January 2009 - Haskell

GTTSE 2009 --- First call for participation (06-11 July 2009)
by João Saraiva 16 Jan '09

16 Jan '09

GTTSE 2009, 06-11 July, 2009, Braga, Portugal 3rd International Summer School on Generative and Transformational Techniques in Software Engineering http://gttse.wikidot.com/ SCOPE AND FORMAT The biannual, week-long GTTSE summer school brings together PhD students, lecturers, as well as researchers and practitioners who are interested in the generation and the transformation of programs, data, software models, data models, metamodels, documentation, and entire software systems. The GTTSE school draws from several areas of the broad software engineering and programming language communities, in particular: software reverse and re-engineering, model-driven software development, program calculation, generic language technology, generative programming, aspect-oriented programming, and compiler construction. The GTTSE school presents the state of the art in automated software engineering and software language engineering: foundations, methods, tools, and case studies. The school's scientific program consists of three modules: 8 full tutorials (see below for a list of speakers and topics), 8 short tutorials (see the website for this part; under construction), and a half day-long participants' workshop. Each of the (8) full tutorials takes 3 hours of plenary time of GTTSE's week-long schedule. These tutorials are given by "veterans" of the field. Each of the (8) short(er) tutorials takes 20 mins of plenary time and approximately 90 mins of "parallel" time (with typically 2 sessions in parallel). These tutorials are (also) by invitation only. Most if not all tutorials will be complemented by articles in the proceedings of the school. The participants' workshop features presentations that were selected among the proposals submitted by the participants (who are typically PhD students). The idea is here to provide committed junior researchers with a slot to present their relevant research and to receive highly qualified feedback from the senior researchers at the school. This time, GTTSE features an award, sponsored by SIG (The Software Improvement Group), to be given to the best presenter at the participants' workshop. After the school, all participants of the school can submit an article for peer review to the post-proceedings. In the past, about 25% of these submissions were selected by the scientific committee to be included in the post-proceedings. All material presented at the school will be collected in informal proceedings to be handed out solely to the participants. Formal and public post-proceedings will be compiled after the summer school where all contributions are subjected to reviewing. Subject to Springer's approval, the post-proceedings of the school will be published in a volume of the Lecture Notes in Computer Science series of Springer-Verlag. The post-proceedings of the previous two instances of the summer school (2005 and 2007) were published as LNCS volumes 4143 and 5235. FULL TUTORIALS * Software Product Line Refactoring Paulo Borba, Universidade Federal de Pernambuco, Recife, Brazil * The TXL Source Transformation Cookbook James R. Cordy, Queen's University, Kingston, Canada * Chasing Diagrams in the Mapping Forests of Model Transformations Zinovy Diskin, University of Waterloo and Univ. of Toronto, Canada * Generating Language Tools with JastAdd Görel Hedin, Lund Institute of Technology, Sweden. * Model Driven Language Engineering with Kermeta Jean-Marc Jézéquel, IRISA, Rennes, France * Rascal: Meta-programming Made Easy Paul Klint, CWI and Universiteit van Amsterdam, Netherlands * Sourcerer: Slicing and Dicing Large Amounts of Open Source Code Cristina Videira Lopes, University of California, Irvine, USA * Theory & Practice of Modeling Language Design for Model-Based Engineering Bran Selic, Malina Software Corp., Canada ORGANIZATION COMMITTEE * João M. Fernandes (Program Co-Chair), Universidade do Minho, Portugal * Ralf Lämmel (Program Co-Chair), Universität Koblenz-Landau, Germany * João Saraiva, Universidade do Minho, Portugal * Joost Visser, Software Improvement Group, The Netherlands ADDITIONAL INFORMATION For additional information on the program, venue, and other details of the summer school, please consult the web page: http://gttse.wikidot.com/ Note that registration for the summer school will open in February 2009. Before that time, those who wish to be notified personally when registration opens are welcome to send an expression of interest to gttse2009 AT list.uni-koblenz.de

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IFL 2009: Call for Papers
by IFL 2009 15 Jan '09

15 Jan '09

Call for Papers IFL 2009 Seton Hall University SOUTH ORANGE, NJ, USA http://tltc.shu.edu/blogs/projects/IFL2009/ The 21st IFL symposium, IFL 2009, will be held for the first time in the USA. The hosting institution is Seton Hall University in South Orange, NJ, USA and the symposium dates are September 23-25, 2009. It is our goal to make IFL a regular event held in the USA. The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2009 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. Following the IFL tradition, IFL 2009 will use a post-symposium review process to produce a formal proceedings which we expect to be published by Springer in the Lecture Notes in Computer Science series. All participants in IFL 2009 are invited to submit either a draft paper or and extended abstract describing work to be presented at the symposium. These submissions will be screened by the program committee chair to make sure they are within the scope of IFL and will appear in the draft proceedings distributed at the symposium. Submissions appearing in the draft proceedings are not peer-reviewed publications. After the symposium, authors will be given the opportunity to incorporate the feedback from discussions at the symposium and will be invited to submit a revised full arcticle for the formal review process. These revised submissions will be reviewed by the program committee using prevailing academic standards to select the best articles that will appear in the formal proceedings. TOPICS IFL welcomes submissions describing practical and theoretical as well as submissions describing applications and tools. If you are not sure if your work is appropriate for IFL 2009, please contact the PC chair at ifl2009(a)shu.edu. Topics of interest include, but are not limited to: language concepts type checking contracts compilation techniques staged compilation runtime function specialization runtime code generation partial evaluation (abstract) interpretation generic programming techniques automatic program generation array processing concurrent/parallel programming concurrent/parallel program execution functional programming and embedded systems functional programming and web applications functional programming and security novel memory management techniques runtime profiling and performance measurements debugging and tracing virtual/abstract machine architectures validation and verification of functional programs tools and programming techniques PAPER SUBMISSIONS Prospective authors are encouraged to submit papers or extended abstracts to be published in the draft proceedings and to present them at the symposium. All contributions must be written in English, conform to the Springer-Verlag LNCS series format and not exceed 16 pages. The draft proceedings will appear as a technical report of the Department of Mathematics and Computer Science of Seton Hall University. IMPORTANT DATES Registration deadline August 15, 2009 Presentation submission deadline August 15, 2009 IFL 2009 Symposium September 23-25, 2009 Submission for review process deadline November 1, 2009 Notification Accept/Reject December 22, 2009 Camera ready version January 15, 2010 PROGRAM COMMITTEE Peter Achten University of Nijmegen, The Netherlands Jost Berthold Philipps-Universität Marburg, Germany Andrew Butterfield University of Dublin, Ireland Robby Findler Northwestern University, USA Kathleen Fisher AT&T Research, USA Cormac Flanagan University of California at Santa Cruz, USA Matthew Flatt University of Utah, USA Matthew Fluet Toyota Technological Institute at Chicago, USA Daniel Friedman Indiana University, USA Andy Gill University of Kansas, USA Clemens Grelck University of Amsterdam/Hertfordshire, The Netherlands/UK Jurriaan Hage Utrecht University, The Netherlands Ralf Hinze Oxford University, UK Paul Hudak Yale University, USA John Hughes Chalmers University of Technology, Sweden Patricia Johann University of Strathclyde, UK Yukiyoshi Kameyama University of Tsukuba, Japan Marco T. Morazán (Chair) Seton Hall University, USA Rex Page University of Oklahoma, USA Fernando Rubio Universidad Complutense de Madrid, Spain Sven-Bodo Scholz University of Hertfordshire, UK Manuel Serrano INRIA Sophia-Antipolis, France Chung-chieh Shan Rutgers University, USA David Walker Princeton University, USA Viktória Zsók Eötvös Loránd University, Hungary PETER LANDIN PRIZE The Peter Landin Prize is awarded to the best paper presented at the symposium every year. The honored article is selected by the program committee based on the submissions received for the formal review process. The prize carries a cash award equivalent to 150 euros.

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writing a shell in Haskell
by nr＠cs.tufts.edu 14 Jan '09

14 Jan '09

As a demo for the first day of class, I thought I'd try to write a simple shell in Haskell, in part so I can show algebraic data types and monads on the first day, but also to convince potential skeptics that functional languages can do systemsy things. All the usual functional stuff is going very nicely, but I don't seem to be able to get my hands on pipe(2) at all, and the language in the documentation for fork() and exec() might as well read Here Be Dragons. Looking for ways to fork, it appears that I have a wealth of abstractions to choose from: System.Process System.Posix.Process IO The 'new' System.Process on the web appears to have some very nice facilities, although it is still not strong enough to do what I want cleanly (capture the output from a command that might be internal or might require me to fork an external process). However, the question is moot because my system seems to have a consistent set of libraries coordinate with the release of GHC 6.8, and I don't know how to put together a consistent set of 'new' libraries to go with 6.10. (I don't even know if such a set exists.) Please advise me: should I give up the idea of writing a shell using GHC and the classic Unix system calls fork/exec/close/pipe? Or if it is possible after all, in what module should I be looking for the proper abstractions? Norman

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Help : data & concurrent packages
by bft 13 Jan '09

13 Jan '09

Hi ! Can someone tell me where to download the *data* and *concurrent *packages. I need them to build FranTk1.1 package ( http://www.dcs.gla.ac.uk/~meurig/FranTk/news.html) Thanks in advance! BFT frantk.conf file : Package {name = "FranTk", import_dirs = ["/local/www.people/personal/meurig/haskell/built/frantk/imports"], source_dirs = [], library_dirs = ["/local/www.people/personal/meurig/haskell/built/frantk"], hs_libraries = ["HSFranTk"], extra_libraries = ["tcl8.3","tk8.3"], include_dirs = [], c_includes = [], *package_deps = [ "concurrent", "data" ],* extra_ghc_opts = [ "-fvia-C", "-fallow-overlapping-instances", "-fallow-undecidable-instances" ], extra_cc_opts = [], extra_ld_opts = ["-lncurses"] }

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ANNOUNCE: zipper-0.1
by Andres Loeh 13 Jan '09

13 Jan '09

zipper-0.1: Generic zipper for systems of recursive datatypes ============================================================= The zipper is a data structure that allows typed navigation on a value. It maintains a subterm as a current point of focus. The rest of the value is the context. Focus and context are automatically updated when navigating up, down, left or right in the value. The term that is in focus can also be modified. This library offers a generic zipper for systems of datatypes. In particular, it is possible to move the focus between subterms of different types, in an entirely type-safe way. This library is built on top of the multirec library, so all that is required to get a zipper for a datatype system is to instantiate the multirec library for that system. Requirements ------------ * GHC 6.8.3 or later * Cabal 1.2.1 or later Download -------- With cabal-install: cabal install zipper Get the package: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/zipper Get the source: svn checkout https://svn.cs.uu.nl:12443/repos/dgp-haskell/zipper/trunk Bugs & Support -------------- Report issues, request features, or just discuss the library with the authors, maintainers, and other interested persons at: http://www.haskell.org/mailman/listinfo/generics -- Andres Loeh, Universiteit Utrecht mailto:andres@cs.uu.nl mailto:mail@andres-loeh.de http://www.andres-loeh.de

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ANNOUNCE: multirec-0.2
by Andres Loeh 13 Jan '09

13 Jan '09

multirec-0.2: Generic programming with systems of recursive datatypes ===================================================================== Many generic programs require information about the recursive positions of a datatype. Examples include the generic fold, generic rewriting or the Zipper data structure. Several generic programming systems allow to write such functions by viewing datatypes as fixed points of a pattern functor. Traditionally, this view has been limited to so-called regular datatypes such as lists and binary trees. In particular, systems of mutually recursive datatypes have been excluded. With the multirec library, we provide a mechanism to talk about fixed points of systems of datatypes that may be mutually recursive. On top of this representations, generic functions such as the fold or the Zipper can then be defined. Changelog (changes w.r.t. multirec-0.1) --------------------------------------- * Constructor information and generic show (Generics.MultiRec.Show). * Variants of fold (Generics.MultiRec.FoldAlg) that make the definition of algebras significantly more convenient. * Template Haskell code to generate the boilerplate required to instantiate this library to a system of datatypes. Requirements ------------ * GHC 6.8.3 or later * Cabal 1.2.1 or later Download -------- With cabal-install: cabal install multirec Get the package: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/multirec Get the source: svn checkout https://svn.cs.uu.nl:12443/repos/dgp-haskell/multirec/trunk Bugs & Support -------------- Report issues, request features, or just discuss the library with the authors, maintainers, and other interested persons at: http://www.haskell.org/mailman/listinfo/generics -- Andres Loeh, Universiteit Utrecht mailto:andres@cs.uu.nl mailto:mail@andres-loeh.de http://www.andres-loeh.de

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ANN: ghci-haskeline 0.1
by Judah Jacobson 13 Jan '09

13 Jan '09

I'm pleased to announce the first release of ghci-haskeline. This package uses the GHC API to reimplement ghci with the Haskeline library as a backend. Haskeline is a library for line input in command-line programs, similar to readline or editline, which is written in Haskell and thus (hopefully) more easily integrated into other Haskell programs. To install, you can use cabal update && cabal install ghci-haskeline, or else download it from: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ghci-haskeline Haskeline is planned to be used officially with GHC in the 6.12 release: http://hackage.haskell.org/trac/ghc/ticket/2812 So the more testing that can be done ahead of time, the better! For more information about Haskeline or to file a bug or feature request, visit its trac: http://trac.haskell.org/haskeline Finally, a partial list of the benefits of ghci-haskeline over the readline/editline versions: - Full interactive interface on Windows. - Support for a wide variety of character encodings in line interaction (http://trac.haskell.org/haskeline/wiki/UnicodeSupport) Note that GHC source files are still required to be UTF-8. - Tab completion of Unicode identifiers and filenames. - Tab completion of quoted filenames within Haskell expressions. Best, -Judah

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type family vs. polymorphism
by Andres Loeh 12 Jan '09

12 Jan '09

Hi. Here's a strange interaction of type families and higher-rank polymorphism (tested with both ghc-6.8.3 and ghc-6.10.1): {-# LANGUAGE TypeFamilies, EmptyDataDecls, RankNTypes #-} data X (a :: *) type family Y (a :: *) -- This works (datatype). i1 :: (forall a. X a) -> X Bool i1 x = x -- This works too (type family and extra arg). i2 :: (forall a. a -> Y a) -> Y Bool i2 x = x True -- This doesn't work (type family). -- i3 :: (forall a. Y a) -> Y Bool -- i3 x = x I would expect i3 to be ok as well. Note that this is a simplified example and not really useful in its simplified form. Cheers, Andres -- Andres Loeh, Universiteit Utrecht mailto:andres@cs.uu.nl mailto:mail@andres-loeh.de http://www.andres-loeh.de

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The Monad.Reader (13) - Call for copy
by Wouter Swierstra 12 Jan '09

12 Jan '09

Call for Copy The Monad.Reader - Issue 13 Please consider writing an article for the next issue of the Monad.Reader. The deadline for the next issue is: ** February 13, 2009 ** * Submission Details * Get in touch with me if you intend to submit something. The sooner you let me know what you're up to, the better. Please submit articles for the next issue to me by e-mail (wss at cs.nott.ac.uk). Articles should be written according to the guidelines available from http://www.haskell.org/haskellwiki/The_Monad.Reader Please submit your article in PDF, together with any source files you used. The sources will be released together with the magazine under a BSD license. If you would like to submit an article, but have trouble with LaTeX please let me know and we'll sort something out. All the best, Wouter This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

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ANN: HLint 1.2
by Neil Mitchell 11 Jan '09

11 Jan '09

Hi, I am pleased to announce HLint version 1.2. HLint is a lint-like tool for Haskell that detects and suggests improvements for your code. HLint is compatible with most GHC extensions, and supports a wide variety of suggestions, and can be extended with additional user suggestions. To install: cabal update && cabal install hlint Web page: http://www-users.cs.york.ac.uk/~ndm/hlint/ Biggest new feature: List recursion suggestions. For example, running HLint over the GHC compiler now suggests things such as: Example.hs:3:1: Warning: Use foldr Found: seqList [] b = b seqList (x : xs) b = x `seq` seqList xs b Why not: seqList xs b = foldr seq b xs Example.hs:6:1: Warning: Use foldr Found: seqIds [] = () seqIds (id : ids) = seqId id `seq` seqIds ids Why not: seqIds ids = foldr (seq . seqId) () ids Example.hs:13:1: Warning: Use foldl Found: rev_app [] xs = xs rev_app (y : ys) xs = rev_app ys (y : xs) Why not: rev_app ys xs = foldl (flip (:)) xs ys HLint will automatically detect if you should have used a map, a foldr or a foldl and suggest how to change your code. In the GHC, darcs and Hoogle code bases there are no obvious map-like functions, which is a good sign :-) Changes from last time: * More GHC extensions supported - including record wild cards and fixes to a number of existing extensions. These changes are thanks to Niklas and the haskell-src-exts package. * Many infix operators are now correctly associated with the right priority. * All hints are now ignored, warnings or errors. Hopefully this should make it clearer what hints are most important. As part of this, the format for defining ignore files has changed completely - see the manual for the new format. * Lots of new hints have been added - many from users of HLint. * Many bugs have been fixed. Can any follow-up discussions please be directed to haskell-cafe@. All comments, questions, bug reports are welcome! Neil

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