November 2009 - Haskell

Final CFP: WFLP 2010. Deadlines extended: Abstract due Nov 18; Full paper due Nov 25 (LNCS)
by Pablo Nogueira 13 Nov '09

13 Nov '09

[Deadlines extended: Abstract due Nov 18; Full paper due Nov 25] ******************************************************************** Final Call For Papers 19th International Workshop on Functional and (Constraint) Logic Programming Madrid, Spain, January 17, 2010 http://babel.ls.fi.upm.es/events/wflp2010/ ********* colocated with Principles of Programming Languages POPL 2010 http://www.cse.psu.edu/popl/10/ ******************************************************************** IMPORTANT DATES Abstract Submission: November 18, 2009 **extended** Full Paper Submission: November 25, 2009 **extended** Acceptance Notification: December 20, 2009 Preliminary Proceedings: January 7, 2010 Workshop: January 17, 2010 SCOPE The aim of the Workshop on Functional and (Constraint) Logic Programming is to bring together researchers interested in functional programming and (constraint) logic programming with special emphasis on the integration of both paradigms and of other declarative programming extensions. It promotes the cross-fertilizing exchange of ideas and experiences among researchers and students from the different communities interested in the foundations, applications, and combinations of high-level declarative programming languages and related areas. The previous WFLP editions are: WFLP 2009 (Brasilia, Brazil), WFLP 2008 (Siena, Italy), WFLP 2007 (Paris, France), WFLP 2006 (Madrid, Spain), WCFLP 2005 (Tallinn, Estonia), WFLP 2004 (Aachen, Germany), WFLP 2003 (Valencia, Spain), WFLP 2002 (Grado, Italy), WFLP 2001 (Kiel, Germany), WFLP 2000 (Benicassim, Spain), WFLP'99 (Grenoble, France), WFLP'98 (Bad Honnef, Germany), WFLP'97 (Schwarzenberg, Germany), WFLP'96 (Marburg, Germany), WFLP'95 (Schwarzenberg, Germany), WFLP'94 (Schwarzenberg, Germany), WFLP'93 (Rattenberg, Germany), and WFLP'92 (Karlsruhe, Germany). LOCATION WFLP 2010 will be held on January 17, 2010 in Madrid, Spain, colocated with the 37th ACM SIGACT-SIGPLAN Symposium on Principles of Programming Languages (POPL 2010). WFLP 2010 solicits papers in all areas of functional and (constraint) logic programming, including but not limited to: * Foundations: formal semantics, logic variables, binding and abstract syntax, rewriting and narrowing, unification, constraint solving, dynamics, type theory, meta-theory, effects, etc. * Language Design: security, services, modules, type systems, multi-paradigm languages, concurrency and distribution, objects, libraries, generic programming, interoperability, etc. * Implementation: abstract machines, parallelism, compile-time and run-time optimizations, foreign-language interfaces, memory management, multi-threading, exploiting parallel hardware, etc. * Transformation and Analysis: abstract interpretation, specialization, partial evaluation, program transformation, program calculation, program proof, meta-programming, generative programming, etc. * Software Development: algorithms, data structures, design patterns, components and composition, specification, proof assistants, verification and validation, model checking, debugging, testing, profiling, tracing, etc. * Paradigm Integration: integration of declarative programming with other paradigms or features such as imperative, object-oriented, aspect-oriented, concurrent, real-time programming, event-driven architectures, etc. * Applications: education, industry, commercial uses, domain-specific languages, visual/graphical user interfaces, embedded systems, WWW applications, XML processing, artificial intelligence, knowledge representation and machine learning, deductive databases, advanced programming environments and tools, etc. SUBMISSIONS and PROCEEDINGS Authors are invited to submit papers presenting original unpublished work. Papers must be at most 15 pages long. Exceptionally, authors may surpass the page limit by providing well-marked appendices intended as reviewing aids. Appendices will not appear in the final publication. Submission categories include regular research papers, system descriptions, and short papers describing on-going work (at most 8 pages). Submissions must be formatted in Lecture Notes in Computer Science (LNCS) style. This requirement needs not apply to appendices. Papers should be submitted in pdf format electronically via the web-based submission site http://www.easychair.org/conferences/?conf=wflp2010 Preliminary proceedings will be available at the workshop. Selected authors will be invited to submit a full version of their papers after the workshop. Contributions accepted for the post-workshop proceedings will be published in Springer's Lecture Notes in Computer Science series. INVITED SPEAKER Mariangiola Dezani (University of Torino, Italy) PROGRAM CHAIR Julio Marino (Universidad Politecnica de Madrid, Spain) PROGRAM COMMITTEE Maria Alpuente (Universidad Politecnica de Valencia, Spain) Sergio Antoy (Portland State University, USA) Bernd Brassel (CAU Kiel, Germany) Olaf Chitil (Univ. of Kent, UK) Rachid Echahed (CNRS-IMAG, France) Santiago Escobar (Universidad Politecnica de Valencia, Spain) Moreno Falaschi (Universita di Siena, Italy) Murdoch Gabbay (Heriot-Watt University, UK) Maria Garcia de la Banda (Monash University, Australia) Victor Gulias (Lambdastream SL, Spain) Michael Hanus (CAU Kiel, Germany) Herbert Kuchen (Univ. of Muenster, Germany) Francisco Lopez-Fraguas (Universidad Complutense de Madrid, Spain) James Lipton (Wesleyan University, USA) Mircea Marin (Univ. of Tsukuba, Japan) Juan Jose Moreno-Navarro (Ministry of Science & Innovation, Spain) Brigitte Pientka (McGill University, Canada)

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ANNOUNCE: dbus-core 0.6 and dbus-client 0.2
by John Millikin 12 Nov '09

12 Nov '09

This is the second public release of my D-Bus implementation. dbus-core is an implementation of the D-Bus protocol, and dbus-client is a set of wrappers and utility computations to simplify writing basic clients. Interesting changes to dbus-core ================================ * Performance improvements: sending and receiving large structures should now be significantly faster. My thanks and appreciation go to Bryan O'Sullivan, whose excellent Criterion library made benchmarking the serialisation code much easier than it had any right to be. * Better support for byte arrays: byte strings (strict and lazy) are now directly supported types, with special cases to avoid most conversion overhead. * Implemented the TCP/IP transport, though it's untested because I can't figure out how to make the server listen on a socket. If anybody cares about remote D-Bus, and this doesn't work, drop me a mail with your configuration and I'll find out why. * Added module to represent "match rules", required for full signal support. * Added module for name reservations -- this is really just moving the bulk of the code from dbus-client into dbus-core, where it belongs. * Fixed possible concurrency issue when receiving messages from a connection in multiple threads. This is still a really bad idea, and it will never work correctly, but at least now it won't corrupt the connection state. Interesting changes to dbus-client ================================== * Fixed dumb signature to mkClient (thanks, Max). Its purpose should now be more obvious. * Shifted around some of the method call APIs -- it's now possible to send method calls without a proxy. * Uses the new MatchRule work to fully support receiving signals. Documentation ============= PDFs of the source; these are the most useful and complete documentation currently available: https://dl.dropbox.com/u/1947532/dbus-core_0.6.pdf https://dl.dropbox.com/u/1947532/dbus-client_0.2.pdf An API listing is also available, good for a quick overview: https://dl.dropbox.com/u/1947532/dbus-core_0.6/index.html https://dl.dropbox.com/u/1947532/dbus-client_0.2/index.html Hackage is currently experiencing some dependency conflicts with the "bytestring" library[1], so it's not generating its own documentation. I'll keep the dropbox pages up until Hackage is in a more usable state. Downloads ========= Available from the usual places: http://hackage.haskell.org/packages/archive/dbus-core/0.6/dbus-core-0.6.tar… http://hackage.haskell.org/packages/archive/dbus-client/0.2/dbus-client-0.2… [1] "binary" uses bytestring-0.9.1.4, "text" uses bytestring-0.9.1.5, kaboom

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Tabla de calculo de dolares viajero CADIVI
by Hector Guilarte 11 Nov '09

11 Nov '09

Tabla del operador cambiario para determinar cuantos dolares te tocan por viaje en el 2009... Saquen sus propias conclusiones... Además de la tabla, miren los bloqueos de ciertas transacciones de abajo... Increíble La reenvío como me llegó... **

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ICFP 2010: Call for papers
by Wouter Swierstra 10 Nov '09

10 Nov '09

===================================================================== Call for Papers ICFP 2010: International Conference on Functional Programming Baltimore, Maryland, 27 -- 29 September 2010 http://www.icfpconference.org/icfp2010 ===================================================================== Important Dates (at 14:00 UTC) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Submission: 2 April 2010 Author response: 24 -- 25 May 2010 Notification: 7 June 2010 Final papers due: 12 July 2010 Scope ~~~~~ ICFP 2010 seeks original papers on the art and science of functional programming. Submissions are invited on all topics from principles to practice, from foundations to features, from abstraction to application. The scope includes all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages with objects or concurrency. Particular topics of interest include * Language Design: type systems; concurrency and distribution; modules; components and composition; metaprogramming; relations to object-oriented or logic programming; interoperability * Implementation: abstract machines; compilation; compile-time and run-time optimization; memory management; multi-threading; exploiting parallel hardware; interfaces to foreign functions, services, components or low-level machine resources * Software-Development Techniques: algorithms and data structures; design patterns; specification; verification; validation; proof assistants; debugging; testing; tracing; profiling * Foundations: formal semantics; lambda calculus; rewriting; type theory; monads; continuations; control; state; effects * Transformation and Analysis: abstract interpretation; partial evaluation; program transformation; program calculation; program proof * Applications and Domain-Specific Languages: symbolic computing; formal-methods tools; artificial intelligence; systems programming; distributed-systems and web programming; hardware design; databases; XML processing; scientific and numerical computing; graphical user interfaces; multimedia programming; scripting; system administration; security; education * Functional Pearls: elegant, instructive, and fun essays on functional programming The conference also solicits Experience Reports, which are short papers that provide evidence that functional programming really works or describe obstacles that have kept it from working in a particular application. Abbreviated instructions for authors ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ By 2 April 2010, 14:00 UTC, submit an abstract of at most 300 words and a full paper of at most 12 pages (6 pages for an Experience Report), including bibliography and figures. The deadline will be strictly enforced and papers exceeding the page limits will be summarily rejected. Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. A submission will be evaluated according to its relevance, correctness, significance, originality, and clarity. It should explain its contributions in both general and technical terms, clearly identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. The technical content should be accessible to a broad audience. Functional Pearls and Experience Reports are separate categories of papers that need not report original research results and must be marked as such at the time of submission. Detailed guidelines on both categories are on the conference web site. Each submission must adhere to SIGPLAN's republication policy, as explained on the web at http://www.acm.org/sigplan/republicationpolicy.htm. Proceedings will be published by ACM Press. Authors of accepted submissions are expected to transfer the copyright to the ACM. Presentations will be videotaped and released online if the presenter consents by signing an additional permission form at the time of the presentation. Formatting: Submissions must be in PDF format printable in black and white on US Letter sized paper and interpretable by Ghostscript. If this requirement is a hardship, make contact with the program chair at least one week before the deadline. Papers must adhere to the standard ACM conference format: two columns, nine-point font on a ten-point baseline, with columns 20pc (3.33in) wide and 54pc (9in) tall, with a column gutter of 2pc (0.33in). A suitable document template for LATEX is available from SIGPLAN at http://www.acm.org/sigs/sigplan/authorInformation.htm. Submission: Submissions will be accepted electronically at a URL to be named later. Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. Author response: Authors will have a 48-hour period, starting at 14:00 UTC on 24 May 2010, to read and respond to reviews. Special Journal Issue: There will be a special issue of the Journal of Functional Programming with papers from ICFP 2010. The program committee will invite the authors of select accepted papers to submit a journal version to this issue. Organization ~~~~~~~~~~~~ Conference Chair Paul Hudak, Yale University Program Chair Stephanie Weirich, University of Pennsylvania Program Committee: Umut Acar, Max Planck Institute for Software Systems Zena Ariola, University of Oregon James Cheney, University of Edinburgh Peter Dybjer, Chalmers University of Technology Robert Bruce Findler, Northwestern University Andy Gill, Kansas University Fritz Henglein, University of Copenhagen Michael Hicks, University of Maryland, College Park Patricia Johann, University of Strathclyde Andres Löh, Utrecht University Simon L. Peyton Jones, Microsoft Research Didier Rémy, INRIA Paris-Rocquencourt John Reppy, University of Chicago Manuel Serrano, INRIA Sophia-Antipolis Matthieu Sozeau, Harvard University

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ANNOUNCE: qtHaskell-1.1.3
by David Harley 08 Nov '09

08 Nov '09

A new release of qtHaskell (version 1.1.3) is available at http://qthaskell.berlios.de See the documentation provided on-line and with the downloads -- in particular the "qtHaskell primer" -- for details of the new features. David Harley -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

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Haskell Weekly News: Issue 138 - November 07, 2009
by jfredett＠gmail.com 07 Nov '09

07 Nov '09

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20091107 Issue 138 - November 07, 2009 --------------------------------------------------------------------------- Welcome to issue 138 of HWN, a newsletter covering developments in the [1]Haskell community. Lots of discussion about [2]Clean this week. As well there was a new DSL, feldspar, announced. It deals with digital signal processing applications. Announcements MonadRandom-0.1.4. Brent Yorgey [3]announced a new version of MonadRandom which adds applicative instances for Rand and RantT, so you can write your code in applicative style. Criterion 0.2, an improved Haskell benchmarking library. Bryan O'Sullivan [4]announced a new version of Criterion, all the details of this release are available on his [5]blog feldspar-language. Emil Axelsson [6]announced feldspar, a DSL for digital signal processing. feldspar-compiler. Emil Axelsson [7]announced the C code backend for the `feldspar` language. fdo-notify 0.1, a client for the Desktop Notifications protocol. Max Rabkin [8]announced a library for FreeDesktop.org's Desktop Notifications Protocol. language-python version 0.2 now available. Bernie Pope [9]announced a new version of the language-python package, which provides an AST and parser for Python 2.x-3.x (previously, only 3.x was supported). timeplot. Eugene Kirpichov [10]announced timeplot, which is useful visualizing log files. Singapore FP Users Group First Meeting. Max Cantor [11]announced the first meeting of the Singapore FP Users Group, it will be Monday, November 2nd at 6pm. Advgame 0.1.1. Tim Wawrzynczak [12]announced his port of Conrad Barski's 'Casting SPELs in Lisp' to Haskell. BlogLiterately-0.2. Robert Greayer [13]announced version 0.2 of BlogLiterately, a simple tool for uploading posts written in markdown and Literate Haskell to blogs. haskell-mode 2.6. Svein Ove Aas [14]announced a bugfix release of the Emac's Haskell mode. Discussion A Problem Defining a Monad instance. Petr Pudlak [15]asked about how to defined an instance of the Monad class for a monad whose argument is restricted by another typeclass. Point Free Case Expressions. Sebastiaan Visser [16]suggested that a new syntax be added for 'point-free' case expressions. Master's thesis topic sought. Matus Tejiscak [17]asked for suggestions for possible Master's Thesis topics. What's the deal with Clean? Deniz Dogan [18]asked about the recent discussion on the -cafe list about Clean, another Pure, Lazy, Strictly Typed language. Blog noise [19]Haskell news from the [20]blogosphere. Blog posts from people new to the Haskell community are marked with >>>, be sure to welcome them! * Neil Brown: [21]Text.Printf and monad transformers. * Bryan O'Sullivan: [22]Criterion 0.2, an improved Haskell benchmarking library. * Galois, Inc: [23]Tech Talk: Hoare-Logic â fiddly details and small print. * Gtk2HS: [24]Writing concurrent programs.. * Tom Schrijvers: [25]Postdoc/PhD Positions on the Monadic Constraint Programming project. * Darcs: [26]darcs weekly news #45. * Tom Schrijvers: [27]Haskell Type Constraints unleashed. * Luke Plant: [28]Building GHC is fun.... * Manuel M T Chakravarty: [29]Status Update of the Glasgow Haskell Compiler, October 2009. * Chris Smith: [30]Monads from Two Perspectives. * Neil Brown: [31]Concurrent Testing and Tracing: Useful Output for Test Failures. * Dan Piponi (sigfpe): [32]Buffon's Needle, the Easy Way. Buffon's needle is a popular probability problem. Rule lines on the floor a distance d apart and toss a needle of length l Quotes of the Week * blackdog: [About Hubris] I tell the Ruby guys that Haskell will help them speed up their Ruby code and keep their apps going, and I tell Haskell guys that it'll Trojan Horse those poor unsuspecting rubyists... * lispy: Great, I leave the channel for a few hours and suddenly Haskell has a new found work ethic. * roconnor: ivanm: I will keep the fail in the code * lament: just remember to ask, 'What are your questions', as opposed to 'Do you have any questions' * mauke: @unpl const (flip const) lambdabot: (\ _ c d -> d) About the Haskell Weekly News New editions are posted to [33]the Haskell mailing list as well as to [34]the Haskell Sequence and [35]Planet Haskell. [36]RSS is also available, and headlines appear on [37]haskell.org. To help create new editions of this newsletter, please see the information on [38]how to contribute. Send stories to jfredett . at . gmail . dot . com. The darcs repository is available at darcs get [39]http://patch-tag.com/r/jfredett/HWN2/pullrepo HWN2 . References 1. http://haskell.org/ 2. http://en.wikipedia.org/wiki/Clean_(programming_language) 3. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65844 4. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65813 5. http://www.serpentine.com/blog/2009/11/06/criterion-0-2-an-improved-haskell… 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65617 7. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65741 8. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65686 9. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65656 10. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65575 11. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65471 12. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65462 13. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65567 14. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65487 15. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/65834 16. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/65750 17. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/65706 18. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/65589 19. http://planet.haskell.org/ 20. http://haskell.org/haskellwiki/Blog_articles 21. http://chplib.wordpress.com/2009/11/06/text-printf-and-monad-transformers/ 22. http://www.serpentine.com/blog/2009/11/06/criterion-0-2-an-improved-haskell… 23. http://www.galois.com/blog/2009/11/04/chapman-hoare/ 24. http://haskell.org/gtk2hs/archives/2009/11/04/writing-concurrent-programs/ 25. http://tomschrijvers.blogspot.com/2009/11/postdocphd-positions-on-monadic.h… 26. http://blog.darcs.net/2009/11/darcs-weekly-news-45.html 27. http://tomschrijvers.blogspot.com/2009/11/haskell-type-constraints-unleashe… 28. http://lukeplant.me.uk/blog.php?id=1107301703 29. http://justtesting.org/post/232566357 30. http://cdsmith.wordpress.com/2009/11/02/monads-from-two-perspectives/ 31. http://chplib.wordpress.com/2009/11/02/concurrent-testing-and-tracing-usefu… 32. http://blog.sigfpe.com/2009/10/buffons-needle-easy-way.html 33. http://www.haskell.org/mailman/listinfo/haskell 34. http://sequence.complete.org/ 35. http://planet.haskell.org/ 36. http://sequence.complete.org/node/feed 37. http://haskell.org/ 38. http://haskell.org/haskellwiki/HWN 39. http://patch-tag.com/r/jfredett/HWN2/pullrepo%20HWN2

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ANNOUNCE: NetSNMP-0.1.6
by John Dorsey 06 Nov '09

06 Nov '09

I'm pleased to annonce the release of NetSNMP-0.1.6, a partial (but useful) binding to the net-snmp library.[1] NetSNMP is a simple and self-contained client interface for doing basic SNMP GET, NEXT, and WALK operations. As far as I know it should work with any version of the C library (net-snmp) from version 5. This release improves threaded performance, and the management of foreign memory objects. I've been using it successfully in a threaded polling daemon which I'm running on 32-bit and 64-bit Linux systems. If you try out NetSNMP, or if you decide it doesn't meet your need, please drop me a line! Regards, John Dorsey

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Fun in the Afternoon, Cambridge, 26 November
by Simon Marlow 06 Nov '09

06 Nov '09

"Fun in the Afternoon" is a termly seminar on functional programming and related topics, and the next one will be held at Microsoft Research, Cambridge (U.K.) on 26 November (that's just under three weeks away). We have a great set of talks lined up - see program and abstracts below. If you'd like to come along, please email msrcevnt(a)microsoft.com with your name and afilliation, preferably by 20 November. Cheers, Simon ------------------------------------------ Fun in Cambridge, 26 November 2009 12:00 Lunch: Various local options 13:00 Andreas Rossberg, "F-ing Modules" 13:30 Ondrej Rypacek, "Distributive Laws in Programming Structures" 14:00 Break 14:30 Thorsten Altenkirch, "ΠΣ: Dependent Types Without the Sugar" 15:00 Robin Adams, "Canonical Logical Frameworks" 15:30 Break 16:00 Matthew Naylor, "Dynamic analysis in the Reduceron" 16:30 Thomas Schilling, "Slicing It" 17:30 Pub 18:30 Dinner ----------------------------------------------------------------------------- Andreas Rossberg F-ing Modules Andreas Rossberg, Claudio Russo, Derek Dreyer Abstract: ML modules are a powerful language mechanism for decomposing programs into reusable components. They also have a reputation for being complex, and dependent on fancy type theory that is mostly opaque to non-experts. While this reputation is certainly understandable, we aim here to demonstrate that it is undeserved. To do so, we give a very simple elaboration semantics for a full-featured, higher-order ML- like module language. Our elaboration defines the meaning of module expressions by a straightforward, compositional translation into vanilla System F (the polymorphic lambda-calculus), under plain F typing contexts. We thereby show that modules are merely a particular mode of use of System F. Our module language supports the usual second-class modules, with SML- style generative functors and local modules. To demonstrate the versatility of our approach, we further extend the language with the ability to package modules as first-class values -- an almost trivial extension, as it turns out. (Our approach also scales to handle OCaml- style applicative functor semantics, but the details are significantly more subtle, so we will not present them here.) Lastly, we report on our experience using the "locally nameless" approach in order to mechanize the soundness of our elaboration semantics in Coq. ----------------------------------------------------------------------------- Ondrej Rypacek Title: Distributive Laws in Programming Structures Abstract: Distributive laws in Computer Science are in general rules governing the transformation of one programming structure into another. In functional programming, they are parametrically polymorphic functions with a characteristic type "swapping the order of two parameterized-type constructors". Their importance has been noted but to date documented only in several isolated cases and by diverse formal approaches such as Backouhse & Hoogendijk's zips, Meertens' functor pullers or McBride's idiomatic functors. In this talk, a formal approach to distributive laws in programming structures will be presented, which discloses their simple nature, a uniform approach to elementary constructions on them and their precise relationship to similar notions elsewhere in Category Theory. Although the approach rests formally on deep results from 2-Category Theory, the presentation will be geometrical as much as possible, making use of the wonderful three dimensional nature of 2-categories. ----------------------------------------------------------------------------- Thorsten Altenkirch ΠΣ: Dependent Types Without the Sugar (Based on joint work with Nils Anders Danielsson, Andres Löh and Nicolas Oury) The recent success of languages like Agda and Coq demonstrates the potential of using dependent types for programming. These systems rely on many high level features like datatype definitions, pattern matching and implicit arguments to facilitate the use of the language. However, these features complicate the metatheoretical study and are a potential source of bugs. To address these issues we introduce ΠΣ, a dependently typed core language. It is small enough for metatheoretical study and the typechecker is small enough to be formally verified. In this language there is only one mechanism for recursion---used for types, functions and infinite objects---and an explicit mechanism to control unfolding, based on lifted types. Furthermore structural equality is used consistently for values and types; this is achieved by a new notion of α-equality for recursive definitions. We show, by translating several high-level constructions, that ΠΣ is suitable as a core language for dependently typed programming. We also provide a formal description of the language and its typing rules. See also: our recent paper (with the same title) http://www.cs.nott.ac.uk/~txa/publ/pisigma-new.pdf or/and download pisigma from hackage. ----------------------------------------------------------------------------- Robin Adams Title: Canonical Logical Frameworks Abstract: A canonical logical framework, or lambda-free logical framework, is a logical framework that deals only with objects in beta-normal, eta-long form. The concept has been invented independently three times over the last 15 years or so: by Aczel, with the Type Framework TF; by Watkins et al, with the Canonical Logical Framework, and by Plotkin, with DMBEL. I shall show how all these frameworks can be fitted into a hierarchy such that they extend one another conservatively. I shall also demonstrate the main selling point of canonical LFs: certain results can be proven more easily in a canonical LF, then 'lifted' - that is, the same result proven for a traditional LF as an immediate corollary. ----------------------------------------------------------------------------- Matthew Naylor Title: Dynamic analysis in the Reduceron The Reduceron is a graph-reduction machine implemented on a field-programmable gate array (FPGA). Last year, we reviewed the machine and set out to improve its runtime performance by a factor of six. If achieved, the performance of leading PC and FPGA implementations of graph-reduction would be on a par for a common class of programs --- an unusual and intriguing state of affairs for such a general-purpose processor. In this talk, I will present our progress towards this goal, beginning with an overview, and then focusing on two recently added features: update avoidance and speculative evaluation of primitive redexes. Both enjoy the accuracy and simplicity of dynamic analysis without incurring the runtime overhead that often makes static analysis perferable in a conventional setting. This talk represents joint work-in-progress with Colin Runciman. ----------------------------------------------------------------------------- Thomas Schilling Title: Slicing It Abstract: Haskell's type error messages are often not as helpful as they could be. One fundamental problem is that they blame a single location while several other locations may fix the error as well. A type error slice does not blame a single location, but a fragment of the failing program. Previous work on type error slices requires reformulating type checking as a constraint solving problem. This makes it very difficult to integrate support for type error slices into existing compilers. In this talk I present how we can overcome this limitation by requiring only a very basic interface to the type checker.

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ANN: ZuriHac: Haskell hackathon in Zurich, March 19-21
by Johan Tibell 06 Nov '09

06 Nov '09

Hi all! I am very pleased to officially announce ZuriHac, a Haskell hackathon/get-together to be held March 19-21 at the Google Office in Zurich, Switzerland. Thanks to everyone who has already expressed interest in attending. I want to stress that everyone is welcome---you do not have to be a Haskell guru to attend! Helping hack on someone else's project could be a great way to increase your Haskell-fu. If you plan on coming, please officially register [1], even if you already put your name on the wiki. Registration, travel, lodging and many other details will soon be available on the ZuriHac wiki [2]. WHEN Friday March 19 2:30pm to 6:30pm Saturday March 20 10am to 6pm Sunday March 21 10am to 6pm WHERE We will be in the TechTalk area of the Google Office at Brandschenkestrasse 110. Please see the wiki [3] for directions. ORGANIZERS Johan Tibell Christophe Poucet Hope to see you in Zurich! - The ZuriHac team [1] http://haskell.org/haskellwiki/ZuriHac/Register [2] http://haskell.org/haskellwiki/ZuriHac [3] http://haskell.org/haskellwiki/ZuriHac#Getting_to_the_Google_Office

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ANNOUNCE: feldspar-compiler
by Emil Axelsson 05 Nov '09

05 Nov '09

On behalf of my project colleagues at ELTE University, I'm happy to announce the release of feldspar-compiler: http://hackage.haskell.org/package/feldspar-compiler This package contains the C code back-end for the Feldspar EDSL, announced yesterday: http://hackage.haskell.org/package/feldspar-language For more information, see http://feldspar.sourceforge.net/ / Emil

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