July 2009 - 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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Call For Papers: APLAS 2009 (Korea, Dec 14-16, 2009)
by Zhenjiang Hu 09 Oct '09

09 Oct '09

=============================================================== FIRST CALL FOR PAPERS The Seventh Asian Symposium on Programming Languages and Systems (APLAS 2009) Seoul, December 14-16, 2009 http://ropas.snu.ac.kr/aplas09/ =============================================================== APLAS aims at stimulating programming language research by providing a forum for the presentation of recent results and the exchange of ideas and experience in topics concerned with programming languages and systems. APLAS is based in Asia, but is an international forum that serves the worldwide programming languages community. The APLAS series is sponsored by the Asian Association for Foundation of Software (AAFS), which has recently been founded by Asian researchers in cooperation with many researchers from Europe and the USA. The past formal APLAS symposiums were successfully held in Bangalore (2008, India), Singapore (2007), Sydney (2006, Australia), Tsukuba (2005, Japan), Taipei (2004, Taiwan) and Beijing (2003, China) after three informal workshops held in Shanghai (2002, China), Daejeon (2001, Korea) and Singapore (2000). Proceedings of the past symposiums were published in Springer-Verlag's LNCS 2895, 3302, 3780, 4279, and 5356. TOPICS: The symposium is devoted to both foundational and practical issues in programming languages and systems. Papers are solicited on, but not limited, to the following topics: * semantics, logics, foundational theory * type systems, language design * program analysis, optimization, transformation * software security, safety, verification * compiler systems, interpreters, abstract machines * domain-specific languages and systems * programming tools and environments INVITED SPEAKERS: TBA IMPORTANT DATES: Abstract Deadline: June 8 (Monday), 2009 Paper Submission Deadline: 24:00 AM (in Samoan Time), June 15 (Monday), 2009 Author Notification: August 17, 2009 Camera Ready: September 14, 2009 Conference: December 14-16, 2009 SUBMISSIONS INFORMATION: Papers should be submitted electronically online via the conference submission web page at URL <http://www.easychair.org/conferences/?conf=aplas2009>. Acceptable formats are PostScript or PDF, viewable by Ghostview or Adobe Reader. Submissions should not exceed 16 pages in LNCS format, including bibliography and figures. Submitted papers will be judged on the basis of significance, relevance, correctness, originality, and clarity. They should clearly identify what has been accomplished and why it is significant. Submitted papers must be unpublished and not submitted for publication elsewhere. The proceedings of the symposium is planned to be published as a volume in Springer-Verlag's Lecture Notes in Computer Science series. Authors of selected papers will be invited after the symposium to submit a full version for publication in a special issue of New Generation Computing. GENERAL CHAIR Kwangkeun Yi (Seoul National University, Korea) PROGRAM CHAIR Zhenjiang Hu (National Institute of Inforamtics, Japan) PROGRAM COMMITTEE Manuel M. T. Chakravarty (University of New South Wales, Australia) Wei-Ngan Chin (National University of Singapore, Singapore) Nate Foster (University of Pennsylvania, USA) Ralf Hinze (Oxford University, United Kingdom) Zhenjiang Hu (National Institute of Informatics, Japan), Chair Ik-Soon Kim (Electronics and Telecommunications Research Institute, Korea) Julia Lawall (DIKU, Denmark) Sebastian Maneth (NICTA and University of New South Wales, Australia) Sungwoo Park (Pohang University of Science and Technology, Korea) G. Ramalingam (Microsoft Research, India) Peter Thiemann (University of Freiburg, Germany) Kazushige Terui (Kyoto University, Japan) Janis Voigtländer (Technical University of Dresden, Germany) Chung-chieh Shan (Rutgers University, USA) Kazunori Ueda (Waseda University, Japan) Bow-Yaw Wang (Academia Sinica, Taiwan) Jianjun Zhao (Shanghai Jiaotong University, China) POSTER CHAIR Kiminori Matsuzaki (University of Tokyo, Japan)

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Data.Generics.gzip3 anyone?
by David Fox 08 Aug '09

08 Aug '09

Is there a Scrap Your Boilerplate guru out there who could whip up a three argument version of gzip for me?

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ANNOUNCE: OpenGL 2.3.0.0
by Sven Panne 31 Jul '09

31 Jul '09

A new version of the OpenGL package has bee uploaded to Hackage. The main change is that it is now only a convenience layer upon the OpenGLRaw and GLURaw packages, written in in pure Haskell without the FFI. The latter two packages load the native libraries dynamically and do not rely on any C headers, making it possible to build all OpenGL-related packages even on machines without any installed native OpenGL support. Apart from that, a bug in vertexAttribPointer has been fixed. Cheers, S.

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ANNOUNCE: nntp 0.0.2
by Maciej Piechotka 31 Jul '09

31 Jul '09

Nntp is a library to connect to nntp (i.e. mainly USENET) servers. Since 0.0.1 nntp undergone an nearly total rewrite. Currently RFC977 + one command of RFC2980 is implemented but RFC3977 is on the top of the TODO list. Changes since 0.0.1: - Put into a NntpT monad. It allows to pass and change the state more easily. As code should not be interleave much with normal IO (servers sometimes have short timeout) additional lifts should not be a problem. - Add basic support for XHDR. Other commands should follow. TODO: - Implement the CAPABILITIES call - Change article headers to allow fetching only some of the headers (for use with XOVER etc.) - Implementing other commands - Writing tests - Implementing extentions (TLS, Auth...) Special thanks for Antti-Juhani Kaijanaho who allowed me to experiment with NNTP protocol on his server. Regards

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ANNOUNCE: GLUT 2.2.0.0
by Sven Panne 29 Jul '09

29 Jul '09

A new version of the GLUT package has been uploaded to Hackage. It depends on the new OpenGL, StateVar and Tensor packages, but apart from that the API is unchanged. Furthermore, a simple, pure OpenGL 3.1 demo has been added, which does not rely on any deprecated OpenGL functionality (SmoothOpenGL3). Cheers, S.

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ANN: The Monad.Reader - Issue 14
by Wouter Swierstra 29 Jul '09

29 Jul '09

Dear all, I am pleased to announce that a new issue of The Monad.Reader is now available: http://themonadreader.wordpress.com/ Issue 14 consists of the following three articles: * Fun with Morse Code by Heinrich Apfelmus * Hieroglyph 2: Purely Functional Information Graphics Revisited by Jefferson Heard * Lloyd Allison’s Corecursive Queues: Why Continuations Matter by Leon P Smith Please note that I've moved the Monad.Reader to a new Wordpress blog. You may want to update your bookmarks. If you’d like to write something for the next issue of The Monad.Reader, please get in touch. I haven’t fixed the deadline for the next issue just yet, but expect a deadline late 2009. Wouter

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Building a library for C users
by Thomas Davie 28 Jul '09

28 Jul '09

Hiya all, I'm trying to build a library that can be called from C code. The ghc manual implies that this can be done, but does not specify the compiler options that I need to throw at it, and into which files I should put initialisation/end routines. Does anyone know the magic I need to invoke to get ghc to produce for me (a) a header file, (b) preferably a dynamic library, put a static one if all else fails. Thanks Tom Davie

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ANN: haskell-src-exts-1.1.0
by Niklas Broberg 26 Jul '09

26 Jul '09

Fellow Haskelleers, I'm pleased to announce the release of haskell-src-exts-1.1.0, bringing you tuple sections, comments, and a few bug fixes. haskell-src-exts is a package for Haskell source code manipulation. In particular it defines an abstract syntax tree representation, and a parser and pretty-printer to convert between this representation and String. It handles (almost) all syntactic extensions to the Haskell 98 standard implemented by GHC, and the parsing can be parametrised on what extensions to recognise. haskell-src-exts 1.1.0: =================== * Adds rudimentary support for retaining comments while parsing a source document. The support currently comes in the following form: - The module Language.Haskell.Exts.Comments defines a datatype Comment with two constructors denoting single-line (--) and multi-line ({- -}) comments. - The Parseable class is extended with a function 'parseWithComments :: Parseable ast => ParseMode -> String -> ParseResult (ast, [Comment])' which simply returns all comments as a list alongside the AST. There are also specialised versions for the usual suspects. Example run: HSE> parseExpWithComments defaultParseMode "1 + {- comment -} 4 -- end\n" ParseOk (InfixApp (Lit (Int 1)) (QVarOp (UnQual (Symbol "+"))) (Lit (Int 4)),[Mu ltiLine (SrcLoc {srcFilename = "<unknown>.hs", srcLine = 1, srcColumn = 3}) " co mment ",SingleLine (SrcLoc {srcFilename = "<unknown>.hs", srcLine = 1, srcColumn = 19}) " end"]) This first release of comment support is as seen very rudimentary, but I'm releasing it early in the hope that people who need features tied to this will start looking at what's there and send me comments on what further support they would like to see and consider missing. * Support for TupleSections: <http://hackage.haskell.org/trac/ghc/ticket/3377> * Fixes a bug where the statements of a list comprehension were returned in the wrong order (oops!). * Fixes a bug where function definitions were printed incorrectly when using PPOffsideRule - thanks to Mathieu Boespflug for the patch. * Fixes the broken 'cabal test' - thanks to Robin Green for the entire test runner support! Cheers and Happy Haskelling, /Niklas

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ANNOUNCE: graphviz-2999.1.0.2
by Ivan Lazar Miljenovic 25 Jul '09

25 Jul '09

This is a bug release that fixes a bug spotted by Srihari Ramanathan where the Dot representation of Color values were double-quoted when they shouldn't have been. -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com IvanMiljenovic.wordpress.com

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