- Haskell-Cafe - Haskell.org

Re: [Haskell-cafe] Runtime selection on types while capturing a dictionary?
by Olaf Klinke 08 Oct '24

08 Oct '24

> It seems like this might work if I could make a GADT with a signature > something like: > > data MaybeRooted t = Unrooted | HasRoots t => Rooted Yes, that is what GADTs can do for you. But as Tom said, avoid this if cou can. Incidentally, there is a pattern known as "trees that grow" [1] Where a skeleton type has rank-1 parameters that can switch on and off certain constructors. E.g. for a rooted tree you would provide an Identity parameter, for an unrooted tree provide a Const Void or Const () parameter. Small example: data Tree' root branch = Tree' (root [branch (Tree root branch)]) type UnrootedLabeled a = Tree' Identity ((,) a) type RootedLabeled r b = Tree' ((,) r) ((,) b) -- etc. As you observed, this can become confusing, if there are too many variants and the types you actually work with are just type aliases. The advantage is (a) no type classes, (b) you can have pattern-matching functions for a variety of different trees if they do not depend on patterns in the type parameters. > Also, the fact that you can do WithBranchLengths > (WithBranchLengths Tree) indicates that the construction of types > should > be obeying certain rules that are not expressed. Having several type parameters instead of the single t, where every parameter plays a single role, can aid in making rules clearer, but only a GADT may enforce them. There are other rules that only a dependently-typed language will be able to express. Finally, have you tried using one of the existing Haskell graph libraries as a starting point? It may save you a lot of boilerplate code. Olaf [1] https://www.microsoft.com/en-us/research/wp-content/uploads/2016/11/trees-t…

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39th Agda Implementor's Meeting (AIM XXXIX) 25-30 Nov 2024 in Gothenburg
by Andreas Abel 20 Sep '24

20 Sep '24

---------------------------------------------------------------------- Agda Implementors' Meeting XXXIX Call for participation https://wiki.portal.chalmers.se/agda/Main/AIMXXXIX ---------------------------------------------------------------------- The 39th Agda Implementors' Meeting will take place in Gothenburg, Sweden, from Monday 25th to Saturday 30th November 2024. (This is our 20th anniversary of Agda meetings, the first took place in Fall 2004 in Gothenburg.) The meeting will consist of: * Presentations concerning theory, implementation, and use cases of Agda and other Agda-like languages. * Discussions around issues related to the Agda language. * Plenty of time to work in, on, under or around Agda, in collaboration with other participants. * A special session dedicated to the 20th anniversary of AIM. Attendance is free of charge, but a registration is warranted until 31st October 2024 (soft deadline). For information how to register check out https://wiki.portal.chalmers.se/agda/Main/AIMXXXIX Looking forward to seeing you in there! Andreas (on behalf of the AIM XXXIX organizing committee) -- Andreas Abel <>< Du bist der geliebte Mensch. Department of Computer Science and Engineering Chalmers and Gothenburg University, Sweden andreas.abel(a)gu.se http://www.cse.chalmers.se/~abela/

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PhD position at KU Leuven
by Tom Schrijvers 16 Sep '24

16 Sep '24

KU Leuven invites applications for a PhD position in Prof. Tom Schrijvers' research team, exploring the interaction between multi-stage programming and computational effects. Ideal candidates hold a Master's in Computer Science, have a strong academic record, and a passion for programming languages like Haskell, type systems, and functional programming. We offer a 4-year scholarship, a dynamic research environment, and opportunities for international collaboration. Join us to push the boundaries of programming language theory! For more information see: https://www.kuleuven.be/personeel/jobsite/jobs/60384347?hl=nl&lang=nl

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Call for Volunteers - Security Response Team
by Jose Calderon 04 Sep '24

04 Sep '24

The Security Response Team (SRT) is formally calling for applications to join the SRT. People from the Haskell community with information security experience are encouraged to apply. This is an opportunity to have a large impact on the practice of Haskell programming going forward. Since its inception, the SRT has had an outsized impact on the Haskell Ecosystem. I can say with confidence that the group conducts its business in an extremely professional and disciplined manner. If you have an interest in helping the team continue its mission, please apply! ## Security Response Team responsibilities The general responsibilities of the SRT are: - Manage the Haskell Security Advisory Database, on behalf of the Haskell community and the Haskell Foundation. - Triage and assess incoming security reports or proposed/candidate security advisories. - Assist reporters to determine CVSS scores and CWE values for confirmed security issues. - Communicate with package maintainers and the community to promote the timely resolution of reported security issues. - Ensure the security advisory data are useful for downstream security tooling. (Development of downstream tooling is not an SRT responsibility, but engaging with the developers is) - Report quarterly on the activities of the SRT and statistics/trends in new security issues. ## How can you help? - You can apply - If you don't want to apply but know someone who would be great, encourage them to apply. - Volunteers should have experience in one or more of the following areas: - web application security - information security incident response - vulnerability research and analysis - penetration testing - cryptography - authentication and identity management - governance, risk management and compliance (GRC) - secure application development - algorithms, data structures, and their role in DoS attacks - related disciplines ## Who is involved? The current membership of the SRT is: - Fraser Tweedale - Gautier Di Folco - Mihai Maruseac - Tristan de Cacqueray The team is hoping to gain 2-3 new members via this call for volunteers. ## How to apply Email `Fraser Tweedale <frase+hasksec(a)frase.id.au>` with subject "Haskell SRT Application". Include a brief overview of your background in security and the specific topics (e.g. from the list above) with which you have experience. ## Deadline Please submit your applications by end of day September 30th, 2024.

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[TFP 2025 Call for Papers] 25th International Symposium on Trends in Functional Programming (Oxford, UK)
by Peter Achten 04 Sep '24

04 Sep '24

# TFP 2025 - Call for Papers (trendsfp.github.io) ## Important Dates Submission deadline (pre-symposium, full papers): Wed 13th Nov 2024 (AOE) Notification (pre-symposium, full papers): Wed 11th Dec 2024 Submission deadline (pre-symposium draft papers): Wed 11th Dec 2024 (AOE) Notification (pre-symposium draft papers): Mon 16th Dec 2024 Submission deadline (post-symposium review): Wed 19th Feb 2025 (AOE) Notification (post-symposium submissions): Wed 26th Mar 2025 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. This year, TFP will take place in-person at the University of Oxford, UK. It is co-located with the Trends in Functional Programming in Education (TFPIE) workshop, which will take on the day before the main symposium. Please be aware that TFP has several submission deadlines. The first, 13th November, is for authors who wish to have their full paper reviewed prior to the symposium. Papers that are accepted in this way must also be presented at the symposium. The second, 11th December, is for authors who wish to present their work or work-in-progress at the symposium first without submitting to the full review process for publication. These authors can then take into account feedback received at the symposium and submit a full paper for review by the third deadline, 19th February. ## Scope The symposium recognizes that new trends may arise through various routes. As part of the Symposium's focus on trends we therefore identify the following five paper categories. High-quality submissions are solicited in any of these categories: * Research Papers: Leading-edge, previously unpublished research work * Position Papers: On what new trends should or should not be * Project Papers: Descriptions of recently started new projects * Evaluation Papers: What lessons can be drawn from a finished project * Overview Papers: Summarizing work with respect to a trendy subject Papers must be original and not simultaneously submitted for publication to any other forum. They may consider any aspect of functional programming: theoretical, implementation-oriented, or experience-oriented. Applications of functional programming techniques to other languages are also within the scope of the symposium. Topics suitable for the symposium include, but are not limited to: * Functional programming and multicore/manycore computing * Functional programming in the cloud * High performance functional computing * Extra-functional (behavioural) properties of functional programs * Dependently typed functional programming * Validation and verification of functional programs * Debugging and profiling for functional languages * Functional programming in different application areas: security, mobility, telecommunications applications, embedded systems, global computing, grids, etc. * Interoperability with imperative programming languages * Novel memory management techniques * Program analysis and transformation techniques * Empirical performance studies * Abstract/virtual machines and compilers for functional languages * (Embedded) domain specific languages * New implementation strategies * Any new emerging trend in the functional programming area If you are in doubt on whether your paper is within the scope of TFP, please contact the programme chair, Jeremy Gibbons. ## Best Paper Awards TFP awards two prizes for the best papers each year. First, to reward excellent contributions, TFP awards a prize for the best overall paper accepted for the post-conference formal proceedings. Second, each year TFP also awards a prize for the best student paper. TFP traditionally pays special attention to research students, acknowledging that students are almost by definition part of new subject trends. A student paper is one for which the authors state that the paper is mainly the work of students, the students are the paper's first authors, and a student would present the paper. In both cases, it is the PC of TFP that awards the prize. In case the best paper happens to be a student paper, then that paper will receive both prizes. ## Instructions to Authors Submission is via EquinOCS (https://equinocs.springernature.com/service/tfp2025) Authors of papers have the choice of having their contributions formally reviewed either before or after the Symposium. Further, pre-symposium submissions may either be full (earlier deadline) or draft papers (later deadline). ## Pre-symposium formal review Papers to be formally reviewed before the symposium should be submitted before the early deadline and will receive their reviews and notification of acceptance for both presentation and publication before the symposium. A paper that has been rejected for publication but accepted for presentation may be revised and resubmitted for the post-symposium formal review. ## Post-symposium formal review Draft papers will receive minimal reviews and notification of acceptance for presentation at the symposium. Authors of draft papers will be invited to submit revised papers based on the feedback received at the symposium. A post-symposium refereeing process will then select a subset of these papers for formal publication. ## Paper categories Draft papers and papers submitted for formal review are submitted as extended abstracts (4 to 10 pages in length) or full papers (up to 20 pages). The submission must clearly indicate which category it belongs to: research, position, project, evaluation, or overview paper. It should also indicate which authors are research students, and whether the main author(s) are students. A draft paper for which all authors are students will receive additional feedback by one of the PC members shortly after the symposium has taken place. ## Format Papers must be written in English, and written using the LNCS style. For more information about formatting please consult the Springer LNCS Guidelines web site (https://www.springer.com/gp/computer-science/lncs/conference-proceedings-gu…) ## Organizing Committee Jeremy Gibbons University of Oxford, UK Programme Chair Jason Hemann Seton Hall University, US Conference Chair Peter Achten Radboud University Nijmegen, NL Publicity Chair Marco T. Morazán Seton Hall University, US Steering Committee Chair ## Programme Committee Peter Achten Radboud University Nijmegen, NL Edwin Brady University of St Andrews, UK Laura Castro University of A Coruña, ES Youyou Cong Tokyo Institute of Technology, JP Paul Downen University of Massachusetts Lowell, US João Paulo Fernandes University of Coimbra, PT Ben Greenman University of Utah, US Jurriaan Hage Heriot-Watt University, UK Jason Hemann Seton Hall University, US Zhenjiang Hu Peking University, CN Hans-Wolfgang Loidl Heriot-Watt University, UK Kazutaka Matsuda Tohoku University, JP Zoe Paraskevopoulou Ethereum Foundation, US Alejandro Serrano 47 Degrees, ES Nick Smallbone Chalmers University, SE Alley Stoughton Boston University, US Wouter Swierstra Utrecht University, NL Niki Vazou IMDEA Software Institute, ES Marcos Viera Universidad de la República, UY Viktória Zsók Eötvös Loránd University of Sciences, HU

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Call for Participation - Haskell Bug Interviews
by Leonhard Applis 02 Sep '24

02 Sep '24

Dear Haskell Mailing List, we are looking for participants for a ~30 minute interview on bugs, debugging and bug-classification in Haskell. There is a big body of literature on this for e.g. Java, but Haskell might has its own challenges (or hidden similarities), and we hope to map out valuable research that helps practitioners. Your opinion really matters, and I want to encourage anyone to reach out to us even if you don't feel "experienced enough". We don't have a measure for what a real Haskell programmer must do, and if you are coming from a different paradigm and background your insights are very valuable too. The only requirement is to use Haskell regularly enough to encounter and fix bugs, preferably in contact with other humans. This research is currently conducted at the TU Delft and underlies its Data Protection and Ethics standards. Participants from Industry are particularly encouraged and it is possible to redact the transcript post-interview to ensure only things are shared you are comfortable sharing. We will not share interviews or transcripts - only excerpts anonymized and gathered in a codebook. Looking forward for all your Bugs! Best Leonhard Applis (L.H.Applis(a)tu-delft.nl , Leonhard.Applis(a)Protonmail.com) Razvan Nistor (rnistor(a)protonmail.com)

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NFData instance for ForeignPtr
by Vanessa McHale 01 Sep '24

01 Sep '24

I see that deepseq/base have NFData instances for Ptr but not ForeignPtr. Is there a reason there can be no such instance? Cheers, Vanessa McHale

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Speeding up trivial programs
by amindfv＠mailbox.org 24 Aug '24

24 Aug '24

I'm working on a small program that has to run many, many times, as quickly as possible (yes, it needs to be a standalone program). I've optimized it in many ways, but I seem to have a time floor, observable with "Hello, world" $ cat Hello.hs main = putStrLn "Hello world" $ ghc -O2 Hello.hs $ time ./Hello Hello world real 0m0.150s user 0m0.117s sys 0m0.032s The equivalent program in C takes only 0.002s (75x faster). What is taking the extra time? Is it the RTS "booting"? Is there any way to speed this up? Thanks, Tom

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[ANN] Dunai 0.13.1, dunai-test 0.13.1 and bearriver 0.14.10
by Ivan Perez 22 Aug '24

22 Aug '24

Dear all, I'm really excited to announce the release of Dunai 0.13.1 and Bearriver 0.14.10! Dunai is a reactive programming library structured around a notion of Monadic Stream Functions. Dunai can be used to implement other reactive and FRP frameworks on top, including Classic FRP and Arrowized FRP variants. Dunai comes with: - bearriver: API-compatible implementation of Yampa. (The Bear River is a tributary to the Yampa river.) - dunai-test: QuickCheck-based temporal testing library that can be connected with the testing system haskell-titan. See https://github.com/ivanperez-keera/dunai#features for details on Dunai's features. This release fixes an issue with the dependency on the list-transformer library as an alternative to transformers. Thanks to @ tomsmeding for the contribution. This release also provides a matching FRP.BearRiver.Integration, FRP.BearRiver.Random, FRP.BearRiver.Task and FRP.BearRiver.Simulation (akin to Yampa's), including the new Yampa combinator trapezoidIntegral. This last combinator was copied almost verbatim from Yampa, and I want to thank @idontgetoutmuch , @miguel-negrao and @thalerjonathan once again for the discussion and for contributing several alternative implementations. We are now just one module away from being able to provide 100% match in bearriver for all definitions in Yampa. Special thanks go to Johannes Riecken (@johannes-riecken on github) for a regular contribution to support the dunai and Yampa projects. As always, dunai, dunai-test and bearriver are released in sync. For details, see: - https://github.com/ivanperez-keera/dunai/releases/tag/v0.13.1 *Releases* You can explore the current versions at: - https://hackage.haskell.org/package/dunai - https://hackage.haskell.org/package/dunai-test - https://hackage.haskell.org/package/bearriver *Code* The github repo is located at: https://github.com/ivanperez-keera/dunai *What's coming* This release comes exactly 2 months after the last release. The next release is planned for Oct 21, 2024. There are several issues open that you can contribute to: https://github.com/ivanperez-keera/dunai/issues Following our roadmap, the pending changes remain as follows: - Match all definitions from FRP.Yampa.Switches. - Use new performance evaluation features of Yampa to improve performance of both Yampa and dunai. - Create new examples that demonstrate the features of dunai and bearriver. *Donations* Our project is now seeking donations to help continue developing dunai, create new open source libraries, new material, and give talks. No donation is too small. Any contribution will absolutely help. See https://github.com/sponsors/ivanperez-keera for details. If you can help, please come forward. All the best, Ivan

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IFL 2024, final call for participation/registration
by Mart Lubbers 16 Aug '24

16 Aug '24

======================================================================= IFL 2024 36rd Symposium on Implementation and Application of Functional Languages venue: Radboud University Nijmegen, The Netherlands August 26 - 28 2024 https://ifl24.cs.ru.nl ======================================================================= ### Scope The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2024 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. ### Industrial track and topics of interest Topics of interest to IFL include, but are not limited to: - language concepts - type systems, type checking, type inferencing - compilation techniques - staged compilation - run-time function specialisation - run-time code generation - partial evaluation - (abstract) interpretation - meta-programming - generic programming - automatic program generation - array processing - concurrent/parallel programming - concurrent/parallel program execution - embedded systems - web applications - (embedded) domain specific languages - security - novel memory management techniques - run-time profiling performance measurements - debugging and tracing - virtual/abstract machine architectures - validation, verification of functional programs - tools and programming techniques ### Peer-review process Following IFL tradition, IFL 2024 will use a post-symposium review process to produce the formal proceedings. Before the symposium authors submit draft papers. These draft papers will be screened by the program chairs to make sure that they are within the scope of IFL. The draft papers will be made available to all participants at the symposium. Each draft paper is presented by one of the authors at the symposium. After the symposium, a formal review process will take place, conducted by the program committee. Reviewing is single blind. There will be at least 3 reviews per paper. The reviewers have 6 weeks to write their reviews. For the camera-ready version the authors can make minor revisions which are accepted without further reviewing. ### Important dates Submission deadline of draft papers August 6th, 2024 EXTENDED Notification of acceptance for presentation August 6th, 2024 Registration deadline August 19th, 2024 IFL symposium August 26-28, 2024 Submission of papers for proceedings December 1st, 2024 Notification of acceptance February 2nd, 2025 Camera-ready version March 2nd, 2025 ### Submission details All contributions must be written in English. Papers must use the ACM two columns conference format, which can be found at: http://www.acm.org/publications/proceedings-template Submit your paper here: https://easychair.org/conferences/?conf=ifl20240 Register here: https://ifl24.cs.ru.nl/Registration Important note to authors about the new ACM open access publishing model ACM has introduced a new open access publishing model for the International Conference Proceedings Series (ICPS). Authors based at institutions that are not yet part of the ACM Open program and do not qualify for a waiver will be required to pay an article processing charge (APC) to publish their ICPS article in the ACM Digital Library. To determine whether or not an APC will be applicable to your article, please follow the detailed guidance here: https://www.acm.org/publications/icps/author-guidance. Further information may be found on the ACM website, as follows: - Full details of the new ICPS publishing model: https://www.acm.org/publications/icps/faq - Full details of the ACM Open program: https://www.acm.org/publications/openaccess - Please direct all questions about the new model to icps-info(a)acm.org. ### Peter Landin Prize The Peter Landin Prize is awarded to the best paper presented at the symposium every year. The honoured article is selected by the program committee based on the submissions received for the formal review process. The prize carries a cash award equivalent to 150 Euros. ### Organisation PC Chairs: Mart Lubbers Radboud University, The Netherlands Local Chairs: Peter Achten Radboud University, The Netherlands Sven-Bodo Scholz, Radboud University, The Netherlands ### Program committee: Benoît Montagu, University of Lorraine, Inria, France Christos Dimoulas, Northwestern University, USA Edsko de Vries, Well-typed, The Netherlands Fritz Henglein, University of Copenhagen, Denmark Ian Mackie, University of Sussex, UK Jason Hemann, Seton Hall University, USA João Saraiva, Universidade do Minho, Portugal Jurriaan Hage, Heriot-Watt University, UK Kenichi Asai, Ochanomizu University, Japan Maja Kirkeby, Roskilde University, Denmark Marco Morazán, Seton Hall University, USA Neil Mitchell, Facebook, UK Ralf Laemmel, University of Koblenz Landau, Germany Rinus Plasmeijer, TOP Software/Radboud University, The Netherlands Stephen Chang, UMass Boston, USA Tim Steenvoorden, Open University, The Netherlands Tom Schrijvers, KU Leuven, Belgium Yusuf Moosa Motara, Rhodes University, South Africa ### Venue IFL 2024 will be held physically in Nijmegen, the Netherlands. See the website for more information. https://ifl24.cs.ru.nl ### Acknowledgments This call-for-papers is an adaptation and evolution of content from previous instances of IFL. We are grateful to prior organisers for their work, which is reused here.

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