in HTML. - Liquori Luigi, Honsell Furio and Rekha Redamalla. A Language for Safe Manipulation of Web Documents - Vicente Luque-Centeno, Carlos Delgado-Kloos, Jesus Arias-Fisteus and Luis Alvarez-alvarez. Web Accessibility Evaluation Tools: a survey and some improvements. - Frederic Rioux and Patrice Chalin. Improving the Quality of Web-based Enterprise Applications with Extended Static Checking: A Case Study. - Roger G. Stone. Validating Scripted Web-Pages. Position papers / Overviews of more extensive work - Shadi Abou-Zahra. Automated Web Site Accessibility Evaluation. - Temur Kutsia. Context Sequence Matching for XML. System demonstrations / Works in progress - David Crocker and John H. Warren. Generating commercial web applications from precise requirements and formal specifications. - Vicent Estruch, Cesar Ferri, Jose Hernandez-Orallo and M. Jose Ramirez-Quintana. Web Categorisation Using Distance-Based Decision Trees. - Javier Garcia Vivo and Demis Ballis. A Rewriting-based system for Web site Verification. - Salvador Lucas. Rewriting-based navigation of Web sites. - Josep Silva. Slicing XML Documents. - Marco Winckler, Eric Barboni, Christelle Farenc and Philippe Palanque. What Kind of Verification of Formal Navigation Modelling for Reliable and Usable Web Applications?

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Call for participation: Summerschool on Gen. and Transf. Techn. in SE, 4-8 July 2005, Braga
by Ralf Lammel 24 Feb '05

24 Feb '05

Please find attached the call for participation for the Summer School on Generative and Transformational Techniques in Software Engineering 4 - 8 July, 2005, Braga, Portugal http://www.di.uminho.pt/GTTSE2005 Registration is open. There are 17 confirmed tutorials and other presentations. -- Ralf Lammel http://homepages.cwi.nl/~ralf/

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