- Haskell - Haskell.org

Fwd: [Haskell-cafe] Question about memory usage
by Alberto G. Corona 16 Aug '10

16 Aug '10

It is not repeated because fiblist is pure and has no arguments. Otherwise it would be repeated. 2010/8/14 Tako Schotanus <tako(a)codejive.org> > I was reading this article: > > http://scienceblogs.com/goodmath/2009/11/writing_basic_functions_in_has.php > > And came to the part where it shows: > > > > fiblist = 0 : 1 : (zipWith (+) fiblist (tail fiblist)) > > > Very interesting stuff for somebody who comes from an imperative world of > course. > But then I read that "Once it's been referenced, then the list up to where > you looked is concrete - the computations *won't* be repeated." > and I started wondering how that works. > Because this seems to mean that functions could have unknown (to the > caller) memory requirements. > How does one, programming in Haskell, keep that in check? > And when does that memory get reclaimed? > > Cheers, > -Tako > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

1 0

Gtk2Hs 0.11.1 released
by Axel Simon 14 Aug '10

14 Aug '10

Dear all, after a few months of shaking out bugs, we've released a new patch- level version of Gtk2Hs, the binding to the Gtk+ GUI library suite. Notable changes: - several bug fixes with respect to concurrency on a variety of platforms - linking problems in ghci have been resolved - pango now includes functions to draw text on Cairo surfaces; this makes it possible to render Unicode text into PDF/PS/SVG/PNG documents without the need for the GUI part in the gtk package - we included the demos in the tar balls (we forgot that last time...) - other bug fixes Please see our web-site http://www.haskell.org/gtk2hs/ for further information and read http://code.haskell.org/gtk2hs/INSTALL if you plan to give it a go! Cheers, Axel

2 1

ANN: hswip-0.3 embedding swi-prolog in haskell
by Evgeny Tarasov 13 Aug '10

13 Aug '10

I would like to announce a small library hswip. It is an analogue of pyswip [1] python library in haskell. Hswip allows to embed swi-prolog [2] interpreter into your haskell applications in a convenient way. Let't look at an example: main = do prologInit ["-q","-nosignals"] prologCall "asserta(a(b,c))." prologCall "asserta(parent(pam, bob))." prologCall "asserta(parent(tom, bob))." prologCall "asserta(parent(tom, liz))." prologCall "asserta(parent(bob, ann))." prologCall "asserta(parent(bob, pat))." prologCall "asserta(parent(pat, jim))." res <- prologCall "parent(X,Y)." print res Output: [[("X","pat"),("Y","jim")],[("X","bob"),("Y","pat")],[("X","bob"),("Y","ann")],[("X","tom"),("Y","liz")],[("X","tom"),("Y","bob")],[("X","pam"),("Y","bob")]] The library still has alpha quality and there are many things missing including exception handling and BSD license. Any feedback is welcome! -Evgeny Tarasov [1] http://code.google.com/p/pyswip/ [2] http://www.swi-prolog.org/ [3] http://hackage.haskell.org/package/hswip-0.3

1 0

ANNOUNCE: Sifflet visual programming language, release 1.0!
by gdweber＠iue.edu 12 Aug '10

12 Aug '10

Sifflet 1.0 is now available on Hackage. Sifflet is a visual, functional programming language and support system for students learning about recursion. Sifflet programmers define functions by drawing diagrams, and the Sifflet interpreter uses diagrams to show how the function calls are evaluated. New in This Release ------------------- - Sifflet now has exporters to Scheme, Python, and Haskell and a small supporting "library" for each of those languages. (These exporters are intended for beginning students who are learning these languages, not for "industrial-strength" code production.) - Although the exporters apparently generate correct code, there are at present too many parentheses -- a few extras in Python, many extras in Haskell. (No extra parentheses in Scheme, of course.) - Sifflet has a new number type, Sifflet.Data.Number.Number, which allows numbers to be exact or inexact, almost as in Scheme. Originally intended for the Scheme exporter, it is now also used internally by Sifflet's interpreter. - The code is reorganized. There is now a separate library package, sifflet-lib, in addition to the sifflet package which provides only the executable. At present, the library's API is highly unstable. - Sifflet has a new parser for user inputs, made with Parsec, allowing more intuitive input of numbers (liberation from Haskell number syntax: for example, 0.0 can now be entered as 0.0, 0., or .0) and providing more intelligible error messages for some kinds of invalid input. - Sifflet requires Gtk2hs packages (gtk, glib, cairo) version 0.11; support for the 0.10 Gtk2hs packages is dropped. About Sifflet ------------- Sifflet is a visual, functional programming language intended as an aid for learning about recursion. * A picture explains Sifflet better than words: please see the screenshot showing how to evaluate 3!: http://mypage.iu.edu/~gdweber/software/sifflet/home.html * Features: - Visual editor. - Visual tracer/debugger which shows how recursive and other function calls are evaluated. To support active learning and avoid screen clutter, Sifflet displays only as much of the computation as the user requests. - A carefully crafted tutorial with 31 pictures and about as many pages. - Number, string, and list data types. - A small collection of primitive functions. - Runnable examples of compound functions. - (New!) Sifflet functions can be "exported" to Scheme, Python 3, and Haskell. * Download: http://hackage.haskell.org/package/sifflet-lib http://hackage.haskell.org/package/sifflet * Home page: http://mypage.iu.edu/~gdweber/software/sifflet/home.html * Tutorial: http://mypage.iu.edu/~gdweber/software/sifflet/doc/tutorial.html -- ___ ___ __ _ / _ \ / _ \| | | | Gregory D. Weber, Associate Professor / /_\// / | | | /\ | | Indiana University East / /_\\/ /__| | |/ \| | http://mypage.iu.edu/~gdweber/ \____/\_____/\___/\__/ Tel. (765) 973-8420; FAX (765) 973-8550

1 0

Workshop on ML 2010 - Call for Participation
by Matthew Fluet 12 Aug '10

12 Aug '10

The 2010 ACM SIGPLAN Workshop on ML http://www.cs.rit.edu/~mtf/ml2010 Baltimore, Maryland, United States Sunday, September 26, 2010 co-located with ICFP 2010 Call for Participation ML is a family of programming languages that includes dialects known as Standard ML, Objective Caml, and F#. The development of these languages has inspired a large amount of computer science research, both practical and theoretical. This workshop aims to provide a forum to encourage discussion and research on ML and related technology (higher-order, typed, or strict languages). The format of the 2010 Workshop on ML will be different than that of recent years, returning to a more informal model: a workshop with presentations selected from submitted abstracts but without published proceedings. We hope that this format will encourage the presentation of more exciting (if unpolished) research and deliver a more lively workshop atmosphere. Invited Speaker ~~~~~~~~~~~~~~~ Luke Hoban (Microsoft) -- Bringing F# to Visual Studio 2010 Program ~~~~~~~ 9:00 Invited Talk Visual F#: Bringing F# to Visual Studio 2010 Luke Hoban (Microsoft Research) 10:00 Break 10:30 Probabilistic programming using first-class stores and first-class continuations Oleg Kiselyov (FNMOC); Chung-chieh Shan (Rutgers University) 10:55 Effective progamming in ML Daan Leijen (Microsoft Research); Ross Tate (University of California, San Diego) 11:20 Discussion 11:30 First-class modules and composable signatures in Objective Caml 3.12 Alain Frisch (LexiFi); Jacques Garrigue (Nagoya University Graduate School of Mathematics) 11:55 First-class modules: hidden power and tantalizing promises Jeremy Yallop (Applicative Ltd); Oleg Kiselyov (FNMOC) 12:20 Discussion 12:30 Lunch break 14:00 Deriving a Typed Implementation for Coroutines in ML Konrad Anton (Universitat Freiburg); Peter Thiemann (Universitat Freiburg) 14:25 The Design Rationale for Multi-MLton Suresh Jagannathan (Purdue University); Armand Navabi (Purdue University); KC Sivaramakrishnan (Purdue University); Lukasz Ziarek (Purdue University) 14:50 Discussion 15:00 Mirage: high-performance ML kernels in the cloud Anil Madhavapeddy (University of Cambridge); Thomas Gazagnaire (INRIA Sophia Antipolis) 15:25 Hosting a Standard ML compiler in a Web Browser: Status Report Martin Elsman 15:50 Discussion 16:00 Break 16:30 A simple and effective method for assigning blame for type errors David MacQueen (University of Chicago) 16:55 The MetaOCaml files: Status report and research proposal Oleg Kiselyov (FNMOC); Chung-chieh Shan (Rutgers University) 17:20 Discussion 17:30 Closing Registration and Local Arrangements ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * https://regmaster3.com/2010conf/ICFP10/register.php * http://www.icfpconference.org/icfp2010/local.html Program Chair ~~~~~~~~~~~~~ Matthew Fluet Rochester Institute of Technology Program Committee ~~~~~~~~~~~~~~~~~ Kathleen Fisher AT&T Labs Research Adam Granicz IntelliFactory Daan Leijen Microsoft Research Johan Nordlander Lulea University of Technology Sungwoo Park Pohang University of Science and Technology Daniel Spoonhower Google

1 0

WGP Call for Participation
by Bruno Oliveira 12 Aug '10

12 Aug '10

====================================================================== CALL FOR PARTICIPATION WGP 2010 6th ACM SIGPLAN Workshop on Generic Programming Baltimore, Maryland, US Sunday, September 26th, 2010 http://osl.iu.edu/wgp2010 Collocated with the International Conference on Functional Programming (ICFP 2010) ====================================================================== Goals of the workshop --------------------- Generic programming is about making programs more adaptable by making them more general. Generic programs often embody non-traditional kinds of polymorphism; ordinary programs are obtained from them by suitably instantiating their parameters. In contrast with normal programs, the parameters of a generic program are often quite rich in structure; for example they may be other programs, types or type constructors, class hierarchies, or even programming paradigms. Generic programming techniques have always been of interest, both to practitioners and to theoreticians, and, for at least 20 years, generic programming techniques have been a specific focus of research in the functional and object-oriented programming communities. Generic programming has gradually spread to more and more mainstream languages, and today is widely used in industry. This workshop brings together leading researchers and practitioners in generic programming from around the world, and features papers capturing the state of the art in this important area. Program ------- * 09.00-10.00: Session 1 Chair: Marcin Zalewski * Welcome + PC chair report Bruno C. d. S. Oliveira and Marcin Zalewski * Outrageous but Meaningful Coincidences (Dependent type-safe syntax and evaluation) Conor McBride * 10.00-10.30: Tea/coffee * 10.30-12.30: Session 2 Chair: Shin-Cheng Mu * Scrap Your Zippers: A Generic Zipper for Heterogeneous Types Michael D. Adams * Generic Storage in Haskell Sebastiaan Visser and Andres Loeh * Generic Selections of Subexpressions Martijn van Steenbergen, José Pedro Magalhães and Johan Jeuring * 12.30-14.00: Lunch * 14.00-16.00: Session 3 Chair: Bruno C. d. S. Oliveira * Generic Multiset Programming for Language-Integrated Querying Fritz Henglein and Ken Friis Larsen * Algorithms for Traversal-Based Generic Programming Bryan Chadwick and Karl Lieberherr * Ad-hoc Polymorphism and Dynamic Typing in a Statically Typed Functional Language Thomas van Noort, Peter Achten and Rinus Plasmeijer * 16.00-16.30: Tea/coffee * 16.30-18.00: Session 4 Chair: Conor McBride * Reason Isomorphically! Ralf Hinze and Daniel James * Constructing Datatype-Generic Fully Polynomial-Time Approximation Schemes Using Generalised Thinning Shin-Cheng Mu, Yu-Han Lyu and Akimasa Morihata Workshop homepage: http://osl.iu.edu/wgp2010/ Registration link: https://regmaster3.com/2010conf/ICFP10/register.php Local arrangements: http://www.icfpconference.org/icfp2010/local.html

1 0

Please take the State of Haskell, 2010 survey
by Johan Tibell 09 Aug '10

09 Aug '10

Hi all, I've put together a quick, 9-question State of Haskell, 2010 survey: http://blog.johantibell.com/2010/08/state-of-haskell-2010-survey.html The survey will hopefully give us some insight into how people use Haskell and perhaps also some ideas on how Haskell tools and libraries could be improved. P.S. Please direct replies to this email to haskell-cafe(a)haskell.org. Cheers, Johan

1 1

ICFP 2010: Call for participation
by Wouter Swierstra 06 Aug '10

06 Aug '10

===================================================================== Call for Participation The 15th ACM SIGPLAN International Conference on Functional Programming (ICFP 2010) http://www.icfpconference.org/icfp2010/ Baltimore, Maryland September 25 – October 2 ===================================================================== ICFP 2010 provides a forum for researchers and developers to hear about the latest work on the design, implementations, principles, and uses of functional programming. The conference covers the entire spectrum of work, from practice to theory, including its peripheries. * Program: http://www.icfpconference.org/icfp2010/program.html * Invited speakers: - Mike Gordon ML: Metalanguage or Object Language? - Matthias Felleisen TeachScheme!: A Checkpoint - Guy Blelloch Functional Parallel Algorithms Schedule including related events: * September 25: Workshop on Mechanizing Metatheory (WMM) Workshop on High-Level Parallel Programming and Applications (HLPP) * September 26: Workshop on ML Workshop on Generic Programming (WGP) * September 27-29: ICFP 2010 * September 30: Haskell Symposium Erlang Workshop * October 1: Commercial Users of Functional Programming – Day 1 (CUFP Tutorials) Haskell Implementors' Workshop * October 2: Commercial Users of Functional Programming – Day 2 (CUFP Talks) Registration information: * Registration link: https://regmaster3.com/2010conf/ICFP10/register.php Local arrangements (including travel and accommodation): * http://www.icfpconference.org/icfp2010/local.html * Conference reservation/rate deadline: September 1st Conference organizers: * General Chair: Paul Hudak, Yale University * Program Chair: Stephanie Weirich, University of Pennsylvania * Local Arrangements Chair: Michael Hicks, University of Maryland * Workshop Co-Chairs: Derek Dreyer, Max Planck Institute for Software Systems Christopher Stone, Harvey Mudd College * Programming Contest Chair: Johannes Waldmann, Hochschule für Technik, Wirtschaft und Kultur, Leipzig * Video Chair: Scott Smith, Johns Hopkins University * Publicity Chair: Wouter Swierstra, Vector Fabrics =====================================================================

5 6

announce: fork of SDL/-image/-mixer/-tff bindings for jhc (and wii target)
by Korcan Hussein 04 Aug '10

04 Aug '10

Hello I've modified the source of the original SDL Haskell bindings (SDL,-image,-ttf,-mixer) to build/compile on jhc (0.7.5-6) and jhc targeting devkitPPC (Wii Homebrew), you can get them from here: https://patch-tag.com/r/snk_kid As cabal and jhc don't really go together, i've written makefiles to automate the build/install. I've written this down in the README file. Please note I've hardly tested it (but I've managed to get code working on it), the point is I've managed to get these all building on jhc but it's not perfect at the moment as I did notice some bugs that look like it's related to jhc of-course I intend on reporting these quite shortly. It does kind of work on the Wii Homebrew but you will need to tweak the generated C code to get this working. I'll explain this somewhere soon or make a template project to set this up.

1 0

ANN: scan-0.1.0.3, a Haskell style scanner
by Christian Maeder 03 Aug '10

03 Aug '10

Dear Haskell friends, I like to announce a Haskell style scanner at http://hackage.haskell.org/package/scan documented under http://projects.haskell.org/style-scanner/ It's best used in conjunction with hlint http://community.haskell.org/~ndm/hlint/ and gives many suggestions regarding the file format. Feedback is welcome. Thanks Christian (Discussions should only be posted to either haskell-cafe@ or beginners@)

1 2