- Haskell-Cafe - Haskell.org

[haskell-cafe] HList maintainer
by Daniil Iaitskov 28 Jan '25

28 Jan '25

Hi List, I am trying to reach HList package maintainer. Maintainer email form cabal file does not exist. There is no feedback on PR <https://bitbucket.org/HList/hlist/pull-requests/3>. Best regards, Daniil Iaitskov

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CGO 25 - Call for Participation - Early Registration
by Luisa Cicolini 27 Jan '25

27 Jan '25

ACM/IEEE International Symposium on Code Generation and Optimization (CGO 2025) Dear all, This is the last week to take advantage of the early registration<https://2025.cgo.org/attending/registration> (deadline: 31st Jan.) for CGO’25, taking place in Las Vegas (1-5 March 2025). The International Symposium on Code Generation and Optimization (CGO) is a premier venue to bring together researchers and practitioners working at the interface of hardware and software on a wide range of optimization and code generation techniques and related issues. The conference spans the spectrum from purely static to fully dynamic approaches, and from pure software-based methods to specific architectural features and support for code generation and optimization. We have an exciting list of accepted papers<https://2025.cgo.org/track/cgo-2025-papers>, workshops and tutorials<https://2025.cgo.org/track/cgo-2025-workshops-and-tutorials> ahead, don’t forget to register! Best, Luisa

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Midlands Graduate School 2025
by Graham Hutton 27 Jan '25

27 Jan '25

Dear all, The Midlands Graduate School (MGS) in the Foundations of Computing Science will be held 7-11 April 2025 in Sheffield, UK. Eight fantastic courses on category theory, type theory, coalgebra, semantics and more. Please share! Best wishes, Graham Hutton ========================================================== Midlands Graduate School 2025 7-11 April 2025, Sheffield, UK https://tinyurl.com/MGS-2025 BACKGROUND: The Midlands Graduate School (MGS) in the Foundations of Computing Science provides an intensive course of lectures on the mathematical foundations of computing. The MGS has been running since 1999, and is aimed at PhD students in their first or second year of study, but the school is open to everyone, and has increasingly seen participation from industry. We welcome participants from all over the world! COURSES: Eight courses will be given. Participants usually take all the introductory courses and choose additional options from the advanced courses depending on their interests. Invited course - Proof-Theoretic Semantics, David Pym Introductory courses - Category Theory, Thorsten Altenkirch - The Curry-Howard Correspondence, Anupam Das - Quantum Computing, Venanzio Capretta Advanced courses - Coalgebra, Paul Blain Levy - Linear Logic, Abhishek De and Charles Grellois - Modular Proofs in Isabelle/HOL, Chelsea Edmonds - Refinement Types in Haskell, Brandon Hewer REGISTRATION: Will be open shortly; further details to be announced. SPONSORSHIP: We offer a range of sponsorship opportunities for industry (bronze, silver, gold and platinum), each with specific benefits. Please see the website for further details. ========================================================== 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 contact the sender and delete the email and attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. Email communications with the University of Nottingham may be monitored where permitted by law.

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CLC Elections January 2025
by Andrew Lelechenko 26 Jan '25

26 Jan '25

Core Libraries Committee seeks nominations for three expiring seats (including my own). <https://discourse.haskell.org/t/clc-elections-january-2025/11126#what-is-cl…>What is CLC? CLC is a volunteer body, primarily tasked with management of API of base <https://hackage.haskell.org/package/base> package, but also owning so-called Core Libraries and responsible for PVP <https://pvp.haskell.org/>. You can find more at our home page <https://github.com/haskell/core-libraries-committee/?tab=readme-ov-file>. <https://discourse.haskell.org/t/clc-elections-january-2025/11126#who-should…>Who should apply? Anyone who meets the following criteria should apply: Candidates should have enough bandwidth to review merge requests to base on a semi-frequent basis (~3-4 per month), and sustain this for their 3 years term in a healthy manner. Candidates should be able to contribute opinions and analysis to issues raised by the community as a part of the CLC proposal process on a semi-frequent basis (~7 per month). Candidates should be good communicators, and at least be able to articulate to the CLC team when they will be available vs. unavailable. Candidates should be productive, and be able to follow through on merge requests and conversations to their completion in a diligent and timely manner. We encourage any and all who satisfy these requirements to apply. Please note that we are not looking for the biggest galaxy brain in the room – quite the opposite. We are looking for productive, motivated individuals who want to help support the ecosystem that we love. As such, we hope to build a broad sample of the community. <https://discourse.haskell.org/t/clc-elections-january-2025/11126#how-can-i-…>How can I apply? To apply for one of these positions, send an email to clc.nominations.2025(a)gmail.com <mailto:clc.nominations.2025@gmail.com> that consists of the following data: The subject “CLC Election September 2025 - {your name}”. Why you think you’re a good fit given the above criteria. If applicable, please point us to some code you’ve written. Please apply before Feb 2. Best regards, Andrew

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Course-of-value recursion by defining a sequence as a self-referential infinite list
by Vanessa McHale 20 Jan '25

20 Jan '25

Laziness turns out to allow course-of-value recursion where one might use memoization in other languages. But I hadn’t seen this articulated! Famously, one can use this to define the Fibonacci numbers, viz. fibs :: [Integer] fibs = 1 : 1: zipWith (+) fibs (tail fibs) Or the Catalan numbers: catalan :: [Integer] catalan = 1 : 1 : [ sum [ (-1)^(k+1) * (pc (n - ((k*(3*k-1)) /. 2)) + pc (n - ((k*(3*k+1))/.2))) | k <- [1..n] ] | n <- [2..] ] where pc m | m >= 0 = part !! m | otherwise = 0 infixl 6 /. (/.) = quot I wrote up the example: http://vmchale.com/static/serve/Comb.pdf Reinhard Zumkeller has a lot of examples on OEIS: https://oeis.org/A000081 Cheers, Vanessa McHale

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Call for Nominations: Haskell.org Committee (2025-2028)
by Rebecca Skinner 18 Jan '25

18 Jan '25

Dear Haskellers, We are pleased to announce that nominations are now open for the Haskell.org <http://haskell.org/> committee. You can nominate yourself or a friend for a three-year term (2025-2028) by sending an email to [committee at haskell.org <http://haskell.org/>] by January 31, 2025. Self-nominations and re-nominations are also welcome. Please include any relevant information about yourself or your nominee that you think will help us make our decision. Committee members do not have to be technical experts in Haskell. We are looking for people who are enthusiastic about improving the Haskell community and come from a variety of backgrounds, such as academia, industry, open-source development, and community building. Our goal is to represent the various facets of the Haskell world, including gender, race, location, and industry or research. The committee’s responsibilities include setting policies, providing guidance for Haskell.org <http://haskell.org/> infrastructure, planning for the long term, and being fiscally responsible with Haskell.org <http://haskell.org/> funds and donations. Being a committee member does not require a significant amount of time, but members should be responsive during discussions and should be able to attend monthly calls and participate in the Haskell.org <http://haskell.org/> Slack and mailing lists. Candidates for the committee should possess strong leadership, communication, and judgment skills. They must be able to set aside personal or business-related biases and make decisions with the good of the open-source Haskell community in mind. For more information about the committee’s roles and responsibilities, please visit https://www.haskell.org/haskell-org-committee/. If you have any questions about the nomination process, please feel free to email us at [committee at haskell.org <http://haskell.org/>], or contact one of us individually.

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2nd Call for Participation: BOB 2025 (Berlin, Mar 14)
by Stefan Wehr 17 Jan '25

17 Jan '25

The early-bird deadline is Jan 17 (TODAY)! ========================================================================= BOB 2025 Conference “What happens if we simply use what’s best?” March 14, 2025, Berlin https://bobkonf.de/2025/ Program: https://bobkonf.de/2025/program.html Registration: https://bobkonf.de/2025/registration.html ========================================================================= BOB conference is a place 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 experience. The program features 16 talks and 8 tutorials on current topics: https://bobkonf.de/2025/program.html Talk subjects includes functional programming, property-based testing, language server implementation, domain-specific languages, domain-driven design, local-first software, formal methods, and microservices. BOB tutorial include sessions on frontend development, local-first programming, data science, Elixir, and software documentation, combining mob programming, TDD, and AI. Annette Bieniusa will give the keynote talk. Registration is open - many discount options are available, as are grants for members of groups underrepresented in tech. Early-bird discounts apply until Jan 17. https://bobkonf.de/2025/registration.html

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PhD Scholarships in Quantum Computing
by Venanzio Capretta 13 Jan '25

13 Jan '25

PhD Scholarships School of Computer Science University of Nottingham The School of Computer Science at the University of Nottingham is advertising 10 fully-founded PhD studentships starting on 1 October 2025: https://jobs.nottingham.ac.uk/vacancy.aspx?ref=SCI298 We are calling for good candidates to apply for a PhD project in Quantum Computing. The range of potential topics for the PhD project will be: * Quantum Data Types and Algorithms; * Applications of Quantum Computing to Artificial Immune System; * Quantum Functional Programming Languages; * Compilation of Higher-Order Quantum Code; * Quantum computing in AI. Expertise in any of this topics is welcome but not necessary. Applicants should have a good background in programming, data structures, discrete mathematics. The application deadline is 6 April 2025. Before applying you must agree with a potential supervisor and write a research project. So, if you intend to apply, please contact one of us as soon as possible: Ulrik Buchholtz (ulrik.buchholtz(a)nottingham.ac.uk) Venanzio Capretta (venanzio.capretta(a)nottingham.ac.uk) Julie Greensmith (pszjg1(a)exmail.nottingham.ac.uk) ------------------------------------- Venanzio Capretta School of Computer Science University of Nottingham, UK -------------------------------------

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ICFP/SPLASH 2025 Workshop Proposal Deadline: Thu, Jan 16
by ICFP Publicity 10 Jan '25

10 Jan '25

ACM SIGPLAN ICFP 2025 and SPLASH 2025 invite proposals for workshops and co-located events to be held in Singapore from Sunday, October 12 to Saturday, October 18, 2025. This joint event will create a forum for researchers, developers, and practitioners to present the latest work in software development, programming languages, functional programming, and emerging new ideas in computing. All co-located events must submit a proposal — workshops, tutorials, symposiums, or side meetings: https://icfpsplash25events.hotcrp.com/ Important Deadlines <https://conf.researchr.org/track/icfp-splash-2025/icfp-splash-2025-workshop…> - Deadline for Proposal Submission for Workshops: January 16, 2025 - Notification of Acceptance: January 31, 2025 - Deadline for Proposal Submission for Tutorials: May 8, 2025 For more information, please see: https://conf.researchr.org/track/icfp-splash-2025/icfp-splash-2025-workshops We look forward to your proposals and hope to see you in Singapore!

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Formal Verification & Modern AI Safety
by Mostafa Touny 10 Jan '25

10 Jan '25

Hello Haskellers, I hope you are doing well. Amazon started to adopt automated theorem provers, to mitigate modern Generative AI hallucination. See "Prevent factual errors from LLM hallucinations with mathematically sound Automated Reasoning checks": https://aws.amazon.com/blogs/aws/prevent-factual-errors-from-llm-hallucinat… This community has ties to formal proofs, type-driven programming, and Logic programming. Do you see any special potential of Haskell for recent AI safety? Sincerely, Mostafa Touny

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[ANN] Darcs 2.18.4 release
by Ben Franksen 09 Jan '25

09 Jan '25

Hello Everyone On behalf of the Darcs [1] team, I would like to announce the release of Darcs 2.18.4 [2]. See [3] for the full release notes. The main reason for this release was to make it build with stack against stackage lts-22.34 on Linux. This in turn should hopefully make it re-appear in the Debian and Ubuntu GNU/Linux distros. Cheers Ben [1] https://darcs.net [2] https://hackage.haskell.org/package/darcs-2.18.4 [3] https://hackage.haskell.org/package/darcs-2.18.4/changelog

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Final call for participation: LMS/BCS-FACS Online Seminar, Annabelle McIver, 15 January 2025
by Andrei Popescu 09 Jan '25

09 Jan '25

LMS/BCS-FACS Seminar 2025 Wednesday 15 January 2025, from 19:00 (GMT) Online via Zoom https://www.lms.ac.uk/events/lms-bcs-facs-seminar-2025 In association with the British Computer Society Formal Aspects of Computing Science (BCS-FACS), the LMS hosts an annual online seminar on aspects of the computer science–mathematics interface. These events are free to anyone who wishes to attend and have attracted high-quality speakers. We are happy to have this verification talk from a wonderful speaker just one day after World Logic Day. Speaker: Annabelle McIver (Macquarie University) Probabilistic Datatypes: automating verification for abstract probabilistic reasoning Abstract: Datatypes - in which data is encapsulated together with methods that access it - play an important role in the organisation of large software projects. Correctness of datatypes has traditionally been carried out using simulation relations to simplify the verification by separating concerns: the datatype can be verified independently from the programs that use it, whilst those programs themselves can be verified using the specifications of the datatype's methods. Use of these principles enables complex programs to be brought within reach of automated proof. When probabilistic choice is included, however, it turns out that obtaining similar simplifications of the verification problem will require distinguishing between "hidden" and "observable" probabilistic behaviour - if demonic choice is allowed in the surrounding program. And that is not required in the non-probabilistic setting: the crucial issue is the potential interaction of probabilistic- and demonic choice. In the main part of this talk I will use examples to explain why the interaction is problematic, and I will suggest how extension of existing pGCL-based automated reasoning-tools, will by taking that interaction into account, enable automated probabilistic abstract reasoning about "hard to crack" probabilistic programs. Registration: To attend remotely via Zoom, please complete the registration form here: https://www.lms.ac.uk/civicrm/event/info?reset=1&id=139 You will receive the link to the meeting upon registration, as well as an automated reminder email sent 24 hours before the event is scheduled to start. For all queries regarding the seminar, please contact lmscomputerscience(a)lms.ac.uk.

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Rebuilding package on hackage to generate documentation
by Ivan Perez 08 Jan '25

08 Jan '25

Hi, I'm trying to trigger a re-build of Yampa on hackage so that the documentation will be generated. I'm being met with the following message: Report not found Build report does not exist Am I doing something wrong? Thanks Ivan

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[ANN] Copilot 4.2
by Ivan Perez 08 Jan '25

08 Jan '25

Hi everyone!! We are really excited to announce Copilot 4.2 [1,2]. Copilot is a stream-based EDSL in Haskell for writing and monitoring embedded C programs, with an emphasis on correctness and hard realtime requirements. Copilot is typically used as a high-level runtime verification framework, and supports temporal logic (LTL, PTLTL and MTL), clocks and voting algorithms. Compilation to Bluespec, to target FPGAs, is also supported. Copilot is NASA Class D open-source software, and is being used at NASA in drone test flights. Through the NASA tool Ogma [3] (also written in Haskell), Copilot also serves as a runtime monitoring backend for NASA's Core Flight System, Robot Operating System (ROS2), FPrime (the software framework used in the Mars Helicopter). This release introduces several big improvements to Copilot: - Specifications can now use the same handler for multiple monitors, provided that the arguments to those handlers always have consistent types and arity. This simplifies the code that uses Copilot, since it's no longer necessary to create multiple boilerplate wrappers around the same handling routines. - The use of structs has been vastly simplified. Before, it was necessary to define class instances for structs, whose implementations were, although repetitive, not intuitive especially for users unfamiliar with Haskell. In Copilot 4.2, it is now possible to define those methods automatically by relying on default method implementations that work well for most cases, although users retain the ability to customize those methods if desired. - We have increased test coverage in `copilot-core`, reaching full coverage of all elements of the public interface that are not automatically generated by GHC. The interface of `copilot-core` has also been simplified, deprecating record fields of an existential type UExpr, which were largely unused outside of Copilot's internals. The new implementation is compatible with versions of GHC from 8.6 to 9.10, as well as Stackage Nightly. This release has been made possible thanks to key submissions from Frank Dedden, Ryan Scott, and Kyle Beech, the last of which is also a first-time contributor to the project. We are grateful to them for their timely contributions, especially during the holidays, and for making Copilot better every day. We also want to thank the attendees of Zurihac 2024 for technical discussions that helped find the right solutions to some of the problems addressed by this release. For details on this release, see [1]. https://github.com/Copilot-Language/copilot/releases/tag/v4.2. As always, we're releasing exactly 2 months since the last release. Our next release is scheduled for Mar 7th, 2025. We want to remind the community that Copilot is now accepting code contributions from external participants again. Please see the discussions and the issues in our github repo [4] to learn how to participate. Current emphasis is on improving the codebase in terms of performance, stability and test coverage, removing unnecessary dependencies, hiding internal definitions, formatting the code to meet our new coding standards, and simplifying the Copilot interface. Users are encouraged to participate by opening issues, asking questions, extending the implementation, and sending bug fixes. Happy Haskelling! Ivan -- [1] https://github.com/Copilot-Language/copilot/releases/tag/v4.2 [2] https://hackage.haskell.org/package/copilot [3] https://github.com/nasa/ogma [4] https://github.com/Copilot-Language/copilot

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POPL 2025 Call for Participation (January 19-25, Denver, Colorado)
by Ningning Xie 07 Jan '25

07 Jan '25

The 52nd ACM SIGPLAN Symposium on Principles of Programming Languages (POPL 2025) will take place in January in Denver, Colorado, the United States. It's going to be an amazing conference - don't miss it - sign up now! https://popl25.sigplan.org/attending/registration Location: Curtis Hotel Denver, 1405 Curtis Street, 80202, Denver, Colorado, United States Dates: - Main conference: Wed 22 - Fri 24 January - Workshops, tutorials, co-located events: Sun 19, Mon 20, Tue 21 and Sat 25 January Accepted papers: https://popl25.sigplan.org/track/POPL-2025-popl-research-papers Full details of the conference and co-located events: https://popl25.sigplan.org/ Sponsors: POPL is supported by generous sponsorship from: - Amazon - Jane Street - Google DeepMind - JetBrains - Microsoft - Epic - Google - Ahrefs

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CGO'25 - early bird registration and student research competition
by Luisa Cicolini 07 Jan '25

07 Jan '25

Dear all, Registrations for the International Symposium on Code Generation and Optimization (CGO) 2025<https://2025.cgo.org/>, taking place in Las Vegas<https://2025.cgo.org/attending/Venue>, from 1st-5th March are now open. The International Symposium on Code Generation and Optimization (CGO) is a premier venue bringing together researchers and practitioners working at the interface of hardware and software on a wide range of optimization and code generation techniques and related issues. The conference spans from purely static to fully dynamic approaches, from pure software-based methods to specific architectural features and support for code generation and optimization. Early registration<https://2025.cgo.org/attending/registration> deadline is on 31st January! We are also hosting a Student Research Competition (SRC)<https://2025.cgo.org/track/cgo-2025-student-research-competition>: a unique opportunity for undergraduate and graduate students to present their original research before a panel of judges and attendees at CGO'25. The winner will be awarded and invited to the 2025 ACM SRC competition. If you know any undergraduate or postgraduate students doing research in compiler-related topics, please invite them to apply - we are excited to welcome young researchers to the community! Best, Luisa Cicolini

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Re: [Haskell-cafe] Configuring cabal to tell HPC to ignore certain functions
by Ryan Scott 29 Dec '24

29 Dec '24

Hi Ivan, Short answer: I'm not aware of a way to automate the process of excluding certain definitions from cabal-generated HPC coverage reports. Long answer: there is a way to manually modify HPC coverage reports using the hpc overlay command. Sadly, most the existing documentation on this command [1] is pretty sparse, so the only way I was able to discover this was by reading the original HPC paper [2] (in that paper, `hpc overlay` is called `hpc-makemtix`) and by finding an example of how to use `hpc overlay` in GHC's test suite [3]. To translate that example into prose: suppose you have the following program (hpc001.hs): main = print (const "Hello" "World") Here, the expression "World" is never evaluated, so by default HPC will claim that there is no coverage for it. This is pretty silly, however, so we'd like to instruct HPC not to warn about "World". To do so, first compile the example above with coverage enabled and run it: $ ghc -fhpc hpc001.hs $ ./hpc001 This should generate an hpc001.tix file. If you run `hpc markup hpc001.tix` and look at the resulting HTML report, you'll see that it warns about "World". Let's fix that. To do so, we have to define an HPC overlay file. The example given in GHC's test suite (sample_overlay.ovr) is: module "Main" { inside "main" { tick "\"World\"" on line 1; } } While I can't find a reference for the syntax that HPC overlay files use, this particular example is pretty self-explanatory: don't report about the expression "World" on line 1, which is found inside the `main` function in the `Main` module. In order to make use of this overlay file, we first have to convert it to a .tix file: $ hpc overlay sample_overlay.ovr > sample_overlay1.tix Then we have to combine it with our original .tix file: $ hpc combine hpc_sample.tix sample_overlay1.tix > total1.tix If we run `hpc markup total1.txt`, we now see that HPC no longer warns about "World", just as we'd hoped for. That is where my understanding of this feature ends, however. In particular, I'm not aware of a better way to generate overlay files (other than to write them by hand, which still feels somewhat laborious), and I'm not aware of any deeper integration with cabal so that these overlay files would be picked up and automatically applied (e.g., for reporting coverage on Hackage). Given that the HPC documentation for `hpc overlay` [1] labels this as an experimental feature, I'd be surprised if such tooling or integration existed. I agree that it would be cool if did, however. Best, Ryan ----- [1] https://hpc-bin.readthedocs.io/en/latest/hpc.html#hpc-overlay-and-hpc-draft [2] https://dl.acm.org/doi/abs/10.1145/1291201.1291203 [3] https://gitlab.haskell.org/ghc/ghc/-/blob/e39c8c993c1da534c5893ca418d1fa4cb…

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[ghc-proposals] Allow reserved identifiers as fields ...
by Anthony Clayden 27 Dec '24

27 Dec '24

And Merry Christmas to all. I counsel against allowing reserved ids to be anything other than reserved ids. "... is fraught with peril, unduly complicates the parser, and harms readability. " says a language implementer I asked. But wanting to use field names dictated outside this language's control is a realistic requirement, for which there are several general approaches. The ghc proposal as it stands seems ad-hoc and very specific to one user organisation. Furthermore, this just ain't true: > ... SQL schemas. anyone working with those is stuck deciding between special-casing its naming, and consistently naming *everything* weirdly, ... SQL consistently supports things like embedded spaces, fields starting upper-case [**], embedded dots or other graphics -- by no means just names that clash with reserved ids. How does it do that? And this answer seems particularly relevant when these ids are going to feed into `HasField` constraints as a type-level String: put the id between quotes. > orgNotification."type" doesn't look too ugly to my eye. And to spj's repeated point: I could envisage allowing fields in `data` decls and record syntax to be quoted. (Again you couldn't use punning nor field-name as function.) The approach is sufficiently general it could be extended to `#"Label naming"`. [**] I'm particularly keen on field names starting upper case, because they're injective/part of the structure, like data constructors. AntC (Why am I posting to the cafe, not github? I seem to be blocked from posting on any topic, either on github or gitlab -- even for pages where I'm the sole author. I'd be grateful if somebody could post the above to the PR.)

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2nd CfP: SLE 2025 - 18th ACM SIGPLAN International Conference on Software Language Engineering
by Andrei Chis 20 Dec '24

20 Dec '24

18th ACM SIGPLAN International Conference on Software Language Engineering (SLE 2025) 12-13 June 2025 Koblenz, Germany https://www.sleconf.org/2025/ https://x.com/sleconf ------------------------------------------------------------------------ We are pleased to invite you to submit papers to the 18th ACM SIGPLAN International Conference on Software Language Engineering (SLE) which is devoted to the principles of software languages: their design, their implementation, and their evolution. The SLE 2025 conference will be co-located with STAF 2025 and hosted in Koblenz, Germany, on 12-13 June 2025. --------------------------- Important Dates --------------------------- * Abstract submission: Fri 7 Feb 2025 * Paper submission: Fri 14 Feb 2025 * Authors response period: Tue 1 Apr - Sat 5 Apr 2025 * Notification: Tue 15 Apr 2025 * Conference: Thu 12 June - Fri 13 June 2025 (co-located with STAF) All dates are Anywhere on Earth. --------------------------- Topics of Interest --------------------------- SLE covers software language engineering in general, rather than engineering a specific software language. Topics of interest include, but are not limited to: * Software Language Design and Implementation - Approaches to and methods for language design - Static semantics (e.g., design rules, well-formedness constraints) - Techniques for specifying behavioral/executable semantics - Generative approaches (incl. code synthesis, compilation) - Meta-languages, meta-tools, language workbenches - AI-assisted language design and optimisation * Software Language Validation - Verification and formal methods for languages - Testing techniques for languages - Simulation techniques for languages - Model-based testing - AI-assisted validation * Software Language Integration and Composition - Coordination of heterogeneous languages and tools - Mappings between languages (incl. transformation languages) - Traceability between languages - Deployment of languages to different platforms - AI-assisted refactoring * Software Language Maintenance - Software language reuse - Language evolution - Language families and variability, language and software product lines * Domain-specific approaches for any aspects of SLE (design, implementation, validation, maintenance) * Empirical evaluation and experience reports of language engineering tools - User studies evaluating usability - Performance benchmarks - Industrial applications * Synergies between Language Engineering and emerging/promising research areas - Generative AI in language engineering (e.g., AI-based language modelling, AI-driven code generation tools) - AI and ML language engineering (e.g., ML compiler testing, code classification) - Quantum language engineering (e.g., language design for quantum machines) - Language engineering for physical systems (e.g., CPS, IoT, digital twins) - Socio-technical systems and language engineering (e.g., language evolution to adapt to social requirements) --------------------------- Types of Submissions --------------------------- SLE accepts the following types of papers: * Research papers: These are “traditional” papers detailing research contributions to SLE. Papers may range from 6 to 12 pages in length and may optionally include 2 further pages of bibliography/appendices. Papers will be reviewed with an understanding that some results do not need 12 full pages and may be fully described in fewer pages. * New ideas/vision papers: These papers may describe new, unconventional software language engineering research positions or approaches that depart from standard practice. They can describe well-defined research ideas that are at an early stage of investigation. They could also provide new evidence to challenge common wisdom, present new unifying theories about existing SLE research that provides novel insight or that can lead to the development of new technologies or approaches, or apply SLE technology to radically new application areas. New ideas/vision papers must not exceed 5 pages and may optionally include 1 further page of bibliography/appendices. * SLE Body of Knowledge: The SLE Body of Knowledge (SLEBoK) is a community-wide effort to provide a unique and comprehensive description of the concepts, best practices, tools, and methods developed by the SLE community. In this respect, the SLE conference will accept surveys, essays, open challenges, empirical observations, and case study papers on the SLE topics. These can focus on, but are not limited to, methods, techniques, best practices, and teaching approaches. Papers in this category can have up to 20 pages, including bibliography/appendices. * Tool papers: These papers focus on the tooling aspects often forgotten or neglected in research papers. A good tool paper focuses on practical insights that will likely be useful to other implementers or users in the future. Any of the SLE topics of interest are appropriate areas for tool demonstrations. Submissions must not exceed 5 pages and may optionally include 1 further page of bibliography/appendices. They may optionally include an appendix with a demo outline/screenshots and/or a short video/screencast illustrating the tool. Workshops: Workshops will be organised by STAF. Please inform us and contact STAF 2025 organisers if you would like to organise a workshop of interest to the SLE audience. Information on how to submit workshops can be found on the STAF 2025 Website. --------------------------- Submission --------------------------- SLE 2025 has a single submission round for papers, including a mandatory abstract registration and a rebuttal phase, where all authors of research papers will have the possibility of responding to the reviews on their submissions. Authors of accepted research papers will be invited to submit artefacts. --------------------------- Format --------------------------- Submissions have to use the ACM SIGPLAN Conference Format “acmart” ( https://sigplan.org/Resources/Author/#acmart-format) please make sure that you always use the latest ACM SIGPLAN acmart LaTeX template, and that the document class definition is `\documentclass[sigplan,anonymous,review]{acmart}`. Do not make any changes to this format! Ensure that your submission is legible when printed on a black and white printer. In particular, please check that colours remain distinct and font sizes in figures and tables are legible. To increase fairness in reviewing, a double-blind review process has become standard across SIGPLAN conferences. Accordingly, SLE will follow the double-blind process. Author names and institutions must be omitted from submitted papers, and references to the authors’ own related work should be in the third person. No other changes are necessary, and authors will not be penalized if reviewers are able to infer their identities in implicit ways. All submissions must be in PDF format. The submission website is: https://sle25.hotcrp.com --------------------------- Concurrent Submissions --------------------------- Papers must describe unpublished work that is not currently submitted for publication elsewhere as described by SIGPLAN’s Republication Policy ( https://www.sigplan.org/Resources/Policies/Republication/) Submitters should also be aware of ACM’s Policy and Procedures on Plagiarism ( https://www.acm.org/publications/policies/plagiarism-overview) Submissions that violate these policies will be desk-rejected. --------------------------- Policy on Human Participant and Subject Research --------------------------- Authors conducting research involving human participants and subjects must ensure that their research complies with their local governing laws and regulations and the ACM’s general principles, as stated in the ACM’s Publications Policy on Research Involving Human Participants and Subjects ( https://www.acm.org/publications/policies/research-involving-human-particip…) If submissions are found to be violating this policy, they will be rejected. --------------------------- Reviewing Process --------------------------- All submitted papers will be reviewed by at least three members of the program committee. Research papers and tool papers will be evaluated concerning soundness, relevance, novelty, presentation, and replicability. New ideas/vision papers will be evaluated primarily concerning soundness, relevance, novelty, and presentation. SLEBoK papers will be reviewed on their soundness, relevance, originality, and presentation. Tool papers will be evaluated concerning relevance, presentation, and replicability. For fairness reasons, all submitted papers must conform to the above instructions. Submissions that violate these instructions may be rejected without review at the discretion of the PC chairs. For research papers, authors will get a chance to respond to the reviews before a final decision is made. --------------------------- Artefact Evaluation --------------------------- SLE will use an evaluation process to assess the quality of artefacts on which papers are based to foster the culture of experimental reproducibility. Authors of accepted research papers are invited to submit artefacts. --------------------------- Awards --------------------------- * Distinguished paper: Award for the most notable paper, as determined by the PC chairs based on the recommendations of the program committee. * Distinguished artefact: Award for the artefact most significantly exceeding expectations, as determined by the AEC chairs based on the recommendations of the artefact evaluation committee. * Distinguished reviewer: Award for the programme committee member that produced the most useful reviews as assessed by paper authors. * Most Influential Paper: Award for the SLE 2015 paper with the greatest impact, as judged by the SLE Steering Committee. --------------------------- Publication --------------------------- All accepted papers will be published in the ACM Digital Library. **AUTHORS TAKE NOTE**: The official publication date is the date the proceedings are made available in the ACM Digital Library. This date may be up to two weeks prior to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work. --------------------------- Organisation --------------------------- * General chair: Görel Hedin, Lunds Universitet, Sweden * PC co-chair: Regina Hebig, Universität Rostock, Germany * PC co-chair: Vadim Zaytsev, Universiteit Twente, The Netherlands * Publicity chair: Andrei Chiş, feenk gmbh, Switzerland * Local chair: Ralf Lämmel, Universität Koblenz, Germany --------------------------- Contact --------------------------- For additional information, clarification, or answers to any questions, please get in touch with the program co-chairs (regina.hebig(a)uni-rostock.de and vadim(a)grammarware.net)

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convert structures from type to value level
by Zoran Bošnjak 20 Dec '24

20 Dec '24

Dear haskell cafe, I would like to describe some structures as types (something like servant does) and I would also need to use the same structure in run-time as a value. I am trying to figure out how could I use GHC.Generics or something to do this for several user defined structures. Currently I am doing it manually (with does not work, but it might serve as intention), for example: -- generic example structure data GTest s n = GTest0 | GTest1 s | GTest2 n type TTest = GTest Symbol Nat -- type level type VTest = GTest String Integer -- value level For all my user defined structure, at the type level it will always be only (Symbol, Nat) which should translate to (Text, Int) or (String, Integer) for simplicity. -- | Convert schema from type to value class IsSchema t a where schema :: a instance KnownNat n => IsSchema n Integer where schema = natVal (Proxy @n) instance KnownSymbol s => IsSchema s String where schema = symbolVal (Proxy @s) instance IsSchema 'GTest0 VTest where schema = GTest0 instance ( IsSchema s String ) => IsSchema ('GTest1 s) VTest where schema = GTest1 (schema @s) instance ( IsSchema n Integer ) => IsSchema ('GTest2 n) VTest where schema = GTest2 (schema @n) I would like to generalize the process, by saying something like (not sure if I even need this): data Usage = TypeLevel | ValueLevel data GTest ? = Gtest0 | GTest1 ? | GTest2 ? (deriving ?) ... and be able to use the same Test structure in both cases, such as: Use it as a phantom type in some other type: data Item (t :: TTest) where Item0 :: Item 'GTest0 Item1 :: String -> Item ('GTest1 s) Item2 :: Integer -> Item ('GTest2 n) And use it as value, something like: data SomeItem = forall t a. IsSchema t a => SomeItem a (Item t) In other words... I would like to work with exact types (Item t) or generically with SomeItem, when the type is not exactly known, but the value level schema is known. I came far with manual approach, but I could not create SomeItem from the value schema. So, for example this does not compile (the error is about KnownSymbol/KnownNat): mkSomeItem :: VTest -> SomeItem mkSomeItem sch = case sch of GTest0 -> SomeItem sch Item0 GTest1 s -> SomeItem sch (Item1 (s <> s)) GTest2 n -> SomeItem sch (Item2 (succ n)) I am curious to know how to fix this problem. But the manual conversion approach is something I would like to avoid in the first place. Appreciate your help. regards, Zoran

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Throwing an exception in STM without rolling back state?
by Tom Ellis 18 Dec '24

18 Dec '24

Dear Cafe, Is it possible to throw an exception in STM without rolling back state? (See program below for an demonstration that throwing an exception does roll back state.) I'm having a great deal of success using exceptions in my effect system Bluefin, to simulate early return and jumps: * https://hackage.haskell.org/package/bluefin-0.0.14.0/docs/Bluefin-EarlyRetu… * https://hackage.haskell.org/package/bluefin-0.0.14.0/docs/Bluefin-Jump.html I'm interested in making a Bluefin interface to STM too, but the value of that would be significantly diminished if all exceptions roll back state. Instead I would like to be able to say "throwing this exception _shouldn't_ roll back state". Is that possible? If not in practice, is it possible in theory, if I were to modify the RTS somehow? Thanks, Tom {-# LANGUAGE GHC2021 #-} import GHC.Conc import GHC.Exception data MyEx = MyEx deriving Show instance Exception MyEx -- > main -- False main = do r <- atomically $ do v <- newTVar False catchSTM @MyEx (do writeTVar v True -- same with throw MyEx` throwSTM MyEx ) (\_ -> pure ()) readTVar v print r

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[TFP (and TFPiE) 2025] Call For Participation (January 13-16, Oxford, UK)
by Peter Achten 18 Dec '24

18 Dec '24

TFP 2025 -- Call For Participation (trendsfp.github.io) Venue TFPiE and TFP will take place in-person in the Wolfson Building of the Department of Computer Science at the University of Oxford. Dates Early registration: December 20, 2024 Late registration: January 6, 2025 TFPiE Workshop: Monday 13th January, 2025 TFP Symposium: Tuesday 14th - Thursday 16th January, 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. Keynote speakers We are happy to have the following keynotes in the programme: * Nicolas Wu (TFPiE), Imperial College London: "Fractal Foundations and Galactic Graphs: Structure and Strategy for Expanding Minds" * Graham Nelson, University of Oxford: "Literate Programming and Cultural Practice" * Mike Sperber, Active Group: "Things We Never Told Anyone About Functional Programming" * Kathrin Stark, Heriot-Watt University: "A Verified Foreign Function Interface Between Coq and C" Programme We have 28 paper presentations. The programme schedule can be found here: trendsfp.github.io/schedule.html Excursion and banquet In the afternoon and evening of Wednesday January 15th we have an excursion to the History of Science Museum. We have a break in a cosy pub, before proceeding to Kellogg College for the conference banquet. During dinner the winners of the best paper awards of last year's TFP are announced.

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Call for Participation: BOB 2025 (Berlin, Mar 14)
by Stefan Wehr 17 Dec '24

17 Dec '24

========================================================================= BOB 2025 Conference “What happens if we simply use what’s best?” March 14, 2025, Berlin https://bobkonf.de/2025/ Program: https://bobkonf.de/2025/program.html Registration: https://bobkonf.de/2025/registration.html ========================================================================= BOB conference is a place 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 experience. The program features 16 talks and 8 tutorials on current topics: https://bobkonf.de/2025/program.html Talk subjects includes functional programming, property-based testing, language server implementation, domain-specific languages, domain-driven design, local-first software, formal methods, and microservices. BOB tutorial include sessions on frontend development, local-first programming, data science, Elixir, and software documentation, combining mob programming, TDD, and AI. Annette Bieniusa will give the keynote talk. Registration is open - many discount options are available, as are grants for members of groups underrepresented in tech. Early-bird discounts apply until Jan 17. https://bobkonf.de/2025/registration.html

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GHC 9.12.1 is now available
by Zubin Duggal 16 Dec '24

16 Dec '24

The GHC developers are very pleased to announce the release of GHC 9.12.1. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][]. We hope to have this release available via ghcup shortly. GHC 9.12 will bring a number of new features and improvements, including: * The new language extension [OrPatterns] allowing you to combine multiple pattern clauses into one. * The [MultilineStrings] language extension to allow you to more easily write strings spanning multiple lines in your source code. * Improvements to the OverloadedRecordDot extension, allowing the built-in `HasField` class to be used for records with fields of non lifted representations. * The [NamedDefaults] language extension has been introduced allowing you to define defaults for typeclasses other than `Num`. * More deterministic object code output, controlled by the `-fobject-determinism` flag, which improves determinism of builds a lot (though does not fully do so) at the cost of some compiler performance (1-2%). See #12935 for the details * GHC now accepts type syntax in expressions as part of [GHC Proposal #281]. * The WASM backend now has support for TemplateHaskell. * Experimental support for the RISC-V platform with the native code generator. * ... and many more A full accounting of changes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. We would like to thank GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. [release notes]: https://downloads.haskell.org/ghc/9.12.1/docs/users_guide/9.12.1-notes.html [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [OrPatterns]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0522-o… [MultilineStrings]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0569-m… [GHC Proposal #281]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-v… [NamedDefaults]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-e…

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Save the date: Haskell Ecosystem Workshop and Haskell Implementors' Workshop 2025
by Andreas Herrmann 15 Dec '24

15 Dec '24

Save the date for the Haskell Ecosystem Workshop and the Haskell Implementors' Workshop taking place on June 5 & 6 2025 near Zurich, Switzerland, hosted by the Haskell Foundation at the OST (Eastern Switzerland University of Applied Sciences) in Rapperswil, and co-located with ZuriHac (June 7-9). Expect a more detailed announcement, registration, and a call for proposals in early 2025. The Haskell Ecosystem Workshop is a workshop organized by the Haskell Foundation for those who want to gain a deeper understanding of the Haskell tooling ecosystem, whether to better leverage those tools or to become contributors. The Haskell Implementors' Workshop is a community event for people involved in the design and development of Haskell implementations, tools, libraries, and supporting infrastructure to share their work and to discuss future directions and collaborations with others. In the past the Haskell Implementors' Workshop used to be co-located with ICFP (International Conference on Functional Programming), next year it will be co-located with ZuriHac to be accessible to a broader audience. Contact Jose Calderon, executive director of the Haskell Foundation, if you have any questions regarding the Haskell Ecosystem Workshop. Contact Andreas Herrmann, program chair for the Haskell Implementors' Workshop 2025, if you have any questions regarding the Haskell Implementors' Workshop.

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Engineering Value of Functional Programming
by Mostafa Touny 10 Dec '24

10 Dec '24

Dear Haskellers, I hope my email finds you in a good shape. Software engineers usually deviate away from Haskell, in the name of rapid development. In Pure Math, I can see the power of abstraction; It resulted in broad applications, with a sustainable and scalable usage in all humanity's sciences. Software development should benefit as well, avoiding technical debts and refactoring costs. Haskell seems more promising as it is empowered by category and type theory. Nonetheless, I cannot find a single management methodology, like Eric Ries' lean startup and iterative agile, that demonstrates the power of functional programming from the perspective of project management. Discussion. - Do you agree category and type theory could reduce projects costs? - Is it true, no guideline is designed for demonstrating their worthiness? Sincerely, Mostafa Touny https://mostafatouny.github.io/

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ANN: hledger 1.41
by Simon Michael 10 Dec '24

10 Dec '24

I'm pleased to announce hledger 1.41 ! This release brings: - a notable valuation fix - pervasive improved HTML and FODS output - multiple depths - terminal pagination - robust export to Beancount ..and more. Thank you to contributors Dmitry Astapov, Stephen Morgan, Bas van Dijk, Gal Lakovnik Gorenec, amano.kenji, gesh, and especially Henning Thielemann ! Best wishes, -Simon - https://github.com/simonmichael/hledger/releases/1.41 - https://hledger.org/relnotes.html#2024-12-09-hledger-141 - https://hledger.org/install hledger is free, robust, friendly, multicurrency, double-entry, plain text accounting software for unix, mac, windows, and the web. Written in Haskell for reliability, it is built around human-readable, version-controllable plain text files. It is inspired by and largely compatible with Ledger CLI, and convertible to and from Beancount. For more info or help, see https://hledger.org and the support page. Newcomers, experts, contributors, sponsors, feedback are welcome!

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Imports as first class functions
by julian getcontented.com.au 08 Dec '24

08 Dec '24

Further to the previous message about modules and imports, what would be *really* useful would be if importing was in some sense “just a function” in IO or some other Monad and therefore also if modules were represented as some Haskell data structure. That’d obviously make the top level ambient context of a module of Haskell into a sort of monadic action, so it’d be a bit weird, tho at the moment who’s to say what it is anyway? It’s certainly not something that’s first class to the language or able to be programmed as it stands. I suppose this is sounding a little like I’m interested in homoiconicity in some sense, and that’s probably not far from the truth. The main reason I would find this useful is similar to what Sylvain was saying about storing modules of code in databases. I have a system that produces “representations” as Text and then sometimes compiles it as Haskell source (and it’s meta-recursive in that there are many of these little pieces of executed code that then compile others’ outputs, etc)… and even if we don’t have programmatic control over actual compilation or which versions of libraries of code to include, having programmatic control over where the data for modules’ sources comes from would be fantastic. Given that importing is just some magic declaration at the moment that’s kind of outside the language’s programmable constructs, tho, I can’t see that happening without some major reworking, tho, really. Is there appetite for such a thing? One of the things a little strange about the programming industry is how quick we are to invent entirely new languages rather than attempt to modify existing ones and beat them into a new more flexible shape so we can shoehorn our new requirements into a more flexible frame. I realise it’s not always possible, but surely if we all got together and worked on it we could do it? Really, I probably don’t know enough about the internal workings of Haskell & GHC to know if this is crazy or partly reasonable, but crazy ideas are sometimes fantastic, so I’m asking anyway. It would be *glorious* if stack (or cabal, or whatever package manager we use) itself were programmable in the sense that it could be called from within Haskell itself using a typed API and data could drive its included packages, and its type could be a function whose range was IO ByteString, providing the compiled binary. I guess where I’m driving with all this is that it’d be amazing if more of the language and package system and build tools and dependencies were first class and/or have an API just like the GHC API exists because being able to manipulate these things from programs would be great and simplify a lot of currently complex stuff; the only way to do that at the moment is to leave Haskell’s type safety and deal with the textual interfaces in System.Process et al. (I’m actually using System.Process.Streaming, but that’s neither here nor there). I do have a further idea I’ve been pondering for a long while that’s even more crazy than these two, but I might leave that for later, if at all; it has to do with programmability of syntax or lack thereof. Essentially, my system is aiming at keeping everything (source, executables, results of all kinds) separated into small pieces, and results cached so that I don’t have to continually recompile and recompute things that have already been compiled and computed before. It has some of the same ideas as unison in the content hashing sense, tho not the caching at the AST level because Haskell doesn’t work like that, and I’m not interested in building a monolithic unison/smalltalk-style “image/database/world” that has to have everything imported into it — rather the other way around — to have little programs that use parsing, do one thing, and have a typed interface between each of them that glues them all together as and when needed. Apologies that it’s so hand-wavey. Maybe there’s a better place or way to discuss such ideas? If so, let me know. Thanks!

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10 PhD studentships in Nottingham
by Graham Hutton 03 Dec '24

03 Dec '24

Dear all, The School of Computer Science at the University of Nottingham in the UK is seeking applications for 10 fully-funded PhD studentships: https://tinyurl.com/ten-phds-2025 Applicants in the area of the Functional Programming Lab (tinyurl.com/fp-notts) are strongly encouraged! If you are interested in applying, please contact a potential supervisor as soon as possible; the application deadline is 6th April 2025: Thorsten Altenkirch - constructive logic, proof assistants, homotopy type theory, category theory, lambda calculus. Ulrik Buchholtz - homotopy type theory, synthetic homotopy theory, proof assistants, constructive mathematics, and related topics. Graham Hutton - not seeking a new student this year, but these notes on the process may be useful: tinyurl.com/phd-notes Nicolai Kraus - not seeking a student through this scheme, but has two other PhD positions available: tinyurl.com/kraus-phds Dan Marsden - category theory, logic, finite model theory, diagrammatic reasoning, foundations of computer science. Best wishes, The FP Lab University of Nottingham +-----------------------------------------------------------+ 10 Fully-Funded PhD Studentships School of Computer Science University of Nottingham, UK https://tinyurl.com/ten-phds-2025 Applications are invited from home and international students for up to 10 fully-funded PhD studentships offered by the School of Computer Science, starting on 1st October 2025. The topics for the studentships are open, but should relate to the interests of one of the School’s research groups: Cyber-Physical Health and Assistive Robotics; Computational Optimisation and Learning Lab; Computer Vision Lab; Cyber Security; Functional Programming; Intelligent Modelling and Analysis; Mixed Reality Lab; Lab for Uncertainty in Data and Decision Making; Visualisation and Computer Graphics; Responsible Digital Futures. The studentships are fully funded for 3.5 years and include a stipend of £19,237 per year and tuition fees. Applicants are normally expected to have a first-class Bachelor or Masters degree or international equivalent, in a related discipline. If you are interested in applying, please contact a potential supervisor as soon as possible, and at least two weeks prior to the closing date. If the supervisor wishes to support your application, they will direct you to make an official application through the MyNottingham system. Closing date for applications: Sunday 6th April 2025 +-----------------------------------------------------------+ 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 contact the sender and delete the email and attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. Email communications with the University of Nottingham may be monitored where permitted by law.

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GHC 9.8.4 is now available
by Ben Gamari 03 Dec '24

03 Dec '24

The GHC developers are happy to announce the availability of GHC 9.8.4. Binary distributions, source distributions, and documentation are available on the [release] page. This release is a small release fixing a few issues noted in 9.8.3, including: * Update the `filepath` submodule to avoid a misbehavior of `splitFileName` under Windows. * Update the `unix` submodule to fix a compilation issue on `musl` platforms * Fix a potential source of miscompilation when building large projects on 32-bit platforms * Fix unsound optimisation of `prompt#` uses A full accounting of changes can be found in the [release notes]. As some of the fixed issues do affect correctness users are encouraged to upgrade promptly. We would like to thank Microsoft Azure, GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket] if you see anything amiss. Happy compiling! - Ben [release]: https://www.haskell.org/ghc/download_ghc_9_8_4.html [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [release notes]: https://downloads.haskell.org/~ghc/9.8.4/docs/users_guide/9.8.4-notes.html

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Re: [Haskell-cafe] Files and Modules
by julian getcontented.com.au 03 Dec '24

03 Dec '24

Thanks. Understood about the Linker. I was thinking the linking could be some final phase that was separated out in such a way that would still be compatible with the file system (a HasLinker constraint? ;-) j/k). But to go back to what you were saying, if we had the ability to decouple modules from files it would mean I could set up a notion of dependency between the modules that I have stored in Texts in such a way that I wouldn’t need to repeat code between the Texts when I want to share code as I’m compiling chunks of it. At the moment I try hard to keep the set of common items shared between all the code I have because it makes it simpler to manage and keeps duplication low, and it also means the call to stack that I have only has to include a small set of packages and can be common between all the combined sets of code I have. On 2 Dec 2024, at 11:00 PM, haskell-cafe-request(a)haskell.org wrote: One compromise GHC could make would be abstract the notion of module from the Haskell source (multiple modules per file, no file involved at all), but ultimately as Brandon says, the file system has to get involved for the linker, so the concept of a module needs to remain compatible with the action of writing it as a file.

2 2

Files and Modules
by julian getcontented.com.au 02 Dec '24

02 Dec '24

In a recent project that compiles Haskell source from data (ie of type Text from the module Data.Text), it would be useful to be able to decouple the dependency between GHC’s notion of where modules are and the file system. This doesn’t seem to be programmatically controllable. How tenable is this? Would it be useful for anyone else to have compilation itself be more first class in the language? If I think about languages such as LISP/Racket/Clojure, there’s a certain flexibility there that Haskell lacks, but it’s not apparent why, other than historical reasons? Would this imply changing compiling and linking into a different Monad than IO? At the moment to compile some source that exists in Text, my system has to write a bunch of temp files including the Text that contains the main module, and then put other modules in directories named a certain way, run the compiler across them via some exec command to call GHC or stack externally, then read the resulting executable back off disk to store it in its final destination. It might be useful to be able to do this from within Haskell code directly, partly similarly to how the hint library works. Though, in this case it would almost certainly also require being able to have two versions of GHC loaded at once, which would also imply being able to simultaneously have multiple or different versions of libraries loaded at once, too, and possibly also just from data, ie not from disk. It feels like a massive, massive project at that point, though, like we’d be putting an entire dependency system into a first-class programmable context. I’m still interested in what folks think about these ideas, though, event though we this may never eventuate. Does it seem to anyone else like abstracting the library and module-access capabilities of compilation so that it’s polymorphic over where it gets its data from might be useful? Is this just ridiculous? Does this step into Backpack's territory? From memory, the Haskell report doesn’t specify that modules necessarily need to be tied to the file system, but I think GHC imposes one file per module and that it be one the FS. Julian

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[ANNOUNCE] GHC 9.12.1-rc1 is now available
by Zubin Duggal 29 Nov '24

29 Nov '24

The GHC developers are very pleased to announce the availability of the release candidate for GHC 9.12.1. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][]. We hope to have this release available via ghcup shortly. GHC 9.12 will bring a number of new features and improvements, including: * The new language extension [OrPatterns] allowing you to combine multiple pattern clauses into one. * The [MultilineStrings] language extension to allow you to more easily write strings spanning multiple lines in your source code. * Improvements to the OverloadedRecordDot extension, allowing the built-in `HasField` class to be used for records with fields of non lifted representations. * The [NamedDefaults] language extension has been introduced allowing you to define defaults for typeclasses other than `Num`. * More deterministic object code output, controlled by the `-fobject-determinism` flag, which improves determinism of builds a lot (though does not fully do so) at the cost of some compiler performance (1-2%). See #12935 for the details * GHC now accepts type syntax in expressions as part of [GHC Proposal #281]. * The WASM backend now has support for TemplateHaskell. * ... and many more A full accounting of changes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. We would like to thank GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. Cheers, Zubin [release notes]: https://downloads.haskell.org/ghc/9.12.1-rc1/docs/users_guide/9.12.1-notes.… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.1-rc1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [OrPatterns]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0522-o… [MultilineStrings]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0569-m… [GHC Proposal #281]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-v… [NamedDefaults]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-e…

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Suggestion for addition to base
by Ivan Perez 23 Nov '24

23 Nov '24

Hi, I have a suggestion of something to add to Control.Arrow. The email address listed here: https://hackage.haskell.org/package/base-4.20.0.1/docs/Control-Arrow.html is libraries(a)haskell.org, which bounces because I'm not subscribed to that mailing list. What's the right mechanism to submit my proposal? Thanks, Ivan

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Re: [Haskell-cafe] attpoarsec and recursive parsing
by Olaf Klinke 23 Nov '24

23 Nov '24

Hi Frederic, Essentially, the '|' character acts like a binary operator in parsing arithmetical expression trees. To that end, the most ergonomic module I know of is provided by parsec [1], which has a port [2] to attoparsec. You have to decide whether the '|' operator should be left- or right- associative. That question vanishes if you decide to re-design your data type as data MaskLocation = MaskLocation Text | MaskLocation'Tmpl Text | MaskLocation'Or (NonEmpty MaskLocation) and use the sepBy1 combinator. Also you should think about whether and how to escape the separator Char inside ordinary MaskLocation strings. Olaf [1] https://hackage.haskell.org/package/parsec-3.1.17.0/docs/Text-ParserCombina… [2] https://hackage.haskell.org/package/attoparsec-expr

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POPL 2025 Call for Participation - Early registration: 20 December
by Ningning Xie 20 Nov '24

20 Nov '24

POPL 2025 -- Call for Participation ** Early registration deadline: 20 December 2024 ** Come and join us for POPL 2025, in January, in Denver, Colorado, the United States. Register here: https://popl25.sigplan.org/attending/registration Location: Curtis Hotel Denver, 1405 Curtis Street, 80202, Denver, Colorado, United States Dates: - Main conference: Wed 22 - Fri 24 January - Workshops, tutorials, co-located events: Sun 19, Mon 20, Tue 21 and Sat 25 January Accepted papers: https://popl25.sigplan.org/track/POPL-2025-popl-research-papers Full details of the conference and co-located events: https://popl25.sigplan.org/ Sponsors: POPL is supported by generous sponsorship from: - Amazon - Jane Street - Google DeepMind - JetBrains - Microsoft - Epic - Google - Ahrefs The 52nd ACM SIGPLAN Symposium on Principles of Programming Languages (POPL 2025) will take place in January in Denver, Colorado, the United States. It's going to be an amazing conference - don't miss it - sign up now! https://popl25.sigplan.org/attending/registration

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Dependent Haskell vs. Explicit Dictionary Application
by Henning Thielemann 20 Nov '24

20 Nov '24

There was an effort to add explicit type class dictionary applications to GHC: https://arxiv.org/abs/1807.11267 Will the new features of Dependent Haskell eventually supersede this approach? The current features in GHC-9.12 do not seem to allow for explicit specification of type class dictionaries.

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[TFP 2025 3rd Call for Papers] 25th International Symposium on Trends in Functional Programming (Oxford, UK)
by Peter Achten 15 Nov '24

15 Nov '24

# TFP 2025 - 3rd Call for Papers (trendsfp.github.io) 26th International Symposium on Trends in Functional Programming 14-16 January 2025, Oxford, UK ## 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) Please observe that it is temporarily closed while we deal with pre-symposium full paper submissions, it will reopening on 2nd December. 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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[ANNOUNCE] GHC 9.12.1-alpha3 is now available
by Zubin Duggal 15 Nov '24

15 Nov '24

The GHC developers are very pleased to announce the availability of the third alpha release of GHC 9.12.1. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][]. We hope to have this release available via ghcup shortly. GHC 9.12 will bring a number of new features and improvements, including: * The new language extension [OrPatterns] allowing you to combine multiple pattern clauses into one. * The [MultilineStrings] language extension to allow you to more easily write strings spanning multiple lines in your source code. * Improvements to the OverloadedRecordDot extension, allowing the built-in `HasField` class to be used for records with fields of non lifted representations. * The [NamedDefaults] language extension has been introduced allowing you to define defaults for typeclasses other than `Num`. * More deterministic object code output, controlled by the `-fobject-determinism` flag, which improves determinism of builds a lot (though does not fully do so) at the cost of some compiler performance (1-2%). See #12935 for the details * GHC now accepts type syntax in expressions as part of [GHC Proposal #281]. * The WASM backend now has support for TemplateHaskell. * ... and many more A full accounting of changes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. We would like to thank GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. [release notes]: https://downloads.haskell.org/ghc/9.12.1-alpha3/docs/users_guide/9.12.1-not… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.1-alpha3 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [OrPatterns]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0522-o… [MultilineStrings]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0569-m… [GHC Proposal #281]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-v… [NamedDefaults]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-e… Cheers, Zubin

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[3 days to go!] Functional Conf 2025 - Call for Proposals closes 17 November
by John Sinclair 14 Nov '24

14 Nov '24

The Functional Conf 2025 Call for Proposals closes on Sunday. This is a golden opportunity to share your insights and innovative applications of Haskell with a vibrant community of like-minded individuals. Whether you have tackled a tricky problem using functional programming, developed a unique application, or have experiences that could enlighten your peers, we want to hear from you! We're open to all topics related to functional programming. Submit your proposal today and help shape the future of functional programming! https://confengine.com/conferences/functional-conf-2025/proposals Submission deadline: 17 November 2024 at 11:59pm IST Functional Conf is an online event running 24-25 January 2025. Learn more about the conference: https://functionalconf.com

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wiki.haskell.org appears to be down
by Markus Läll 08 Nov '24

08 Nov '24

Hi! Not sure on who to contact this about, but https://wiki.haskell.org/ appears to be mostly down. Mostly in the sense that for every page MediaWiki does seem to run, but fails to retrieve any content, and also no styling. Hope someone can forward this info in the right direction! -- Markus Läll

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Re: [Haskell-cafe] Derive ET from DN in calculus of constructions
by Olaf Klinke 06 Nov '24

06 Nov '24

The derivation of the double negation of ET is in line 243 of https://hub.darcs.net/olf/haskell_for_mathematicians/browse/haskell_for_log… Then use DN on that term, as Tom Smeding suggested. Olaf

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Problem with Haskellwiki - Backend not available
by Henk-Jan van Tuyl 05 Nov '24

05 Nov '24

L.S., I am having trouble with the Haskellwiki, the page https://wiki.haskell.org/Haskell displays the message: Error 503 Backend unavailable, connection timeout Backend unavailable, connection timeout Error 54113 The page https://www.haskell.org/ is correct. Can someone repair this? Regards, Henk-Jan van Tuyl

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[ANNOUNCE] GHC 9.12.1-alpha1 is now available
by Zubin Duggal 05 Nov '24

05 Nov '24

The GHC developers are very pleased to announce the availability of the first alpha release of GHC 9.12.1. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][]. We hope to have this release available via ghcup shortly. GHC 9.12 will bring a number of new features and improvements, including: * The new language extension [OrPatterns] allowing you to combine multiple pattern clauses into one. * The [MultilineStrings] language extension to allow you to more easily write strings spanning multiple lines in your source code. * Improvements to the OverloadedRecordDot extension, allowing the built-in `HasField` class to be used for records with fields of non lifted representations. * The [NamedDefaults] language extension has been introduced allowing you to define defaults for typeclasses other than `Num`. * More deterministic object code output, controlled by the `-fobject-determinism` flag, which improves determinism of builds a lot (though does not fully do so) at the cost of some compiler performance (1-2%). See #12935 for the details * GHC now accepts type syntax in expressions as part of [GHC Proposal #281]. * ... and many more A full accounting of changes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. We would like to thank GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. [release notes]: https://downloads.haskell.org/ghc/9.12.1-alpha1/docs/users_guide/9.12.1-not… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.1-alpha1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [OrPatterns]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0522-o… [MultilineStrings]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0569-m… [GHC Proposal #281]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-v… [NamedDefaults]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-e… Cheers, Zubin

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Derive ET from DN in calculus of constructions
by Dmitriy Matrosov 05 Nov '24

05 Nov '24

Hi. I've reading "Type theory and formal proof, an introduction" book and in chapter 7.4 authors say, that in constructive logic plus either excluded third law (ET) or double negation law (DN) we can derive the other. And then authors derive DN from ET in calculus of constructions. But they didn't say anything (yet?) about the vice versa: deriving ET from DN in calculus of constructions. I've tried to do this, but the best i can come up with is just case analysis: - assume, that 'a' is true, then 'a or not a' is also true (by 'or-intro' rule). - or if after assuming that 'a' is true we can derive bottom, then 'not a' is true (by 'not-intro' rule). Then using the 'or-intro' rule we again end up with 'a or (not a)' being true. - assume 'not a' and if we can derive bottom again, then 'not (not a)' is true. Then by using DN we again end up with 'a' being true. etc. I.e. I may reduce any (not.. (n times) .. not a) into either 'a' or 'not a' by using DN and function composition. Thus, i probable can derive ET from DN using induction, but i can't code neither induction, nor above case analysis in calculus of constructions. So, is it possible to derive ET from DN in calculus of constructions? If it is, i'd appreciate not a direct answer, but a hint on how to do this. And if it is not, well, probably, authors will explain this later in the book and I should just continue reading. Thanks.

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2nd Call for Contributions: BOB 2025 (Berlin, March 14 - Deadline Nov 15)
by Stefan Wehr 05 Nov '24

05 Nov '24

================================================================================ BOB Conference 2025 "What happens when we use what's best for a change?" https://bobkonf.de/2025/cfc.html Berlin, Mar 14 Call for Contributions Deadline: November 15, 2024 ================================================================================ You are actively engaged in advanced software engineering methods, solve ambitious problem with software and are open to cutting-edge innovation? Attend this conference, meet people that share your goals, and get to know the best software tools and technologies available today. We strive to offer a day full of new experiences and impressions that you can use to immediately improve your daily life as a software developer. If you share our vision and want to contribute, submit a proposal for a talk or tutorial! NOTE: The conference fee will be waived for presenters. Travel expenses will not be covered (for exceptions see "Speaker Grants"). Shepherding ----------- The program committee offers shepherding to all speakers. Shepherding provides speakers assistance with preparing their sessions. Specifically: - advice on structure and presentation - review of talk slides Speaker Grants -------------- BOB has Speaker Grants available to support speakers from groups under-represented in technology. We specifically seek women speakers, speakers of color, and speakers who are not able to attend the conference for financial reasons. Topics ------ We are looking for talks about best-of-breed software technology, e.g.: - functional programming - persistent data structures and databases - event-based modelling and architecture - "fancy types" (dependent types, gradual typing, linear types, ...) - formal methods for correctness and robustness - abstractions for concurrency and parallelism - metaprogramming - probabilistic programming - math and programming - controlled side effects - program synthesis - next-generation IDEs - effective abstractions for data analytics - … everything really that isn’t mainstream, but you think should be - … includeing rough ideas worth discussing. Presenters should provide the audience with information that is practically useful for software developers. Challenges ---------- Furthermore, we seek contributions on successful approaches for solving hard problems, for example: - bias in machine-learning systems - digital transformation in difficult settings - accessibiltity - systems with critical reliability requirements - ecologically sustainable software development We're especially interested in experience reports. Other topics are also relevant, e.g.: - introductory talks on technical background - overviews of a given field - demos and how-tos Requirements ------------ We accept proposals for presentations of 45 minutes (40 minutes talk + 5 minutes questions), as well as 90 minute tutorials for beginners. The language of presentation should be either English or German. Your proposal should include (in your presentation language of choice): - An abstract of max. 1500 characters. - A short bio/cv - Contact information (including at least email address) - A list of 3-5 concrete ideas of how your work can be applied in a developer's daily life - additional material (websites, blogs, slides, videos of past presentations, …) Organisation ------------ - Direct questions to konferenz at bobkonf dot de - Proposal deadline: November 15, 2024 - Notification: December 4, 2024 - Program: December 11, 2024 Submit here: https://pretalx.com/bob-2025/submit/ Program Committee ----------------- (more information here: https://bobkonf.de/2025/programmkomitee.html) - Matthias Fischmann, Wire - Matthias Neubauer, SICK AG - Nicole Rauch, Softwareentwicklung und Entwicklungscoaching - Michael Sperber, Active Group - Stefan Wehr, Hochschule Offenburg Scientific Advisory Board - Annette Bieniusa, TU Kaiserslautern - Torsten Grust, Uni Tübingen - Peter Thiemann, Uni Freiburg

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ICFP 2025: Call for Papers
by ICFP Publicity 04 Nov '24

04 Nov '24

PACMPL Volume 7, Issue ICFP 2025 Call for Papers Accepted papers to be invited for presentation at The 30th ACM SIGPLAN International Conference on Functional Programming October 12-18, 2025 Singapore https://icfp25.sigplan.org/ ### Important Dates and Deadlines Paper Submissions: February 27, 2025 Author Response: April 28 - May 1, 2025 Notifications of Acceptance: May 23, 2025 All deadlines are Anywhere on Earth (AoE). Conference dates: October 12-18, 2025 ### New This Year For the first time, ICFP will be co-located with SPLASH! https://conf.researchr.org/home/icfp-splash-2025 Note that the conference will be held in October this year, instead of September. The conference dates are October 12-18, 2025. ### Scope PACMPL issue ICFP 2025 seeks original papers on the art and science of functional programming. Submissions are invited on all topics from principles to practice, from foundations to features, and from abstraction to application. The scope includes all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages with objects, concurrency, or parallelism. Topics of interest include (but are not limited to): * Language Design: concurrency, parallelism, and distribution; modularity; components and composition; meta-programming; macros; pattern matching; type systems; type inference; dependent types; effect types; gradual types; refinement types; session types; interoperability; domain-specific languages; imperative programming; object-oriented programming; logic programming; probabilistic programming; reactive programming; generic programming; bidirectional programming. * Implementation: abstract machines; virtual machines; interpretation; compilation; compile-time and run-time optimisation; garbage collection and memory management; runtime systems; multi-threading; exploiting parallel hardware; interfaces to foreign functions, services, components, or low-level machine resources. * Software-Development Techniques: algorithms and data structures; design patterns; specification; verification; validation; proof assistants; debugging; testing; tracing; profiling; build systems; program synthesis. * Foundations: formal semantics; lambda calculus; program equivalence; rewriting; type theory; logic; category theory; computational effects; continuations; control; state; names and binding; program verification. * Analysis and Transformation: control flow; data flow; abstract interpretation; partial evaluation; program calculation. * Applications: symbolic computing; formal-methods tools; artificial intelligence; systems programming; distributed systems and web programming; hardware design; databases; scientific and numerical computing; graphical user interfaces; graphics and multimedia; GPU programming; scripting; system administration; security. * Education: teaching introductory programming; mathematical proof; algebra. Submissions will be evaluated according to their relevance, correctness, significance, originality, and clarity. Each submission should explain its contributions in both general and technical terms, clearly identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. The technical content should be accessible to a broad audience. PACMPL issue ICFP 2025 also welcomes submissions in two separate categories — Functional Pearls and Experience Reports — that must be marked as such when submitted and that need not report original research results. Detailed guidelines on both categories are given at the end of this call. In an effort to achieve a balanced, diverse program, each author may be listed as a (co)author on a maximum of four submissions. Authors who require financial support to attend the conference can apply for PAC funding (http://www.sigplan.org/PAC/) The General Chair and PC Chair may not submit papers. PC members (other than the PC Chair) may submit papers. Please contact the Program Chair if you have questions or are concerned about the appropriateness of a topic. ### Full Double-Blind Reviewing Process ICFP 2025 will use a full double-blind reviewing process (similar to the one used for ICFP 2024 but different from the lightweight double-blind process used in previous years). This means that identities of authors will not be made visible to reviewers until after conditional-acceptance decisions have been made, and then only for the conditionally-accepted papers. The use of full double-blind reviewing has several consequences for authors. *Submissions*: Authors must omit their names and institutions from their paper submissions. In addition, references to authors’ own prior work should be in the third person (e.g., not "We build on our previous work ..." but rather "We build on the work of ..."). *Supplementary material*: Authors must fully anonymize any supplementary material (see below). Links to supplementary material on external websites are not permitted. *Author response*: In responding to reviews, authors should not say anything that reveals their identity, since author identities will not be revealed to reviewers at that stage of the reviewing process. *Dissemination of work under submission*: Authors are welcome to disseminate their ideas and post draft versions of their paper(s) on their personal website, institutional repository, or arXiv (reviewers will be asked to turn off arXiv notifications during the review period). But authors should not take steps that would almost certainly reveal their identities to members of the Program Committee, e.g., directly contacting PC members or publicizing the work on widely-visible social media or major mailing lists used by the community. The purpose of the above restrictions is to help the Program Committee and external reviewers come to a judgment about the paper without bias, not to make it impossible for them to discover the authors’ identities if they were to try. In particular, nothing should be done in the name of anonymity that weakens the quality of the submission. However, there are occasionally cases where adhering to the above restrictions is truly difficult or impossible for one reason or another. In such cases, the authors should contact the Program Chair to discuss the situation and how to handle it. The FAQ on Double-Blind Reviewing ( https://popl24.sigplan.org/track/POPL-2024-popl-research-papers#FAQ-on-Doub… ) addresses many common scenarios and answers many common questions about this topic. But there remain many grey areas and trade-offs. If you have any doubts about how to interpret the double-blind rules or you encounter a complex case that is not clearly covered by the FAQ, please contact the Program Chair for guidance. ### Preparation of submissions *Deadline*: The deadline for submissions is Thursday, 27 February, 2025, Anywhere on Earth (https://www.timeanddate.com/time/zones/aoe) This deadline will be strictly enforced. *Formatting*: Submissions must be in PDF format, printable in black and white on US Letter sized paper and interpretable by common PDF tools. All submissions must adhere to the "ACM Small" template that is available (in both LaTeX and Word formats) from https://www.acm.org/publications/authors/submissions. Please download the latest version of the ACM style from https://www.acm.org/publications/authors/submissions, since the citation format has recently been changed. See also PACMPL’s Information and Guidelines for Authors at https://pacmpl.acm.org/authors.cfm. There is a limit of 25 pages for a full paper or Functional Pearl and 12 pages for an Experience Report; in either case, the bibliography and an optional clearly marked appendix will not be counted against these limits. Submissions that exceed the page limits or, for other reasons, do not meet the requirements for formatting, will be summarily rejected. *Submission*: Submissions will be accepted at https://icfp25.hotcrp.com/ Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. *Author Response Period*: Authors will have a 96-hour period, starting at 00:00 (midnight) AOE on Monday, 28 April, 2025, to read reviews and respond to them. *Appendix and Supplementary Material*: Authors have the option to include a clearly marked appendix and/or to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at such an appendix or supplementary material. Supplementary material may be uploaded as a separate PDF document or tarball. Any supplementary material must be uploaded at submission time, not by providing a URL in the paper that points to an external repository. All supplementary material must be anonymised. *Authorship Policies*: All submissions are expected to comply with the ACM Policies for Authorship that are detailed at https://www.acm.org/publications/authors/information-for-authors. *Republication Policies*: Each submission must adhere to SIGPLAN’s republication policy, as explained on the web at http://www.sigplan.org/Resources/Policies/Republication. ### Review Process This section outlines the two-stage process with double-blind reviewing that will be used to select papers for PACMPL issue ICFP 2025. Like last year, ICFP 2025 will adapt a full double-blind reviewing process. More information see below. ICFP 2025 will have an Associate Chair who will help the PC Chair monitor reviews, solicit external expert reviews for submissions when there is not enough expertise on the committee, and facilitate reviewer discussions. ICFP 2025 will employ a two-stage review process. The first stage in the review process will assess submitted papers using the criteria stated above and will allow for feedback and input on initial reviews through the author response period mentioned previously. As a result of the review process, a set of papers will be conditionally accepted and all other papers will be rejected. Authors will be notified of these decisions on 23 May, 2025. Authors of conditionally accepted papers will be provided with committee reviews along with a set of mandatory revisions. By 12 June, 2025, the authors should provide a second revised submission. The second and final reviewing phase assesses whether the mandatory revisions have been adequately addressed by the authors and thereby determines the final accept/reject status of the paper. The intent and expectation is that the mandatory revisions can feasibly be addressed within three weeks. The second submission should clearly identify how the mandatory revisions were addressed. To that end, the second submission must be accompanied by a cover letter mapping each mandatory revision request to specific parts of the paper. The cover letter will facilitate a quick second review, allowing for confirmation of final acceptance within two weeks. Conversely, the absence of a cover letter will be grounds for the paper’s rejection. ### Information for Authors of Accepted Papers * As a condition of acceptance, final versions of all papers must adhere to the ACM Small format. The page limit for the final versions of papers will be increased by two pages to help authors respond to reviewer comments and mandatory revisions: 27 pages plus bibliography for a regular paper or Functional Pearl, 14 pages plus bibliography for an Experience Report. * Authors of accepted submissions will be required to agree to one of the three ACM licensing options, one of which is Creative Commons CC-BY publication; this is the option recommended by the PACMPL editorial board. A reasoned argument in favour of this option can be found in the article Why CC-BY? published by OASPA, the Open Access Scholarly Publishers Association. The other options are copyright transfer to ACM or retaining copyright but granting ACM exclusive publication rights. * PACMPL is a Gold Open Access journal, and authors are encouraged to publish their work under a CC-BY license. Gold Open Access guarantees permanent free online access to the definitive version in the ACM Digital Library, and the recommended CC-BY option also allows anyone to copy and distribute the work with attribution. Gold Open Access has been made possible by generous funding through ACM SIGPLAN, which will cover all open access costs in the event authors cannot. Authors who can cover the costs may do so by paying an Article Processing Charge (APC). PACMPL, SIGPLAN, and ACM Headquarters are committed to exploring routes to making Gold Open Access publication both affordable and sustainable. * ACM Author-Izer is a unique service that enables ACM authors to generate and post links on either their home page or institutional repository for visitors to download the definitive version of their articles from the ACM Digital Library at no charge. Downloads through Author-Izer links are captured in official ACM statistics, improving the accuracy of usage and impact measurements. Consistently linking to the definitive version of an ACM article should reduce user confusion over article versioning. After an article has been published and assigned to the appropriate ACM Author Profile pages, authors should visit http://www.acm.org/publications/acm-author-izer-service to learn how to create links for free downloads from the ACM DL. * The official publication date is the date the papers are made available in the ACM Digital Library. This date may be up to two weeks prior to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work. * Authors of each accepted submission are invited to attend and be available for the presentation of that paper at the conference. The schedule for presentations will be determined and shared with authors after the full program has been selected. *ORCID*: ORCID provides a persistent digital identifier (an ORCID iD) that you own and control, and that distinguishes you from every other researcher: https://orcid.org/. ACM now require an ORCID iD for every author of a paper, not just the corresponding author. So, the author who is filling out the permission form should make sure they have the ORCID iDs for all of their coauthors before filling out the form. Any authors who do not yet have an ORCID iD can go to https://orcid.org/register to have one assigned. ### Artifact Evaluation Authors of papers that are conditionally accepted in the first phase of the review process will be encouraged (but not required) to submit supporting materials for Artifact Evaluation. These items will then be reviewed by an Artifact Evaluation Committee, separate from the paper Review Committee, whose task is to assess how the artifacts support the work described in the associated paper. Papers that go through the Artifact Evaluation process successfully will receive a seal of approval printed on the papers themselves. Authors of accepted papers will be encouraged to make the supporting materials publicly available upon publication of the papers, for example, by including them as "source materials" in the ACM Digital Library. An additional seal will mark papers whose artifacts are made available, as outlined in the ACM guidelines for artifact badging. Participation in Artifact Evaluation is voluntary and will not influence the final decision regarding paper acceptance. ### Special categories of papers In addition to research papers, PACMPL issue ICFP solicits two kinds of papers that do not require original research contributions: Functional Pearls, which are full papers, and Experience Reports, which are limited to half the length of a full paper. Authors submitting such papers should consider the following guidelines. ### Functional Pearls A Functional Pearl is an elegant essay about something related to functional programming. Examples include, but are not limited to: * a new and thought-provoking way of looking at an old idea * an instructive example of program calculation or proof * a nifty presentation of an old or new data structure * an interesting application of functional programming techniques * a novel use or exposition of functional programming in the classroom While pearls often demonstrate an idea through the development of a short program, there is no requirement or expectation that they do so. Thus, they encompass the notions of theoretical and educational pearls. Functional Pearls are valued as highly and judged as rigorously as ordinary papers, but using somewhat different criteria. In particular, a pearl is not required to report original research, but, it should be concise, instructive, and entertaining. A pearl is likely to be rejected if its readers get bored, if the material gets too complicated, if too much-specialised knowledge is needed, or if the writing is inelegant. The key to writing a good pearl is polishing. A submission that is intended to be treated as a pearl must be marked as such on the submission web page and should contain the words "Functional Pearl" somewhere in its title or subtitle. These steps will alert reviewers to use the appropriate evaluation criteria. Pearls will be combined with ordinary papers, however, for the purpose of computing the conference’s acceptance rate. ### Experience Reports The purpose of an Experience Report is to describe the experience of using functional programming in practice, whether in industrial application, tool development, programming education, or any other area. Possible topics for an Experience Report include, but are not limited to: * insights gained from real-world projects using functional programming * comparison of functional programming with conventional programming in the context of an industrial project or a university curriculum * project-management, business, or legal issues encountered when using functional programming in a real-world project * curricular issues encountered when using functional programming in education * real-world constraints that created special challenges for an implementation of a functional language or for functional programming in general An Experience Report is distinguished from a normal PACMPL issue ICFP paper by its title, by its length, and by the criteria used to evaluate it. * Both in the papers and in any citations, the title of each accepted Experience Report must end with the words "(Experience Report)" in parentheses. The acceptance rate for Experience Reports will be computed and reported separately from the rate for ordinary papers. * Experience Report submissions can be at most 12 pages long, excluding bibliography. * Each accepted Experience Report will be presented at the conference, but depending on the number of Experience Reports and regular papers accepted, authors of Experience Reports may be asked to give shorter talks. * Because the purpose of Experience Reports is to enable our community to understand the application of functional programming, an acceptable Experience Report need not add to the body of knowledge of the functional-programming community by presenting novel results or conclusions. It is sufficient if the report describes an illuminating experience with functional programming, or provides evidence for a clear thesis about the use of functional programming. The experience or thesis must be relevant to ICFP, but it need not be novel. The review committee will accept or reject Experience Reports based on whether they judge the paper to illuminate some aspect of the use of functional programming. Anecdotal evidence will be acceptable provided it is well-argued and the author explains what efforts were made to gather as much evidence as possible. Typically, papers that show how functional programming was used are more convincing than papers that say only that functional programming was used. It can be especially effective to present comparisons of the situations before and after the experience described in the paper, but other kinds of evidence would also make sense, depending on context. Experience drawn from a single person’s experience may be sufficient, but more weight will be given to evidence drawn from the experience of groups of people. An Experience Report should be short and to the point. For an industrial project, it should make a claim about how well functional programming worked and why; for a pedagogy paper, it might make a claim about the suitability of a particular teaching style or educational exercise. Either way, it should produce evidence to substantiate the claim. If functional programming worked in this case in the same ways it has worked for others, the paper need only summarise the results — the main part of the paper should discuss how well it worked and in what context. Most readers will not want to know all the details of the experience and its implementation, but the paper should characterise it and its context well enough so that readers can judge to what degree this experience is relevant to their own circumstances. The paper should take care to highlight any unusual aspects; specifics about the experience are more valuable than generalities about functional programming. If the paper not only describes experience but also presents new technical results, or if the experience refutes cherished beliefs of the functional-programming community, it may be better to submit it as a full paper, which will be judged by the usual criteria of novelty, originality, and relevance. The Program Chair will be happy to advise on any concerns about which category to submit to. ### About PACMPL Proceedings of the ACM on Programming Languages (PACMPL https://pacmpl.acm.org/) is a Gold Open Access journal publishing research on all aspects of programming languages, from design to implementation and from mathematical formalisms to empirical studies. Each issue of the journal is devoted to a particular subject area within programming languages and will be announced through publicised Calls for Papers, like this one. ### ICFP Organizers General Chair: Ilya Sergey (NUS) Program Chair: Dominique Devriese (KU Leuven) Associate Program Chair: Peter Thiemann (University of Freiburg) Workshops Co-Chairs: Ben Greenman (University of Utah) Chandrakana Nandi (Certora) Artifact Evaluation Co-Chairs: Benoît Montagu (INRIA) Lionel Parreaux (HKUST) Industrial Relations Chair: Daniel Winograd-Cort (Nectry Inc.) Student Volunteer Chair: Joe Watt (Institute for Infocomm Research, A*STAR) SRC Co-Chair: Kuen-Bang Hou (Favonia) (University of Minnesota) Publicity Chair: Sam Westrick (NYU) Diversity Co-Chairs: Alejandro Russo (Chalmers, DPella) KC Sivaramakrishnan (Tarides, IIT Madras) Web Chair: Jules Jacobs (Cornell) Doctoral Symposium Chair: Conrad Watt (Nanyang Technological University) Programming Contest Organizer: Liam O'Connor (Australian National University) SIGPLAN Conference Manager: Neringa Young

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PhD Scholarship at St Andrews
by Christopher Brown 04 Nov '24

04 Nov '24

We have a fully funded PhD scholarship available at the School of Computer Science at the University of St Andrews on "Dependent Types and Parallel Programming". Any potential candidates are advised to contact Dr Chris Brown (cmb21(a)st-andrews.ac.uk<mailto:cmb21@st-andrews.ac.uk>) for more information. Full details of the scholarship, the topic, and how to apply are here: https://blogs.cs.st-andrews.ac.uk/csblog/2024/10/24/fully-funded-phd-schola… The deadline for applications is the 1st March 2025, with a September start date (although there is room for some flexibility due to circumstances). International applications are welcome. We especially encourage female applicants and underrepresented minorities to apply. The School of Computer Science was awarded the Athena SWAN Silver award for its sustained progression in advancing equality and representation, and we welcome applications from those suitably qualified from all genders, all races, ethnicities and nationalities, LGBT+, all or no religion, all social class backgrounds, and all family structures to apply for our postgraduate research programmes.

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Journal of Functional Programming - Call for PhD Abstracts
by Graham Hutton 04 Nov '24

04 Nov '24

Dear all, If you or one of your students recently completed a PhD (or Habilitation) in the area of functional programming, please submit the dissertation abstract for publication in JFP: simple process, no refereeing, open access, 200+ published to date, deadline 31st May 2024. Please share! Best wishes, Graham Hutton ============================================================ CALL FOR PHD ABSTRACTS Journal of Functional Programming Deadline: 31st May 2024 http://tinyurl.com/jfp-phd-abstracts ============================================================ PREAMBLE: Many students complete PhDs in functional programming each year. As a service to the community, twice per year the Journal of Functional Programming publishes the abstracts from PhD dissertations completed during the previous year. The abstracts are made freely available on the JFP website, i.e. not behind any paywall. They do not require any transfer of copyright, merely a license from the author. A dissertation is eligible for inclusion if parts of it have or could have appeared in JFP, that is, if it is in the general area of functional programming. The abstracts are not reviewed. Please submit dissertation abstracts according to the instructions below. We welcome submissions from both the student and the advisor/supervisor although we encourage them to coordinate. Habilitation dissertations are also eligible for inclusion. ============================================================ SUBMISSION: Please submit the following information to Graham Hutton <graham.hutton(a)nottingham.ac.uk> by 31st May 2024. o Dissertation title: (including any subtitle) o Student: (full name) o Awarding institution: (full name and country) o Date of award: (month and year; depending on the institution, this may be the date of the viva, corrections being approved, graduation ceremony, or otherwise) o Advisor/supervisor: (full names) o Dissertation URL: (please provide a permanently accessible link to the dissertation if you have one, such as to an institutional repository or other public archive; links to personal web pages should be considered a last resort) o Dissertation abstract: (plain text, maximum 350 words; you may use \emph{...} for emphasis, but we prefer no other markup or formatting; if your original abstract exceeds the word limit, please submit an abridged version within the limit) Please do not submit a copy of the dissertation itself, as this is not required. JFP reserves the right to decline to publish abstracts that are not deemed appropriate. ============================================================ PHD ABSTRACT EDITOR: Graham Hutton School of Computer Science University of Nottingham Nottingham NG8 1BB United Kingdom ============================================================ 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 contact the sender and delete the email and attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. Email communications with the University of Nottingham may be monitored where permitted by law.

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Polymorphic equality in LiquidHaskell
by Henning Thielemann 24 Oct '24

24 Oct '24

I want to assert statically assert equality of polymorphic parameters using LiquidHaskell. See for instance the following simplified Array type containing an array shape and for demonstration purposes only a single element: data Array sh a = Array {shape :: sh, element :: a} {-@ lift2 :: (Eq sh) => (a -> b -> c) -> arrA : Array sh a -> {arrB : Array sh b | shape arrA == shape arrB} -> Array sh c @-} lift2 :: (Eq sh) => (a -> b -> c) -> Array sh a -> Array sh b -> Array sh c lift2 f (Array sha a) (Array shb b) = if sha == shb then Array sha $ f a b else error "shapes mismatch" Running liquidhaskell yields Illegal type specification ... Sort Error in Refinement: {arrB : (Example.Equality.Array sh##a31s b##a31u) | Example.Equality.shape arrA == Example.Equality.shape arrB} Unbound symbol Example.Equality.shape I think the Haskell function (==) is not automatically lifted to LiquidHaskell's logic language. Is there another way to assert a kind of equality in LiquidHaskell?

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