July 2005 - Haskell - Haskell.org

ICFP 2005 - Final Call for Papers
by Benjamin C. Pierce 28 Jul '05

28 Jul '05

NEWS: * submission and formatting instructions are now available * the dates of the author response period have changed slightly --------- International Conference on Functional Programming (ICFP 2005) Call for Papers September 26-28, 2005 Tallinn, Estonia Submission deadline: 13 April, 2005 Submission instructions: http://www.cis.upenn.edu/~bcpierce/icfp05 ICFP 2005 seeks original papers on the art and science of functional programming. Submissions are invited on all topics ranging 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 and concurrency. Particular topics of interest include: * Applications and domain-specific languages: Systems programming, scientific and numerical computing, symbolic computing and artificial intelligence, databases, graphical user interfaces, multimedia programming, application scripting, system administration, distributed-systems and web programming, XML processing, security. * Foundations: Formal semantics, lambda calculus, type theory, monads, continuations, control, state, effects. * Design: Algorithms and data structures, modules and type systems, concurrency and distribution, components and composition, relations to object-oriented and logic programming. * Implementation: Abstract machines, compile-time and run-time optimization, just-in-time compilers, memory management. Interfaces to foreign functions, services, components and low-level machine resources. * Transformation and analysis: Abstract interpretation, partial evaluation, program transformation. * Software-development techniques for functional programming: Design patterns, specification, verification, validation, debugging, test generation, tracing and profiling. * Practice and experience: Functional programming in education and industry. * Functional pearls: Elegant, instructive examples of functional programming. Papers in the last three categories need not necessarily report original research results; they may instead, for example, report practical experience that will be useful to others, re-usable programming idioms, or elegant new ways of approaching a problem. A special issue of the Journal of Functional Programming will highlight selected papers from the meeting. Submission instructions are available here: http://www.cis.upenn.edu/~bcpierce/icfp05 Important Dates: Submission deadline: 13 April, 2005, at 6PM (in Philadelphia) On-line response to reviews: 19-21 May, 2005 Author notification: 3 June, 2005 Camera-ready copy: 10 July, 2005 Organizers: Conference Chair: Olivier Danvy (BRICS, University of Aarhus) Program Chair: Benjamin Pierce (University of Pennsylvania) Program Committee: Mariangiola Dezani (Universita di Torino) Mary Fernandez (AT&T Labs) Matthew Flatt (University of Utah) Cedric Fournet (Microsoft Research) Jacques Garrigue (Kyoto University) Jason Hickey (California Institute of Technology) John Hughes (Chalmers University) Johan Jeuring (Utrecht University) Frank Pfenning (Carnegie Mellon University) Benjamin Pierce (University of Pennsylvania) Andrew Pitts (University of Cambridge) Norman Ramsey (Harvard University) Manuel Serrano (INRIA Sophia Antipolis) Peter Thiemann (Universitat Freiburg) Jan Vitek (Purdue University)

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Call for participation: CUFP 2005
by Andy Moran 28 Jul '05

28 Jul '05

IMPORTANT NOTE: Registration is now available at: http://www.cs.ioc.ee/tfp-icfp-gpce05/ CUFP 2005 THE SECOND ACM SIGPLAN COMMERCIAL USERS OF FUNCTIONAL PROGRAMMING WORKSHOP http://www.galois.com/cufp/ Talinn, Estonia September 24th 2005 Co-located with ICFP http://www.brics.dk/~danvy/icfp05/ ---------------------------------------------------------------------- Important dates Early registration deadline July 29, 2005 Late registration deadline September 2, 2005 Workshop September 24, 2005 Registration is available at: http://www.cs.ioc.ee/tfp-icfp-gpce05 ---------------------------------------------------------------------- The goal of CUFP is to build a community for users of functional programming languages and technology, be they using functional languages in their professional lives, in an open source project (other than implementation of functional languages), as a hobby, or any combination thereof. In short: anyone who uses functional programming as a /means/, but not an /end/. ---------------------------------------------------------------------- Schedule The meeting will last a full day, with a mix of invited presentations and discussion sessions. This year, we have the following confirmed speakers: * Atrijus Tang; talking about PUGS, a Perl6 implementation, written in Haskell; * Fabrice Le Fessant; talking about MLDonkey, a popular multi-platform, multi-network P2P client written in OCaml. * Michael Sperber; talking about uses of Scheme in the banking industry. * David Roundy; talking about darcs, a popular and flexible revision control system well-suited to highly distributed development, written in Haskell. * Jim Grundy; talking his experiences with functional programming at Intel's Strategic CAD Labs. * Robert Boone; talking about his experiences at FreeScale. * Jonathan Soebel; talking about lessons the FP community can learn from the OMG's Model Driven Architecture (MDA) and its related marketing efforts. We will also be having two working sessions, where lively debate and brainstorming will be the order of the day: * FP, Education, and Industry: industry folks complain that there aren't enough FP folks being produced by schools, and educators complain that students don't see any point in studying FP if there are no jobs to be had. How can we break this stalemate? Simon Thompson of Functional and Declarative Programming in Education (FDPE05) will be joining us, and we'll be debriefing at FDPE05. * Stimulating a CUFP Community: we'd like the buzz and excitement surrounding CUFP to persist beyond the workshops. What would such a community look like? How do we make it happen? The session will kick off with two separate but complimentary starting points: a proposed "Users of FP" community web site and a proposed "Haskell Consortium" web site. There will be no published proceedings, as the meeting is intended to be more a discussion forum than a technical interchange. A full report of last year's workshop appeared in the Functional Programming column of the December 2004 issue of SIGPLAN Notices, and we plan to do the same this year. -- Andy Moran Phone: 503.626.6616, x113 Galois Connections Inc. Fax: 503.350.0833 12725 SW Millikan Way, Suite #290 http://www.galois.com Beaverton, OR 97005 moran(a)galois.com

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runProcess with out=err
by Ian Lynagh 28 Jul '05

28 Jul '05

Hi, With the below code (compiled by ghc) I get "a.out: thread blocked indefinitely". Changing the second (Just hout) to Nothing makes it run as expected. If I dup fdout to get an fderr and then try to also convert that to a handle then I get "a.out: openFile: resource busy (file is locked)". Is there a way to write this with stdout and stderr going to the same handle? ------------------- module Main (main) where import System.Posix (openFd, defaultFileFlags, stdFileMode, OpenMode(ReadOnly, WriteOnly), fdToHandle) import System.Process (runProcess, waitForProcess) main :: IO () main = exec "echo" ["foo"] "in" "out" exec :: String -> [String] -> FilePath -> FilePath -> IO () exec c args inp out = do fdin <- openFd inp ReadOnly Nothing defaultFileFlags fdout <- openFd out WriteOnly (Just stdFileMode) defaultFileFlags hin <- fdToHandle fdin hout <- fdToHandle fdout ph <- runProcess c args Nothing Nothing (Just hin) (Just hout) (Just hout) waitForProcess ph >>= print ------------------- Thanks Ian

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RE: [Haskell] combining IntMaps
by Scherrer, Chad 28 Jul '05

28 Jul '05

Ok, it looks like I have some more reading to do. Do you know where I can find a description of the Hedge algorithm? Also, I'm pretty new here - these conversations eventually need to get moved to haskell-cafe, right? Is there any concrete guidance regarding when that should happen? The distinction between the two lists is still vague to me. -Chad -----Original Message----- From: Adrian Hey [mailto:ahey@iee.org] Sent: Wednesday, July 27, 2005 12:04 AM To: Scherrer, Chad Cc: haskell(a)haskell.org Subject: Re: [Haskell] combining IntMaps Hello, On Tuesday 26 Jul 2005 7:58 pm, Scherrer, Chad wrote: > Thanks! It's interesting the way your AVL tree library is set up -- > there seems to be a much broader degree of functionality than that > provided by Data.Set. But I'm trying to see, is there a significant > difference in the fundamental data structure. Well Data.Set is based on a different balanced tree type (weight balanced trees), similar to those used in the Adams paper. I'm also quite sceptical about the Hedge algorithm, so the AVL library doesn't use it. It uses divide and conquer, but not quite as Adams describes it. But IMO the biggest problem with Data.Set is the inflexible API. For example.. >From Data.Set: union :: Ord a => Set a -> Set a -> Set a intersect :: Ord a => Set a -> Set a -> Set a >From Data.Tree.AVL: genUnion :: (e -> e -> COrdering e) -> AVL e -> AVL e -> AVL e genIntersection :: (a -> b -> COrdering c) -> AVL a -> AVL b -> AVL c Of course there's no reason why similar functions could not be provided by Data.Set, but they're not there at present. > or is the main point that > the additional functionality could not have otherwise been provided in > an efficient way without going into the guts of Data.Set? Yes. This why producing useable libraries like this is so difficult. There's plenty of reasonable things you just can't do efficiently with Data.Set. Same is probably true of Data.Tree.AVL of course, but I'm trying to make it more complete all the time. Anyway, please try out AVL and let me know if there's anything more missing. Regards -- Adrian Hey

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stack overflow - nonobvious thunks?
by Scherrer, Chad 27 Jul '05

27 Jul '05

I'm trying to write a function to build a table of values from a list. Here's my current attempt: table :: (Ord a) => [a] -> [(a,Int)] table xs = Map.assocs $! foldl' f Map.empty xs where f m x = Map.insertWith (+) x 1 m The ($!) and the foldl' were my clumsy attempts to avoid the stack overflows I keep getting, but it's not working right yet. If I set unif :: [Int] unif = randomRs (1,10) $ mkStdGen 1 then I should be able to use f :: Int -> [(Int, Int)] f n = table $ take n unif I would think this should work using very little memory, since unif is evaluated lazily, and the table is built eagerly. But I must be keeping around more thunks than I think, since I get (in ghci) *Main> f 1000000 [(1,99816),(2,100187),(3,99969),(4,99892),(5,100194),(6,100190),(7,99776 ),(8,100347),(9,100125),(10,99504)] *Main> f 10000000 [(1,*** Exception: stack overflow So it works on big lists, but not huge ones. What am I missing? Is there a way to do this other than just increasing the memory allocation? Thanks, Chad Scherrer

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Haskell SOE Question
by Alex Edelsburg 27 Jul '05

27 Jul '05

Hello! I'm a student in Professor John Peterson's Elements of Computing (class site located here: http://cs.yale.edu/cs110-05) and he's having me learn Haskell with Paul Hudak's SOE book. I'm working on the PaddleBall in 20 lines at the end of Chapter 15 and I'm having a problem with HUGS. I downloaded the version from http://haskell.org/soe/software.htm which is recommended but I'm still having trouble. I copied the code verbatim from the book and I still get the following error. ERROR "Animation.hs" - Unknown entity "word32ToInt" imported from module "Word" It looks like this is a problem with one of the Haskell or Hugs libraries, not an SOE library. If anyone has any suggestions, they would be greatly appreciated. If anyone would like to see my code, please let me know and I'll post it ASAP. ~Alex

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CFP: Computational Models of Scientific Reasoning and Applications (CMSRA-IV)
by Luis Moniz Pereira 23 Jul '05

23 Jul '05

Please relay --------------------------- Computational Models of Scientific Reasoning and Applications (CMSRA-IV) Lisbon, 21-23 September 2005 http://centria.di.fct.unl.pt/~greg/conf/CMSRA-IV.html Program Invited speakers: Teddy Seidenfeld H. A. Simon Professor of Philosophy and Statistics, Carnegie Mellon University, USA Wiebe van der Hoek Professor of Computer Science, Head of the (Agent ART) Group University of Liverpool, UK Accepted papers: The Mathematics of Family Resemblance R. Jennings and D. Nicholson Nonmonotonic Conditionals that Behave Like Conditional Probabilities Above a Threshold J. Hawthorne An Adaptive Logic for Compassionate Relevantism H. Lycke Preferential Theory Revision P. Dell'Acqua and L.M. Pereira Defeasible Reasoning Partial Models: a Formal Framework for the Methodology of Research Programs F. Tohmé, C. Delrieux and O. Bueno Some Comments on History Based Structures E. Pacuit Types of Coherence and Coherence among Types P. Bandyopadhyay Conditionals and Consequences H. E. Kyburg, C. M. Teng and G. Wheeler Confirmation Theory and the Logic of Inductive Implication R. Silvestre, H. Tarcisio and C. Pequeno A Mathematical Comment on the Fundamental Difference between Legal Theory Formation and Scientific Theory Formation R. Loui

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Ambiguity problem
by Mads Lindstrøm 22 Jul '05

22 Jul '05

Hi I am struggling with an ambiguity problem. I have the following code: > foo :: Constr -> Int > foo = numChildren . fromConstr > > numChildren :: (Data a) => a -> Int > numChildren x = sum $ gmapQ (\_ -> 1) x which I thought would work, but the GHC-6.4 says: > Ambiguous type variable `a' in the constraint: > `Data a' arising from use of `numChildren' at AutoForm.hs:87:6-16 > Probable fix: add a type signature that fixes these type variable(s) I cannot see why I need to add (Data a), as fromConstr signatur is: fromConstr :: forall a. (Data a) => Constr -> a I do not know where to add it either. Hope, somebody can enlighten me. Greetings, Mads Lindstrøm

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Haskell workshop 2005 -- Call for participation.
by Daan Leijen 22 Jul '05

22 Jul '05

2005 Haskell Workshop Tallinn, Estonia, 30 September, 2005 http://www.cs.uu.nl/~daan/hw2005 Call for participation -- Important Dates --------------------------------------------------- Early registration deadline : July 29 Late registration deadline : September 2 Haskell workshop : September 30 Registration is available from <http://www.cs.ioc.ee/tfp-icfp-gpce05>. -- Preliminary Programme --------------------------------------------- The preliminary programme is available from the Haskell workshop website at <http://www.cs.uu.nl/~daan/hw2005> and is appended in plain text to this section. This year, David Roundy gives an invited talk about Darcs: a popular distributed version control system written Haskell. 8:45 Welcome by Daan Leijen 9:00 - 10:30 Invited talk: Lessons from Darcs David Roundy Visual Haskell – A full-featured Haskell development environment Krasimir Angelov and Simon Marlow Haskell ready to Dazzle the real world Martijn M. Schrage, Arjan van IJzendoorn, and Linda C. van der Gaag 11:00 - 12:30 Dynamic applications from the ground up Don Stewart and Manuel M. T. Chakravarty Haskell server pages through dynamic loading Niklas Broberg Haskell on a shared-memory multiprocessor Tim Harris, Simon Marlow, and Simon Peyton Jones 14:00 - 15:30 Verifying Haskell programs using constructive type theory Andreas Abel, Marcin Benke, Ana Bove, John Hughes, Ulf Norell Putting Curry-Howard to work Tim Sheard There and Back Again – Arrows for Invertible Programming Artem Alimarine, Sjaak Smetsers, Arjen van Weelden, Marko van Eekelen, and Rinus Plasmeijer 16:00 - 17:15 TypeCase: A design pattern for type-indexed functions Bruno C. d. S. Oliveira and Jeremy Gibbons Functional pearl: Polymorphic pattern matching Richard S. Bird Tool demonstration: Halfs – the Haskell file system Isaac Jones 17:15 - 17:45 Discussion: The future of Haskell -- The Haskell Workshop ---------------------------------------------- The Haskell Workshop 2005 is an ACM SIGPLAN sponsored workshop affiliated with the 2005 International Conference on Functional Programming (ICFP). Previous Haskell Workshops have been held in La Jolla (1995), Amsterdam (1997), Paris (1999), Montreal (2000), Firenze (2001), Pittsburgh (2002), Uppsala (2003), and Snowbird (2004). -- Scope ------------------------------------------------------------- The purpose of the Haskell Workshop is to discuss experience with Haskell, and future developments for the language. The scope of the workshop includes all aspects of the design, semantics, theory, application, implementation, and teaching of Haskell. Topics of interest include, but are not limited to, the following: * Language Design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, in the form of a formal treatment of the semantics of the present language or future extensions, type systems, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management as well as foreign function and component interfaces; * Tools, in the form of profilers, tracers, debuggers, pre-processors, and so forth; * Applications, Practice, and Experience, with Haskell for scientific and symbolic computing, database, multimedia and Web applications, and so forth as well as general experience with Haskell in education and industry; * Functional Pearls, being elegant, instructive examples of using Haskell. Papers in the latter two categories need not necessarily report original research results; they may instead, for example, report practical experience that will be useful to others, re-usable programming idioms, or elegant new ways of approaching a problem. The key criterion for such a paper is that it makes a contribution from which other practitioners can benefit. It is not enough simply to describe a program! -- Program committee ------------------------------------------------- Martin Erwig Oregon State University John Hughes Chalmers University of Technology Mark Jones OGI School of Science and Engineering at OHSU Ralf Lämmel Microsoft Corp. Daan Leijen Universiteit Utrecht (Program Chair) Andres Löh Universiteit Utrecht Andrew Moran Galois Connections Inc. Simon Thompson University of Kent Malcolm Wallace University of York

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WS-FM 2004 Call For Participation
by Mario Bravetti 20 Jul '05

20 Jul '05

---------------------------------------------------------------------- We apologize if you receive multiple copies of this announcement. ---------------------------------------------------------------------- ====================================================================== 1st International Workshop on Web Services and Formal Methods (WS-FM 2004) February 23-24, 2004, Pisa, Italy Workshop affiliated to COORDINATION 2004, February 24-27, 2004 WS-FM 2004 homepage: http://www.cs.unibo.it/~lucchi/ws-fm04/ ====================================================================== - The technical program is available at: http://www.cs.unibo.it/~lucchi/ws-fm04/ - Information about registration, travel and accomodation can be found at the COORDINATION 2004 web site: http://www.di.unipi.it/Coordination2004/ If you intend to participate, we recommend you to register and book the hotel as soon as possible. The Coordination 2004 Organizing Committee informed us that hotels are going to be fully booked in short time.

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