- Haskell - Haskell.org

ANN: hledger 0.16
by Simon Michael 01 Oct '11

01 Oct '11

I'm pleased to announce version 0.16 of the hledger packages. This is a stability/bugfix/polish release (which may become the pattern for even-numbered releases in future.) hledger is a library and set of user tools for working with financial data (or anything that can be tracked in a double-entry accounting ledger.) It is a haskell port and friendly fork of John Wiegley's Ledger. hledger provides command-line, curses and web interfaces, and aims to be a reliable, practical tool for daily use. Given a plain text file describing transactions of money or any other commodity, it will print the chart of accounts, account balances, or just the transactions you're interested in. It can also help you record new transactions, or convert CSV data from your bank. Home: http://hledger.org To install: cabal update, cabal install hledger. If you have trouble, let me know or watch the mail list/bug tracker for updates. Optional add-ons: hledger-web hledger-vty hledger-chart hledger-interest. Pre-built platform-specific binaries, which are time-consuming to make and support, are provided on request to anyone who donates. This is a great way to give back and support the project! http://hledger.org/DOWNLOAD.html Release notes for 0.16: * cli: strip the -- when calling add-on commands, so their options work (#64) * cli: hledger ADDON --version now shows add-on command's version * cli: only the add and web commands auto-create the journal file * cli: give a non-confusing error if LEDGER_FILE contains a literal tilde * add: clearer prompts, more validation, use . to end also * add: use unix line endings consistently, avoiding parse error on windows (#51) * add: avoid excess whitespace between transactions (#46) * balance: ledger compatibility fix: don't elide parent accounts with multiple displayed subaccounts * convert: always order converted transactions by date * convert: rename currency -> base-currency, in-field, out-field -> amount-in-field, amount-out-field * convert: give an error, not a zero when date or amount-in-field/amount-out-field parsing fails * register: show more useful range of intervals with --empty and a query pattern * print, web: always show both dates, ignoring --effective (#42) * web: production builds (the default with cabal) have all web content embedded (dev builds use ./static/) (#63) * web: update to yesod 0.9 * web: obey at least some of the general reporting options, like --cost * web: adjust the default base url when a custom port is specified * web: prevent an infinite redirect when custom base url has a trailing slash * web: fix "not:'multi word'" patterns * web: hide old title and search form when adding/editing * web: adjust --help to indicate command-line arguments are not expected * web: don't bother running cli unit tests at startup Stats: - Release contributors: Simon Michael - 30 days, 100 commits, 4 end-user features and 18 end-user bugfixes since last major release - 219 unit & functional tests and 55% unit test coverage (hledger, hledger-lib packages) - 7632 lines of code (all packages) Best, -Simon

1 0

VSTTE 2012 verification competition: call for participation
by Gudmund Grov 30 Sep '11

30 Sep '11

VSTTE 2012 Verification Competition ----------------------------------- A software verification competition is organized on behalf of the VSTTE 2012 conference (https://sites.google.com/site/vstte2012) The purposes of this competition are: to help promote approaches and tools, to provide new verification benchmarks, to stimulate further development of verification techniques, and to have fun. The contest takes place during two days, 17-19 November 2011, two months prior to the conference. Problems will be put on the website of the conference. Solutions must be sent by email to the competition organizers. Any programming language, specification language, and verification tool is allowed. Problems -------- There will be several, independent problems. Each problem is presented as an algorithm, using English or pseudocode, and a list of properties to formally prove about it, also expressed in plain English and standard mathematical notation. Evaluation ---------- Submissions are ranked according to the total sum of points they score. Each problem includes several sub-tasks, e.g. safety, termination, behavioral correctness, etc., and each sub-task is given a number of points. While evaluating the submissions, judges take into account the accuracy and thoroughness of solutions as well as their terseness and elegance. A certain degree of subjectivity is inevitable and should be considered as part of the game. Participants ------------ Anybody interested can take part in the contest. Team work is allowed. However, only teams up to 4 members are eligible for the first prize. The technical requirements are as follows: - access to the web to download the problems (PDF file); - access to the email to submit the solutions; - any software used in the solutions should be freely available to the public (this does not exclude closed source programs such as Microsoft's Z3) and usable on an x86 Linux or Windows machine. Submission ---------- A submission is a (possibly compressed) tarball that contains exactly one directory (named by the team, for instance). This directory should contain at least a text file named README, and one directory for each problem solved. Thus it must look like: team/ -+ +- README +- problem1/ +- problem2/ + ... +- problemN/ +- other stuff... The README file should contain the following information: - contact information (email); - detailed description of the submitted solutions: properties that have been specified and/or proved, restrictions and/or generalizations, anything that may facilitate the review; - detailed instructions to replay the solutions, including the software to use, URLs to get it from, compilation commands, etc. Organizers ---------- - Jean-Christophe Filliâtre (CNRS, France) - Andrei Paskevich (Univ Paris Sud, France) - Aaron Stump (University of Iowa, USA) Schedule -------- Thursday 17 Nov 2011, 15:00 UTC - competition starts Saturday 19 Nov 2011, 15:00 UTC - competition stops Monday 12 Dec 2011 - the winner is notified 28-29 Jan 2012 - results are announced at VSTTE 2012 Prize ----- The winner is awarded a talk slot at VSTTE 2012, to present any research of his/her choice of interest for the VSTTE community. In particular, a presentation of solutions to the competition problems and/or of the techniques and system used would be appreciated. -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

1 0

PhD studentship in Nottingham
by Graham Hutton 29 Sep '11

29 Sep '11

Dear all, I am currently advertising a PhD Studentship in Functional Programming at the University of Nottingham in the UK: http://tinyurl.com/phd-nottingham Due to the nature of the funding, the position is only to UK/EU students who have resided in the UK for the last three years. If you are interested in applying yourself, please drop me a note by email. If you know of any good candidates who may be interested in applying, or there is a local mailing list for advertising such things, I'd be much obliged if you could pass on the above link. Many thanks, Graham Hutton -- Prof Graham Hutton Functional Programming Lab School of Computer Science University of Nottingham, UK http://www.cs.nott.ac.uk/~gmh This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please send it back to me, and immediately delete it. Please do not use, copy or disclose the information contained in this message or in any attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. This message has been checked for viruses but the contents of an attachment may still contain software viruses which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

1 0

Haskell Weekly News: Issue 201
by Daniel Santa Cruz 29 Sep '11

29 Sep '11

Welcome to issue 201 of the HWN, a newsletter covering developments in the Haskell community. This release covers the week of September 18 to 24, 2011. You can find the HTML version of this issue at: http://contemplatecode.blogspot.com/2011/09/haskell-weekly-news-issue-201.h… Announcements Jasper Van der Jeugt sent more details about the 9th GhentFPG meeting, which will take place on October the 4th, at 19:30 in the Technicum building of Ghent University. "You don't have to be a Functional Programming guru to attend, everyone eager to learn is welcome." [1] http://goo.gl/hAa5Zn New and Updated Projects * usb, bindings-libusb, usb-iteratee (Bas van Dijk; 1.0, 1.4.4, 0.4) Wrapers around the portable C library libusb-1.0 [2] http://goo.gl/lTMNJn * ivy-web (James Deng; 0.1) A lightweight web framework, with type-safe routes, based on invertible syntax, and i18n support, influenced by Django, Snap and Yesod. [3] http://goo.gl/dTcPEn * lushtags (Bit Connor) ctags compatible tags files for Haskell programs. [4] http://goo.gl/30TYen * lightweight monadic regions family (Bas van Dijk; multiple versions) Updates to regios, regions-mtl, regions-monadstf, regional-pointers, safer-file-handles, safer-file-handles-bytestring, safer-file-handles-text, and usb-safe. [5] http://goo.gl/g8P6Kn * skein (Felipe Almeida Lessa; 0.1) A family of fast secure cryptographic hash functions. [6] http://goo.gl/xwafmn Quotes of the Week * dafis: I thought a C++ friend class was one you allowed to touch your private parts * edwardk: any time i can help, just ask. i may not actually help, but i'll be sure to note your suffering. * edwardk: i have a lot fewer [haddock problems] now since i stopped bothering trying to document ;) * edwardk: Had i thought of it earlier i could have named trifecta kessel run. at this point it looks like it'll contain at least 12 parsecs. * ddarius: The history of iteratees is making a simple idea complex. * shachaf: You can never escape having learned monads. If you learn two monads, though, you can go back to only knowing one. Top Reddit Stories * GHCi now supports all top-level declarations Domain: github.com, Score: 104, Comments: 35 On Reddit: [7] http://goo.gl/GfTc9n Original: [8] http://goo.gl/Md5B3n * The best ghc bug ever Domain: twitter.com, Score: 93, Comments: 27 On Reddit: [9] http://goo.gl/3sCHUn Original: [10] http://goo.gl/N7IGdn * Running a startup on Haskell Domain: bos.github.com, Score: 73, Comments: 33 On Reddit: [11] http://goo.gl/HevD3n Original: [12] http://goo.gl/IsXedn * No chrome, Haskell is not Danish. Domain: i.imgur.com, Score: 73, Comments: 26 On Reddit: [13] http://goo.gl/AYyq4n Original: [14] http://goo.gl/whKijn * Did Haskell Platform miss the July release? It's already September. Domain: trac.haskell.org, Score: 46, Comments: 12 On Reddit: [15] http://goo.gl/6m8Yln Original: [16] http://goo.gl/r9k6tn * Iteratees at Tsuru Capital: various contributions to the hackage iteratee library used in a production trading system Domain: blog.kfish.org, Score: 36, Comments: 12 On Reddit: [17] http://goo.gl/rCTO6n Original: [18] http://goo.gl/PikaAn * Apprendre Haskell vous fera le plus grand bien ! -- LYAH in French Domain: lyah.haskell.fr, Score: 33, Comments: 15 On Reddit: [19] http://goo.gl/pV3jvn Original: [20] http://goo.gl/ixiXWn * Would You Bet $100,000,000 on Haskell? Domain: digitalmars.com, Score: 28, Comments: 44 On Reddit: [21] http://goo.gl/oPI5Kn Original: [22] http://goo.gl/YYeOln * Galois offers Haskell course: The Tao of Functional Programming Domain: corp.galois.com, Score: 26, Comments: 9 On Reddit: [23] http://goo.gl/6HX8Kn Original: [24] http://goo.gl/n7urdn Top StackOverflow Questions * What are Haskell's strictness points? votes: 59, answers: 7 Read on SO: [25] http://goo.gl/5PiDHn * Can someone explain the traverse function in Haskell votes: 14, answers: 3 Read on SO: [26] http://goo.gl/P5WtFn * Why do we have map, fmap and liftM? votes: 13, answers: 1 Read on SO: [27] http://goo.gl/TCRKwn * Does a function like this already exist? (Or, what's a better name for this function?) votes: 12, answers: 4 Read on SO: [28] http://goo.gl/QY6i8n * Question about the ~ and @ operators in Haskell votes: 11, answers: 2 Read on SO: [29] http://goo.gl/pXnV6n * Folding across Maybes in Haskell votes: 8, answers: 5 Read on SO: [30] http://goo.gl/y1ALtn * How is foldl lazy? votes: 7, answers: 4 Read on SO: [31] http://goo.gl/LQAxNn * avoid explicit passing of lookup table votes: 7, answers: 4 Read on SO: [32] http://goo.gl/tKh2wn * Why is [Char]-based input so much slower than the [Char]-based output in Haskell? votes: 7, answers: 1 Read on SO: [33] http://goo.gl/2nuqNn Until next time, Daniel Santa Cruz References 1. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/92680 2. http://permalink.gmane.org/gmane.comp.lang.haskell.general/18935 3. http://permalink.gmane.org/gmane.comp.lang.haskell.general/18936 4. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/92480 5. http://permalink.gmane.org/gmane.comp.lang.haskell.general/18940 6. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/92528 7. https://github.com/ghc/ghc/commit/3db757241ce7fb99c096c30481aefa86bb9855a1 8. http://www.reddit.com/r/haskell/comments/kmxf2/ghci_now_supports_all_toplev… 9. http://twitter.com/#!/bos31337/status/116372971509121025 10. http://www.reddit.com/r/haskell/comments/kmk6q/the_best_ghc_bug_ever/ 11. http://bos.github.com/strange-loop-2011/talk/talk.html#(1) 12. http://www.reddit.com/r/haskell/comments/km2b8/running_a_startup_on_haskell/ 13. http://i.imgur.com/D4QEO.png 14. http://www.reddit.com/r/haskell/comments/koom1/no_chrome_haskell_is_not_dan… 15. http://trac.haskell.org/haskell-platform/wiki/ReleaseTimetable 16. http://www.reddit.com/r/haskell/comments/kk9hl/did_haskell_platform_miss_th… 17. http://blog.kfish.org/2011/09/iteratees-at-tsuru.html 18. http://www.reddit.com/r/haskell/comments/kjem1/iteratees_at_tsuru_capital_v… 19. http://lyah.haskell.fr/ 20. http://www.reddit.com/r/haskell/comments/km1l6/apprendre_haskell_vous_fera_… 21. http://www.digitalmars.com/d/archives/digitalmars/D/Would_You_Bet_100_000_0… 22. http://www.reddit.com/r/haskell/comments/klhln/would_you_bet_100000000_on_h… 23. http://corp.galois.com/haskell-course 24. http://www.reddit.com/r/haskell/comments/kp6as/galois_offers_haskell_course… 25. http://stackoverflow.com/questions/7490768/what-are-haskells-strictness-poi… 26. http://stackoverflow.com/questions/7460809/can-someone-explain-the-traverse… 27. http://stackoverflow.com/questions/7463500/why-do-we-have-map-fmap-and-liftm 28. http://stackoverflow.com/questions/7518589/does-a-function-like-this-alread… 29. http://stackoverflow.com/questions/7506684/question-about-the-and-operators… 30. http://stackoverflow.com/questions/7464208/folding-across-maybes-in-haskell 31. http://stackoverflow.com/questions/7487455/how-is-foldl-lazy 32. http://stackoverflow.com/questions/7504012/avoid-explicit-passing-of-lookup… 33. http://stackoverflow.com/questions/7510078/why-is-char-based-input-so-much-…

1 1

mapM with Traversables
by thomas burt 28 Sep '11

28 Sep '11

Hi - I have a function, "f :: Monad m => a -> m b", as well as a list of a's. I'd like to produce a sequence (Data.Sequence) of b's, given the a's: g :: [a] -> m (Seq b) g a = do Data.Traversable.mapM f a -- type error! I see that "Data.Traversable.mapM f a" doesn't work... is this like asking the compiler to infer the cons/append operation from the type signature of g? Do I need to write my own function that explicitly calls the "append" functions from Data.Sequence or can I do something else that would work for any "g :: Traversable t, Traversable u => t a -> m (u b)" given "f :: a -> m b"? Thanks for any comments! Thomas

1 0

MSFP 2012: Call for Papers
by James Chapman 28 Sep '11

28 Sep '11

Fourth Workshop on MATHEMATICALLY STRUCTURED FUNCTIONAL PROGRAMMING 25 March, Tallinn, Estonia A satellite workshop of ETAPS 2012 http://cs.ioc.ee/msfp/msfp2012/ The fourth workshop on Mathematically Structured Functional Programming is devoted to the derivation of functionality from structure. It is a celebration of the direct impact of Theoretical Computer Science on programs as we write them today. Modern programming languages, and in particular functional languages, support the direct expression of mathematical structures, equipping programmers with tools of remarkable power and abstraction. Where would Haskell be without monads? Functional reactive programming without arrows? Call-by-push-value without adjunctions? Type theory without universes? The list goes on. This workshop is a forum for researchers who seek to reflect mathematical phenomena in data and control. The first MSFP workshop was held in Kuressaare, Estonia, in July 2006, affiliated with MPC 2006 and AMAST 2006. The second MSFP workshop was held in Reykjavik, Iceland as part of ICALP 2008. The third MSFP workshop was held in Baltimore, USA, as part of ICFP 2010. Important Dates: ================ Submission of papers: 16 December 2011 Notification: 20 January 2012 Final versions due: 3 Feburary 2012 Workshop: 25 March 2012 Invited Speakers: ================= To be arranged. Submission: =========== Papers must report previously unpublished work and not be submitted concurrently to another conference with refereed proceedings. Accepted papers must be presented at the workshop by one of the authors. There is no specific page limit, but authors should strive for brevity. Accepted regular papers will be published in the Electronic Proceedings in Theoretical Computer Science (EPTCS). After the workshop, there might be an opportunity to publish selected papers in a journal special issue. All submissions must be in PDF format and use the EPTCS style files. Submissions can be made through the EasyChair website, at http://www.easychair.org/conferences/?conf=msfp2012 ETAPS: ====== European Joint Conferences on Theory and Practice of Software (ETAPS) is the primary European forum for academic and industrial researchers working on topics relating to software science. ETAPS, established in 1998, is a confederation of six main annual conferences (one of them, POST, being new in 2012), accompanied by satellite workshops. ETAPS 2012 is the fifteenth event in the series. http://www.etaps.org/2012 Host City: ========== Tallinn, a city of 412,000 people, is the capital and largest city of Estonia, a small EU member country in Northern Europe, bordering Russia to the East and Latvia to the south. Located in the north of the country, on the southern shores of the Gulf of Finland, opposite Helsinki in Finland, Tallinn is most well known for its picturesque medieval Old Town, a UNESCO World Heritage site. But it also has a vivid cultural scene, outperforming most European centres of similar size. In 2011, Tallinn, along with Turku in Finland, is the Cultural Capital of Europe. Tallinn is easy to travel to. Estonia is part of Schengen and the Eurozone. The Lennart Meri International Airport of Tallinn /TLL) is only 4km from the city centre. Programme Committee: ==================== * James Chapman (co-chair), Institute of Cybernetics, Tallinn, Estonia * Paul Blain Levy (co-chair), University of Birmingham, UK * Thorsten Altenkirch, University of Nottingham, UK * Robert Atkey, University of Strathclyde, Glasgow, UK * Nils Anders Danielsson, Chalmers University and University of Gothenburg, Sweden * Martin Escardo, University of Birmingham, UK * Ichiro Hasuo, University of Tokyo, Japan * Ralf Hinze, University of Oxford, UK * Neelakantan Krishnaswami, Microsoft Research, Cambridge, UK * Daniel R. Licata, Carnegie Mellon University, Pittsburgh, PA * Ulrich Schoepp, LMU Munich, Germany * Alex Simpson, University of Edinburgh, UK * Matthieu Sozeau, INRIA, Paris, France * Sam Staton, University of Cambridge, UK Further Information: ==================== For more information about the workshop, go to: http://cs.ioc.ee/msfp/msfp2012/ With any other questions please do not hesitate to contact the co-chairs at msfp2012(a)easychair.org.

1 0

Haskell Job Opportunity at Sensor Sense
by Bas van Dijk 27 Sep '11

27 Sep '11

Sensor Sense is looking for a software developer to work on the design and implementation of ultra-sensitive trace gas detectors. These instruments belong to the most sensitive in the world. You will work closely with physicists, electronic – and mechanical engineers to design new detectors and improve existing detectors. As a software developer you will be responsible for the complete design and implementation of the software required to operate these instruments. This includes embedded software for data-acquisition, measuring algorithms, data analysis and user interface design. For the next generation of detectors we are developing, we have chosen Haskell to write the control software. Except for some low-level embedded C code, Haskell is used for everything else: interfacing with custom hardware, data analysis and handling the web-based user interface. The ideal candidate has experience with C and Python and is familiar with functional programming. Experience with Haskell is certainly a plus. But rather than developers with experience in specific languages we are looking for fast learners with a flexible mindset. Sensor Sense is a young spin-off company based in Nijmegen (NL). See our website www.sensor-sense.nl for more information. If you are interested or have questions please contact Sacco te Lintel Hekkert <lintelhekkert(a)sensor-sense.nl>.

1 0

Job opportunities at Citrix Systems (Cambridge, UK)
by Mike McClurg 26 Sep '11

26 Sep '11

Hi folks, I just wanted to let everyone know that Citrix is hiring developers to work on the OCaml-based XenAPI toolstack. We are looking to recruit top-class engineers to work on the toolstack; applicants must have a good knowledge of data structures and algorithms, experience of programming in the context of large systems and general aesthetic good taste when it comes to code and architecture. Our code base is significant and varied: over 130,000 lines of OCaml, solving problems ranging from the low-level (Xen hypercalls) to the high-level (resource pool management), to the compiler-driven (generating language bindings for our Xen datamodel). Our ideal candidate will have: * significant experience with applications programming in high-level functional languages (such as OCaml) * an aptitude for implementing (and reasoning about) complex concurrent and distributed systems * the skills required to contribute to both the architectural design and day-to-day development of a large code-base * strong communication skills and problem solving ability * a determination to deliver clean and reliable solutions that meet our customers' needs So if you want to tackle interesting and challenging programming problems and contribute to an innovative, fast-growing product that is already used by tens of thousands of customers across the world, please don't hesitate to send me your CV. Thanks, Mike McClurg PS: Please note that you must have UK right to work. Here are the official job postings, but if you apply please send me your CV directly. * Req #11673 - Software Development Engineer: http://careers.peopleclick.com/careerscp/client_citrix/emea_region/jobDetai… * Req #11897 - Senior Software Developer: http://careers.peopleclick.com/careerscp/client_citrix/emea_region/jobDetai… And here are some links to our company, products and open source projects and code. * The Xen Hypervisor - http://xen.org/ * Citrix XenServer - http://www.citrix.com/English/ps2/products/product.asp?contentID=683148 * Our GitHub account - https://github.com/xen-org

1 0

ANN: ParserFunction-0.0.5
by Enzo Fabrizio 25 Sep '11

25 Sep '11

Dear Haskellers, I am pleased to announce the latest release of ParserFunction. ParserFunction provides utilities for parsing and evaluating mathematical expressions. The central parsing function in this package is stringToExpr, which parses an expression (as a string) and returns an expression tree of type Expr (or nothing if the string is malformed). Example: > stringToExpr "cos(x^2)+4*(1+y)" Just (Add (Cos (Pow (Var 'x') (Num 2.0))) (Mul (Num 4.0) (Add (Num 1.0) (Var 'y')))) Expressions can be evaluated using the function evaluateExpression. Example: > evaluateExpression "1+1" [] 2.0 > evaluateExpression "exp(x)" [('x',1)] 2.718281828459045 > evaluateExpression "sin(arctan(x))*sqrt(y)" [('x',1),('y',2)] 1.0 More information can be found by viewing the source code on Hackage. (http://hackage.haskell.org/package/ParserFunction-0.0.5) The functionality of this package provides the primary framework for several Haskell-based web applications found at (http://www.inputyourdata.com/mathematics.html) Comments and questions regarding this package or its implementation in web programming are welcomed. Regards, Enzo Haussecker University of California, San Diego Applied Mathematics Major Email: enzo [at] ucsd [dot] edu

1 0

ANN: flexiwrap-0.1.0 etc.
by Iain Alexander 23 Sep '11

23 Sep '11

New versions of the package flexiwrap (supplying flexible wrappers for instance selection) and related packages have been released to Hackage. flexiwrap-0.1.0 data-type-0.1.0 function-combine-0.1.0 flexiwrap-smallcheck-0.0.1 flexiwrap version 0.1.0 supports instances of many additional classes for FlexiWrap, and improved documentation, although much remains to be done - more class instances for FlexiWrap, and other wrappers, and more documentation. data-type version 0.1.0 adds a proxy type Data.Type.Proxy. function-combine version 0.1.0 updates its dependencies to support the new version of data-type. flexiwrap-smallcheck version 0.1.0 is a new package supplying support for instances of Serial for FlexiWrap, for use with the smallcheck package. Support for Serial instances for other wrappers is outstanding. Regards, Iain. -- ia(a)stryx.demon.co.uk

1 0