- Haskell-Cafe - Haskell.org

Nominations close Jan 11th for the Haskell Foundation Board
by Simon Peyton Jones 05 Jan '21

05 Jan '21

Friends Happy new year! The closing date for self-nominations for membership of the Board of the Haskell Foundation<https://haskell.foundation/> is in just under a week: Monday January 11th 2021 The Haskell Foundation is a new non-profit organisation that seeks to articulate the benefits of functional programming to a broader audience, to erase barriers to entry, and to support Haskell as a solidly reliable basis for mission-critical applications. The Board provides the strategic leadership for the Foundation, including its goals, governance, finances, and staff. Membership of the Board is a key leadership role, not an honorary appointment. The Call for Nominations<https://haskell.foundation/board-nominations/> gives more details. Please do consider nominating yourself, or encouraging a suitable (but perhaps modest) colleague to do so. The HF needs a strong Board, and that means strong nominations. Thanks! Please do forward this message on social media or elsewhere. Simon Peyton Jones

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[TFPIE'21] Third and Final Call For Papers: Trends in Functional Programming *in Education* 2021, 16 February 2021 (with Lambda Days 2021 & TFP 2021)
by Peter Achten 04 Jan '21

04 Jan '21

---------------------------------------------- TFPIE 2021 3rd and Final Call for papers ---------------------------------------------- *************************************************************** - Submission deadline: January 11 2021, Anywhere on Earth. *************************************************************** https://wiki.tfpie.science.ru.nl/TFPIE2021#TFPIE_2021 (February 16 2021, co-organized with TFP 2021 and Lambda Days 2021) Because of the covid pandemic, the events are online this year. The goal of the International Workshops on Trends in Functional Programming in Education is to gather researchers, professors, teachers, and all professionals that use or are interested in the use of functional programming in education. TFPIE aims to be a venue where novel ideas, classroom-tested ideas, and work in progress on the use of functional programming in education are discussed. The one-day workshop will foster a spirit of open discussion by having a review process for publication after the workshop. TFPIE 2021 welcomes submissions in the above mentioned areas. This year many teaching programmes have had to make a rapid transition to online teaching, and we explicitly solicit papers that explore this area of teaching functional programming. Topics of interest include, but are not limited to: - FP and beginning CS students - FP and Computational Thinking - FP and Artificial Intelligence - FP in Robotics - FP and Music - Advanced FP for undergraduates - FP in graduate education - Engaging students in research using FP - FP in Programming Languages - FP in the high school curriculum - FP as a stepping stone to other CS topics - FP and Philosophy - The pedagogy of teaching FP - FP and e-learning: MOOCs, automated assessment etc. - Best Lectures - more details below In addition to papers, we are requesting best lecture presentations. What's your best lecture topic in an FP related course? Do you have a fun way to present FP concepts to novices or perhaps an especially interesting presentation of a difficult topic? In either case, please consider sharing it. Best lecture topics will be selected for presentation based on a short abstract describing the lecture and its interest to TFPIE attendees. The length of the presentation should be comparable to that of a paper. On top of the lecture itself, the presentation can also provide commentary on the lecture. Submissions Potential presenters are invited to submit an extended abstract (4-6 pages) or a draft paper (up to 20 pages) in EPTCS style. The authors of accepted presentations will have their preprints and their slides made available on the workshop's website. Papers and abstracts can be submitted via easychair at the following link: https://easychair.org/conferences/?conf=tfpie2021 After the workshop, presenters are invited to submit (a revised version of) their article for review. The PC will select the best articles for publication in the Electronic Proceedings in Theoretical Computer Science (EPTCS). Articles rejected for presentation and extended abstracts will not be formally reviewed by the PC. Dates - Submission deadline: January 11 2021, Anywhere on Earth. - Notification: January 15 2021 - Workshop: February 16 2021 - Submission for formal review: April 20 2021, Anywhere on Earth. - Notification of full article: June 7 2021 - Camera ready: July 1st 2021 Program Committee - Peter Achten, Radboud University, Netherlands (chair) - Edwin Brady, University of St Andrews, UK - Laura Castro, Universidade da Coruña, Spain - Stephen Chang, University of Massachusetts Boston, USA - Youyou Cong, Tokyo Institute of Technology, Japan - Matthew Flatt, University of Utah, USA - Seth Fogarty, Trinity University, USA - Alex Gerdes, University of Gothenburg, Sweden - Gabriele Keller, Utrecht University, Netherlands - Prabhakar Ragde, University of Waterloo, Canada - Melinda Tóth, Eötvös Loránd University, Budapest, Hungary Registration TFPIE is part of Lambda Days. Please visit the Lambda Days 2021 pages when registration information becomes available. Only papers that have been presented at TFPIE may be submitted to the post-reviewing process. Information on Lambda Days is available at https://www.lambdadays.org/lambdadays2021 Information on TFP is available at http://tfp2021.org

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Re: [Haskell-cafe] How to do reversible parsing?
by Michal J Gajda 03 Jan '21

03 Jan '21

Hi Askar, > Hi. How to do deterministic reversible parsing in Haskell? Please, point me to some libs or tools. > Or give some advice on how to write such lib or tool. (Also, I am interested in solutions for C or C++.) > > Now let me explain my task in detail. I liked the bidirectional applicatives and monads described in here: 1. Composing bidirectional programs monadically (with appendices) - Li-yao Xia, Dominic Orchard, Meng Wang https://arxiv.org/abs/1902.06950 You can use it for both bidirectional parsing/pretty pretting and type inference/type checking. 2. BiGuL is a bit more complicated: https://bitbucket.org/prl_tokyo/bigul/src/master/ -- Cheers Michał

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[ANN] fp-ieee v0.1
by ARATA Mizuki 03 Jan '21

03 Jan '21

Hi all, I'd like to announce the first release of fp-ieee. https://hackage.haskell.org/package/fp-ieee This library aims to provide IEEE 754-2019 compliant operations, including * fusedMultiplyAdd * correctly-rounding versions of fromInteger (GHC's fromInteger for Float and Double do not round correctly; see https://gitlab.haskell.org/ghc/ghc/-/issues/17231) * realFloatToFrac: an alternative of realToFrac with well-defined semantics. Other notes: * Most of the functions are generic, and any RealFloat instance can be used. However, manipulation of NaN's sign and payload requires an additional constraint (RealFloatNaN, provided by this library). * Access to floating-point environment is not provided. If you want to control rounding direction, look at my another library: https://hackage.haskell.org/package/rounded-hw * Decimal-specific operations (like quantize, quantum) are not provided, and the preferred exponent is not honored. * Use of FFI can be disabled via a package flag (maybe useful when using non-native targets). Mizuki

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ghc/cabal problems - mystery?
by Gregory Guthrie 31 Dec '20

31 Dec '20

I reported several odd and inconsistent results that I can't understand, and after some further trials, a few more data points, but still confused. A directory of files, cabal build runs fine, then trying to execute; I get three different results; Linking D:\CS\Courses\long path\All Solutions\dist-newstyle\build\x86_64-windows\ghc-8.10.1\apl-0.0.1\build\apl\apl.exe ... Seems fine. Then; from that same shell (PS) in the same directory - >From cabal run: Fails PS D:\CS\Courses\long path\All Solutions> cabal run Up to date D:\CS\Courses\long path\All Solutions\dist-newstyle\build\x86_64-windows\ghc-8.10.1\apl-0.0.1\build\apl\apl: createProcess: invalid argument (Invalid argument) >From using the explicit path: Fails PS D:\CS\Courses\long path\All Solutions> dist-newstyle\build\x86_64-windows\ghc-8.10.1\apl-0.0.1\build\apl\apl.exe Program 'apl.exe' failed to run: The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detailAt line:1 char:1 + dist-newstyle\build\x86_64-windows\ghc-8.10.1\apl-0.0.1\build\apl\apl ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. At line:1 char:1 + dist-newstyle\build\x86_64-windows\ghc-8.10.1\apl-0.0.1\build\apl\apl ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : ResourceUnavailable: (:) [], ApplicationFailedException + FullyQualifiedErrorId : NativeCommandFailed >From going to the dist folder: runs fine. PS D:\CS\Courses\long path\All Solutions> cd dist-newstyle\build\x86_64-windows\ghc-8.10.1\apl-0.0.1\build\apl PS D:\CS\Courses\long path\All Solutions\dist-newstyle\build\x86_64-windows\ghc-8.10.1\apl-0.0.1\build\apl> apl.exe "APL: Examples and labs" I get a few other errors & results sometimes; copy the full directory to somewhere else, "cabal clean", And it won't build, "no target specified", even though the entire folder is identical. Again; every time just copying the entire directory, no editing of any files, just running cabal as above. Any hints or ideas why I am getting these issues & errors? GHC 8.10.2 Cabal 3.2.0.0 (Windows 10) ------------------------------------------------------------------------ PS: One more... I (again) copied the entire directory to another place and retested, in that case "cabal run" did run, but gave results from a different file in the directory (multiple tests there, only one run from Main.hs, same .cabal file), and can run it by explicit path or "cabal run". All results should be "DSem_imp", one is from a different file, "DSem_impc" ?? Certainly looks like they should all be running the same apl.exe. ?? Output"" PS G:\Testing\All Solutions> cabal clean PS G:\Testing\All Solutions> cabal run Resolving dependencies... Build profile: -w ghc-8.10.2 -O1 In order, the following will be built (use -v for more details): - apl-0.0.1 (exe:apl) (first run) Configuring apl-0.0.1... Preprocessing executable 'apl' for apl-0.0.1.. Building executable 'apl' for apl-0.0.1.. ... Linking G:\Testing\All Solutions\dist-newstyle\build\x86_64-windows\ghc-8.10.2\apl-0.0.1\build\apl\apl.exe ... "APL: Examples and labs" "======================" "------ APL:: DSem_imp" PS G:\Testing\All Solutions> dist-newstyle\build\x86_64-windows\ghc-8.10.2\apl-0.0.1\build\apl\apl.exe "APL: Examples and labs" "======================" "------ APL:: DSem_imp" PS G:\Testing\All Solutions> cd dist-newstyle\build\x86_64-windows\ghc-8.10.2\apl-0.0.1\build\apl PS G:\Testing\All Solutions\dist-newstyle\build\x86_64-windows\ghc-8.10.2\apl-0.0.1\build\apl> ls Directory: G:\Testing\All Solutions\dist-newstyle\build\x86_64-windows\ghc-8.10.2\apl-0.0.1\build\apl Mode LastWriteTime Length Name ---- ------------- ------ ---- d----- 12/30/2020 12:18 PM apl-tmp d----- 12/30/2020 12:17 PM autogen -a---- 12/30/2020 12:18 PM 11230184 apl.exe PS G:\Testing\All Solutions\dist-newstyle\build\x86_64-windows\ghc-8.10.2\apl-0.0.1\build\apl> apl.exe "APL: Examples and labs" "======================" "------ APL:: DSem_impc" Gregory Guthrie Maharishi International University ----------------------------------------------------------------

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cabal errors
by Gregory Guthrie 29 Dec '20

29 Dec '20

I'm having some issues with Cabal , wonder if they are known issues. 1) I had a previously working installation of files, hadn't used them for some time, did Haskell upgrades (chocolatey), and tried to recompile. I got a weird error on running the build - Program 'apl.exe' failed to run: The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detailAt line:1 char:1 + ./apl + ~~~~~. At line:1 char:1 + ./apl + ~~~~~ + CategoryInfo : ResourceUnavailable: (:) [], ApplicationFailedException + FullyQualifiedErrorId : NativeCommandFailed Chasing this all around - no solutions so I started over, in a new location, adding one file at a time. Worked fine. 2) So I then has a current working build in some top level xTest temporary directory. (Just a direct copy of all the files, and "cabal v2-build") 3) So I then just copied all the source files back to a desired installation place, with a longer path name. 4) But there it fails to build: PS D:\CS\Courses\long path\Solns\All Solutions> cabal v2-install Wrote tarball sdist to D:\CS\Courses\long path\Solns\All Solutions\dist-newstyle\sdist\apl-0.0.1.tar.gz Resolving dependencies... Build profile: -w ghc-8.10.1 -O1 In order, the following will be built (use -v for more details): - apl-0.0.1 (exe:apl) (requires build) cabal.exe: Failed to unpack apl-0.0.1. The exception was: dieVerbatim: user error (cabal.exe: Package .cabal file not found in the tarball: C:\Users\guthrie\AppData\Local\Temp\cabal-install.-2584\dist-newstyle\tmp\src-2584\apl-0.0.1\apl.cabal) 5) Just copying (again) the same folder of files which is failing to a top level new folder (yTest), deleting the dist-newstyle folder, And running "cabal v2-buld" again, all works fine, no errors, executable built. Three directories, all with the same files - one fails. ?? The only difference I can see is the long path name with blanks in it - is that an issue? Dr. Gregory Guthrie Maharishi International University ----------------------------------------------------------------

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Re: [Haskell-cafe] [Ann] group-theory
by Olaf Klinke 27 Dec '20

27 Dec '20

Koji Miyazato wrote: > > You can use `MonoidNull`. from monoid-subclasses to avoid an `Eq` > constraint. > > For groups, there is no difference between `MonoidNull` and `Eq`, as > you can define `x == y` be > `null (x <> inv y)`. There are monoids which `==` is not even > decidable but `null` is (e.g. context-free grammars > with equality defined by the language it defines), but such monoid > necessarily has no `Group` instance. A beautiful example of topological groups: Their topology is completely determined by the neighbourhoods of the identity element. If the identity element is isolated, the entire group is discrete. Olaf

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[Ann] group-theory
by Emily Pillmore 26 Dec '20

26 Dec '20

Hello all, I am pleased to announce the release of the group-theory ( https://hackage.haskell.org/package/group-theory ) package: a package aimed at implementing the theory of finite groups in a reasonably ergonomic, well-documented, and featureful way. It's hardly finished, but my co-maintainer, Reed Mullanix (@totbwf) and I thought this was a good mvp with which we could announce. Contributions are very welcome, and I hope everyone enjoys. Cheers, Emily Pillmore

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Haskell-language-server is looking for a logo
by Alan & Kim Zimmerman 24 Dec '20

24 Dec '20

Hi all, The haskell language server is coming up for its first birthday in January. To celebrate we would like to collectively choose a logo. So if you have a creative streak and would like to donate a lasting contribution to the project, please submit for consideration at [1]. We will aim to close the judging on 25 Jan 2021, being the anniversary of the Bristol Hackathon[2] where HLS was born. Alan [1] https://github.com/haskell/haskell-language-server/issues/694 [2] https://mpickering.github.io/bristol2020.html

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Supporting Haskell.org
by Rebecca Skinner 24 Dec '20

24 Dec '20

Hi everyone. Apologies for the second email here. I originally sent this message with an incorrect subject, and I wanted to re-post here with a correct subject for visibility. This has been an eventful year for many of us, and haskell.org is no different. This year we've continued to support a significant part of the Haskell community infrastructure- including haskell.org, Hackage, Hoogle, and GHC build infrastructure. We're able to do this thanks to the support of the Haskell community. In addition to our ongoing work maintaining Haskell community infrastructure, we once again participated in the Google Summer of Code this year, supporting 12 projects. You can read more about the projects here: https://summer.haskell.org/news/2020-10-12-final-results.html As many of you are likely aware, this year also saw some of our community successfully launch a new initiative, the Haskell Foundation. We are thrilled for the Haskell Foundation and congratulate them on their successful launch. Haskell.org is an independent organization, and while we welcome any opportunities to collaborate with the Haskell Foundation, we will continue to pursue our mission of managing and supporting Haskell community infrastructure. If you would like to support Haskell.org in our mission, you can donate via several method, including PayPay and check: https://www.haskell.org/donations/ Haskell.org can also accept donations through employers via Benevity using the unique ID 475236502. Haskell.org is a 501(c)(3) non-profit, so donations may be tax-deductible in your jurisdiction. Another way to help haskell.org is to serve on the committee. We have three positions opening in 2021, and our call for nominations is open through Jan 7th 2021. Please email the committee at committee(a)haskell.org if you would like to nominate yourself or someone else for a position. We look forward to continuing this work with your support in 2021 as well as exploring new projects to improve the Haskell community infrastructure. Best wishes, Rebecca Skinner on behalf of the haskell.org committee.

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