October 2012 - Haskell

ANNOUNCE: ioctl 0.0.1
by Maciej Piechotka 13 Sep '15

13 Sep '15

A package for type-safe I/O control. Currently only ioctl is supported. Currently simply a extract from my tuntap fork TODO: - Return the integer as well as structure (will break the API) - Port for Windows Network.Socket.IOCtl (as soon as I manage to setup some sane environment on this platform) - Wrapping around DeviceIoControl Example (in hsc): data NotRead = NotRead instance NotRead Int where ioctlReq _ = #const FIONREAD notRead s = ioctlsocket' s NotRead Regards

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CFP: Term and Graph rewriting, special issue of MSCS
by Rachid Echahed 13 Feb '14

13 Feb '14

-------------------------------------------------------------------------- First Call for Papers Special Issue of Mathematical Structures in Computer Science (MSCS) on "TERM and GRAPH Rewriting" -------------------------------------------------------------------------- Scope -------------------------------------------------------------------------- Rewriting techniques constitute a foundational theory of computing science. They are being investigated for several structures such as lambda-terms, first-order terms or graphs and have been successfully used in many areas such as programming languages, automated reasoning, program verification, security, etc. This is witnessed by the leading international events ICGT, RTA or TLCA among others. During the last decade, a particular interest has been devoted to the study of the impact of shared structures in term and graph rewriting through the international editions of TERMGRAPH series of workshops. Sharing is indeed ubiquitous in several research areas, for instance: the modelling of first- and higher-order term rewriting by (acyclic or cyclic) graph rewriting, the modelling of biological or chemical abstract machines, the implementation techniques of programming languages. Term and graph rewriting are also used in automated theorem proving and symbolic computation systems working on shared structures... This special issue is devoted to recent developments in all aspects of TERM and GRAPH rewriting. This includes (but is not limited to): term rewriting, graph transformation, proof methods, programming languages, infinitary rewriting, rewrite strategies, semantics, properties of rewriting ... -------------------------------------------------------------------------- Submissions -------------------------------------------------------------------------- Submitted papers must be original and not submitted for publication elsewhere, and will be subject to the standard journal refereeing process of the Mathematical Structures in Computer Science (MSCS) journal. Submissions should be in pdf format following the MSCS instruction for contributors (http://assets.cambridge.org/MSC/MSC_ifc.pdf) and should be submitted electronically via the following easy-chair web site: https://www.easychair.org/conferences/?conf=mscsrewriting2012 -------------------------------------------------------------------------- Important Dates -------------------------------------------------------------------------- January 20, 2012 : Abstract submission February 20, 2012: Paper submission June 15, 2012 : Notification of acceptance -------------------------------------------------------------------------- Guest Editor: -------------------------------------------------------------------------- Rachid Echahed, CNRS LIG Lab., Grenoble, France echahed(a)imag.fr --------------------------------------------------------------------------

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Call for Contributions - Haskell Communities and Activities Report, November 2012 edition
by Janis Voigtländer 01 Nov '12

01 Nov '12

Dear all, I would like to collect contributions for the 23rd edition of the ================================================================ Haskell Communities & Activities Report http://www.haskell.org/haskellwiki/Haskell_Communities_and_Activities_Report Submission deadline: 1 November 2012 (please send your contributions to hcar at haskell.org, in plain text or LaTeX format) ================================================================ This is the short story: * If you are working on any project that is in some way related to Haskell, please write a short entry and submit it. Even if the project is very small or unfinished or you think it is not important enough --- please reconsider and submit an entry anyway! * If you are interested in an existing project related to Haskell that has not previously been mentioned in the HCAR, please tell me, so that I can contact the project leaders and ask them to submit an entry. * Feel free to pass on this call for contributions to others that might be interested. More detailed information: The Haskell Communities & Activities Report is a bi-annual overview of the state of Haskell as well as Haskell-related projects over the last, and possibly the upcoming six months. If you have only recently been exposed to Haskell, it might be a good idea to browse the May 2012 edition --- you will find interesting projects described as well as several starting points and links that may provide answers to many questions. Contributions will be collected until the submission deadline. They will then be compiled into a coherent report that is published online as soon as it is ready. As always, this is a great opportunity to update your webpages, make new releases, announce or even start new projects, or to talk about developments you want every Haskeller to know about! Looking forward to your contributions, Janis (current editor) FAQ: Q: What format should I write in? A: The required format is a LaTeX source file, adhering to the template that is available at: http://haskell.org/communities/11-2012/template.tex There is also a LaTeX style file at http://haskell.org/communities/11-2012/hcar.sty that you can use to preview your entry. If you do not know LaTeX, then use plain text. If you modify an old entry that you have written for an earlier edition of the report, you should already have received your old entry as a template (provided I have your valid email address). Please modify that template, rather than using your own version of the old entry as a template. Q: Can I include Haskell code? A: Yes. Please use lhs2tex syntax (http://people.cs.uu.nl/andres/lhs2tex/) The report is compiled in mode polycode.fmt. Q: Can I include images? A: Yes, you are even encouraged to do so. Please use .jpg format, then. Q: Should I send files in .zip archives or similar? A: No, plain file attachements are the way. Q: How much should I write? A: Authors are asked to limit entries to about one column of text. A general introduction is helpful. Apart from that, you should focus on recent or upcoming developments. Pointers to online content can be given for more comprehensive or "historic" overviews of a project. Images do not count towards the length limit, so you may want to use this opportunity to pep up entries. There is no minimum length of an entry! The report aims for being as complete as possible, so please consider writing an entry, even if it is only a few lines long. Q: Which topics are relevant? A: All topics which are related to Haskell in some way are relevant. We usually had reports from users of Haskell (private, academic, or commercial), from authors or contributors to projects related to Haskell, from people working on the Haskell language, libraries, on language extensions or variants. We also like reports about distributions of Haskell software, Haskell infrastructure, books and tutorials on Haskell. Reports on past and upcoming events related to Haskell are also relevant. Finally, there might be new topics we do not even think about. As a rule of thumb: if in doubt, then it probably is relevant and has a place in the HCAR. You can also ask the editor. Q: Is unfinished work relevant? Are ideas for projects relevant? A: Yes! You can use the HCAR to talk about projects you are currently working on. You can use it to look for other developers that might help you. Q: If I do not update my entry, but want to keep it in the report, what should I do? A: Tell the editor that there are no changes. The old entry will typically be reused in this case, but it might be dropped if it is older than a year, to give more room and more attention to projects that change a lot. Do not resend complete entries if you have not changed them. Q: Will I get confirmation if I send an entry? How do I know whether my email has even reached the editor, and not ended up in a spam folder? A: Prior to publication of the final report, the editor will send a draft to all contributors, for possible corrections. So if you do not hear from the editor within two weeks after the deadline, it is safer to send another mail and check whether your first one was received.

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ANNOUNCE: btree-concurrent
by Johan Brinch 31 Oct '12

31 Oct '12

Greetings Haskellers, We are pleased to announce this new package, featuring a concurrent b-tree developed as part of our master's thesis on backup systems. The package features code related to STM, caching, QuickCheck and of course concurrency and parallelism. And it's also on Hackage: http://hackage.haskell.org/package/btree-concurrent In case the build fails on Hackage and the documentation doesn't work, it's also available here: http://hindsight.dk/doc/html/btree-concurrent Credits to Thomas Conway of Melbourne University, for discussions related to the implementation, and to our supervisor Ken Friis Larsen of University of Copenhagen. And now, the description of the package: ===== A backend agnostic, concurrent BTree with relaxed balance[1] written in Haskell using a mix of IO operations and pure STM. Although the code does work, it is neither production-ready nor complete. Features include: * Caching: While nodes are periodically saved on persistent storage (e.g. disk) they are cached in-memory during operations. * Live flushing: It is possible to save the current version of the tree to disk and run modifying operations at the same time. The nodes are updated buttom-up to ensure a valid tree in the case of a crash. * Backend agnosticism: A simple API is used as an abstraction for the persistent storage. * Verification: The test-suite uses QuickCheck to compare the trees behaviour to that of Data.Map. Deficients include: * Memory greedy. Nodes are not stored in a compact fashion and are constantly being serialised/deserialised. * findMin and findMax are incomplete and may fail (see the TODO for details). * The implementation does not parallelise well. [1] B-trees with relaxed balance, K. S. Larsen & R. Fagerberg, Parallel Processing Symposium, 1995. Proceedings., 9th International -- Johan Brinch & Morten Brøns-Pedersen

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TAP 2013: 1st Call for Papers
by Achim D. Brucker 30 Oct '12

30 Oct '12

(Apologies if you receive this announcement multiple times. We also apologize for resending the first call for papers, the original announcement contained an incorrect URL to easychair.) **************************************************** *** *** *** TAP 2013 *** *** *** *** Abstract submission: January 25, 2013 *** *** Paper submission: February 1, 2013 *** **************************************************** *** TAP 2013 solicits both full papers and *** *** (industrial) experience/tool papers *** *** in combining proofs and (security) testing *** **************************************************** CALL FOR PAPERS 7th INTERNATIONAL CONFERENCE ON TESTS AND PROOFS (TAP 2013) http://www.spacios.eu/TAP2013 Budapest, Hungary, June 17-21, 2013 The TAP conference is devoted to the synergy of proofs and tests, to the application of techniques from both sides and their combination for the advancement of software quality. Testing and proving seem to be contradictory techniques: once you have proved your program to be correct then additional testing seems pointless; on the other hand, when such a proof in not feasible, then testing the program seems to be the only option. This view has dominated the research community since the dawn of computer science, and has resulted in distinct communities pursuing the seemingly orthogonal research areas. However, the development of both approaches has lead to the discovery of common issues and to the realization of potential synergy. Perhaps, use of model checking in testing was one of the first signs that a counterexample to a proof may be interpreted as a test case. Recent breakthroughs in deductive techniques such as satisfiability modulo theories, abstract interpretation, and interactive theorem proving, have paved the way for new and practically effective methods of powering testing techniques. Moreover, since formal, proof-based verification is costly, testing invariants and background theories can be helpful to detect errors early and to improve cost effectiveness. Summing up, in the past few years an increasing number of research efforts have encountered the need for combining proofs and tests, dropping earlier dogmatic views of incompatibility and taking instead the best of what each of these software engineering domains has to offer. The TAP conference aims to bring together researchers and practitioners working in the converging fields of testing and proving, and will offer a generous allocation of papers, panels and informal discussions. Topics of interest cover theory definitions, tool constructions and experimentations, and include (other topics related to TAP are welcome): - Bridging the gap between concrete and symbolic techniques, e.g. using proof search in satisfiability modulo theories solvers to enhance various testing techniques - Transfer of concepts from testing to proving (e.g., coverage criteria) and from proving to testing - Program proving with the aid of testing techniques - New problematics in automated reasoning emerging from specificities of test generation - Verification and testing techniques combining proofs and tests - Generation of test data, oracles, or preambles by deductive techniques such as: theorem proving, model checking, symbolic execution, constraint logic programming - Model-based testing and verification - Generation of specifications by deduction - Automatic bug finding - Debugging of programs combining static and dynamic analysis - Formal frameworks - Tool descriptions and experience reports - Case studies combining tests and proofs - Domain specific applications of testing and proving to new application domains such as validating security protocols, vulnerability detection of programs, security Important Dates: ================ Abstract submission: January 25, 2013 Paper submission: February 1, 2013 Notification: March 3, 2013 Camera ready version: April 5, 2013 TAP conference: June 17-21, 2013 Program Chairs: =============== Margus Veanes (Microsoft Research, USA) Luca Vigano` (University of Verona, Italy) Program Committee: ================== TBA Submission: =========== Please submit your papers via easychair https://www.easychair.org/conferences/?conf=tap2013 (submission page to be opened in due time) TAP 2013 will accept two types of papers: - Research papers: full papers with at most 16 pages in LNCS format (pdf), which have to be original, unpublished and not submitted elsewhere. - Short contributions: work in progress, (industrial) experience reports or tool demonstrations, position statements; an extended abstract with at most 6 pages in LNCS format (pdf) is expected. Subject to final approval by Springer, accepted papers will be published in the Springer LNCS series and will be available at the conference. The contents of previous TAP proceedings is available at: http://www.informatik.uni-trier.de/~ley/db/conf/tap/ -- Dr. Achim D. Brucker, SAP AG, SAP Research Vincenz-Priessnitz-Str. 1, D-76131 Karlsruhe, Phone: +49 6227 7-52595 http://www.brucker.ch

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ICFP 2013: Call for workshops and co-located events
by David Van Horn 29 Oct '12

29 Oct '12

CALL FOR WORKSHOP AND CO-LOCATED EVENT PROPOSALS ICFP 2013 18th ACM SIGPLAN International Conference on Functional Programming September 22 - 28, 2013 Boston, Massachusetts, USA http://icfpconference.org/icfp2013/ The 18th ACM SIGPLAN International Conference on Functional Programming will be held in Boston, Massachusetts on September 22-28, 2013. ICFP provides a forum for researchers and developers to hear about the latest work on the design, implementations, principles, and uses of functional programming. Proposals are invited for workshops (and other co-located events, such as tutorials) to be affiliated with ICFP 2013 and sponsored by SIGPLAN. These events should be more informal and focused than ICFP itself, include sessions that enable interaction among the attendees, and foster the exchange of new ideas. The preference is for one-day events, but other schedules can also be considered. The workshops are scheduled to occur on September 22-24 (the three days before ICFP) and September 28 (the day after ICFP). ---------------------------------------------------------------------- Submission details Deadline for submission: December 7, 2012 Notification of acceptance: January 7, 2013 Prospective organizers of workshops or other co-located events are invited to submit a completed workshop proposal form in plain text format to the ICFP 2013 workshop co-chairs (Patrik Jansson and Sam Tobin-Hochstadt), via email to icfp13-workshops(a)ccs.neu.edu by December 7, 2012. (For proposals of co-located events other than workshops, please fill in the workshop proposal form and just leave blank any sections that do not apply.) Please note that this is a firm deadline. Organizers will be notified if their event proposal is accepted by January 7, 2013, and if successful, depending on the event, they will be asked to produce a final report after the event has taken place that is suitable for publication in SIGPLAN Notices. The proposal form is available at: http://www.icfpconference.org/icfp2013/icfp13-workshops-form.txt Further information about SIGPLAN sponsorship is available at: http://acm.org/sigplan/sigplan_workshop_proposal.htm ---------------------------------------------------------------------- Selection committee The proposals will be evaluated by a committee comprising the following members of the ICFP 2013 organizing committee, together with the members of the SIGPLAN executive committee. Workshop Co-Chair: Patrik Jansson (Chalmers University of Technology) Workshop Co-Chair: Sam Tobin-Hochstadt (Northeastern University) General Chair : Greg Morrisset (Harvard University) Program Chair: Tarmo Uustalu (Tallinn University of Technology) ---------------------------------------------------------------------- Further information Any queries should be addressed to the workshop co-chairs (Patrik Jansson and Sam Tobin-Hochstadt), via email to icfp13-workshops(a)ccs.neu.edu

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Call for workshop proposals at CAV13
by Igor Konnov 29 Oct '12

29 Oct '12

[ Our apologies if you receive multiple copies of this call ] ***** CALL FOR WORKSHOP PROPOSALS ***** 25th International Conference on Computer Aided Verification (CAV 2013) July 13-19, 2013, Saint Petersburg, Russia Website: http://cav2013.forsyte.at/ The 2013 Computer-Aided Verification (CAV) Workshops provide an opportunity for participants to discuss topics in the broader verification related domains. CAV 2013 Workshops will be held before the main conference on July 13 and 14. Workshop proposals will be reviewed by the workshop chair along with the program chairs and members of the steering committee. Proposals must consist of the following two parts: -- Part I: Technical Information -- A short (about 1 page) scientific justification of the proposed topic, its significance and relevance to CAV, and the particular benefits of the workshop to the verification community, as well as a list of previous or related workshops (if relevant). -- Part II: Organizational Information -- - contact information of the workshop organizers - identifying a main contact for the workshop (i.e. a workshop chair) - the desired length of the workshop, (one or two days) - estimate of the audience size - proposed format and agenda (for example, demo sessions, tutorials, etc.) - potential invited speakers - procedures for selecting papers and participants - plans for dissemination, if any (for example, special issues of journals) - special technical, AV, or USB stick needs - links to a preliminary website of the workshop and call for papers (if possible) - information if workshop has been previously held Important Dates: Proposals are due by Nov 23, 2012 by email to the workshop chair. Organizers will be notified by Nov 30, 2012. The workshop proposals will be reviewed and evaluated on the following criteria: * Potential to advance state of the art in verification technologies, especially ability to break new ground. * Relevance to CAV. * Overlap of topics with other proposed workshops. * Past-successes of the workshop and association with previous CAV conferences. * Organizers' ability and experience to lead a successful workshop. All accepted workshops will be asked to provide a webpage, call for papers, and list of invited speakers. The workshop participants will be required to register for the workshop through the CAV main registration page. The registration rates for workshops will be set by CAV organizers in consultation with the workshop organizers, following rate structures similar to (but not the same as) those followed in the past. The workshop organizers are strongly encouraged to seek external funding and sponsorships. For further enquiries or information, please contact: Igor Konnov (CAV2013 Workshop Chair) Vienna University of Technology, Institute of Information Systems 184 Favoritenstrasse 9-11, 1040 Vienna, Austria email: konnov AT forsyte.at http: http://forsyte.tuwien.ac.at/people/konnov/ Phone: +43-158801-184807

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ANNOUNCE: pretty-tree
by Ivan Lazar Miljenovic 26 Oct '12

26 Oct '12

For a project I'm working on, I got sick of writing out trees by hand. Data.Tree has a drawTree function, but whilst it's better than nothing, I prefer a more top-down "traditional" approach to drawing trees. So I wrote a package to do just that: http://hackage.haskell.org/package/pretty-tree (I didn't think to check whether diagrams had capabilities to do so until after I finished, though in this case I prefer a textual approach anyway.) I'm more than happy to consider adding other forms of drawing trees (though off-hand I can't think of any), or of course you can send me patches since I'm taking advantage of the nice new shiny hub.darcs.net (thanks Darcs team!). I was going to put an example here but it only really comes out nicely if you're using a monospaced font, so have a look at the Haddock docs for the module once Hackage builds it (in hindsight, I should probably have come up with better labels before releasing the package... oh well :) -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com http://IvanMiljenovic.wordpress.com

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Haskell Weekly News: Issue 248
by Daniel Santa Cruz 25 Oct '12

25 Oct '12

Welcome to issue 248 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of October 14 to October 20, 2012. Quotes of the Week * shachaf: Don't fixity fit ain't broken. * shachaf: SIKP, the cheap knockoff book that uses the less-known programming language "skeem" * shachaf: category-extras was so great until the antitrust lawsuit. * Cale: If there was a second syntax and we named it cata' would that be a catastrophe? * acowley: I just don't want edwardk to name them, because he'll choose a name like "x" * cmccann: so edwardk has abstracted things to the point where you can use his libraries without even installing them * Jafet: Agda has an evaluator? * johnw: but probably the other package is more "idiomatic". if by that you mean "uses mathematics to such a degree that most people walk away in consternation" * copumpkin: if I throw enough CT terms out there, one of them is bound to be right eventually * spj: "Our imperative colleagues do a lot of reasoning about their systems. Well, they have to." * spj: "You do the category theory, and you talk to Gordon. And he talks to Phil. And Phil talks to me." * ciaranm: a confusion is just the categorical dual of a fusion, which is just a fusoid in the category of brainofunctors Top Reddit Stories * The University of Heidelberg now uses Haskell for the intro cs course! Domain: self.haskell, Score: 85, Comments: 60 On Reddit: [1] http://goo.gl/abq2b Original: [2] http://goo.gl/abq2b * Cartesian Closed Comic #15: Iteratees Domain: ro-che.info, Score: 74, Comments: 2 On Reddit: [3] http://goo.gl/9NpD2 Original: [4] http://goo.gl/SB7HZ * Fast Code Nation: The Bright Side of High-Level Languages Domain: bos.github.com, Score: 63, Comments: 11 On Reddit: [5] http://goo.gl/KmBRt Original: [6] http://goo.gl/jm9s7 * VIDEO: Simon Marlow on High Performance Concurrency at the Haskell eXchange at Skills Matter Oct. 10th Domain: skillsmatter.com, Score: 44, Comments: On Reddit: [7] http://goo.gl/IuJhH Original: [8] http://goo.gl/BeHRg * Cellular automata as comonads Domain: blog.sigfpe.com, Score: 36, Comments: 10 On Reddit: [9] http://goo.gl/73nr2 Original: [10] http://goo.gl/vH4TK * VIDEO: Simon Peyton Jones at the Haskell eXchange about the origins and the future of Haskell Domain: skillsmatter.com, Score: 31, Comments: 6 On Reddit: [11] http://goo.gl/Iklcf Original: [12] http://goo.gl/WxJhc * Duality for Haskellers : Inside 206-105 Domain: blog.ezyang.com, Score: 31, Comments: 1 On Reddit: [13] http://goo.gl/qhohx Original: [14] http://goo.gl/VuHMS * Communication Patterns in Cloud Haskell (Part 4): K-Means Domain: well-typed.com, Score: 27, Comments: On Reddit: [15] http://goo.gl/9bT02 Original: [16] http://goo.gl/7S5XQ * VIDEO: Duncan Coutts on Cloud Haskell at the Haskell eXchange at Skills Matter Oct 10 Domain: skillsmatter.com, Score: 26, Comments: 29 On Reddit: [17] http://goo.gl/lLyGD Original: [18] http://goo.gl/eUd0W * How to use Yesod without Template Haskell Domain: yesodweb.com, Score: 26, Comments: On Reddit: [19] http://goo.gl/HT3aD Original: [20] http://goo.gl/s81mw * Variance Shadow Mapping with LambdaCube 3D Domain: lambdacube3d.wordpress.com, Score: 23, Comments: 5 On Reddit: [21] http://goo.gl/g3Hs0 Original: [22] http://goo.gl/jDv0S * Thinking Functionally with Haskell | PragPub 2012/10 Domain: pragprog.com, Score: 21, Comments: 1 On Reddit: [23] http://goo.gl/N9HRL Original: [24] http://goo.gl/6ptKX * Haskell Automatic Information Labeling System - new release and video Domain: self.haskell, Score: 18, Comments: 4 On Reddit: [25] http://goo.gl/ujURP Original: [26] http://goo.gl/ujURP * Livecoding with the Happstack web framework. (2 hour video) Domain: youtube.com, Score: 18, Comments: 22 On Reddit: [27] http://goo.gl/POkCB Original: [28] http://goo.gl/n5uNA * VIDEO: Blake Rain on Scalable web applications with YESOD at the Haskell eXchange at Skills Matter Oct 10 Domain: skillsmatter.com, Score: 17, Comments: 2 On Reddit: [29] http://goo.gl/kFPsJ Original: [30] http://goo.gl/zUNBb * Measuring the performance of Warp Domain: yesodweb.com, Score: 17, Comments: 13 On Reddit: [31] http://goo.gl/MBPnT Original: [32] http://goo.gl/p3HUq * Tail Recursive Sorting (QuickSort) Domain: self.haskell, Score: 15, Comments: 31 On Reddit: [33] http://goo.gl/qkECv Original: [34] http://goo.gl/qkECv * a class that generalizes over Functor, Functor2, Functor3, and so on — Redshift Phase 2: types classes for types with arbitrary numbers of * parameters Domain: csks.wordpress.com, Score: 15, Comments: 17 On Reddit: [35] http://goo.gl/gjQL2 Original: [36] http://goo.gl/0XsPN * Wiggling Sums: a somewhat interesting Traversable problem Domain: jaspervdj.be, Score: 13, Comments: 12 On Reddit: [37] http://goo.gl/FKPw3 Original: [38] http://goo.gl/xu2oX * VIDEO: Lennart Augustsson on 'Making EDSL's Fly at the Haskell eXchange at Skills Matter Oct 10 Domain: skillsmatter.com, Score: 12, Comments: 5 On Reddit: [39] http://goo.gl/hFlF6 Original: [40] http://goo.gl/TXMg4 Top StackOverflow Questions * Why not be dependently typed? votes: 25, answers: 1 Read on SO: [41] http://goo.gl/1TSVh * Writing cojoin or cobind for n-dimensional grid type votes: 23, answers: 0 Read on SO: [42] http://goo.gl/qbz7z * Monad Transformers vs Passing parameters to functions votes: 21, answers: 1 Read on SO: [43] http://goo.gl/UpU57 * SOAP web services in haskell? votes: 16, answers: 1 Read on SO: [44] http://goo.gl/1fiiM * How does one statisfy a class constraint in an instance of a class that requires a type constructor rather than a concrete type? votes: 13, answers: 1 Read on SO: [45] http://goo.gl/DD00Q * If “List” is a monoid, what is its “set”? votes: 13, answers: 2 Read on SO: [46] http://goo.gl/bYYar * Lambda calculus in Haskell: Is there some way to make Church numerals type check? votes: 13, answers: 2 Read on SO: [47] http://goo.gl/66qKc * Relation between Haskell Threads and OS Threads in the GHC votes: 13, answers: 1 Read on SO: [48] http://goo.gl/2u8pS * Can Scala's Cake Pattern be implemented in Haskell? votes: 12, answers: 2 Read on SO: [49] http://goo.gl/QiMfg * Agda Type-Checking and Commutativity / Associativity of + votes: 9, answers: 1 Read on SO: [50] http://goo.gl/CqnMJ Until next time, Daniel Santa Cruz References 1. http://www.reddit.com/r/haskell/comments/11klmw/the_university_of_heidelber… 2. http://www.reddit.com/r/haskell/comments/11klmw/the_university_of_heidelber… 3. http://ro-che.info/ccc/15.html 4. http://www.reddit.com/r/haskell/comments/11t7ru/cartesian_closed_comic_15_i… 5. http://bos.github.com/reaktor-dev-day-2012/reaktor-talk-slides.html 6. http://www.reddit.com/r/haskell/comments/11sl47/fast_code_nation_the_bright… 7. http://skillsmatter.com/podcast/home/high-performance-concurrency/ac-5258 8. http://www.reddit.com/r/haskell/comments/11geat/video_simon_marlow_on_high_… 9. http://blog.sigfpe.com/2006/12/evaluating-cellular-automata-is.html 10. http://www.reddit.com/r/haskell/comments/11o6nu/cellular_automata_as_comona… 11. http://skillsmatter.com/podcast/home/front-end-language-features/ac-5258 12. http://www.reddit.com/r/haskell/comments/11ge03/video_simon_peyton_jones_at… 13. http://blog.ezyang.com/2012/10/duality-for-haskellers/ 14. http://www.reddit.com/r/haskell/comments/11s0j0/duality_for_haskellers_insi… 15. http://www.well-typed.com/blog/74 16. http://www.reddit.com/r/haskell/comments/11iijo/communication_patterns_in_c… 17. http://skillsmatter.com/podcast/home/cloud-haskell/ac-5258 18. http://www.reddit.com/r/haskell/comments/11gia8/video_duncan_coutts_on_clou… 19. http://www.yesodweb.com/blog/2012/10/yesod-pure 20. http://www.reddit.com/r/haskell/comments/11jap2/how_to_use_yesod_without_te… 21. http://lambdacube3d.wordpress.com/2012/10/14/variance-shadow-mapping/ 22. http://www.reddit.com/r/haskell/comments/11ijjg/variance_shadow_mapping_wit… 23. http://pragprog.com/magazines/2012-10/thinking-functionally-with-haskell 24. http://www.reddit.com/r/haskell/comments/11o5oa/thinking_functionally_with_… 25. http://www.reddit.com/r/haskell/comments/11kpin/haskell_automatic_informati… 26. http://www.reddit.com/r/haskell/comments/11kpin/haskell_automatic_informati… 27. http://www.youtube.com/watch?v=7Wmszk4wZxQ 28. http://www.reddit.com/r/haskell/comments/11obty/livecoding_with_the_happsta… 29. http://skillsmatter.com/podcast/home/scalable-web-applications-with-yesod/a… 30. http://www.reddit.com/r/haskell/comments/11ggaf/video_blake_rain_on_scalabl… 31. http://www.yesodweb.com/blog/2012/10/measuring-warp 32. http://www.reddit.com/r/haskell/comments/11kfqu/measuring_the_performance_o… 33. http://www.reddit.com/r/haskell/comments/11lybk/tail_recursive_sorting_quic… 34. http://www.reddit.com/r/haskell/comments/11lybk/tail_recursive_sorting_quic… 35. http://csks.wordpress.com/2012/10/17/redshift-phase-2-types-classes-for-typ… 36. http://www.reddit.com/r/haskell/comments/11nj47/a_class_that_generalizes_ov… 37. http://jaspervdj.be/posts/2012-10-17-wiggling-sums.html 38. http://www.reddit.com/r/haskell/comments/11mnw5/wiggling_sums_a_somewhat_in… 39. http://skillsmatter.com/podcast/home/making-edsls-fly/ac-5258 40. http://www.reddit.com/r/haskell/comments/11gg80/video_lennart_augustsson_on… 41. http://stackoverflow.com/questions/12961651/why-not-be-dependently-typed 42. http://stackoverflow.com/questions/12963733/writing-cojoin-or-cobind-for-n-… 43. http://stackoverflow.com/questions/12968351/monad-transformers-vs-passing-p… 44. http://stackoverflow.com/questions/12904377/soap-web-services-in-haskell 45. http://stackoverflow.com/questions/12922187/how-does-one-statisfy-a-class-c… 46. http://stackoverflow.com/questions/12927152/if-list-is-a-monoid-what-is-its… 47. http://stackoverflow.com/questions/12942397/lambda-calculus-in-haskell-is-t… 48. http://stackoverflow.com/questions/12944151/relation-between-haskell-thread… 49. http://stackoverflow.com/questions/12947176/can-scalas-cake-pattern-be-impl… 50. http://stackoverflow.com/questions/12949323/agda-type-checking-and-commutat…

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ANN: hledger 0.19
by Simon Michael 21 Oct '12

21 Oct '12

I'm pleased to announce the release of hledger 0.19! This release has just two visible changes: a much faster balance command, and support for the latest GHC and libs. (A hledger-web update will follow.) hledger is a command-line tool and haskell library for tracking financial transactions, which are stored in a human-readable plain text format. In addition to reporting, it can also help you record new transactions, or convert CSV data from your bank. Add-on packages include hledger-web, a web interface. hledger is inspired by and compatible with John Wiegley's Ledger. For more, see http://hledger.org . Install it: cabal update; cabal install hledger . For installation help, see http://hledger.org/MANUAL.html#installing . Or, sponsor a ready-to-run binary for your platform: http://hledger.org/DOWNLOAD.html . Release notes: hledger, hledger-lib: support GHC 7.6 and latest cmdargs, haskeline, split balance report no longer has an O(n^2) slowdown with large numbers of accounts, and is generally more speedy. Benchmark on a 2010 macbook: +-------------------------------------------++--------------+--------------+--------+ | || hledger-0.18 | hledger-0.19 | ledger | +===========================================++==============+==============+========+ | -f data/100x100x10.journal balance || 0.21 | 0.07 | 0.09 | | -f data/1000x1000x10.journal balance || 10.13 | 0.47 | 0.62 | | -f data/1000x10000x10.journal balance || 40.67 | 0.67 | 1.01 | | -f data/10000x1000x10.journal balance || 15.01 | 3.22 | 2.36 | | -f data/10000x1000x10.journal balance aa || 4.77 | 4.40 | 2.33 | +-------------------------------------------++--------------+--------------+--------+ build version is set with CPP instead of cabal-file-th Release contributors: Simon Michael, Sergei Trofimovich Release stats: 106 days, 21 commits, 1 end-user fix, 0 end-user features since last release Project stats: 222 unit & functional tests, 7740 lines of code including hledger-web, 21 committers

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