May 2008 - Haskell - Haskell.org

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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Programme terminates silently
by Thomas Bevan 04 Jun '08

04 Jun '08

Hi, I've written the programme below. The lircLoop should never terminate. Unfortunately it does. Worse, no error messages are generated. Not even the final line "Closing down" is printed. How is this possible? Thanks for your help. import Hmpf.Tree as T import Control.Concurrent hiding (forkIO) import Control.Exception import Prelude hiding (catch) import Hmpf.Fork import System.Log.Logger import System.Log.Handler.Simple import System.Log.Handler import System.IO import Network.MPD import Control.Monad.Trans (liftIO) main :: IO () main = do initializeLogging lirc <- newChan lcd <- newChan startLirc device lirc startLCD "localhost" 13666 lcd forkIO logger $ mpdLoop lcd mpd catch (lircLoop lirc lcd mpd) (\e -> errorM logger "Lirc loop died" >> (errorM logger (show e))) putStrLn "Closing down"

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Re: [Haskell] Announce: hback - dual n-back memory game (0.0.2)
by Gwern Branwen 03 Jun '08

03 Jun '08

> On 2008.05.30 19:44:32 +0200, Norbert Wojtowicz <wojtowicz.norbert(a)gmail.com> scribbled 0.7K characters: > I'm pleased to publically announce a little project I've worked on. > Based on a recent research paper [0] that claims fluid intelligence > could be improved by training working memory, I wrote up a dual n-back > test memory game in Haskell and gtk2hs. This is still essentially an > alpha release: all comments are most welcome. > > Original post (includes gameplay instructions): > http://pithyless.com/blog/2008/05/18/hback-haskell-n-back-memory-game/ > > Updated version (overhaul of game with some feature updates): > http://pithyless.com/blog/2008/05/30/hback-0_0_2/ > > Cabal file can be found on hackage: > http://hackage.haskell.org/packages/archive/hback/0.0.2/hback-0.0.2.tar.gz > > [0] http://www.pnas.org/cgi/content/abstract/0801268105v1 This looks fairly interesting, but I think there are a few improvements you could make: * hback does not seem to work with GHC 6.8.x/split-base - I had to add some build-depends like time,random,unix,directory to build. * hback seems to need to be run in its source directory. For example, I installed and went to try it out: hback hback b n b is the number of tests [default=20] n determines the starting n-back test [default=1] (hback:24854): libglade-WARNING **: could not find glade file 'hback.glade' hback: Can't find the glade file "hback.glade" in the current directory It worked when I cded into ~/hback though. There is a nice way to handle this problem with Cabal, FWIW (I used it when packaging Nymphaea which had the same problem with glade files): <http://neilmitchell.blogspot.com/2008/02/adding-data-files-using-cabal.html>. -- gwern Bletchley al-Askari erco AG. Bletchley DJC RG codes Operation Meta-hackers

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Announce: hback - dual n-back memory game (0.0.2)
by Norbert Wojtowicz 30 May '08

30 May '08

I'm pleased to publically announce a little project I've worked on. Based on a recent research paper [0] that claims fluid intelligence could be improved by training working memory, I wrote up a dual n-back test memory game in Haskell and gtk2hs. This is still essentially an alpha release: all comments are most welcome. Original post (includes gameplay instructions): http://pithyless.com/blog/2008/05/18/hback-haskell-n-back-memory-game/ Updated version (overhaul of game with some feature updates): http://pithyless.com/blog/2008/05/30/hback-0_0_2/ Cabal file can be found on hackage: http://hackage.haskell.org/packages/archive/hback/0.0.2/hback-0.0.2.tar.gz [0] http://www.pnas.org/cgi/content/abstract/0801268105v1

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PPDP'08: Call for Participation
by Elvira Albert 30 May '08

30 May '08

................................................................ ACM PPDP 2008 - Call For Participation 10th ACM-SIGPLAN International Symposium on Principles and Practice of Declarative Programming Valencia, Spain, July 15-17, 2008 **** EARLY REGISTRATION: June 10 2008 **** http://www.dsic.upv.es/~slp2008 ................................................................ SCOPE: PPDP 2008 is a forum for the declarative programming communities, gathering researchers working on logic, constraint and functional programming, but also on other programming language paradigms like visual programming, executable specification languages, database languages, AI and knowledge representation languages for the "semantic web". RELATED EVENTS: PPDP 2008 will be co-located with the 15th International Static Analysis Symposium (SAS 2008), the 18th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2008) and the 4th International Workshop on Programming Language Interference and Dependence (PLID 2008). PROGRAMME: Invited Speaker: ----------------- Michael Leuschel. Declarative Programming for Verification: Lessons and Outlook Accepted Papers: ---------------- Veronique Benzaken, Giuseppe Castagna, Dario Colazzo and Cedric Miachon. Pattern by Example: type-driven visual programming of XML queries Lunjin Lu. Inferring Precise Polymorphic Type Dependencies in Logic Programs Olaf Chitil and Thomas Davie. Comprehending Finite Maps for Algorithmic Debugging of Higher-Order Functional Programs Christian Schulte and Peter Stuckey. Dynamic Variable Elimination during Propagation Solving Thibaut Feydy, Andreas Schutt and Peter Stuckey. Global Difference Constraint Propagation for Finite Domain Solvers Romain Pchoux and Jean-Yves Marion. Characterizations of polynomial complexity with a better intensionality rinus plasmeijer, Jan Martin Jansen, Pieter Koopman and Peter Achten. Declarative Ajax and Client Side Evaluation of Workflows using iTasks Peter Thiemann and Matthias Neubauer. Macros for Context-Free Grammars Yves Bertot and Vladimir Komendantsky. Fixed point semantics and partial recursion in Coq Martin Sulzmann and Edmund Lam. Parallel Execution of Multi-Set Constraint Rewrite Rules Raphael Chenouard, Laurent Granvilliers and Ricardo Soto. Model-Driven Constraint Programming Manuel Montenegro, Ricardo Pena and Clara Segura. A Type System for Safe Memory Management and its Proof of Correctness Hendrik Decker and Davide Martinenghi. Classifying Integrity Checking Methods with regard to Inconsistency Tolerance Mauro Piccolo and Luca Paolini. Semantically Linear Programming Languages Salvador Lucas and Jose Meseguer. Order-Sorted Dependency Pairs Edison Mera, Pedro Lopez-Garcia, Manuel Carro and Manuel Hermenegildo. Towards Execution Time Estimation in Abstract Machine-Based (Logic) Languages Clara Bertolissi and Maribel Fernandez. A rewriting framework for the composition of access control policies Michael Hanus. Call Pattern Analysis for Functional Logic Programs Sonia EstÃ©vez, Antonio J. FernÃ¡ndez, Teresa HortalÃ¡ GonzÃ¡lez, Mario RodrÃguez Artalejo, Fernando Saenz-Perez and Rafael del Vado VÃrseda. Cooperation of Constraint Domains in the TOY System Brigitte Pientka and Joshua Dunfield. Programming with proofs and explicit contexts Rafael Caballero, Mario RodrÃÂguez Artalejo and Carlos A. Romero-DÃaz. Similarity-based Reasoning in Qualified Logic Programming Paulo F. Silva and Jose Oliveira. 'Galculator': Functional prototype of a Galois-connection based proof assistant Carlos Olarte and Frank D. Valencia. On the Expressivity of Universal Timed CCP: Undecidability of Monadic FLTL and Closure Operators for Security JosÃ© Morales, Manuel Carro and Manuel Hermenegildo. Comparing Tag Scheme Variations Using an Abstract Machine Generator ORGANIZATION PROGRAM CHAIR: Sergio Antoy, Portland State University SYMPOSIUM CHAIR: Elvira Albert, Complutense University of Madrid LOCAL CHAIR: Christophe Joubert, Technical University of Valencia PROGRAM COMMITTEE: Elvira Albert Complutense University of Madrid, Spain Sergio Antoy Portland State University, USA Maribel Fernandez King's College London, UK Maurizio Gabbrielli University of Bologna, Italy Neil Ghani University of Nottingham, UK Masami Hagiya University of Tokyo, Japan Joxan Jaffar National University, Singapore Claude Kirchner INRIA Bordeaux, France Herbert Kuchen University of Muenster, Germany Michael Maher NICTA and University of New South Wales, Australia Dale Miller INRIA Saclay, France Eugenio Moggi University of Genova, Italy Kostis Sagonas Uppsala University, Sweden Carsten Schurmann, IT University of Copenhagen, Denmark Peter Sestoft IT University of Copenhagen, Denmark

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SecReT 2008 - Reminder
by Santiago Escobar 30 May '08

30 May '08

SecReT 2008 - CALL FOR PARTICIPATION !!! Early registration deadline: JUNE 1, 2008 !!! ******************************************************************** SecReT 2008 3rd International Workshop on Security and Rewriting Techniques http://www.dsic.upv.es/workshops/secret08 Sunday, June 22, 2008, Pittsburgh, USA Affiliated workshop of the 21st IEEE Computer Security Foundations Symposium (CSF) and the 23rd IEEE Symposium on Logic In Computer Science (LICS) The aim of this workshop is to bring together rewriting researchers and security experts, in order to foster their interaction and develop future collaborations in this area, provide a forum for presenting new ideas and work in progress, and enable newcomers to learn about current activities in this area. The workshop focuses on the use of rewriting techniques in all aspects of security. Specific topics include: authentication, encryption, access control and authorization, protocol verification, specification of policies, intrusion detection, integrity of information, control of information leakage, control of distributed and mobile code, etc. The SecReT 2008 program includes 6 regular papers and two invited talks by Jonathan Millen (MITRE,USA) and Hubert Comon (Cachan, France).

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ANNOUNCE: Haskell Communities and Activities Report (14th ed., May 2008)
by Janis Voigtlaender 30 May '08

30 May '08

On behalf of the many, many contributors, we are pleased to announce that the Haskell Communities and Activities Report (14th edition, May 2008) http://www.haskell.org/communities/ is now available from the Haskell Communities home page in PDF and HTML formats. Many thanks go to all the people that contributed to this report, both directly, by sending in descriptions, and indirectly, by doing all the interesting things that are reported. We hope you will find it as interesting a read as we did. If you haven't encountered the Haskell Communities and Activities Reports before, you may like to know that the first of these reports was published in November 2001. Their goal is to improve the communication between the increasingly diverse groups, projects and individuals working on, with, or inspired by Haskell. The idea behind these reports is simple: Every six months, a call goes out to all of you enjoying Haskell to contribute brief summaries of your own area of work. Many of you respond (eagerly, unprompted, and well in time for the actual deadline ;) ) to the call. The editor collects all the contributions into a single report and feeds that back to the community. When we try for the next update, six months from now, you might want to report on your own work, project, research area or group as well. So, please put the following into your diaries now: ---------------------------------------- End of October 2008: target deadline for contributions to the November 2008 edition of the HC&A Report ---------------------------------------- Unfortunately, many Haskellers working on interesting projects are so busy with their work that they seem to have lost the time to follow the Haskell related mailing lists and newsgroups, and have trouble even finding time to report on their work. If you are a member, user or friend of a project so burdened, please find someone willing to make time to report and ask them to `register' with the editor for a simple e-mail reminder in the middle of November (you could point us to them as well, and we can then politely ask if they want to contribute, but it might work better if you do the initial asking). Of course, they will still have to find the ten to fifteen minutes to draw up their report, but maybe we can increase our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! Andres Loeh and Janis Voigtlaender <hcar at haskell.org> -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:voigt@tcs.inf.tu-dresden.de

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