February 2008 - Haskell

Announcing Djinn, version 2004-12-11, a coding wizard
by Lennart Augustsson 07 Apr '11

07 Apr '11

Howdy, y'all! I've written a small program that takes a (Haskell) type and gives you back a function of that type if one exists. It's kind of fun, so I thought I'd share it. It's probably best explained with a sample session. calvin% djinn Welcome to Djinn version 2005-12-11. Type :h to get help. # Djinn is interactive if not given any arguments. # Let's see if it can find the identity function. Djinn> f ? a->a f :: a -> a f x1 = x1 # Yes, that was easy. Let's try some tuple munging. Djinn> sel ? ((a,b),(c,d)) -> (b,c) sel :: ((a, b), (c, d)) -> (b, c) sel ((_, v5), (v6, _)) = (v5, v6) # We can ask for the impossible, but then we get what we # deserve. Djinn> cast ? a->b -- cast cannot be realized. # OK, let's be bold and try some functions that are tricky to write: # return, bind, and callCC in the continuation monad Djinn> type C a = (a -> r) -> r Djinn> returnC ? a -> C a returnC :: a -> C a returnC x1 x2 = x2 x1 Djinn> bindC ? C a -> (a -> C b) -> C b bindC :: C a -> (a -> C b) -> C b bindC x1 x2 x3 = x1 (\ c15 -> x2 c15 (\ c17 -> x3 c17)) Djinn> callCC ? ((a -> C b) -> C a) -> C a callCC :: ((a -> C b) -> C a) -> C a callCC x1 x2 = x1 (\ c15 _ -> x2 c15) (\ c11 -> x2 c11) # Well, poor Djinn has a sweaty brow after deducing the code # for callCC so we had better quit. Djinn> :q Bye. To play with Djinn do a darcs get http://darcs.augustsson.net/Darcs/Djinn or get http://darcs.augustsson.net/Darcs/Djinn/Djinn.tar.gz Then just type make. (You need a Haskell 98 implementation and some libraries.) And then start djinn. For the curious, Djinn uses a decision procedure for intuitionistic propositional calculus due to Roy Dyckhoff. It's a variation of Gentzen's LJ system. This means that (in theory) Djinn will always find a function if one exists, and if one doesn't exist Djinn will terminate telling you so. This is the very first version, so expect bugs. :) Share and enjoy. -- Lennart

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Haskell-mode 2.0
by Stefan Monnier 02 Feb '09

02 Feb '09

I have recently taken over maintainership of Haskell-mode, and after making a bunch of changes, I figured it would be a good idea to make a new release. You can find this new release at: http://www-perso.iro.umontreal.ca/~monnier/elisp/ If you think it should also be found at http://www.haskell.org/haskell-mode/, then please tell John Peterson to get back to me (my email to him seem to go straight to the bitbucket. John?). This release has several changes that have all been only lightly tested, especially w.r.t compatibility with various Emacsen. See appended the NEWS file that describes some of the notewirthy changes. Stefan Changes since 1.45: * keybindings C-c <char> have been replaced by C-c C-<char> so as not to collide with minor modes. * The following modules are now automatically activated without having to add anything to haskell-mode-hook: haskell-font-lock (just turn on global-font-lock-mode). haskell-decl-scan (just bind `imenu' to some key). * In recent Emacsen, haskell-doc hooks into eldoc-mode. * haskell-hugs and haskell-ghci are superceded by inf-haskell. * Indentation rules have been improved when using layout inside parens/braces. * Symbols like -> and \ can be displayed as actual arrows and lambdas. See haskell-font-lock-symbols. * Tweaks to the font-lock settings. Among other things paren-matching with things like \(x,y) should work correctly now. * New maintainer <monnier(a)gnu.org>.

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The real Monad Transformer
by Henning Thielemann 13 Nov '08

13 Nov '08

It was argued that people avoid Haskell because of terms from Category theory like 'Monad'. This problem can now be solved by a wrapper which presents all the WWW without monads! Start e.g. at http://saxophone.jpberlin.de/MonadTransformer?source=http%3A%2F%2Fwww%2Ehas… Of course the tool is written in Haskell, that is, Haskell helps solving problems which only exist because of Haskell. Bug reports and feature requests can be tracked at https://sourceforge.net/projects/parallelweb

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NW Functional Programming Interest Group
by Greg Meredith 19 Jul '08

19 Jul '08

All, Apologies for multiple listings. A small cadre of us are organizing a Northwest Functional Programming Interest Group (hey... NWFPIG, that's kinda funny). Our first official meeting is at the The Seattle Public Library 1000 - 4th Ave. Seattle, WA 98104 from 17:00 - 18:00 on February 20th. On the first meeting's agenda we'll be - giving people who are interested in or actively using FP for work or play a chance to meet - seeking to build up a pipeline of presentations and guest speakers - trying to keep organizational mishigosh to a minimum Hope to see you there. Monadically yours, --greg -- L.G. Meredith Managing Partner Biosimilarity LLC 806 55th St NE Seattle, WA 98105 +1 206.650.3740 http://biosimilarity.blogspot.com

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2nd call for participation AFP 2008, The Netherlands
by Peter Achten 29 Feb '08

29 Feb '08

2ND CALL FOR PARTICIPATION 6TH INTERNATIONAL SUMMER SCHOOL ON ADVANCED FUNCTIONAL PROGRAMMING 2008 (AFP ’08) RADBOUD UNIVERSITY NIJMEGEN AND UTRECHT UNIVERSITY, THE NETHERLANDS MAY 19-24, 2008 http://www.st.cs.ru.nl/AFP_TFP_2008/ [ EARLY REGISTRATION OPENS ] AFP is a series of international summer schools which aims to bring computer scientists, in particular young researchers and programmers, up to date with the latest advances in practical advanced functional programming. Functional programming emphasizes the evaluation of expressions rather than the execution of commands. We focus on functional programming techniques in “programming in the real world” and bridge the gap between results presented at programming conferences and material from textbooks on functional programming. In this school you will receive in depth lectures about advanced functional programming techniques, taught by experts in the field. Lectures are accompanied by practical problems to be solved by the students at the school. AFP 2008 is hosted by the Radboud University Nijmegen, and Utrecht University, The Netherlands, and will be held in the rural setting of Center Parcs “Het Heijderbos”, Heijen (in the vicinity of Nijmegen), The Netherlands. AFP 2008 is co-located with the 9th Symposium on Trends in Functional Programming (TFP’08), which is held after AFP’08. PROGRAM INFORMATION The following speakers will give the lectures (in alphabetic order): Umut Acar (Toyota Technological Institute, University of Chicago, US) Richard Bird (University of Oxford, UK) Olivier Danvy (University of Aarhus, DK) Johan Jeuring (Utrecht University, NL) Mark Jones (Portland State University, US) Ulf Norell (Chalmers University, SE) Simon Peyton Jones (Microsoft Research, UK) Rinus Plasmeijer (Radboud University Nijmegen, NL) During the summer school, all participants receive printed lecture notes. Participants are expected to have a notebook, in order to be able to participate with the practical problems. After the summer school, all lecture notes will be revised, reviewed, and published in the LNCS series of Springer. All registered participants receive a copy of these lecture notes. VENUE INFORMATION AFP (and TFP) is held in The Netherlands, at Center Parcs “Het Heijderbos” which is a holiday resort in the woodlands near the city of Nijmegen. We accomodate participants in DeLuxe Cottages, each of which has three separate bed-rooms, shared bathroom, toilet, kitchen, and terrace. Cottages will be shared by three participants. If you wish to reduce costs, you can choose to share a bedroom. The summer school and symposium will take place in the business center of the venue. Breakfast, lunch and diner is included within the limits of the venue. The resort features, amongst others, a sub-tropical swimming pool (free for participants), restaurants, shops, water sports lake, midget golf court, squash court, and outdoor and indoor tennis courts. Nijmegen is considered to be the oldest city of the Netherlands, being approximately 2000 years old. Nijmegen is located at the east border of the Netherlands, near Germany. Nijmegen can be reached easily from several airports such as Schiphol airport, Eindhoven airport, and Düsseldorf airport, as well as by train and car. Conveniently close to Center Parcs “Het Heijderbos” you will find airport Weeze in Germany. The venue Center Parcs “Het Heijderbos” can be reached from Nijmegen by train to Boxmeer (25 minutes). From there you will need to order a taxi. The venue can also be reached by car: parking is free for participants of AFP and TFP. SUMMER SCHOOL FEES AFP 2008 includes accommodation, conference, breakfast – lunch – diner, speakers, and proceedings costs. The early registration fee is € 995; the late registration fee is € 1095. Please note that if you require financial support, you can apply for a grant (see below). GRANT INFORMATION We have taken great care to reduce the registration cost as much as possible. We can grant a subsidy for a limited number of PhD student participants for whom the costs are still too high. In order to apply for this subsidy, you need to send (by surface mail or e-mail) a request for subsidy which contains your personal information, affiliation, a description of your current status, project description, a motivation why you should receive the grant, and a recommendation from your PhD supervisor. This letter should arrive before april 7 2008 to: Rinus Plasmeijer Radboud University Nijmegen Toernooiveld 1 6525ED Nijmegen rinus(a)cs.ru.nl You will receive a notification whether your request has been granted before april 14 2008. REGISTRATION INFORMATION Early registration opens at march 1 2008. Late registration opens at april 15 2008. Registration closes at may 5 2008. We can not guarantee accommodation in case you wish to register later than may 5 2008. IMPORTANT DATES (ALL 2008) Early Registration Opens: March 1 Early Registration Deadline: April 14 Late Registration Opens: April 15 Late Registration Deadline: May 5 AFP Summer School: May 19-24 ORGANIZATION Programme Chair: Rinus Plasmeijer, Pieter Koopman, Radboud University Nijmegen, NL Doaitse Swierstra, Utrecht University, NL Arrangements: Peter Achten, Simone Meeuwsen, Radboud University Nijmegen, NL E-mail: afp_tfp_2008(a)cs.ru.nl

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Third Call For Papers TFP 2008, The Netherlands (deadline extended march 10 2008)
by Peter Achten 29 Feb '08

29 Feb '08

3RD CALL FOR PAPERS TRENDS IN FUNCTIONAL PROGRAMMING 2008 RADBOUD UNIVERSITY NIJMEGEN, THE NETHERLANDS MAY 26-28, 2008 INVITED SPEAKER: PROF. HENK BARENDREGT http://www.st.cs.ru.nl/AFP_TFP_2008/ [EXTENDED DEADLINE SUBMISSIONS: march 10 2008] [ SUBMISSION SITE IS OPEN ] [ REGISTRATION SITE IS OPEN ] The symposium on Trends in Functional Programming (TFP) is an international forum for researchers with interests in all aspects of functional programming languages, focusing on providing a broad view of current and future trends in Functional Programming. It aspires to be a lively environment for presenting the latest research results through acceptance by extended abstracts and full papers. A formal post-symposium refereeing process selects the best articles presented at the symposium for publication in a high-profile volume. TFP 2008 is hosted by the Radboud University Nijmegen, The Netherlands, and will be held in the rural setting of Center Parcs “Het Heijderbos”, Heijen (in the vicinity of Nijmegen), The Netherlands. TFP 2008 is co-located with the 6th Int’l. Summer School on Advanced Functional Programming (AFP’08), which is held immediately before TFP’08. SCOPE OF THE SYMPOSIUM The symposium recognizes that new trends may arise through various routes. As part of the Symposium's focus on trends we therefore identify the following five article categories. High-quality articles are solicited in any of these categories: Research: leading-edge, previously unpublished research. Position: on what new trends should or should not be. Project: descriptions of recently started new projects. Evaluation: what lessons can be drawn from a finished project. Overview: summarizing work with respect to a trendy subject. Articles must be original and not submitted for simultaneous publication to any other forum. They may consider any aspect of functional programming: theoretical, implementation-oriented, or more experience-oriented. Applications of functional programming techniques to other languages are also within the scope of the symposium. Contributions on the following subject areas are particularly welcomed: * Dependently Typed Functional Programming * Validation and Verification of Functional Programs * Debugging for Functional Languages * Functional Programming and Security * Functional Programming and Mobility * Functional Programming to Animate/Prototype/Implement Systems from Formal or Semi-Formal Specifications * Functional Languages for Telecommunications Applications * Functional Languages for Embedded Systems * Functional Programming Applied to Global Computing * Functional GRIDs * Functional Programming Ideas in Imperative or Object-Oriented Settings (and the converse) * Interoperability with Imperative Programming Languages * Novel Memory Management Techniques * Parallel/Concurrent Functional Languages * Program Transformation Techniques * Empirical Performance Studies * Abstract/Virtual Machines and Compilers for Functional Languages * New Implementation Strategies * Any new emerging trend in the functional programming area If you are in doubt on whether your article is within the scope of TFP, please contact the TFP 2008 program chairs, Peter Achten and Pieter Koopman, at afp_tfp_2008(a)cs.ru.nl. SUBMISSION AND DRAFT PROCEEDINGS Acceptance of articles for presentation at the symposium is based on the review of full papers (15 pages) and extended abstracts (at least 3 pages) by the program committee. TFP encourages PhD students to submit papers. PhD students may request the program committee to provide extensive feedback on their full papers at the time of submission. Full papers describing work accepted for presentation must be completed before the symposium for publication in the draft proceedings and on-line. Further details can be found at the TFP 2008 website http://www.st.cs.ru.nl/AFP_TFP_2008/. POST-SYMPOSIUM REFEREEING AND PUBLICATION In addition to the draft symposium proceedings, we continue the TFP tradition of publishing a high-quality subset of contributions in the Intellect series on Trends in Functional Programming. IMPORTANT DATES (ALL 2008) Paper Submission: March 10 (extended) Notification of Acceptance: March 31 Early Registration Deadline: April 14 Late Registration Deadline: May 5 Camera Ready Symposium: May 5 TFP Symposium: May 26-28 Post Symposium Paper Submission: June 20 Notification of Acceptance: September 7 Camera Ready Revised Paper: September 21 PROGRAMME COMMITTEE Peter Achten (co-chair) Radboud Univ. Nijmegen, NL Andrew Butterfield Trinity College, IE Manuel Chakravarty Univ. of New South Wales, AU John Clements Cal Poly State Univ., USA Matthias Felleisen Northeastern Univ., USA Jurriaan Hage Utrecht Univ., NL Michael Hanus Christian-Albrechts Univ. zu Kiel, DE Ralf Hinze Univ. of Oxford, UK Graham Hutton Univ. of Nottingham, UK Johan Jeuring Utrecht Univ., NL Pieter Koopman (co-chair) Radboud Univ. Nijmegen, NL Shriram Krishnamurthi Brown Univ., USA Hans-Wolfgang Loidl Ludwig-Maximilians Univ.München, DE Rita Loogen Philipps-Univ. Marburg, DE Greg Michaelson Heriot-Watt Univ., UK Marco T. Morazán (symp. chair) Seton Hall Univ., USA Sven-Bodo Scholz Univ. of Hertfordshire, UK Ulrik Schultz Univ. of Southern Denmark, DK Clara Segura Univ. Complutense de Madrid, ES Olin Shivers Northeastern Univ., USA Phil Trinder Heriot-Watt Univ., UK Varmo Vene Univ. of Tartu, EE Viktória Zsók Eötvös Loránd Univ., HU ORGANIZATION Symposium Chair: Marco T. Morazán, Seton Hall University, USA Programme Chair: Peter Achten, Pieter Koopman, Radboud University Nijmegen, NL Treasurer: Greg Michaelson, Heriot-Watt University, UK

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Haskell goes GPCE/OOPSLA 2008
by Ralf Laemmel 28 Feb '08

28 Feb '08

[One-liner version: please submit workshop/tutorial proposals for GPCE 2008.] The conference on Generative Programming and Component Engineering (GPCE) had some functional programming input over the last few years. It is a good idea to continue this trend. For instance, Haskell-hosted ideas of meta programming and more general (FP-based) ideas of staged programming are at the heart of GPCE. Likewise, aggressive optimization and advanced modularization concepts are in the intersection of the Haskell crowd and the GPCE scope. This year's GPCE conference again co-locates with OOPSLA. We are looking for strong proposals for workshops and tutorials that complement the GPCE technical programme, and thereby also contribute to the combined GPCE/OOPSLA programme. It will be great to get a submission or two from the Haskell community. Please have a look at the call for proposals, at the list of topics, and at the history of the GPCE conference series. For instance, it would be appropriate to see a workshop or a tutorial on type functions, general type-level programming, hygienic templates or macros, advanced partial evaluation, FP refactorings, component programming in FP, ..., something like that. I specifically encourage you to reach out for the crowd at GPCE/OOPSLA so that we extend our impact. http://www.hope.cs.rice.edu/twiki/bin/view/GPCE08/ http://www.hope.cs.rice.edu/twiki/bin/view/GPCE08/CallForWorkshops http://www.hope.cs.rice.edu/twiki/bin/view/GPCE08/CallForTutorials [Deadline: 20th March] Regards, Ralf Laemmel Satellite Chair GPCE 2008 PS: The paper deadline for GPCE is in May.

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Haskell Jobs
by Tom Hawkins 28 Feb '08

28 Feb '08

Hi, We have an opening for a software engineer, with the potential for a lot of Haskell development. Our group at Eaton (http://www.eaton.com/) develops real-time control software for vehicle and machinery applications. This position is specifically for the design and verification of hydraulic hybrid vehicle systems. Think Toyota Prius, but with a accumulator and hydraulic pump instead of a battery and an electric motor. That, and these vehicles can weight over 30,000 pounds. The primary tasks would include vehicle software design, system verification with simulation and possibly formal analysis, telemetry development for remote diagnostics, and tool development to further automate our design flows. Currently we use Haskell for our in-house data analysis tools, and some vehicles run code partially generated by a Haskell DSL. We hope to expand our use of Haskell, especially for simulation regression suites -- maybe QuickCheck in combination with a system modeling and verification DSL. If interested, send a resume. Thanks! -Tom

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ANN: Hoogle 3.1
by Neil Mitchell 28 Feb '08

28 Feb '08

Hi, I am pleased to announce Hoogle 3.1. Hoogle is a search engine for Haskell functions, that allows the user to search by name or approximate type signature. Hoogle can be used without installing anything, by simply visiting the online interface, or can be installed locally. * Online interface: http://www.haskell.org/hoogle/ * Cabal release: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hoogle-3.1 The Cabal release contains a command line version of the Hoogle tool, which you can install with the standard Cabal commands. Hoogle 3.1 has a number of new features. Command line version: * A proper cabal release, including proper installing of the search database. * cabal-install compatible * No longer requires haskell-source-extensions (trhsx) to be installed Web interface: * Better entity escaping in some bits of the web interface * Keyword links work again * Lambdabot suggestions work * Update to the most recent version of base * Security fixes, specifically possible code injection bugs (http://en.wikipedia.org/wiki/Code_injection) - none of which were ever exploited, or could have been exploited (as far as I can tell) I intend to write a more detailed account of the security fixes in a blog post, which will be available from http://planet.haskell.org/ . Running a custom version of the web interface is not really supported, but if you are, please upgrade to the latest darcs version. There are still several known bugs in the Hoogle 3.1 release, but these are more difficult to fix, and will probably be solved in a forthcoming Hoogle 4.0. Thanks Neil

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ANN: MacOSX - A library some Haskell users on OS X might find useful.
by Corey O'Connor 27 Feb '08

27 Feb '08

I've been working on integrating haskell code with some Objective-C/C++ Cocoa Mac OS X applications. Nothing fancy like a Haskell/Cocoa bridge. Just trying to get the build process smooth. The default cabal build system was incomplete to do this effectively;* Extending XCode was no good either. With some effort I created some Cabal build hooks to fix up the behavior of build on OS X and add support for packaging an executable into a ".app" package. That's not much, but I packaged it up, plus some extras, into a library in case other projects would like to use it: http://tothepowerofdisco.com/repo/HaskellLibraries/ Of course, this is all hackish and very incomplete. EG: * No fat binary support. I only have a PPC Mac and the only fat-binary process usable with GHC I know of requires executing the x86 GHC. * The build hook in MacOSX.Build will only work on the Cabal distributed with GHC 6.6.1 and *completely* replaces the standard GHC build hook. * GHC compiled to use the framework version of GMP installed to /Library/Frameworks is required. * The name is vague... Still, I've used it to add haskell support and replace XCode for building for 3 exisitng Cocoa applications. Maybe somebody else will find it useful as well. -- -Corey O'Connor * I neglected to make a good list of why the default Cabal build hook doesn't work.

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