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Algebra in Haskell
by Robert Goss 09 May '13

09 May '13

Dear all, There are several libraries in haskell for abstract algebra but they don't seem to cover my use case I was wondering if other people have had similar issues and if there are any packages I am missing. What I am prinicpaly interested in is operation on algebraic stuctures (homomorphisms, kernels, quotients, colimits, etc) whereas most algebra packages seem to just give operations on the elements of an algebraic structure. So I would like to be able to write something like... g = freeGroup(["x","y"]) h = freeGroup(["z"]) phi = grpMorphismOnGens([("x","z"^6) , ("y","z")]) k = grpKernel phi (gens,rels) = grpPresentation (grpQuotient g k) Thank you, Robert Goss

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Formal Methods/Functional programming job position at Intel
by Levent Erkok 09 May '13

09 May '13

Our formal methods team at Intel has a full-time position available that I think would be a good fit for functional programming and formal methods enthusiasts. I'm including the description below. Do not hesitate to contact me if you've any questions, or just want to talk about it in general. To apply for the position, please visit: http://www.intel.com/jobs/jobsearch/index.htm, and in the "advanced search" area enter the job number: 709631. Thanks, -Levent. Job Description *Formal Methods & Validation Architect* *-* *709631* Description If you're interested in products going into future super computer markets then the Intel® Many Integrated Core (Intel® MIC) Hardware Engineering Group is the place for you! We design and validate silicon chips with many Intel cores integrated inside being used in high performance computing architectures. In this position you will work as part of the pre-silicon formal methods, tools, and verification team to support a continued high quality of the future Intel many core processor products. You will work together with Intel's formal verification and validation community, the Formal Verification Center of Expertise (FV CoE) in a team of experts in formal methods and AV Validation. Your specific responsibilities will include defining formal verification (FV) test plans as well as Cluster Test Environment (CTE) based test plans for dynamic simulation validation (DV). The goal is to help optimize a combined use of FV and CTE based validation techniques (DV) and contribute to an increasing use of formal methods at Intel. Based on the test plans you will write properties in formal language, and prove the properties using our model checkers and theorem proving tools. You will also write CTE based test cases and coverage plans. Your area of strength may currently lie within either FV or DV with strong skills rooted in software development. But through your skills and work, you will become an expert in both formal methods and validation technologies. You will interact very closely with design teams, and other validation teams, as well as with Intel's internal R&D groups that continue to improve and develop formal method and verification tools. You must be able to communicate effectively with various technical groups and coordinate activities amongst those groups.

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Categories (cont.)
by Christopher Howard 08 May '13

08 May '13

I've perhaps been trying everyones patiences with my noobish CT questions, but if you'll bear with me a little longer: I happened to notice that there is in fact a Category class in Haskell base, in Control.Category: quote: -------- class Category cat where A class for categories. id and (.) must form a monoid. Methods id :: cat a a the identity morphism (.) :: cat b c -> cat a b -> cat a c morphism composition -------- However, the documentation lists only two instances of Category, functions (->) and Kleisli Monad. For instruction purposes, could someone show me an example or two of how to make instances of this class, perhaps for a few of the common types? My initial thoughts were something like so: code: -------- instance Category Integer where id = 1 (.) = (*) -- and instance Category [a] where id = [] (.) = (++) ------- But these lead to kind mis-matches. -- frigidcode.com

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Mutually recursive modules
by Roman Cheplyaka 08 May '13

08 May '13

I wonder whether it's always possible to break cycles using GHC's .hs-boot files. Consider the following schematic example: module A where import B data A f :: B -> A f = undefined B.g module B where import A data B g :: A -> B g = undefined A.f A.hs-boot must give a type signature for f, and since the signature contains 'B', it must import 'B'. Ditto for B.hs-boot — it must import 'A'. Even if we treat all imports as {-# SOURCE #-}, there is still a cycle between the hs-boot files. So, am I right in understanding that these recursive modules cannot be compiled by GHC at all? Roman

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Incrementation fails
by John 08 May '13

08 May '13

Hello All, I'm in a big trouble with incrementation of a counter in this code. It doesn't increment. Could you please tell me where the problem ist and how can I solve it? replaceBasedIdx :: String -> [String] -> String -> String replaceBasedIdx findStr replaceStrList myText = replaceBasedIdxSub findStr replaceStrList myText 0 replaceBasedIdxSub :: String -> [String] -> String -> Int -> String replaceBasedIdxSub findStr replaceStrList myText counter = loop myText where loop [] = [] loop myText = let (prefix, rest) = splitAt n myText in if findStr == prefix -- found an occurrence? then (replaceStrList !! (counter+1)) ++ loop rest -- yes: replace it else head myText : loop (tail myText) -- no: keep looking n = length findStr Thank you very mutch! Greetings! -- View this message in context: http://haskell.1045720.n5.nabble.com/Incrementation-fails-tp5729905.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Munich 13.5., live sequencer
by Heinrich Hördegen 08 May '13

08 May '13

Dear all, Henning Thielemann will give a demonstration of his live sequencer in Munich on the 13th of May (next Monday): http://www.youtube.com/watch?v=88jK162l6mE We begin at 19h00 at Oetingenstr. 67, 80538 Munich, room 157 (first floor, central). As everything is live, please bring your laptops along, if you want to participate interactivly. Heinrich

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Stream fusion and span/break/group/init/tails
by Edward Z. Yang 07 May '13

07 May '13

Hello all, (cc'd stream fusion paper authors) I noticed that the current implementation of stream fusion does not support "multiple-return" stream combinators, e.g. break :: (a -> Bool) -> [a] -> ([a], [a]). I thought a little bit about how might one go about implement this, but the problem seems nontrivial. (One possibility is to extend the definition of Step to support multiple return, but the details are a mess!) Nor, as far as I can tell, does the paper give any treatment of the subject. Has anyone thought about this subject in some detail? Thanks, Edward

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PPDP 2013: 2nd Call for Papers
by Tom Schrijvers 07 May '13

07 May '13

===================================================================== 2nd Call for papers 15th International Symposium on Principles and Practice of Declarative Programming PPDP 2013 Special Issue of Science of Computer Programming (SCP) Madrid, Spain, September 16-18, 2013 (co-located with LOPSTR 2013) http://users.ugent.be/~tschrijv/PPDP2013/ ====================================================================== EXTENDED SUBMISSION DEADLINE: JUNE 13, 2013 PPDP 2013 is a forum that brings together researchers from the declarative programming communities, including those working in the logic, constraint and functional programming paradigms, but also embracing a variety of other paradigms such as visual programming, executable specification languages, database languages, and knowledge representation languages. The goal is to stimulate research in the use of logical formalisms and methods for specifying, performing, and analysing computations, including mechanisms for mobility, modularity, concurrency, object-orientation, security, verification and static analysis. Papers related to the use of declarative paradigms and tools in industry and education are especially solicited. Topics of interest include, but are not limited to: * Functional programming * Logic programming * Answer-set programming * Functional-logic programming * Declarative visual languages * Constraint Handling Rules * Parallel implementation and concurrency * Monads, type classes and dependent type systems * Declarative domain-specific languages * Termination, resource analysis and the verification of declarative programs * Transformation and partial evaluation of declarative languages * Language extensions for security and tabulation * Probabilistic modelling in a declarative language and modelling reactivity * Memory management and the implementation of declarative systems * Practical experiences and industrial application This year the conference will be co-located with the 23nd International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2013) and held in cooperation with ACM SIGPLAN. The conference will be held in Madrid, Spain. Previous symposia were held at Leuven (Belgium), Odense (Denmark), Hagenberg (Austria), Coimbra (Portugal), Valencia (Spain), Wroclaw (Poland), Venice (Italy), Lisboa (Portugal), Verona (Italy), Uppsala (Sweden), Pittsburgh (USA), Florence (Italy), Montreal (Canada), and Paris (France). Papers must describe original work, be written and presented in English, and must not substantially overlap with papers that have been published or that are simultaneously submitted to a journal, conference, or workshop with refereed proceedings. Work that already appeared in unpublished or informally published workshop proceedings may be submitted (please contact the PC chair in case of questions). Proceedings will be published in the ACM International Conference Proceedings Series. After the symposium, a selection of the best papers will be invited to extend their submissions in the light of the feedback solicited at the symposium. The papers are expected to include at least 30% extra material over and above the PPDP version. Then, after another round of reviewing, these revised papers will be published in a special issue of SCP with a target publication date by Elsevier of 2014. Important Dates Abstract Submission: June 10, 2013 Paper submission: June 13, 2013 Notification: July 18, 2013 Camera-ready: August 4, 2013 Symposium: September 16-18, 2013 Invites for SCP: October 2, 2013 Submission of SCP: December 11, 2013 Notification from SCP: February 22, 2014 Camera-ready for SCP: March 14, 2014 Authors should submit an electronic copy of the paper (written in English) in PDF. Each submission must include on its first page the paper title; authors and their affiliations; abstract; and three to four keywords. The keywords will be used to assist us in selecting appropriate reviewers for the paper. Papers should consist of no more than 12 pages, formatted following the ACM SIG proceedings template (option 1). The 12 page limit must include references but excludes well-marked appendices not intended for publication. Referees are not required to read the appendices, and thus papers should be intelligible without them. Program Committee Sergio Antoy Portland State University, USA Manuel Carro IMDEA Software Institute, Spain Iliano Cervesato Carnegie Mellon University, Qatar Agostino Dovier Universita degli Studi di Udine, Italy Maria Garcia de la Banda Monash University, Australia Ralf Hinze University of Oxford, UK Yukiyoshi Kameyama University of Tsukuba, Japan Oleg Kiselyov USA Yanhong Annie Liu State University of New York at Stony Brook, USA Stefan Monnier Universite de Montreal, Canada Alan Mycroft University of Cambrige, UK Bruno C. d. S. Oliveira National University of Singapore, Singapore Alberto Pettorossi Universita di Roma Tor Vergata, Italy Enrico Pontelli New Mexico State University, USA Kristoffer Rose IBM Research, USA Sukyoung Ryu KAIST, South Korea Vitor Santos Costa University of Porto, Portugal Torsten Schaub University Potsdam, Germany Tom Schrijvers Ghent University, Belgium Martin Sulzmann Hochschule Karlsruhe, Germany Wouter Swierstra Universiteit Utrecht, The Netherlands Tarmo Uustalu Institute of Cybernetics, Estonia Janis Voigtlaender University of Bonn, Germany Meng Wang Chalmers University of Technology, Sweden Jan Wielemaker Universiteit van Amsterdam, The Netherlands Program Chair Tom Schrijvers Department of Applied Mathematics and Computer Science Ghent University 9000 Gent, Belgium General Chair Ricardo Pena Facultad de Informatica Universidad Complutense de Madrid 28040 Madrid, Spain

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Request for input on "Programming in Haskell"
by Graham Hutton 07 May '13

07 May '13

Have you taught a course using Hutton's textbook on Programming in Haskell? If so, please read on! As part of the national assessment of universities in the UK that takes place every 5-6 years, I'm producing a case study on the impact of the book on student and professional training. The case study will include a number of quotes from academic and industrial users who have used the book for teaching purposes. If you have taught a course using the book any time from January 2008 onwards, and would be willing to provide a short quote (2-3 sentences) for the case study, that would be very much appreciated. It doesn't matter if you are no longer teaching the course or are not currently using the book. If you are interested, drop me an email and I'll explain what's involved. 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.

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Re: [Haskell-cafe] Hackage checking maintainership of packages
by Clark Gaebel 07 May '13

07 May '13

If there's a github link in the package url, it could check the last update to the default branch. If it's more than 6 months ago, an email to the maintainer of "is this package maintained?" can be sent. If there's no reply in 3 months, the package is marked as unmaintained. If the email is ever responded to or a new version is uploaded, the package can be un-marked. - Clark On Sunday, May 5, 2013, Lyndon Maydwell wrote: > I've got it! > > The answer was staring us in the face all along... We can just introduce > backwards-compatibility breaking changes into GHC-head and see if the > project fails to compile for x-time! That way we're SURE it's unmaintained. > > I'll stop sending emails now. > > > On Mon, May 6, 2013 at 10:44 AM, Clark Gaebel <cgaebel(a)uwaterloo.ca>wrote: > > If there's a github link in the package url, it could check the last > update to the default branch. If it's more than 6 months ago, an email to > the maintainer of "is this package maintained?" can be sent. If there's no > reply in 3 months, the package is marked as unmaintained. If the email is > ever responded to or a new version is uploaded, the package can be > un-marked. > > - Clark > > > On Sunday, May 5, 2013, Lyndon Maydwell wrote: > > But what if the package is already perfect? > > Jokes aside, I think that activity alone wouldn't be a good indicator. > > > On Mon, May 6, 2013 at 9:59 AM, Conrad Parker <conrad(a)metadecks.org>wrote: > > On 6 May 2013 09:42, Felipe Almeida Lessa <felipe.lessa(a)gmail.com> wrote: > > Just checking the repo wouldn't work. It may still have some activity > > but not be maintained and vice-versa. > > ok, how about this: if the maintainer feels that their repo and > maintenance activities are non-injective they can additionally provide > an http-accessible URL for the maintenance activity. Hackage can then > do an HTTP HEAD request on that URL and use the Last-Modified response > header as an indication of the last time of maintenance activity. I'm > being a bit tongue-in-cheek, but actually this would allow you to > point hackage to a blog as evidence of maintenance activity. > > I like the idea of just pinging the code repo. > > Conrad. > > > On Sun, May 5, 2013 at 2:19 PM, Doug Burke <dburke.gw(a)gmail.com> wrote: > >> > >> On May 5, 2013 7:25 AM, "Petr Pudlák" <petr.mvd(a)gmail.com> wrote: > >>> > >>> Hi, > >>> > >>> on another thread there was a suggestion which perhaps went unnoticed > by > >>> most: > >>> > >>>> ---------- Forwarded message ---------- > >>>> From: Niklas Hambüchen <mail(a)nh2.me> > >>>> Date: 2013/5/4 > >>>> ... > >>>> I would even be happy with newhackage sending every package > maintainer a > >>>> quarterly question "Would you still call your project X 'maintained'?" > >>>> for each package they maintain; Hackage could really give us better > >>>> indications concerning this. > >>> > >>> > >>> This sounds to me like a very good idea. It could be as simple as "If > you > >>> consider yourself to be the maintainer of package X please just hit > reply > >>> and send." If Hackage doesn't get an answer, it'd just would display > some > >>> red text like "This package seems to be unmaintained since D.M.Y." > >>> > >>> Best regards, > >>> Petr > >>> > >> > >> For those packages that give a repository, a query could be done > >> automatically to see when it was last updated. It's not the same thing > as > >> 'being maintained', but is less annoying for those people with many > packages > >> on hackage. > >> > >> Doug > >> > >> > >> _______________________________________________ > >> Haskell-Cafe mailing list > >> Haskell-Cafe(a)haskell.org > >> http://www.haskell.org/mailman/listinfo/haskell-cafe > >> > > > > > > > > -- > > Felipe. > > > > _______________________________________________ > > Haskell-Cafe mailing list > > Haskell-Cafe(a)haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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