April 2002 - Haskell - Haskell.org

(no subject)
by patrick mwananaga 30 Apr '02

30 Apr '02

CONFIDENTIAL FROM MR PATRICK MWANANAGA. PHONE+31-612-798-459. REF: TRANSACTION REQEST. DEAR PARTNER. I am aware that it is amazing when a business proposal letter come From Some one that you Don"t know however, you address was to the consideration of your profile and i became aware of your credibility and co-operation in this transaction that would be profitable to both of us. I am Mr Patrick Mwananaga. The son of Dr Nanapanga Mwananaga.Finance Minister of Democratic Republic of Congo(DRC),presently i am in the Netherlands on a senior Legal Management course. Recently I was contacted by my father over the issue am to explain.Dr Nanapanga Mwananaga was appointed the finance Minister in the government of president Laurent Desire Kabila of the Democratic Republic of congo(DRC),Being close friend and also old school mate of president Laurent Desire Kabila, make them have trust in each other. Early Last year,a contract was awarded to a foreign company in congo minig corporation on Diamond mining.Before the contract was awarded to the foreign firm,a required amount was Agreed upon and was paid by the contrecting company to ensure that it is their favour. The money paid was (US$15. 500.000.00 Million United State Dollars) and was paid to the then president kabila through his finance minister Dr Nanapanga Mwananaga.There after the whole money was de-faced to avoid being traced by their political rivals,and was moved out to the Netherland through diplomatic channel. Now the box containing the money is with a financial deposit company in the Netherlands. Deposited as photographic materials with out the deposit company knowing the exact contents of the box, because the entire money was intentionally de-faced out mint stage. The code to the deposited box and the certificate of deposit and all the transfer documents are still with my father in congo,which will be send as soon as a trusted confident partner is found.Unfortunately president Laurent Kabila whom my father had his arrangement with was attacked in his home town, by one of his own body guard, but did not survive.now that his son has succeeds him,l will want us to use this opportunity to move the money out from the Netherlands to another safe place you will provide.lf you accept this proposal and ready to corporate with out directives you will be rewarded with 25% of the total sum,All areas for the smooth transaction is already being taken care off.Be rest assured that this business will attract no risk.For more clarification,you are to use the above telephone or e-mail. Yours sincerely Mr Patrick Mwananaga.

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HC&A Report (May edition) - LAST CALL
by C.Reinke 29 Apr '02

29 Apr '02

Dear Haskellers, over the last weeks, more and more of you have (been;-) volunteered to provide short summaries of recent and planned activities in your area of work with or on Haskell (for details, and for the current status, see http://www.haskell.org/communities/) Those summaries, as far as they haven't reached me already (special thanks to those early contributors!-), are due in this week (rather sooner than later), and after putting everything together, the second edition of the collective report should get out to this list sometime next week. The web page shows which areas are covered, and which summaries have reached me. ** This is the FINAL CALL for CONTRIBUTIONS to this edition. ** So, please, have a last look at the web page, and check for: missing topics? If your favourite Haskell topic isn't covered yet, get in touch with me as soon as possible (preferably by sending in a summary, but at least by naming possible contacts). This also applies if your topic is listed, but no contact has come forward yet! If you've released your latest and greatest Haskell software during the last six months, and want it to be represented, NOW is the last opportunity to send in a paragraph or two. micro-reports? late-breaking news?-) If you don't have any big project/group/area to report on, you might still want to let the Haskell community know that you're there and what you are working on. Just drop me a line or two on your work, and a link to your home page. missing reports? If you've promised a report, remember to send it to me!-) missing emails? If I've asked for your help, could you please let me know whether or not you'll be able to provide a report?-( Cheers, Claus -- Haskell Communities and Activities Report (May edition) All contributions are due in this week! http://www.haskell.org/communities/

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(no subject)
by laurent mpeti kabila 29 Apr '02

29 Apr '02

REQUEST FOR URGENT BUSINESS ASSISTANCE -------------------------------------- Your contact was availed to me by the chamber of commerce. It was given to me because of my diplomatic status as I did not disclose the actual reasons for which I sought your contact. But I was assured That you are reputable and trustworthy if you will be of assistance. I am Laurent Mpeti Kabila (Jnr) the second son of Late President LAURENT DESIRE KABILA the immediate Past president of the DEMOCRATIC REPUBLIC OF CONGO in Africa who was murdered by his opposition through his personal bodyguards in his bedroom on Tuesday 16th January, 2001. I have the privilege of being mandated by my father colleagues to seek your immediate and urgent co-operation to receive into your bank account the sum of US $165m. (One hundred and sixty-five million Dollars) and some thousands carats of Diamond. This money and treasures was lodged in a vault with a security firm in Europe and South-Africa. SOURCES OF DIAMONDS AND FUND In August 2000, my father as a defence minister and president has a meeting with his cabinet and armychief about the defence budget for 2000 to 2001 which was US $700m. so he directed one of his best friend. Frederic Kibasa Maliba who was a minister of mines and a political party leader known as the Union Sacree de, I opposition radicale et ses allies (USORAL) to buy arms with US $200m on 5th January 2001; for him to finalized the arms deal, my father was murdered. f.K. Maliba (FKM) and I have decided to keep the money with a foreigner after which he will use it to contest for the political election. Inspite of all this we have resolved to present your or your company for the firm to pay it into your nominated account the above sum and diamonds. This transaction should be finalized within seven (7) working days and for your co-operation and partnership, we have unanimously agreed that you will be entitled to 5.5% of the money when successfully receive it in your account. The nature of your business is not relevant to the successful execution of this transaction what we require is your total co-operation and commitment to ensure 100% risk-free transaction at both ends and to protect the persons involved in this transactio! n, strict confidence and utmost secrecy is required even after the successful conclusion of this transaction. If this proposal is acceptable to you, kindly provide me with your personal telephone and fax through my E-mail box for immediate commencement of the transaction. I count on your honour to keep my secret, SECRET. Looking forward for your urgent reply Thanks. Best Regards MPETI L. KABILA (Jnr)

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RE: Haskell Style Guide/Coding Standards?
by Simon Marlow 29 Apr '02

29 Apr '02

> Does anyone know where I might be able to find some Haskell > coding standards, > or perhaps a general style guide? There are some style guidelines in the document describing the new hierarchical libraries, here: http://www.haskell.org/~simonmar/libraries/libraries.html It would be nice to flesh this out a bit, contributions are most welcome. Cheers, Simon

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Haskell Style Guide/Coding Standards?
by Jeffrey Palmer 29 Apr '02

29 Apr '02

Hello all, Does anyone know where I might be able to find some Haskell coding standards, or perhaps a general style guide? Thanks, - j

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ANN: Normal-order evaluation as bottom-up parsing
by oleg＠pobox.com 28 Apr '02

28 Apr '02

This message announces a normal-order lambda-calculator integrated with Haskell. The calculator implements what seems to be an efficient and elegant algorithm of normal order reductions. The algorithm is "more functional" than the traditionally used approach. The algorithm seems identical to that employed by yacc sans one critical difference. The calculator also takes a more "functional" approach to the hygiene of beta-substitutions, which is achieved by coloring of identifiers where absolutely necessary. This approach is "more functional" because it avoids a "global" counter or the threading of the paint bucket through the whole the process. The integration with Haskell lets us store terms in variables and easily and intuitively combine them. A few examples (including 'greaterp', a term comparing two Church numerals in magnitude) show how easy it is to program the calculator. This message is an indirect reply to a recently posted query about the treatment of free variables. The lambda-calculator in this message shows one way of doing that. The traditional recipe for normal-order reductions includes an unpleasant phrase "cook until done". The phrase makes it necessary to keep track of reduction attempts, and implies an ugly iterative algorithm. We're proposing what seems to be efficient and elegant technique that can be implemented through intuitive re-writing rules. Our calculator, like yacc, possesses a stack and works by doing a sequence of 'shift' and 'reduce' steps. We consider an application (a b) as a _delayed_ normalization. We delay dealing with 'b' and with the application until we figure out what to do with the term 'a'. The calculator's stack contains all the terms to be applied to the current one. The evaluator does a 'reduce' step when it is sure it has the redex or it is sure it does not (e.g., (x (\y. y)) where 'x' is free). When the evaluator is not sure about the current term, it 'shifts'. The only difference from yacc is that the lambda-calculator "reparses" the result after the successful reduce step. The source and the target languages of our "parser" (lambda-calculator) are the same; therefore, the parser can indeed apply itself. The evaluator's source code: http://pobox.com/~oleg/ftp/Haskell/Lambda_calc.lhs explains the algorithm in detail. The file has five times more lines of comments than lines of code. The file also expounds upon the hygiene of beta-substitutions achieved by "local painting". The following are few examples: First, we make a few variables. > make_var = Var . VC 0 -- a convenience function > [a,b,c,x,y,z,f,g,h,p,q] = > map make_var ["a","b","c","x","y","z","f","g","h","p","q"] If we type at the hugs prompt: LC> eval $ (x ^ x # x) # (y ^ y # z) we will see the answer "z z" The substitutions are hygienic, as the following example demonstrates: LC> eval $ a ^ (x ^ a ^ a # x) # (a # x) ==> (\a. (\a~1. a~1 (a x))) A less trivial example (of integration with Haskell): > c0 = f ^ x ^ x -- Church numeral 0 > succ = c ^ f ^ x ^ f # (c # f # x) -- Successor > c1 = eval $ succ # c0 -- pre-evaluate other numerals > c2 = eval $ succ # c1 > c3 = eval $ succ # c2 > c4 = eval $ succ # c3 It is indeed convenient to store terms in Haskell variables and pre-evaluate (i.e., normalize) them. They are indeed terms. We can always ask the interpreter to show the term. For example, "show c4" yields "(\f. (\x. f (f (f (f x)))))". > mul = a ^ b ^ f ^ a # (b # f) -- multiplication Now, the interesting thing: eval $ mul # c1 ---> (\b. b), the identity function eval $ mul # c0 ---> (\b. (\f. (\x. x))), which is "const 0" These are _algebraic_ results: multiplication of any number by zero is always zero. Another algebraic result: eval $ zerop # (succ # a) ---> (\x. (\y. y)), that is, false. Forall a, (succ a) is not zero. We can see now how lambda-calculus can be useful for theorem proving (even over universally-quantified formulas). Finally, as even less trivial example, here is the term that compares two Church numerals in magnitude. The example is excerpted from LC_neg.lhs referenced below. The latter file provides all the definitions and a long explanation. > greaterp = eval $ > a ^ b ^ > -- Checking if anything is left of the list: if the current > -- cell is nil > (car > # (b > -- deconstructing the list. Once we hit the nil, we stop > # (z ^ lif # (car # z) # (cdr # z) # z) > -- Building the list > # (a > # (z ^ (cons # true # z)) > # (cons # false # false)) -- Initial cell, the nil > )) This is the bona fide lambda-term, with no cheating. We can ask the interpreter to print it, to make sure: LC_neg> greaterp (\a. (\b. b (\z. z (\x. (\y. x)) (z (\x. (\y. y))) z) (a (\z. (\p. p (\x. (\y. x)) z)) (\p. p (\x. (\y. y)) (\x. (\y. y)))) (\x. (\y. x)))) To check, we can evaluate eval $ greaterp # c1 # c0 ---> (\x. (\y. x)), that is, true eval $ greaterp # c2 # c3 ---> (\x. (\y. y)), that is, false Note that using Haskell variables makes programming in lambda calculus pleasant. Files http://pobox.com/~oleg/ftp/Haskell/LC_basic.lhs http://pobox.com/~oleg/ftp/Haskell/LC_neg.lhs show many more definitions and examples of lambda arithmetics and algebraic equalities. To be added shortly is the code to compare terms modulo alpha-conversion, and the systematic treatment of negative numbers and their operations (including division). The latter merely need to be ported from the different notation.

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ANN: Open postdoc position at UNSW
by Manuel M. T. Chakravarty 28 Apr '02

28 Apr '02

We are currently looking for a postdoc interested in compilers for functional languages and high-performance computing who would be interested to join us in a Haskell-related research project at UNSW. The details of the position are advertised at http://www.hr.unsw.edu.au/employment/26040208.htm Please contact me if you are interested to get to know more about the project, UNSW and/or living in Sydney. Manuel

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ANN: H98 FFI Addendum 1.0, Release Candidate 4
by Manuel M. T. Chakravarty 28 Apr '02

28 Apr '02

Dear Haskell Community, Release Candidate 4 of the Haskell 98 FFI Addendum is now available from http://www.cse.unsw.edu.au/~chak/haskell/ffi/ Changes since RC1 are summarised below. Please check this version for problems. If there are no problems reported within the coming month, I would propose to make RC4 into the final 1.0 definition. Cheers, Manuel -=- * 5.8: Clarified documentation for `MarshalAlloc.free'. * 5.8: Added `MarshalAlloc.realloc'. * 3: Added the new safety level `threadsafe' with an explanation at the end of 3.3 (this has been prompted by Sigbjorn Finne's addition of OS thread to GHC) * 3: Replaced the nontermional `entity' by `impent' and `expent' to distinguish between import and export entities (as they are defined differently in later sections). * 3.2: Clarified the description of foreign types; in the previous discussion, `IO ()' was strictly speaking not included as a valid return type. * 4.1.5: New section discussing the traps & pitfalls of type promotion with C bindings. * Renamed the functions constructing `ErrorType's, as `userError' collided with a function name in the Prelude. * Various minor fixes

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RE: Lexing character literals in H98
by Simon Peyton-Jones 26 Apr '02

26 Apr '02

| Yet another H98 question, this time regarding the module | Char: Is it a deliberate design decision that readLitChar | handles decimal, octal, and hex escapes, but lexLitChar | handles only decimal ones? It looks more like an oversight to me... Me too. It's a messy part of the language that both readLitChar and lexLitChar exist, with pretty much duplicate code. Still, I'd rather not rewrite it all (easy to introduce more bugs). But it is unfortunate that the two actually parse different escape sequences. Would anyone like to volunteer to write missing code for lexLitChar? Below is the stuff from the Report that describes the spec | Another question is if the uppercase variants '\O...' and | '\X...' should be forbidden explicitly. Current | implementations seem to differ in this aspect. Implementation shouldn't accept \O \X etc. I don't think it's appropriate to forbid it... should we forbid \A (read number base 35) too? Simon The function showLitChar converts a character to a string using only printable characters, using Haskell source-language escape conventions. The function lexLitChar does the reverse, returning the sequence of characters that encode the character. The function readLitChar does the same, but in addition converts the to the character that it encodes. For example: showLitChar '\n' s = "\\n" ++ s lexLitChar "\\nHello" = [("\\n", "Hello")] readLitChar "\\nHello" = [("\n", "Hello")]

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SAVE02 call for papers *** EXTENDED DEADLINE ***
by Sandro.Etalle＠cwi.nl 26 Apr '02

26 Apr '02

FloC 2002 workshop SAVE 2002 Workshop on Specification, Analysis and Validation for Emerging Technologies Copenhagen , Denmark, July 27, 2002 CALL FOR PAPERS EXTENDED DEADLINE: MAY 15, 2002 ^^^^^^^^^^^^ TOPICS * Specification languages and rapid prototyping: * Logic programming and its extensions * First-order, constructive, modal and temporal logic * Constraints * Type theory * Analysis: * Abstract interpretation * Program analysis and transformation * Validation: * Simulation and testing * Deductive methods * Model checking * Theorem proving The preferred issues include, but are not limited to: * Mobility: specification and verification of mobile code. * Security: e.g. specification and verification of security protocols. * Interaction, coordination, negotiation, communication and exchange on the Web. * Open and Parametrized Systems. PUBLICATION The proceedings of the workshop will be published as technical report. We are planning a journal special issue: a selection of the workshop papers will be invited for submitting a full version to it. MOTIVATIONS AND GOALS The huge increase in interconnectivity we have witnessed in the last decade has boosted the development of systems which are often large-scale, distributed, time-critical, and possibly acting in an unreliable or malicious environment. Furthermore, software and hardware components are often mobile, and have to interact with a potentially arbitrary number of other entities. These systems require solid formal techniques for their verification and analysis. In this respect, computational logic plays an increasingly important role, both providing formal methods for proving system's correctness and tools - e.g. using techniques like constraint programming and theorem proving - for verifying their properties. In addition, computational logic is gaining importance as tool for the specification of these systems. For instance, one can think at the specification, in a form of temporal logic, of a communication protocol. Such specification offers the advantage that one can reason about it using formal methods, and at the same time it is often easily executable by rewriting it into a logic-based programming language. The first edition of SAVE 2001 took place as a one-day satellite event of ICLP/CP 2001 in Paphos, Cyprus. The technical program consisted of an invited talk and seven paper presentations covering problems related to security, real time systems, simulation and performance evaluation, and general purpose verification techniques (all papers are available on line in the here). The aim of this new edition is to bring together researchers interested in the use of computational logic as a tool for the specification, analysis and validation of systems, with particular emphasis on (but not restricted to) emerging technologies like World Wide Web and e-commerce, (protocols for) smart cards and mobile telephony, wireless technology, control and real-time systems, open and distributed systems. IMPORTANT DATES * Deadline for submissions: May 15, 2002 * Notification: June 4, 2002 * Final papers due: June 24, 2002 * Workshop date: July 27, 2002 PROGRAM COMMITTEE Alessandro Armando DIST, University of Genova, Italy Radhia Cousot, Ecole Polytecnique, France Thierry Massart, U. Libre de Brussels, Belgium Catuscia Palamidessi, Penn State University, USA Frank Pfenning, Carnegie Mellon University, USA Andreas Podelski Max-Planck-Institut, Germany Sriram Rajamani, Microsoft Research, USA Jean-Francois Raskin, U. Libre Brussels, Belgium INSTRUCTION FOR AUTHORS Please send your submission as a (uuencoded, gzipped, if possible) Postscript or PDF file to: giorgio(a)disi.unige.it The paper must not exceed 15 pages, and must contain a cover page with: title, name and addresses of the authors, abstract and keywords. Please prepare the manuscript using LaTex article style, single column, 12.2cm x 19.3cm text area. The proceedings will be published in electronic format. A printed version will be distributed to all participants of the workshop. WORKSHOP ORGANISERS/PC CHAIRS * Giorgio Delzanno - Dipartimento di Informatica e Scienze * dell'Informazione - Universita' di Genova. e-mail: giorgio(a)disi.unige.it * Sandro Etalle - Department of Computer Science- University of Twente and CWI. e-mail: etalle(a)cwi.nl * Maurizio Gabbrielli - University of Bologna, Italy e-mail: gabbri(a)cs.unibo.it

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