December 2010 - Haskell-Cafe

Re: [Haskell-cafe] [Haskell] ANNOUNCE: genprog-0.1
by Alberto G. Corona 09 Dec '10

09 Dec '10

> > Hi! >> >> On Thu, Dec 9, 2010 at 1:48 PM, Alberto G. Corona <agocorona(a)gmail.com> >> wrote: >> > assign rates of mutation for each statement, >> >> This could be assigned by evolution itself. If "if" will have high >> probability of mutation then resulting programs will not survive. So >> those probabilities can be assigned by evolution itself and be also >> something which is passed on with generations (with again possibility >> of mutations of those probabilities itself). >> > > As any part in a genetic algoritm, it is a trading of flexibility for huge > gains of speed. take into accout that some of these tricks neded a > subtantial fraction of the age of the universe to evolve using massively > paralell hardware (ecosystems). > > > >> What would be interesting is to have an evolution algorithm which >> would allow such protections to evolve during its run. So some kind of >> protection which would lower the rate of mutation for some code part. >> >> > Species of programs means that the seed of the genetic algoritm must not >> be >> > turing comoplete I guess. It must be specific for each problem. >> >> I do not see this as necessity. Just that those specimens which would >> use this power too much would probably not survive. (If they would >> remove protection for some sentences they have build before.) >> > > The mutation weigths are something conventional for coventional languages. Another option is to design an automodifying evolving language from scratch. That "software DNA" I guess, should follow closely the techniques of the real DNA. Your idea fits more here In the conventional approach, the turing incomplete templates can have pre-assigned mutation weights for each statement. These mutation rates can evolve too. However, nothing prevents from having an additional level for selecting the appropriate template for each problem. > >> >> Mitar >> > > Alberto

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Re: [Haskell-cafe] ANN: hledger 0.13
by Simon Michael 09 Dec '10

09 Dec '10

On Dec 9, 2010, at 3:35 AM, Peter Simons wrote: > you said that a dependency of one of those packages would require > process >= 1.0.1.4. Now, what I don't understand is why you added > that restriction to hledger then? Picture this common scenario, which I saw during installability testing - you install hledger to try it out. Cabal builds it with process 1.0.1.3. You get enthusiastic and later try to cabal install hledger-X, but this fails ("can not install hledger-X because hledger requires process-1.0.1.3"). (In other, similar-seeming cases I have seen cabal rebuild the installed depender; I don't understand all of cabal's behaviour.) I presume the user could work around this by - ghc-pkg unregister hledger; cabal install hledger-X - installing hledger the first time with --constraint process-1.0.1.4 but I figured a low-impact to make things "just work" was to bump hledger's process dependency. Is it making sense ? I welcome further insights or better solutions.

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ICFP 2011: Call for papers
by Wouter Swierstra 09 Dec '10

09 Dec '10

===================================================================== Call for Papers ICFP 2011: International Conference on Functional Programming Tokyo, Japan, Monday 19 -- Wednesday 21 September 2011 http://www.icfpconference.org/icfp2011 ===================================================================== Important Dates ~~~~~~~~~~~~~~~ Titles, abstracts & keywords due: Thursday 17 March 2011 at 14:00 UTC Submissions due: Thursday 24 March 2011 at 14:00 UTC Author response: Tuesday & Wednesday 17-18 May Notification: Monday 30 May 2011 Final copy due: Friday 01 July 2011 Conference: Monday-Wednesday 19-21 September 2011 Scope ~~~~~ ICFP 2011 seeks original papers on the art and science of functional programming. Submissions are invited on all topics from principles to practice, from foundations to features, and from abstraction to application. The scope includes all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages with objects, concurrency, or parallelism. Particular topics of interest include * Language Design: type systems; concurrency and distribution; modules; components and composition; metaprogramming; relations to imperative, object-oriented, or logic programming; interoperability * Implementation: abstract machines; virtual machines; interpretation; compilation; compile-time and run-time optimization; memory management; multi-threading; exploiting parallel hardware; interfaces to foreign functions, services, components, or low-level machine resources * Software-Development Techniques: algorithms and data structures; design patterns; specification; verification; validation; proof assistants; debugging; testing; tracing; profiling * Foundations: formal semantics; lambda calculus; rewriting; type theory; mathematical logic; monads; continuations; delimited continuations; global, delimited, or local effects * Transformation and Analysis: abstract interpretation; partial evaluation; program transformation; program calculation; program proofs; normalization by evaluation * Applications and Domain-Specific Languages: symbolic computing; formal-methods tools; artificial intelligence; systems programming; distributed-systems and web programming; hardware design; databases; XML processing; scientific and numerical computing; graphical user interfaces; multimedia programming; scripting; system administration; security; education * Functional Pearls: elegant, instructive, and fun essays on functional programming * Experience Reports: short papers that provide evidence that functional programming really works or describe obstacles that have kept it from working in a particular application Abbreviated instructions for authors ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * By 17 March 2011, 14:00 UTC, submit a title, an abstract of at most 300 words, and keywords. * By 24 March 2011, 14:00 UTC, submit a full paper of at most 12 pages (6 pages for a Functional Pearl and for an Experience Report), including bibliography and figures. The deadlines will be strictly enforced and papers exceeding the page limits will be summarily rejected. * Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. * Each submission must adhere to SIGPLAN's republication policy, as explained on the web at http://www.acm.org/sigplan/republicationpolicy.htm In addition, authors of resubmitted (but previously rejected) papers have the option to attach an annotated copy of the reviews of their previous submission(s), explaining how they have addressed these previous reviews in the present submission. If a reviewer identifies him/herself as a reviewer of this previous submission and wishes to see how his/her comments have been addressed, the program chair will communicate to this reviewer the annotated copy of his/her previous review. Otherwise, no rewiewer will read the annotated copies of the previous reviews. Overall, a submission will be evaluated according to its relevance, correctness, significance, originality, and clarity. It should explain its contributions in both general and technical terms, clearly identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. The technical content should be accessible to a broad audience. Functional Pearls and Experience Reports are separate categories of papers that need not report original research results and must be marked as such at the time of submission. Detailed guidelines on both categories are on the conference web site. Proceedings will be published by ACM Press. Authors of accepted submissions are expected to transfer the copyright to the ACM. Presentations will be videotaped and released online if the presenter consents by signing an additional permission form at the time of the presentation. Formatting: Submissions must be in PDF format printable in black and white on US Letter sized paper and interpretable by Ghostscript. If this requirement is a hardship, make contact with the program chair at least one week before the deadline. Papers must adhere to the standard ACM conference format: two columns, nine-point font on a ten-point baseline, with columns 20pc (3.33in) wide and 54pc (9in) tall, with a column gutter of 2pc (0.33in). A suitable document template for LaTeX is available from SIGPLAN at http://www.acm.org/sigs/sigplan/authorInformation.htm Submission: Submissions will be accepted electronically at a URL to be named later. Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. Author response: Authors will have a 48-hour period, starting at 14:00 UTC on Tuesday 17 May 2010, to read reviews and respond to them. Special Journal Issue: There will be a special issue of the Journal of Functional Programming with papers from ICFP 2011. The program committee will invite the authors of select accepted papers to submit a journal version to this issue. Conference Chairs: Manuel M T Chakravarty, University of New South Wales, Australia Zhenjiang Hu, National Institute of Informatics (NII), Japan Program Chair: Olivier Danvy, Aarhus University, Denmark Program Committee: Kenichi Asai, Ochanomizu University, Japan Josh Berdine, Microsoft Research, UK Adam Chlipala, Harvard University, USA William Cook, University of Texas at Austin, USA Maribel Fernandez, King's College London, UK Ronald Garcia, Carnegie Mellon University, USA Neal Glew, Intel Labs, USA Jacques Garrigue, Nagoya University, Japan Suresh Jagannathan, Purdue University, USA Sam Lindley, University of Edinburgh, UK Frank Pfenning, Carnegie Mellon University, USA Paola Quaglia, University of Trento, Italy Alexis Saurin, University of Paris VII, France Mike Spivey, Oxford University, UK Kristian Stoevring, University of Copenhagen, Denmark Doaitse Swierstra, Utrecht University, The Netherlands David Van Horn, Northeastern University, USA Rene Vestergaard, JAIST, Japan Edwin Westbrook, Rice University, USA

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Haskell Weekly News: Issue 161 - December 08, 2010
by Daniel Santa Cruz 09 Dec '10

09 Dec '10

Welcome to issue 161 of the HWN, a newsletter covering developments in the [1]Haskell community in the week of November 28 - December 04. Jan Snajder [2]announced the release of genprog, a genetic programming library. Ian Lynagh informed us that the haskell.org server migration is now complete. There might still be some issues lying around, if you happen to spot one, please let the admins know. The biggest announcement this week came from Galois, Inc. on the [3]immediate release of the Haskell Lightweight Virtual Machine. "The HaLVM is a port of the GHC runtime system to the Xen hypervisor, allowing programmers to create Haskell programs that run directly on Xen's "bare metal."" Isabelle Perseil informed us that there is an [4]extension to the submission deadline for papers for International Conference on the Engineering of Complex Computer Systems (ICECCS) until December 15th. Gregory D. Weber [5]informed us of an update to his Sifflet tool, and sifflet-lib. "Sifflet is a visual, functional programming language and support system for students learning about recursion." This week we had 48 new StackOverflow questions, and 33 new Reddit stories. Hackage saw 108 uploads/updates from 59 distinct contributors. Most active uploaders to hackage were Michael Snoyman (16 uploads) and Andy Stewart (13 uploads). Big note of thanks to Janis Voigtländer and to Benjamin L. Russell for sending in bits for this newsletter. So, what went on this week? Top Reddit Stories * Galois releases the Haskell Lightweight Virtual Machine (HaLVM) Domain: galois.com, Score: 105, Comments: 26 On Reddit: http://www.reddit.com/r/haskell/comments/ee4ve/galois_releases_the_haskell_… Original: http://www.galois.com/blog/2010/11/30/galois-releases-the-haskell-lightweig… * Steve Yegge: Haskell Researchers Announce Discovery of Industry Programmer Who Gives a @#!& Domain: steve-yegge.blogspot.com, Score: 54, Comments: 42 On Reddit: http://www.reddit.com/r/haskell/comments/eeqw9/steve_yegge_haskell_research… Original: http://steve-yegge.blogspot.com/2010/12/haskell-researchers-announce-discov… * Fun with monad comprehensions Domain: blog.n-sch.de, Score: 35, Comments: 9 On Reddit: http://www.reddit.com/r/haskell/comments/ecu0w/fun_with_monad_comprehension… Original: http://blog.n-sch.de/2010/11/27/fun-with-monad-comprehensions/ * The Arrow Calculus Domain: wadler.blogspot.com, Score: 34, Comments: 2 On Reddit: http://www.reddit.com/r/haskell/comments/ee0ux/the_arrow_calculus/ Original: http://wadler.blogspot.com/2010/11/arrow-calculus.html * My strings can beat up your string Domain: finger-tree.blogspot.com, Score: 32, Comments: 13 On Reddit: http://www.reddit.com/r/haskell/comments/eecw2/my_strings_can_beat_up_your_… Original: http://finger-tree.blogspot.com/2010/11/my-strings-can-beat-up-your-strings… * Haskell Package Layout: a proposal Domain: mtnviewmark.wordpress.com, Score: 27, Comments: 8 On Reddit: http://www.reddit.com/r/haskell/comments/efhde/haskell_package_layout_a_pro… Original: http://mtnviewmark.wordpress.com/2010/12/02/haskell-package-layout/ * Real World Haskell ebook today: 60% off. Use code DDF2H Domain: oreil.ly, Score: 25, Comments: 16 On Reddit: http://www.reddit.com/r/haskell/comments/edexw/real_world_haskell_ebook_tod… Original: http://oreil.ly/free2choose * Comprehensive Monad Notation Domain: zenzike.com, Score: 23, Comments: On Reddit: http://www.reddit.com/r/haskell/comments/ef5rf/comprehensive_monad_notation/ Original: http://zenzike.com/posts/2010-12-02-comprehensive-monad-notation/ * Google AI Challenge: Languages Used by the Best Programmers Domain: r-bloggers.com, Score: 23, Comments: 13 On Reddit: http://www.reddit.com/r/haskell/comments/efrfv/google_ai_challenge_language… Original: http://www.r-bloggers.com/google-ai-challenge-languages-used-by-the-best-pr… * A small matter of illegal characters Domain: serpentine.com, Score: 22, Comments: 2 On Reddit: http://www.reddit.com/r/haskell/comments/edkhz/a_small_matter_of_illegal_ch… Original: http://www.serpentine.com/blog/2010/11/29/a-small-matter-of-illegal-charact… Top StackOverflow Questions * Whats really more performant? Haskell or OCaml votes: 12, answers: 4 Read on SO: http://stackoverflow.com/questions/4308137/whats-really-more-performant-has… * Problems on migrating from functional to OO votes: 10, answers: 5 Read on SO: http://stackoverflow.com/questions/4348788/problems-on-migrating-from-funct… * Getting a list of all possible data type values in Haskell votes: 8, answers: 3 Read on SO: http://stackoverflow.com/questions/4299319/getting-a-list-of-all-possible-d… * Haskell: Want a better way of doing: value == x || value == y || … votes: 6, answers: 1 Read on SO: http://stackoverflow.com/questions/4294652/haskell-want-a-better-way-of-doi… * Is/Should wrapping functions into a monad transformer be considered bad practice? votes: 6, answers: 3 Read on SO: http://stackoverflow.com/questions/4317101/is-should-wrapping-functions-int… * Trick for “reusing” arguments in Haskell? votes: 5, answers: 2 Read on SO: http://stackoverflow.com/questions/4333864/trick-for-reusing-arguments-in-h… * How to write common “if” branching in Haskell votes: 4, answers: 5 Read on SO: http://stackoverflow.com/questions/4296887/how-to-write-common-if-branching… * Comparing functions in Haskell votes: 4, answers: 4 Read on SO: http://stackoverflow.com/questions/4328620/comparing-functions-in-haskell * Encapsulating a list of functions in haskell in a single one votes: 4, answers: 2 Read on SO: http://stackoverflow.com/questions/4343951/encapsulating-a-list-of-function… * Can I have a value constructor named “/”"? votes: 4, answers: 3 Read on SO: http://stackoverflow.com/questions/4348605/can-i-have-a-value-constructor-n… Quotes from the Week * camccann: A humor monad? So basically that's a model where jokes about something are equivalent to jokes about jokes about something. In other words, meta-humor in-jokes. * djahandarie: I'm like a massively parallel but slow clocked processor * wlangstroth: It's disgusting hom much talent there is at galois About the Haskell Weekly News New editions are posted to [6]the Haskell mailing list as well as to [7]the Haskell Sequence and [8]Planet Haskell. [9]RSS is also available, and headlines appear on [10]haskell.org. To help create new editions of this newsletter, please send stories to dstcruz * at * gmail * dot * com. The code used to produce this version of the newsletter is not yet publicly available, as it is a complete hack designed to get things started again. Until next time, Daniel Santa Cruz References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.general/18322 3. http://article.gmane.org/gmane.comp.lang.haskell.general/18328 4. http://article.gmane.org/gmane.comp.lang.haskell.general/18339 5. http://article.gmane.org/gmane.comp.lang.haskell.general/18344 6. http://www.haskell.org/mailman/listinfo/haskell 7. http://sequence.complete.org/ 8. http://planet.haskell.org/ 9. http://sequence.complete.org/node/feed 10. http://haskell.org/

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ANNOUNCE: packdeps 0.0.0
by Michael Snoyman 08 Dec '10

08 Dec '10

Hi all, I'm happy to announce the first release of packdeps[1]. This is a library and executable containing the same functionality as the original packdeps website[2], namely letting you know when your version bounds exclude the use of the newest version of a library available. While the website is very useful for keeping you up-to-date on your already released packages, it does not help you during the development phase, or for packages not released on Hackage. The executable (packdeps) should be a good fit here. Its usage is very simple: simply pass it a list of cabal files, and it will check each one of them against your 00-index.tar file. (In other words, make sure to run a cabal update before relying on its results too much.) The library, frankly, is a mess: the naming is bad, the performance tradeoffs were chosen for a long-running web application instead of a short-lived console app, and it eats a baby panda each time you run it. I'm more than happy to accept patches on this. Nonetheless, I'm not aware of any bugs in the code, and I think it will be generally useful in its current state. Cheers, Michael [1] http://hackage.haskell.org/package/packdeps [2] http://packdeps.haskellers.com/

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hackage dependencies for cabal setup scripts
by Sönke Hahn 08 Dec '10

08 Dec '10

Hi! If you write a cabal setup script with user hooks, is there a way to tell cabal-install that the setup script itself depends on some package from hackage? (The dependency would be cabal-macosx in my case.) Thanks, Sönke

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Re: [Haskell-cafe] ANN: hledger 0.13
by Simon Michael 08 Dec '10

08 Dec '10

On Dec 8, 2010, at 5:58 AM, Peter Simons wrote: > do you by any chance remember which dependency that was? I wonder, > because I had no trouble compiling hledger 0.13's dependencies on a > standard GHC 6.12.3 system -- only hledger itself fails the "cabal > configure" stage --, so it seems to me like all dependencies work > fine with process 1.0.1.3. Is there something I miss? Hi Peter.. I haven't been able to track it down yet. If I wasn't clear before, hledger-lib and hledger-lib build fine with process-1.0.1.3, but my recollection was that one of hledger-{chart,vty,web} did not. However I might have been outwitted by cabal again. If it turns out we actually can cabal install all five packages with process-1.0.1.3, I'll make a bugfix release.

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LLVM, type-level?
by Lally Singh 08 Dec '10

08 Dec '10

Hey all, I'm generating a structure definition from input, and would like to generate some LLVM code that can use it. I see an 'alloca' function in LLVM.Core that may do the trick, but takes a static type (Ptr a), which I wouldn't have. Is there a dynamic variant? I'm currently generating a TypeDesc Struct type. Also, is everything under LLVM.Core.* private (not LLVM.Core, but LLVM.Core.Util,etc)? I saw from some blog posts that Core.Util has a function for (I think) getting the a function's parameters, but I can't seem to find a way to access it. Is there another way to get the arguments to a function? Thanks for your help, -Lally

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Re: [Haskell-cafe] [Haskell] ANNOUNCE: genprog-0.1
by Alberto G. Corona 08 Dec '10

08 Dec '10

Off topic I was deeply involved in genetic programming in the past (in fact I discovered Haskell on looking for a functional language for genetic programing with better syntax than LISP). But I soon realized that GP was not the holy grial after all. The problem with evolving arbitrary programming code is the fitness landscape<http://www.google.com/search?hl=en&q=fitness+landscape>. Any evolutionary process needs a way to produce small changes that produces small increases or decreases of fitness (parsimony). This is why it is relatively easy to evolve a continuous function towards a desired value. A smal change in a parameter has a small effect in the resulting fitness, so the algoritm can step up trough the smooth fitness landscape upto a local maximum. But programs are non lineal. If I change the expression in a conditional, the flow of the program becomes radically different, so the fitness landscape, instead of a smoth continuous surface is a fractal where there are no way to climb up the mount improbable (Dawkins dixit). http://www.google.com/search?hl=en&q=mount+improbable+dawkins The only way to overcome this is to indentify the smooth parts of the fitness landscape and restrict the exploration to them trough some techniques such is the use of rules, division of the problem in subproblems and ...well any trick programmers use in their ordinary work to restrict and direct the program mutations. It is theoretically possilble to define metalevels of genetic algoritms where rules and strategies are selected by extracting sucessful patterns after evolving a big number of sucessful programs, These metaleves can discover from simple rules such are "if a push is inserted, a pop must be inserted somewhere else (push-pop gene mutation rule), upto the re-discovery of complex rules above mentioned. These rules later would be used to restrict the mutations of the lower levels. Finally the rules could become so accurate that no mutation at the lower level is necessary because the evolved higuer level rules give the solution at the first try. So the genetic algoritms have the potential to design arbitrary complex programs right from scratch, but it may require a few billion years of computing. Anyway this stuff is really interesting and I suspect that the combination of rules and metalevels has some future, at least for helping programmers with intelligent IDEs. 2010/12/8 Kenneth Hoste <kenneth.hoste(a)ugent.be> > Hi Jan, > > Hi Jan, > > On 11/29/2010 12:55 PM, Jan Snajder wrote: > > Dear Haskellers, > > > > I am pleased to announce the release of genprog-0.1, a genetic > > programming library. > > > > (snip) > > Very interesting, and nice job on the code (elegant, well-structured, > well-documented, ...)! > > Genetic programming recently got my attention because one of the bots in > the Google AI contest was built using this technique (see > http://ai-contest.com/forums/viewtopic.php?f=17&t=1136) and it > performed really well (way better than my hand-crafted bot). > > I have a bit of experience with genetic algorithms, on a practical and > pragmatic level. The field of genetic programming is something I hope to > look at and play with in the upcoming months (just for fun). > > I was kind of planning to implement my own genetic programming library > in Haskell as I became familiar with the field, but after diving into > your code it quickly became clear to me you've done a way better job > than I would have. > > I really like the example you provided for evolving an expression that > computes a specified integer value. I plan to start playing with that > and improve the example (faster convergence to a perfect solution, and > also tweaking the current GP config to obtain smaller solutions). > > > A couple of questions (some fairly unrelated to Haskell): > > How hard would it be to extend the current version to support the > evolution of actual Haskell programs? As far as I can tell, the current > version has support for (simple?) self-defined expressions, but this > seems like a long way from supporting Haskell programs with > multi-argument functions that operate on lists, etc., even if you just > limit it to non-monadic Haskell98 code. > > Have you considered playing with dynamic values for the various > parameters that steer the evolution, i.e. population size, > crossover/mutation probabilities, etc.? > One thing I've always wanted to try (but never really got to it) is e.g. > increasing the mutation probability as the evolution seems to be getting > stuck in a (local?) optimum. Also, shrinking the population size if > enough progress is being made could be interesting, to speed up the > evolutionary process. Are you aware of studies that do such a thing? > > Are you planning to actively maintain and extend this library? Are you > using it for research purposes, or did you hack this together just for > fun (if so, nice job!). What do you plan to use it for? > > > Anyway, great job, I hope I'll find the time to play around with this. > > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell >

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Location of .cabal folder
by Michael Snoyman 08 Dec '10

08 Dec '10

Hi all, I'm trying to figure out how to determine the location of the .cabal folder. I'm trying to release the code powering the package dependency site[1] as a standalone library/application, but currently I've simply hardcoded the path to my 00-index.tar file. Thanks, Michael [1] http://packdeps.haskellers.com/

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