May 2015 - Haskell-Cafe

Automatically generate sum type members -> [String]
by Cody Goodman 19 May '15

19 May '15

Can I use either template Haskell, GHC Generics, or something else to get the list of Constructors in Codes? Then I could do `map show codeSumTypeMembers` and get `["A0100A","A0500A"]`? Here's an example of solving this problem manually: data Codes = A0100A | A0500A deriving Show codeExists "A0100A" = True codeExists "A0500A" = True codeExists _ = False main = print $ codeExists xmlElementName where xmlElementName = "A0500A" -- λ> main -- True

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New Functional Programming Job Opportunities
by Functional Jobs 18 May '15

18 May '15

Here are some functional programming job opportunities that were posted recently: Senior Software Engineer (Functional Programming/Scala) at AdAgility http://functionaljobs.com/jobs/8826-senior-software-engineer-functional-pro… Cheers, Sean Murphy FunctionalJobs.com

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data EitherF m1 m2 a = LeftF (m1 a) | RightF (m2 a)
by Daniel van den Eijkel 18 May '15

18 May '15

Hi, I am wondering if there is a library with a datatype like the following defined: data EitherF m1 m2 a = LeftF (m1 a) | RightF (m2 a) I could not find anything with Hoogle. Does anybody know such a thing? Thank you & best, Daniel

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FIXME pragma
by Christopher Done 18 May '15

18 May '15

What's the feeling on having a FIXME pragma so that I can attach warnings to unfinished things? {-# FIXME foo "Reasons here." #-} I would use the WARNING pragma but that doesn't work within a module and only triggers on use. Compiler errors are the one thing I and everyone else pays attention to, it would be very handy to have more control over things GHC reports to the developer to aid development. Ciao

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OCL 2015: First Call for Papers
by Achim D. Brucker 18 May '15

18 May '15

(Apologies for duplicates) CALL FOR PAPERS 15th International Workshop on OCL and Textual Modeling Tools and Textual Model Transformations Co-located with ACM/IEEE 18th International Conference on Model Driven Engineering Languages and Systems (MODELS 2015) September 28th, 2015, Ottawa, Canada http://ocl2015.lri.fr Modeling started out with UML and its precursors as a graphical notation. Such visual representations enable direct intuitive capturing of reality, but some of their features are difficult to formalize and lack the level of precision required to create complete and unambiguous specifications. Limitations of the graphical notations encouraged the development of text-based modeling languages that either integrate with or replace graphical notations for modeling. Typical examples of such languages are OCL, textual MOF, Epsilon, and Alloy. Textual modeling languages have their roots in formal language paradigms like logic, programming and databases. The goal of this workshop is to create a forum where researchers and practitioners interested in building models using OCL or other kinds of textual languages can directly interact, report advances, share results, identify tools for language development, and discuss appropriate standards. In particular, the workshop will encourage discussions for achieving synergy from different modeling language concepts and modeling language use. The close interaction will enable researchers and practitioners to identify common interests and options for potential cooperation. Topics of interest include (but are not limited to) =================================================== - Mappings between textual modeling languages and other languages/formalisms - Algorithms, evaluation strategies and optimizations in the context of textual modeling languages for -- validation, verification, and testing, -- model transformation and code generation, -- meta-modeling and DSLs, and -- query and constraint specifications - Alternative graphical/textual notations for textual modeling languages - Evolution, transformation and simplification of textual modeling expressions - Libraries, templates and patterns for textual modeling languages - Tools that support textual modeling languages (e.g., verification of OCL formulae, runtime monitoring of invariants) - Complexity results for textual modeling languages - Quality models and benchmarks for comparing and evaluating textual modeling tools and algorithms - Successful applications of textual modeling languages - Case studies on industrial applications of textual modeling languages - Experience reports -- usage of textual modeling languages and tools in complex domains, -- usability of textual modeling languages and tools for end-users - Empirical studies about the benefits and drawbacks of textual modeling languages - Innovative textual modeling tools - Comparison, evaluation and integration of modeling languages - Correlation between modeling languages and modeling tasks This year, we particularly encourage submissions describing tools that support - in a very broad sense - textual modeling languages (if you have implemented OCL.js to run OCL in a web browser, this is the right workshop to present your work) as well as textual model transformations. Venue ===== The workshop will be organized as a part of MODELS 2015 Conference in Ottawa, Canada. It continues the series of OCL workshops held at UML/MODELS conferences: York (2000), Toronto (2001), San Francisco (2003), Lisbon (2004), Montego Bay (2005), Genova (2006), Nashville (2007), Toulouse (2008), Denver (2009), Oslo (2010), Zurich (2011, at the TOOLs conference), 2012 in Innsbruck, 2013 in Miami, and 2014 in Valencia, Spain. Similar to its predecessors, the workshop addresses both people from academia and industry. The aim is to provide a forum for addressing integration of OCL and other textual modeling languages, as well as tools for textual modeling, and for disseminating good practice and discussing the new requirements for textual modeling. Workshop Format =============== The workshop will include short (about 15 min) presentations, parallel sessions of working groups, and sum-up discussions. Submissions =========== Three types of papers will be considered: * short papers (between 6 and 8 pages) describing ideas, * tool papers (between 6 and 8 pages), and * full papers (between 12 and 16 pages) in LNCS format. Submissions should be uploaded to EasyChair (https://easychair.org/conferences/?conf=ocl20150) The program committee will review the submissions (minimum 2 reviews per paper, usually 3 reviews) and select papers according to their relevance and interest for discussions that will take place at the workshop. Accepted papers will be published online in a pre-conference edition of CEUR (http://www.ceur-ws.org) Important Dates =============== Submission of papers: July 17, 2015 Notification: August 21, 2015 Workshop date: September 28, 2015 Organizers ========== Achim D. Brucker, SAP SE, Germany Marina Egea, Indra Sistemas S.A., Spain Martin Gogolla, University of Bremen, Germany Frederic Tuong, Univ. Paris-Sud - IRT SystemX - LRI, France Programme Committee =================== Mira Balaban, Ben-Gurion University of the Negev, Israel Tricia Balfe, Nomos Software, Ireland Achim D. Brucker, SAP SE, Germany Fabian Buettner, Inria - Ecole des Mines de Nantes, France Jordi Cabot, Inria - Ecole des Mines de Nantes, France Dan Chiorean, Babes-Bolyai University, Romania Robert Clariso, Universitat Oberta de Catalunya, Spain Tony Clark, Middlesex University, UK Manuel Clavel, IMDEA Software Institute, Spain Carolina Dania, IMDEA Software Institute, Spain Birgit Demuth, Technische Universitat Dresden, Germany Marina Egea, Indra Sistemas S.A., Spain Geri Georg, Colorado State University, USA Martin Gogolla, University of Bremen, Germany Shahar Maoz, Tel Aviv University, Israel Istvan Rath, Budapest University of Technology and Economics, Hungary Bernhard Rumpe, RWTH Aachen, Germany Frederic Tuong, Univ. Paris-Sud - IRT SystemX - LRI, France Claas Wilke, Technische Universitat Dresden, Germany Edward Willink, Willink Transformations Ltd., UK Burkhart Wolff, Univ. Paris-Sud - LRI, France Steffen Zschaler, King's College, UK -- Dr. Achim D. Brucker, SAP SE, Vincenz-Priessnitz-Str. 1, D-76131 Karlsruhe Phone: +49 6227 7-52595, http://www.brucker.ch/

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CFP: Haskell Symposium Regular Track Final Call
by Ben Lippmeier 17 May '15

17 May '15

===================================================================== ACM SIGPLAN CALL FOR SUBMISSIONS Haskell Symposium 2015 Vancouver, Canada, 3-4 September 2015, directly after ICFP http://www.haskell.org/haskell-symposium/2015 ===================================================================== Reminder that the Haskell Symposium Regular Track abstract deadline is this: Tuesday 19th of May, with full papers due this: Friday 22nd of May. Authors that have *already submitted to the early track*, have until 5th of June to resubmit an improved version of those papers. Deadlines stated are valid anywhere on earth. (the HotCRP submission site states them in US EDT, but don't fret) See the website for further details http://www.haskell.org/haskell-symposium/2015 =====================================================================

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Announcement: Gipeda, the git performance dashboard
by Joachim Breitner 17 May '15

17 May '15

Dear Haskellers, a while ago, I set up a performance dashboard¹ for GHC, based on codespeed², but I was dissatisfied, so in the end, I wrote a new one, called Gipeda for “Git Performance Dashboard”. The git in the name as, in contrast to codespeed, I do not try to be VCS-agnostic but do want to use and expose the structure of your project’s git repository in the output. You can have a look at http://perf.haskell.org/ghc. It should be relatively self-explanatory. Just note that by default it hides boring stuff (commits and results with no significant change), you can select what to show in the top-right corner. The idea behind gipeda is relatively simple. Starting with a directory with one file for each of your project’s benchmarked commit, gipeda digests this to produce a bunch of JSON files. It uses shake³ to avoid unnecessary recalculations. A static HTML file with lots of JavaScript (using handlebars as a templating engine, and other JS libraries like jQuery and flot) then presents this data, in a hopefully snappy and intuitive way. I have announced the GHC instance on the ghc-dev mailing list⁴, so why do I write here as well? Because you can use gipeda for your own projects! And because you can contribute! The program is not GHC-specific, so if you have a way to produce benchmark numbers (or any other kind of metric) for your project, you can feed them to gipeda to be visualized. See the README at https://github.com/nomeata/gipeda for instructions (and ask me if you are stuck). If it makes sense we can host the result at http://perf.haskell.org/ (but you still need to run the benchmarks yourself). And although it is quite nice so far, there are a lot of things it should also be able to do. Here are a few ideas: * Integrate data from multiple build hosts. * Compare the results from arbitrary two commits. * Visualize non-linear git histories, e.g. due to branches. * Know about named branches and tags. * RSS feeds and email notifications. * Find a way to efficiently run gipeda on travis. * General UI polishing. Some of that is possible without touching any JavaScript, some without touching any Haskell, so if you want to contribute, I’m sure you’ll find something. I plan to work on that during ZuriHac⁵ (only two more weeks), so if you are there and looking for a project, please join me! Greetings, Joachim ¹ http://ghcspeed-nomeata.rhcloud.com/ ² https://github.com/tobami/codespeed ³ http://shakebuild.com/ ⁴ https://mail.haskell.org/pipermail/ghc-devs/2015-May/009032.html ⁵ https://wiki.haskell.org/ZuriHac2015 PS: Thanks to davean from the haskell.org admin team for setting up perf.haskell.org. -- Joachim “nomeata” Breitner mail(a)joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata(a)joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata(a)debian.org

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Re: [Haskell-cafe] Static executables in minimal Docker containers
by Greg Weber 17 May '15

17 May '15

Haskell is not that great at producing statically linked libraries independent of the OS. The issue you are running into would likely show up in another non-ubuntu image (or even possibly a different version of an ubuntu image), so you could probably use a Fedora image that has tracing. How are you addressing the linker warning about needing a particular glibc version at runtime? On Mon, Apr 13, 2015 at 3:28 AM, Sharif Olorin <sharif.olorin(a)gmail.com> wrote: > Unfortunately, strace and ltrace aren't available in that Docker image, >> but it's a good idea to see if I can get them running there somehow. >> > > Failing that, you might be able to get useful information of the same kind > by running docker (the server, not the `docker run` command) under perf[0] > and then running your busybox container. It should at least give you an > idea of what it's doing when it explodes. > > Sharif > > [0]: https://perf.wiki.kernel.org/index.php/Tutorial > > -- > You received this message because you are subscribed to the Google Groups > "Commercial Haskell" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to commercialhaskell+unsubscribe(a)googlegroups.com. > To post to this group, send email to commercialhaskell(a)googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/commercialhaskell/86ca2603-37f2-4645-9cd2… > <https://groups.google.com/d/msgid/commercialhaskell/86ca2603-37f2-4645-9cd2…> > . > > For more options, visit https://groups.google.com/d/optout. >

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Re: [Haskell-cafe] Haskell-Cafe Digest, Vol 141, Issue 25
by Michael Baikov 16 May '15

16 May '15

> > Suppose the following data type for encoding Boolean expressions: > > data BExpr a = BTrue > | BFalse > | Id String > | Not a > | And a a > | Or a a > | BEq a a > deriving (Functor) > type Expr = Fix BExpr > > It is easy to produce a string representation of an expression or evaluate > it: > > estr :: BExpr String -> String > eval :: BExpr Bool -> Bool > > with the cata function from Data.Functor.Fixedpoint. > > Could you suggest a solution for transforming trees encoded as Exp into > equivalent Expr (e.g Not Not a ~> a)? > cata does not work since it expects a function f a -> a while a > transformation would be f a -> f a. Actually cata works just fine, all you need following transformation which is f a -> a alg :: BExpr Expr -> Expr alg (Not (Fix (Not a))) = a alg x = Fix x

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[ANN] relational-record - relational-algebraic query building DSL
by Kei Hibino 16 May '15

16 May '15

Hello everybody, I am happy to announce relational-record library and its project page. relational-record is domain specific language for type-safe SQL query building, and database access API with compile time schema generators. Code is avaiable on github and hackage. https://github.com/khibino/haskell-relational-record/ http://hackage.haskell.org/package/relational-record/ Tutorial, examples and documentations are available from project page links. http://khibino.github.io/haskell-relational-record/ Supported features are below, * Type safe query building. * Composable query. * Outer join. * Aggregation. * Compile time compile code generation along with RDBMS schema. * Schema support of ProsgreSQL, SQLite3, MySQL, IBM DB2, MicroSoft SQL Server, and Oracle. Any comments, any questions about this library are welcome. -- Kei Hibino ex8k.hibino at gmail.com https://github.com/khibino/

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