- Haskell-Cafe - Haskell.org

Haskell.org Committee Nomination Results
by Emily Pillmore 20 Jan '20

20 Jan '20

Hello Everyone, I'm pleased to announce that the results for the Haskell.org ( http://haskell.org/ ) committee nominations are in, and voting has completed. The following tally is the final result: Jaspe Van der Jeugt: 6 Alexandre Garcia de Oliveira: 5 April Gonçalves: 2 Rebecca Skinner: 5 With no votes for anyone else. This means that Jasper's renomination was successful, and we get to welcome 2 new faces to the Haskell.org ( http://haskell.org/ ) ; congratulations Rebecca and Alexandre! Thanks, Emily

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persistent and safe-money packages
by Debasish Ghosh 16 Jan '20

16 Jan '20

Hi - I am using "persistent" for database access in Haskell. However in my domain model I have used the Dense data type from safe-money ( https://hackage.haskell.org/package/safe-money) as the money datatype. It looks like this data type is not supported by default in persistent. Is there a way around ? Thanks in advance. -- Debasish Ghosh http://manning.com/ghosh2 http://manning.com/ghosh Twttr: @debasishg Blog: http://debasishg.blogspot.com Code: http://github.com/debasishg

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[ANN] 2nd Call for Participation: BOB 2020 (February 28, Berlin, early-bird until Jan 20)
by Stefan Wehr 15 Jan '20

15 Jan '20

================================================================================ BOB 2020 Conference “What happens if we simply use what’s best?” February 28, 2020, Berlin http://bobkonf.de/2020/ Program: http://bobkonf.de/2020/en/program.html Registration: http://bobkonf.de/2020/en/registration.html ================================================================================ BOB is the conference for developers, architects and decision-makers to explore technologies beyond the mainstream in software development, and to find the best tools available to software developers today. Our goal is for all participants of BOB to return home with new insights that enable them to improve their own software development experiences. The program features 14 talks and 8 tutorials on current topics: http://bobkonf.de/2020/en/program.html The subject range of talks includes functional programming, formal methods, architecture documentation, functional-reactive programming, and language design. The tutorials feature introductions to Idris, Haskell, F#, TLA+, ReasonML, and probabilistic programming. Heather Miller will give the keynote talk. Registration is open online: http://bobkonf.de/2020/en/registration.html NOTE: The early-bird rates expire on January 20, 2020! BOB cooperates with the Racketfest conference on the day before BOB: https://racketfest.com/ BOB cooperates with the :clojureD conference on the day after BOB: https://clojured.de/

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[Job] Hiring Numerical Programmers at Anduril Industries
by Travis Whitaker 14 Jan '20

14 Jan '20

Greetings Fellow Haskellers, Anduril Industries is hiring Haskellers for numerical programming work. Quick Details: - Seeking Haskellers familiar with numerical programming techniques. - Familiarity with LLVM, FORTRAN, Linux, and compiler engineering is advantageous. - Positions for internships and new graduates are available. - Regrettably, no remote opportunities are available at this time. We are located in southern California, USA. Anduril is looking for engineers to rapidly develop high-reliability solutions to numerical problems by leveraging lightweight formal methods. We are working on problems from a wide range of disciplines, including robotics, flight control, guidance & navigation, and radar signal processing. If you're interested in numerical programming, physics, and lightweight formal verification techniques, then you'd likely enjoy working on our team! With respect to internships, our program is extremely flexible and we can adapt to whatever structure your university might require. If this sounds interesting, please drop me a line at travis(a)anduril.com. Thanks for your time, Travis Whitaker

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database programming with Haskell
by Debasish Ghosh 14 Jan '20

14 Jan '20

Hello - I am looking for some good practices on how to design database access APIs in applications using Haskell. I have been going through various libraries like persistent, Esqueleto etc. All of them have nice APIs. However I am looking for practices around designing APIs that also offer testability without plugging in a concrete database engine. Like the one we can design using tagless final approaches where we can switch out the Database monad with some mocked one (maybe that uses some hashmap instead of a real database) for unit tests. Is there any recommended practice on this or may be some sample application that's designed around these practices ? Or is this at all a recommended practice in Haskell ? regards. -- Debasish Ghosh http://manning.com/ghosh2 http://manning.com/ghosh Twttr: @debasishg Blog: http://debasishg.blogspot.com Code: http://github.com/debasishg

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[TFP'20] call for participation: Trends in Functional Programming 2020, 13-14 February, Krakow, Poland
by Peter Achten 14 Jan '20

14 Jan '20

------------------------------------------------------------------------- Call for participation 21st Symposium on Trends in Functional Programming tfp2020.org ------------------------------------------------------------------------- The list of accepted papers is available at http://www.cse.chalmers.se/~rjmh/tfp/ The symposium on Trends in Functional Programming (TFP) is an international forum for researchers with interests in all aspects of functional programming, taking a broad view of current and future trends in the area. It aspires to be a lively environment for presenting the latest research results, and other contributions. * TFP is moving to new winter dates, to provide an FP forum in between the annual ICFP events. * TFP offers a supportive reviewing process designed to help less experienced authors succeed, with two rounds of review, both before and after the symposium itself. Authors have an opportunity to address reviewers' concerns before final decisions on publication in the proceedings. * TFP offers two "best paper" awards, the John McCarthy award for best paper, and the David Turner award for best student paper. * This year we are particularly excited to co-locate with Lambda Days in beautiful Krakow. Lambda Days is a vibrant developer conference with hundreds of attendees and a lively programme of talks on functional programming in practice. TFP will be held in the same venue, and participants will be able to session-hop between the two events. Important Dates --------------- Submission deadline for pre-symposium review: 15th November, 2019 -- passed -- Submission deadline for draft papers: 10th January, 2020 -- passed -- Registration (regular): 2nd February, 2020 Registration (late): 13th February, 2020 Symposium dates: 13-14th February, 2020 Visit tfp2020.org for more information.

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Fwd: State of BNFC-meta and friends
by Artem Pelenitsyn 13 Jan '20

13 Jan '20

Dear cafe, I tried to contact Jonas, the maintainer of BNFC-meta[1], twice (a week ago and 1.5 months ago, see below the copies of emails) with regards to updating the package to recent GHC, but with no luck. I'm interested in taking over the package if nobody minds... [1]: http://hackage.haskell.org/package/BNFC-meta -- Kind regards, Artem ---------- Forwarded message --------- From: Artem Pelenitsyn <a.pelenitsyn(a)gmail.com> Date: Sun, 5 Jan 2020 at 15:06 Subject: Re: State of BNFC-meta and friends To: <jonas.duregard(a)gmail.com> Hey Jonas, Just wanted to check if you saw my mail… -- Best, Artem On Thu, 21 Nov 2019 at 20:44, Artem Pelenitsyn <a.pelenitsyn(a)gmail.com> wrote: > Hello Jonas, > > I'm writing to let you know that your Hackage packages > > * BNFS-meta, > * happy-meta, > * alex-meta > > fail to build with current versions of GHC (8.6, 8.8). I wonder if you > intend to update them? > > All of them require bumping the template-haskell upper bound to <2.16. > > happy-meta seems to have weird interactions with newer Cabal because of > "Build-type: Custom" along the lines > https://github.com/haskell/cabal/issues/5278 Given that your Setup.hs > uses Distribution.Simple, I don't really see the point of having Custom. > Switching to "Build-type: Simple" seems to work just fine. > > alex-meta has one broken Monoid instance as per SMP proposal. Easily > upgraded. > > With these changes, I was able to build BNFC-meta successfully with GHC > 8.6.5, cabal 2.4. I'd be happy to supply pull requests but I don't see > {alex,happy}-meta repositories anywhere, and I noticed BNFC-meta repo on > GitHub has the version of the package different from what is on Hackage. > > There is a bunch of deprecation and tabs warnings also. > > Kind regards, > Artem Pelenitsyn > PhD student at Northeastern U. > http://www.ccs.neu.edu/~artem/ > >

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Possibly an error in Tutorial?
by Ignat Insarov 13 Jan '20

13 Jan '20

In this line: > For example, the principal type of `head` is `[a]->a`; `[b]->a`, `a->a`, or even `a` are correct types, but too general, whereas something like `[Integer]->Integer` is too specific. — It is not clear how `a → a` can be a correct type for `head`, insofar as all occurrences of a type variable must be instantiated to the same concrete type. If this sentence is actually correct, perhaps it could be clarified to address the issue? This concern was raised on Reddit: https://www.reddit.com/r/haskellquestions/comments/enqhu0/how_does_head_hav… Link to tutorial: https://www.haskell.org/tutorial/goodies.html

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[GSoC 2020] Call for Ideas
by Jasper Van der Jeugt 12 Jan '20

12 Jan '20

Google Summer of Code [1] will take place again in 2020! Haskell.org has been able to take part in this program in the past two years, and we'd like to keep this momentum up since it greatly benefits the community. Google is not extremely open about what factors it considers for applications from organizations, but they have stated multiple times that a well-organized ideas list is crucial. For that, we would like to count on all of you again. If you are the maintainer or a user of a Haskell project, and you have an improvement in mind which a student could work on during the summer, please submit an idea here: https://summer.haskell.org/ideas.html For context, Google Summer of Code is a program where Google sponsors students to work on open-source projects during the summer. Haskell.org has taken part in this program in 2006-2015, and 2018-2019. Many important improvements to the ecosystem have been the direct or indirect result of Google Summer of Code projects, and it has also connected new people with the existing community. Projects should benefit as many people as possible – e.g. an improvement to GHC will benefit more people than an update to a specific library or tool, but both are definitely valid. New libraries and applications written in Haskell, rather than improvements to existing ones, are also accepted. Projects should be concrete and small enough in scope such that they can be finished by a student in three months. Past experience has shown that keeping projects "small" is almost always a good idea. [1]: https://summerofcode.withgoogle.com/ Warm regards Jasper

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ETAPS Workshop on Trends, Extensions, Applications and Semantics of Logic Programming (TEASE-LP 2020)
by Ekaterina Komendantskaya 12 Jan '20

12 Jan '20

Call for Contributions Workshop on Trends, Extensions, Applications and Semantics of Logic Programming (TEASE-LP 2020) Dublin, Ireland, 25 April 2020 (co-located with ETAPS 2020) www.coalg.org/tease-lp Logic programming is a framework for expressing programs, propositions and relations as Horn clause theories, with the purpose of performing automatic inference in these theories. Horn clause theories are famous for their well-understood declarative semantics, in which models of logic programs are given inductively or coinductively. At the same time, Horn clauses give rise to efficient inference procedures, usually involving resolution. Logic programming found applications in type inference, verification, and AI. While logic programming was originally conceived for describing simple facts, it was extended to account for much more complex theories. This includes higher-order theories, inductive and coinductive data, and stochastic/probabilistic theories. The aim of this workshop is to bring together researchers that work on extensions of logic programming and inference methods, and to foster an exchange of methods and applications that have emerged in different communities. Topics --------------------------- The central idea of this workshop is to discuss the theory of logic programming and associated topics that have as well the goal to automatically infer knowledge and proofs. Our intention is to bring together researchers that work on the numerous topics that contribute to automatic proof inference and foster an exchange that may lead to advances in the theory of logic programming. Topics of interest include, but are not limited to, the following: * Proof theory (e.g. focalised and uniform proofs), * Logic programming beyond the classical Horn clause theories (e.g. coinduction, higher-order Horn clauses, probabilities, categorical logic, inductive LP), * Extensions of logic programming (e.g. DataLog, description logic, relational programming), * Advanced implementations (e.g. λProlog, ELPI, miniKanren), * Type theory (e.g. polarised λ-calculus, proofs-as-programs, types for logic programming), * Semantics (e.g. classical, categorical, algebraic, coalgebraic) , and * Applications. Venue and Event --------------------------- TEASE-LP 2020 will be held in Dublin, Ireland, co-located with ETAPS 2020 on 25 April 2020. Important Dates --------------------------- Abstract submission Wednesday, 26 February 2020 AoE Notification Wednesday, 25 March 2020 AoE Camera-ready copy Wednesday, 1 April 2020 AoE Workshop Saturday, 25 April 2020 Programme Committee --------------------------- Henning Basold (chair), Leiden University, NLD William Byrd, University of Alabama at Birmingham, USA Gopal Gupta, The University of Texas at Dallas, USA Ekaterina Komendantskaya (chair), Heriot-Watt University, GBR Dale Miller, INRIA and LIX/Ecole Polytechnique, FRA Gopalan Nadathur, University of Minnesota, USA Frank Pfenning, Carnegie Mellon University, USA Hiroshi Unno, University of Tsukuba, JPN Noam Zeilberger, University of Birmingham, GBR Submission Instructions --------------------------- Since the aim of the workshop is to foster exchange and discussions on trends, extensions, applications and semantics of logic programming, we invite presentations of possibly already published as well as ongoing work. Submissions should be abstracts of at most two pages in EPTCS style (http://style.eptcs.org/) and will be only be published in the informal pre-proceedings and on the website of the workshop. Post-proceedings volume may be solicited by the PC, based on the quality of contributions. Contributions should be submitted via the Easychair system: https://easychair.org/my/conference?conf=teaselp2020 All contributions will be refereed by the programme committee and it is expected that at least one of the authors will be present during the workshop.

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