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for all quantifier
by peter＠premise.demon.co.uk 09 Jun '03

09 Jun '03

On the hskell list, spj wrote > I forget whether I've aired this on the list, but I'm seriously > thinking = that we should change 'forall' to 'exists' in existential > data constructors Thanks! It made me wonder what colour the sky is on planet Haskell. >From a Curry-Howard point of view, (I think) the quantifiers are currently the wrong way round. It is actually painful! Peter Hancock

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Multiparameter class confusion
by Graham Klyne 09 Jun '03

09 Jun '03

There is a recurring difficulty I'm having using multiparameter classes. Most recently, I have a class Rule: [[ class (Expression ex, Eq (rl ex)) => Rule rl ex where ... ]] Which I wish to instantiate for a type GraphClosure via something like: [[ instance (Label lb, LDGraph lg lb) => Expression (lg lb) where ... data (Label lb, LDGraph lg lb) => GraphClosure lg lb = ... instance Rule GraphClosure (NSGraph RDFLabel) where ... ]] This gives an error that I think is indicative of a kind error in the use of GraphClosure. If I unbracket the (NSGraph RDFLabel) then the error transfers to the use of Rule. I think that what I really *want* to do here is change the kind of GraphClosure to be (* -> *) rather than (* -> * -> *). But if I try this: [[ data (Label lb, LDGraph lg lb) => GraphClosure (lg lb) = ... ]] a syntax error is reported by Hugs and GHC. If I simply drop lb from the definition of GraphClosure, I get different errors because the type lb (and its associated contraint) is significant to its implementation [Later...] After further trial-and-error, I find that by reversing the arguments to GraphClosure and rearranging some other type signatures thus: [[ data (Label lb, Eq lg) => GraphClosure lb lg = ... ]] and [[ instance Rule (GraphClosure RDFLabel) RDFGraph where ]] I can get things to compile. But I note that I'm forced to drop the LDGraph constraint from the declaration of GraphClosure. This is all feeling rather like black magic to me. Does it really all need to be this confusing, or am I overlooking some fundamental? #g ------------------- Graham Klyne <GK(a)NineByNine.org> PGP: 0FAA 69FF C083 000B A2E9 A131 01B9 1C7A DBCA CB5E

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RE: Typesafe MRef with a regular monad
by Simon Marlow 09 Jun '03

09 Jun '03

Simon P.J. writes: > ... So it's reasonable that there should be some language extension. > I'm just looking for the minimal such extension. unsafeCoerce# is quite a minimal extension :-) Cheers, Simon

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ANNOUNCE: HSHGL 3.00
by Alastair Reid 09 Jun '03

09 Jun '03

HSHGL 3.00 A Portable Graphics Library In preparation for a major release of HSHGL, we are making an alpha release for folk to play with. This release only works with X11 and GHC (it almost certainly still runs on Hugs too but we haven't tested recently). We welcome bug reports, comments on how the system is packaged, the web page, examples, comments from those who build binary and source packages, etc. and especially welcome comments accompanied by patches or cvs commit messages. We are pleased to announce a new release of the HGL: a portable graphics library. The HGL gives the programmer access to the most interesting and portable parts of the Win32 and X11 library. The library is distributed as open source and is suitable for use in teaching and applications. This version supports: Filled and unfilled 2-dimensional objects (text, lines, polygons, ellipses). Bitmaps (Win32 version only, for now). Control over text alignment, fonts, color. Simple input events (keyboard, mouse, window resize) to support reactivity. Timers and double-buffering to support simple animation. Use of concurrency to avoid the usual inversion of the code associated with event-loop programming. Multiple windows may be handled at one time. To keep the library simple and portable, the library makes no attempt to support: User interface widgets (menus, toolbars, dialog boxes, etc.) Palette manipulation and other advanced features. Many kinds of input event. This release is only for X11 and GHC. We hope to have a Win32 release soon. The library can be downloaded from: http://www.haskell.org/graphics/. You will need GHC 6.0 and HSX11 1.00 to build the library. Installation instructions are in HGL-3.00/INSTALL. Bug reports should be sent to alastair at reid-consulting-uk.ltd.uk Enjoy! -- Alastair Reid http://www.reid-consulting-uk.ltd.uk/

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ANNOUNCE: HSX11 1.00
by Alastair Reid 09 Jun '03

09 Jun '03

HSX11 1.00 A Haskell binding for X11 In preparation for a major release of HSX11, we are making an alpha release for folk to play with. We welcome bug reports, comments on how the system is packaged, the web page, examples, comments from those who build binary and source packages, etc. and especially welcome comments accompanied by patches or cvs commit messages. We are pleased to announce a new release of the Haskell binding for X11 which provides a binding to most of Xlib. The library is distributed as open source. The library can be downloaded from: http://www.haskell.org/packages. You will need GreenCard 3.00 and GHC 6.0 to build the library. Installation instructions are in HSX11-1.0/INSTALL. Bug reports should be sent to X11(a)reid-consulting-uk.ltd.uk Enjoy! -- Alastair Reid http://www.reid-consulting-uk.ltd.uk ps Though they are really independent issues, it is worth noting two other things about this release: 1) We have created a page http://www.haskell.org/packages which contains a list of Haskell packages and acts as a 'homepage' for packages like this that are too small to justofy a full homepage. Please feed this page. 2) This release is based on the GHC team's fptools infrastructure which is evolving in the direction of supporting packages like this one. We welcome comments on this infrastructure and, especially, offers to help make it better.

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ANNOUNCE: buddha 0.7 released
by Bernard James POPE 09 Jun '03

09 Jun '03

Announcing the release of buddha version 0.7 -------------------------------------------- www.cs.mu.oz.au/~bjpop/buddha Buddha is a declarative debugger for Haskell 98. It is based on program transformation and relies on GHC version 5.04 or greater (but not version 6 yet). It also needs GHC's libraries compiled for profiling. New in this release: - support for deriving Eq, Ord, Enum, Bounded, Show, Read, - more efficient transformation, - standard module Random now supported. Features still missing: - record syntax, - some standard libraries (notably: Ratio, Numeric, Directory, Time), - mutually recursive modules, - deriving Ix. Platforms supported: - tested on linux, Mac OSX, - (should work in any unix-like environment), - not tested on Windows (sorry). Note that buddha does not yet work with GHC version 6.0. This will be fixed in coming releases. Cheers, Bernie.

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ANNOUNCE: GreenCard 3.01
by Alastair Reid 09 Jun '03

09 Jun '03

Green Card 3.01 A Foreign Function Interface Preprocessor for Haskell In preparation for a major release of Green Card, we are making an alpha release for folk to play with. This release fixes a bunch of little details that people commented on in the 3.00 release. We welcome bug reports, comments on how the system is packaged, the web page, examples, comments from those who build binary and source packages, etc. and especially welcome comments accompanied by patches or cvs commit messages. This is a major release of Green Card, a foreign function interface pre-processor for Haskell. GreenCard 3.01 has been updated to work with Haskell compilers that support the foreign function interface and hierarchial libraries. The major changes from the 2.x series of GreenCard are: - Support for hierarchial module names. - The StdDIS module has been renamed Foreign.GreenCard. - Support for all the types provided by the FFI specification. - Removed deprecated types like Addr: use the Ptr type provided by the FFI specification. - The Hugs and NHC-specific backends has been removed since FFI support renders it irrelevant. Pointers to downloadable distributions, documentation etc. is available via the Green Card home page: http://www.haskell.org/greencard/ Please send any bug reports or suggestions for improvements to alastair at reid-consulting-uk.ltd.uk. Enjoy! -- Alastair Reid http://www.reid-consulting-uk.ltd.uk/

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[ANNOUNCE] rsa-haskell 2.0.0
by David Sankel 08 Jun '03

08 Jun '03

=================== rsa-haskell 2.0.0 =================== RSA implementation in Haskell (rsa-haskell) contains the Simple and Strong Cryptography program set and Haskell libraries of several cryptographic standards. The libraries include haskell implementations of SHA1, EME-OAEP, EMSA-PSS, MGF, RSAES-OAEP, and RSA-PSS. These standards implement signature/verification, strong cryptography, and hashing. Also included in the library is a general number theory library. The Simple and Strong Cryptography program set contains simple programs for encrypting and decrypting files with public key cryptography as well as signature verification with public key cryptography. Changes from 1.2.0 to 2.0.0: ---------------------------- Added implementation for several standard cryptographic protocols including SHA1, EME-OAEP, EMSA-PSS, MGF, RSAES-OAEP, and RSA-PSS. Refactored client code. Program names are now ssdecrypt, ssencrypt, sskeygen, sssign, and ssverify. Renamed client programs to the Simple and Strong Cryptography program set. see http://www.electronconsulting.com/rsa-haskell for details. David J. Sankel

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ITCLS 2003 Call for Papers and Participation
by colognet-ws＠clip.dia.fi.upm.es 06 Jun '03

06 Jun '03

[Apologies if you receive this more than once] Call for Papers and Participation COLOGNET Workshop on Implementation Technology for Computational Logic Systems (ITCLS 2003) Satellite Workshop of FME 2003 Symposium 9 September 2003, Pisa, Italy http://clip.dia.fi.upm.es/Conferences/ITCLS-2003/ CoLogNet, the European Network of Excellence in Computational Logic is organizing the Second Workshop on Implementation Technology for Computational Logic Systems (ITCLS) as a satellite workshop of Formal Methods 2003, to take place in Pisa. The previous edition was held in September 2002 in Madrid, affiliated with Logic-based Program Development and Transformation (LOPSTR'02), and co-located with the International Static Analysis Symposium (SAS'02) and the APPIA-GULP-PRODE Joint Conference on Declarative Programming (AGP'02). The workshop is a forum open to both academia and industry and whose aim is to present and discuss work (possibly in progress) related to the topics mentioned below. The ITCLS workshop builds on the tradition of the series of workshops on Implementations of Logic Programming Systems held in the context of COMPULOG NET, the former Network of Excellence in Computational Logic, but opens up its scope to a broader use of logic and formal methods within computational systems. ITCLS 2003 focuses on implementation techniques from the different areas addressed by CoLogNet. The aim is to bring together researchers from fields such as automated reasoning, formal methods and theorem proving, natural language processing, constraint logic programming, inductive logic programming, non-monotonic logic programming, etc. in order to share common problems and solutions regarding implementation and usability issues which arise in formal and logic-based computational systems. Topics of interest for this workshop include, but are not limited to: * Implementation techniques for all aspects of the implementation of systems related to computational logic and formal systems, including: + Formal Methods and its relationship with Computational Logic, + Compiling Specifications, + Theorem Proving, + Non-monotonic Reasoning, Higher Order, Linear Logics, + Logic Programming, + Constraint Programming, and + Natural Language Processing * Environments for computational logic and formal systems, including: + User-interfaces and User-needs, + Software Development, + Debugging and Visualization Techniques, and + Interfaces to Other (possibly Computational Logic) Systems PROGRAMME The workshop will take place during the afternoon and evening of September 9th. The programme will consist of an invited talk (to be announced later) and the presentation of the accepted papers. SUBMISSIONS AND DEADLINES Authors are invited to contribute to the workshop by submitting extended abstracts (6 pages maximum) or full papers (12 pages maximum) on the workshop themes. Limits are strict, and the llncs format (http://www.springer.de/comp/lncs/authors.html) must be used. Submissions are to be sent in PS or PDF format to the organizing committee by emailing them to: colognet-ws-submission_at_clip.dia.fi.upm.es (substitute _at_ by the @ symbol to send email). Submissions originally prepared with LaTeX are highly encouraged, as this will help in preparing the final proceedings, which will be available at the workshop in printed form, as well as electronically. The table below highlights the important dates: Submission deadline: July 7 Notification to authors: July 28 Camera-ready copies: August 15 Workshop: September 9 ORGANIZING COMMITTEE Jesus Correas, UPM, Madrid, Spain Manuel Hermenegildo, UPM, Madrid, Spain Manuel Carro, UPM, Madrid, Spain Christian Schulte, KTH, Stockholm, Sweden Please address any question directly related to the workshop to colognet-ws_at_clip.dia.fi.upm.es (substitute _at_ by @).

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Early phase of Semantic Web inferencing skeleton in Haskell
by Graham Klyne 06 Jun '03

06 Jun '03

This announces availability of an early phase of my Semantic Web inferencing skeleton in Haskell (Swish), which has been posted on my web site at: http://www.ninebynine.org/Software/Intro.html#Swish (links) http://www.ninebynine.org/Software/Swish-0.1.zip (software source+doc) http://www.ninebynine.org/Software/swish-0.1.html (documentation) For Semantic Web information, see: http://www.w3.org/2001/sw/ This first phase is mainly a platform for future development, consisting of: - A data types and functions for manipulating RDF models, with a simple interface for creating, combining, accessing and comparing RDF graphs - A Notation3 parser. Notation3 is an alternative syntax for RDF, easier than RDF/XML: for some purposes. For information, see: http://www.w3.org/DesignIssues/Notation3.html http://www.w3.org/2000/10/swap/doc/ - A basic Notation3 formatter - A command-line utility for testing the above - Numerous test programs The code's a bit tacky (by Haskell standards) but it does seem to work pretty reliably. It has been tested with the Hugs and GHC Haskell systems. As it stands, it doesn't do much other than testing for RDF graph structural equivalence and merging graphs (renaming nodes as needed to "free variable" type conflicts). I'm currently working on designing some modules for doing simple queries and inferences on the RDF data. #g ------------------- Graham Klyne <GK(a)NineByNine.org> PGP: 0FAA 69FF C083 000B A2E9 A131 01B9 1C7A DBCA CB5E

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