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TyDe 2025 - Final Call for Papers
by Andras Kovacs 02 Jun '25

02 Jun '25

========================================================================= The Tenth International Workshop on TYPE-DRIVEN DEVELOPMENT Call for papers and extended abstracts Singapore, 12 October 2025 https://icfp25.sigplan.org/home/tyde-2025 ========================================================================= The Workshop on Type-Driven Development (TyDe) aims to show how static type information may be used effectively in the development of computer programs. Co-located with ICFP and SPLASH, this workshop brings together leading researchers and practitioners who are using or exploring types as a means of program development. We welcome all contributions, both theoretical and practical, on a range of topics including: * dependently typed programming; * generic programming; * design and implementation of programming languages, exploiting types in novel ways; * exploiting typed data, data dependent data, or type providers; * static and dynamic analyses of typed programs; * tools, IDEs, or testing tools exploiting type information; * pearls, being elegant, instructive examples of types used in the derivation, calculation, or construction of programs. ### Important dates ### * Mon 9 Jun 2025 (AoE): Submission deadline for papers and extended abstracts * Wed 16 Jul 2025: Notification of acceptance * Wed 30 Jul 2025: Submission of camera-ready papers to ACM * Sun 12 Oct 2025: Workshop ### Proceedings and Copyright ### We will have formal proceedings for full-length papers, published by the ACM. Accepted papers will be included in the ACM Digital Library. Authors must grant ACM publication rights upon acceptance, but may retain copyright if they wish. Authors are encouraged to publish auxiliary material with their paper (source code, test data, and so forth). The proceedings will be freely available for download from the ACM Digital Library from one week before the start of the conference until two weeks after the conference. 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. ### Submission Details ### Submissions should fall into one of two categories: * regular research papers (12 pages); * extended abstracts (3 pages). The bibliography will not be counted against the page limits for either category. Regular research papers are expected to present novel and interesting research results, and will be included in the formal proceedings. Extended abstracts should report work in progress that the authors would like to present at the workshop. Extended abstracts will be distributed to workshop attendees but will not be published in the formal proceedings. We welcome submissions from PC members (with the exception of the two co-chairs), but these submissions will be held to a higher standard. Submission is handled through HotCRP: > https://tyde25.hotcrp.com All submissions should be in portable document format (PDF) and formatted using the ACM SIGPLAN style guidelines: > https://www.sigplan.org/Resources/Author/ Note that submissions should use the new ‘acmart’ format and the two-column ‘sigplan’ subformat (not to be confused with the one-column ‘acmsmall’ subformat). Extended abstracts must be submitted with the label ‘Extended Abstract’ clearly in the title. ### Presentations ### We expect that each accepted submission is presented at the workshop. Presentations are around 20 minutes plus questions. Remote presentation is possible. ### Participant Support ### Student attendees with accepted papers can apply for a SIGPLAN PAC grant to help cover participation-related expenses. PAC also offers other support, such as for child-care expenses during the meeting or for accommodations for members with physical disabilities. For details on the PAC program, see its web page: > https://www.sigplan.org/PAC/ ### Workshop Organization ### Organizing Committee: - András Kovács (University of Gothenburg and Chalmers University of Technology) - Yuting Wang (Shanghai Jiao Tong University, China) Program Committee: - Nathan Corbyn (University of Oxford, United Kingdom) - Stephen Dolan (Jane Street, United Kingdom) - Paul Downen (University of Massachusetts at Lowell, United States) - Brandon Hewer (University of Nottingham, United Kingdom) - Hongwei Xi (Boston University, United States) - Wen Kokke (University of Edinburgh, United Kingdom) - Yao Li (Portland State University, United States) - Hidehiko Masuhara (Institute of Science Tokyo, Japan) - Stefan Monnier (Université de Montréal, Canada) - Steven Ramsay (University of Bristol, United Kingdom) - Di Wang (Peking University, China) - Zhixuan Yang (Imperial College London, United Kingdom)

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Haskell Symposium 2025 Call for Papers (deadline June 9 AOE)
by Ningning Xie 29 May '25

29 May '25

======================================================================== Haskell Symposium 2025 Call for Papers Thu 16 - Fri 17 Oct 2025, Singapore https://conf.researchr.org/home/icfp-splash-2025/haskellsymp-2025 ======================================================================== The ACM SIGPLAN Haskell Symposium 2025 will be co-located with the 2025 International Conference on Functional Programming (ICFP) and the 2025 International Conference on Systems, Programming, Languages and Applications: Software for Humanity (SPLASH). The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. Submission deadline: 9 June 2025 (Mon) Notification: 17 July 2025 (Thu) Deadlines are valid anywhere on Earth. Papers should be submitted through HotCRP at: https://haskell25.hotcrp.com/ Topics of interest include: * Language design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, such as formal semantics of the present language or future extensions, type systems, effects, metatheory, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management, as well as foreign function and component interfaces; * Libraries, that demonstrate new ideas or techniques for functional programming in Haskell; * Tools, such as profilers, tracers, debuggers, preprocessors, and testing tools; * Applications, to scientific and symbolic computing, databases, multimedia, telecommunication, the web, and so forth; * Functional Pearls, being elegant and instructive programming examples; * Experience Reports, to document general practice and experience in education, industry, or other contexts; * Tutorials, to document how to use a particular language feature, programming technique, tool or library within the Haskell ecosystem; * System Demonstrations, based on running software rather than novel research results. Keynote Speakers ================= * Richard A. Eisenberg * Simon Peyton Jones Program Committee ================= Andreas Abel Gothenburg University Patrick Bahr IT University of Copenhagen Matthew Fluet Rochester Institute of Technology Adam Gundry Well-Typed LLP Xuejing Huang IRIF Hideya Iwasaki Meiji University Patricia Johann Appalachian State University Hsiang-Shang 'Josh' Ko Institute of Information Science, Academia Sinica András Kovács University of Gothenburg and Chalmers University of Technology Andres Löh Well-Typed LLP J. Garrett Morris (co-chair) University of Iowa Liam O'Connor Australian National University Maciej Piróg University of Wrocław Arnaud Spiwack Tweag Meng Wang University of Bristol Li-yao Xia Inria Ningning Xie (co-chair) University of Toronto Gergő Érdi Standard Chartered Bank

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Best way to implement "scoped exceptions"?
by Tom Ellis 27 May '25

27 May '25

I'd like to implement "scoped exceptions"[1], that is, a combinator of type withScopedException :: ((forall a. e -> IO a) -> IO r) -> IO (Either e r) so I can use exceptions in a convenient way, without having to set up fragile "action at a distance" based on the type of the thing I'm throwing and catching, for example: scopedExceptionExample :: IO (Either String (Either Int Void)) scopedExceptionExample = do withScopedException $ \throw1 -> withScopedException $ \throw2 -> if (1 :: Int) < 0 then throw1 "Hello" else throw2 1234 -- ghci> scopedExceptionExample -- Right (Left 1234) Here's a hacky way of doing it, based on tagging each exception with a unique value, and then filtering when handling: data MyException where MyException :: e -> Data.Unique.Unique -> MyException instance Show MyException where show _ = "<MyException>" instance Exception MyException withScopedException :: ((forall a. e -> IO a) -> IO r) -> IO (Either e r) wiathScopedException f = do fresh <- Data.Unique.newUnique flip tryJust (f (\e -> throwIO (MyException e fresh))) $ \case MyException e tag -> -- unsafeCoerce is very unpleasant if tag == fresh then Just (unsafeCoerce e) else Nothing This is the approach taken by the effectful library[2]. But is there a better way? Can I persuade GHC's RTS to work like this directly? Tom [1] I don't know if these already have a name [2] https://hackage.haskell.org/package/effectful-core-2.2.1.0/docs/src/Effectf…

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[ANN] Copilot 4.4
by Ivan Perez 25 May '25

25 May '25

Hi everyone!! We are really excited to announce Copilot 4.4 [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 programming language and runtime framework for NASA's Core Flight System, Robot Operating System (ROS2), FPrime (the software framework used in the Mars Helicopter). Ogma now supports producing flight and robotics applications directly in Copilot, not just for monitoring, but for implementing the logic of the applications themselves. This release introduces several updates, bug fixes and improvements to Copilot: - The Kind2 backend is now able to distinguish between existentially and universally quantified properties. - The fields of the existential record type Copilot.Core.Type.UType have now been removed. - The build status icon in the README has now been corrected to show the current build status. The new implementation is compatible with versions of GHC from 8.6 to 9.12. This release has been made possible thanks to key submissions from Ryan Scott (Galois) and Kyle Beechly, both recurrent contributors to Copilot. We are grateful to them for their contributions, and for making Copilot better every day. For details on this release, see [1]. As always, we're releasing exactly 2 months since the last release. Our next release is scheduled for July 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 using Copilot for full data processing applications (e.g, system control, arduinos, rovers, drones), merging stable features (i.e., visualizer, Bluespec backend, verifier) into the mainline, improving usability, performance, and stability, increasing 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/v4.4 [2] https://hackage.haskell.org/package/copilot [3] https://github.com/nasa/ogma [4] https://github.com/Copilot-Language/copilot

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2nd CfP: Functional Software Architecture (FUNARCH, Deadline June 16)
by Michael Sperber 18 May '25

18 May '25

====================================================================== *** FUNARCH 2025 -- CALL FOR PAPERS *** Third ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large 17th October 2025, Singapore Co-located with ICFP 2025 https://functional-architecture.org/events/funarch-2025/ ====================================================================== TIMELINE: Paper submission 16th June 2025 Author notification 21st July 2025 Camera ready copy 25th August 2025 Workshop 17th October 2025 BACKGROUND: "Functional Software Architecture" refers to methods of construction and structure of large and long-lived software projects that are implemented in functional languages and released to real users, typically in industry. The goals for the workshop are: - To assemble a community interested in software architecture techniques and technologies specific to functional programming; - To identify, categorize, and document topics relevant to the field of functional software architecture; - To connect the functional programming community to the software architecture community to cross-pollinate between the two. The workshop follows on from the Functional Software Architecture open space that was held at ICFP 2022 in Slovenia. SCOPE: The workshop seeks submissions in a range of categories: - You're a member of the FP community and have thought about how to support programming in the large, for example by framing functional ideas in architectural terms or vice verse, comparing different languages in terms of their architectural capabilities, clarifying architectural roles played by formal methods, proof assistants and DSLs, or observing how functional concepts are used in other language and architecture communities. Great, submit a research paper! - You're a member of the architecture community, and have thought about how your discipline might help functional programmers, for example by applying domain-driven design, implementing hexagonal architecture, or designing self-contained systems. Excellent, submit a research paper! - You've worked on a large project using functional programming, and it's worked out well, or terribly, or a mix of both; bonus points for deriving architectural principles from your experience. Wonderful, submit an experience report! - You know a neat architectural idiom or pattern that may be useful to others developing large functional software systems. Fabulous, submit an architectural pearl! - You have something that doesn't fit the above categories, but that still relates to functional software architecture, such as something that can be written up, or that could be part of the workshop format like a panel debate or a fishbowl. Superb, submit to the open category! Research papers should explain their research contributions in both general and technical terms, identifying what has been accomplished, explaining why it is significant, and relating it to previous work, and to other languages where appropriate. Experience reports and architectural pearls need not necessarily report original research results. The key criterion for such papers is that they make a contribution from which others can benefit. It is not enough simply to describe a large software system, or to present ideas that are specific to a particular system. Open category submissions that are not intended for publication are not required to follow the formatting guidelines, and can submit in PDF, word or plain text format as preferred. Not knowing what kinds of submissions we will receive, we cannot be specific as to how they will be evaluated. However, submissions that seem likely to stimulate discussion around practices in functional architecture are encouraged. If you are unsure whether your contribution is suitable, or if you need any kind of help with your submission, please email the program chairs (Jeff (jmy6342(a)gmail.com) and Christine (christine.rizkallah(a)unimelb.edu.au)) Papers must be submitted by 16th June 2025 using the hotcrp submission page (https://funarch25.hotcrp.com/) Formatting: submissions intended for publication must be in PDF format and follow the ACM SIGPLAN style guidelines, using the acmart format and the sigplan sub-format. Please use the review option when submitting, as this enables line numbers for easy reference in reviews. For further details, see SIGPLAN's author information: http://www.sigplan.org/Resources/Author/#acmart-format If your submission is not a research paper, please mark this using a subtitle (Experience Report, Architectural Pearl, Open Category). Length: submissions must adhere to the limits specified below. However, there is no requirement or expectation that all pages are used, and authors are encouraged to strive for brevity. Research papers 5 to 12+ pages Architectural pearls 5 to 12 pages Experience reports 3 to 6 pages Open category 1 to 6 pages Publication: The proceedings of FUNARCH 2024 will be published in the ACM Digital Library, and authors of accepted papers are required to agree to one of the standard ACM licensing options. Accepted papers must be presented at the workshop by one of the authors, but in special cases we may consider remote presentation. 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. PROGRAM CHAIRS: Jeffrey Young (Unaffiliated) Cristine Rizkallah (University of Melbourne) PROGRAM COMMITTEE: Isabella Stilkerich (Schaeffler Technologies) Ryan Scott (Galois) Facundo Dominguez (Tweag) J. Garrett Morris (University of Iowa) Nada Amin (Harvard University) Tom Ellis (Groq) KC Sivaramakrishnan (IIT Madras and Tarides) Hidehiko Masuhara (Institute of Science Tokyo) WORKSHOP VENUE: Room to be determined. The workshop will be co-located with the ICFP 2025 conference at the Marina Bay Sands Convention Centre, Singapore.

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Fwd: CGO'26 - Call for Papers and first submission round
by Luisa Cicolini 17 May '25

17 May '25

ACM/IEEE International Symposium on Code Generation and Optimization (CGO 2026) Call for Papers - First Submission Deadline The Call for Papers<https://2026.cgo.org/track/cgo-2026-papers> is out for the next International Symposium on Code Generation and Optimization (CGO’26)<https://2026.cgo.org/>, taking place next year in Sydney, Australia. CGO provides 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 optimisation. The first submission round is coming up, with the following deadlines: * Paper Submission: 29 May 2025 * Author Rebuttal Period: 8–10 July 2025 * Paper Notification: 21 July 2025 For more information, please visit the CGO’26 website<https://2026.cgo.org/>. We look forward to receiving your submissions! Best, Luisa Cicolini

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ZuriHac 2025 Schedule Online
by Farhad D. Mehta 12 May '25

12 May '25

Dear Friends of Haskell, The schedule for ZuriHac 2025 is now online on https://zurihac.info ! This year’s keynote speakers include Lennart Augustson (who will talk about “MicroHs”, a Haskell compiler with a runtime system so small that is can run on a microcontroller), Tom Ellis (author of the Bluefin effect system), and Brent Yorgey (of “Diagrams” and “Swarm” fame, who will talk about competitive programming in Haskell). We also have a track on Category Theory, given by Richard Southwell (of YouTube fame), as well as a track on WASM+Haskell and Nix+Haskell given by Cheng Shao and Julian Arni respectively. The Beginners’ Track this year will be given by Andres Löh. Our website https://zurihac.info contains further information on keynotes and tracks and will be updated regularly. In case you have not registered yet, please do so ASAP via the link https://zureg.zfoh.ch/register (also on our website). Although registration is free for participants, it allows us to plan appropriately for the event: Jane Street is generously hosting a BBQ on Saturday evening, and we want to get the number of grillables correct. For the uninitiated: ZuriHac 2025 will take place Saturday 7 June – Monday 9 June 2025 as a physical event at the Rapperswil-Jona campus of the OST Eastern Switzerland University of Applied Sciences. ZuriHac is the biggest Haskell community event in the world: a completely free, three-day grassroots coding festival co-organized by the Zürich Friends of Haskell and the OST Eastern Switzerland University of Applied Science. It is not your standard conference with papers and presentations, but features fantastic keynotes, hands-on tracks, hacking on many of your favourite projects, and of course lots of socializing! Organizing ZuriHac would not be possible without the support of our sponsors and partners, including: * The Haskell Foundation * IOHK * Jane Street * OST * Tweag * Type Theory Forall * Well-Typed In case you would like to support ZuriHac, as a company or as an individual, please get in touch with us, we would be grateful: https://zfoh.ch/#donations. We hope to see you there! The Zurich Friends of Haskell

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State of redis-resp and redis-io?
by Magnus Therning 11 May '25

11 May '25

I've looked around for Haskell packages for Redis and found the API of redis-io nice. I did notice that neither it, not redis-resp which it depends on, have gotten much love the last few years. Does anyone here know what the state of these packages are? Are they abandoned, or simply "finished" and therefore needing very little maintenance? /M Magnus Therning OpenPGP: 0xAB4DFBA4 email: magnus(a)therning.org jabber: magnus(a)therning.org twitter: magthe http://therning.org/magnus

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application of the record field may fail
by Johannes Waldmann 09 May '25

09 May '25

Dear Cafe, (ignore following email, but perhaps the observation is still useful, the answer is to use `-Weverything`, which gives more than `-Wall`. Obviously.) For two constructors with fields of identical type but different name, data T = A {foo::()} | B {f00 ::()} GHC detects a typo in the field name ghci> f x = case x of A{f00 = f} -> f ; B {} -> () <interactive>:2:19: error: [GHC-53822] • Constructor ‘A’ does not have field ‘f00’ Good. Now changing the program slightly, ghci> f x = case x of A{} -> f00 x ; B {} -> () the program becomes statically correct. Can we get a warning here? (to detect the typo). This example is close to real code, not foo and f00 but something_longer and something_longerr. Yes I shoudn't do this, and make names more descriptive/distinct. And types! It's only a typo because it's not a type error. [EDIT] the answer is yes, we can, with -Weverything, <interactive>:9:24: warning: [GHC-17335] [-Wincomplete-record-selectors] The application of the record field ‘f00’ may fail for the following constructors: A this sounds over-cautious, because it _will_ fail (if evaluated at all). - J.W.

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Call for Participation: SLE 2025 - 18th ACM SIGPLAN International Conference on Software Language Engineering
by Andrei Chis 08 May '25

08 May '25

** Call for Participation ** 18th ACM SIGPLAN International Conference on Software Language Engineering (SLE 2025) 12-13 June 2025 Koblenz, Germany https://conf.researchr.org/home/sle-2025 https://www.sleconf.org/2025/ https://x.com/sleconf ------------------------------------------------------------------------ The ACM SIGPLAN International Conference on Software Language Engineering (SLE) is devoted to the principles of software languages: their design, their implementation, and their evolution. Like its predecessors, the 18th edition of the SLE conference, SLE 2025, will bring together researchers from different areas united by their common interest in the creation, capture, and tooling of software languages. It overlaps with traditional conferences on the design and implementation of programming languages, model-driven engineering, and compiler construction, and emphasises the fusion of their communities. To foster the latter, SLE traditionally fills a two-day program with a single track, with the only temporal overlap occurring between co-located events. --------------------------- Registration --------------------------- Registration happens via the STAF registration page Early Bird Registration Deadline is May 10th, 2025 https://conf.researchr.org/attending/staf-2025/staf-2025-registration --------------------------- Venue --------------------------- University of Koblenz https://conf.researchr.org/venue/sle-2025/staf-2025-venue --------------------------- Keynotes --------------------------- * Thorsten Berger, Ruhr University Bochum, Germany A New DSL Textbook in Town! * Friedrich Steimann, Fernuniversität in Hagen, Germany an Programming Be Liberated from the Functional Style? https://conf.researchr.org/home/sle-2025#Keynotes --------------------------- Awards --------------------------- During the conference, we will announce the following 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. * COLA Award: 2024 Journal of Computer Languages Best Paper Award --------------------------- Accepted Papers --------------------------- * A Model-Driven Approach to Design, Generation, and Deployment of GUI Component Libraries Arkadii Gerasimov, Nico Jansen, Judith Michael, Bernhard Rumpe, Sebastian Will * AnyText: Incremental, left-recursive Parsing and Pretty-Printing from a single Grammar Definition with first-class LSP support Georg Hinkel, Alexander Hert, Niklas Hettler, Kevin Weinert * Boosting Parallel Parsing through Cyclic Operator Precedence Grammars Michele Chiari, Michele Giornetta, Dino Mandrioli, Matteo Pradella * Detecting Resource Leaks on Android with Alpakka Gustavo Amorim Santos, Alexandra Mendes, João Bispo * Dynamic Dependency-Based Purity Checking Anton Risberg Alaküla, Niklas Fors, Christoph Reichenbach * Exploratory, Omniscient, and Multiverse Diagnostics in Debuggers for Non-Deterministic Languages Damian Frölich, Tommaso Pacciani, L. Thomas van Binsbergen * Handling Grammar Cycles in the 1997 Standard ML Definition Elizabeth Scott, Adrian Johnstone * Integrating Model Checking into a Live Modeling Environment Joeri Exelmans, Ciprian Teodorov, Hans Vangheluwe * Lessons Learned: Challenges of Modular Language Design Alex Lüpges, Nico Jansen, Bernhard Rumpe * Optimal Language Design is Hard: A Case Study in ECMAScript (JavaScript) Standardization Philipp Riemer, Yury Nikulin, Ashley Claymore, Mikhail Barash * Optimize Effect Handling for Tail-resumption with Stack Unwinding Yuze Fu, Shigeru Chiba * Property-based Testing of Attribute Grammars José Nuno Macedo, Marcos Viera, João Saraiva * Scheduling the Construction and Interrogation of Scope Graphs Using Attribute Grammars Luke Bessant, Eric Van Wyk * (Semantic) Feature Model Differences with (Q)SAT Simone Heisinger, Maximilian Heisinger, Martina Seidl * TranspileJS, an Intelligent Framework for Transpiling JavaScript to WebAssembly José Pedro Ferreira, João Bispo, Susana Lima * Variability Fault Localization by Abstract Interpretation and its Application to SPL Repair Aleksandar S. Dimovski

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TyDe 2025 - Second Call for Papers
by Andras Kovacs 07 May '25

07 May '25

========================================================================= The Tenth International Workshop on TYPE-DRIVEN DEVELOPMENT Call for papers and extended abstracts Singapore, 12 October 2025 https://icfp25.sigplan.org/home/tyde-2025 ========================================================================= The Workshop on Type-Driven Development (TyDe) aims to show how static type information may be used effectively in the development of computer programs. Co-located with ICFP and SPLASH, this workshop brings together leading researchers and practitioners who are using or exploring types as a means of program development. We welcome all contributions, both theoretical and practical, on a range of topics including: * dependently typed programming; * generic programming; * design and implementation of programming languages, exploiting types in novel ways; * exploiting typed data, data dependent data, or type providers; * static and dynamic analyses of typed programs; * tools, IDEs, or testing tools exploiting type information; * pearls, being elegant, instructive examples of types used in the derivation, calculation, or construction of programs. ### Important dates ### * Mon 9 Jun 2025 (AoE): Submission deadline for papers and extended abstracts * Wed 16 Jul 2025: Notification of acceptance * Wed 30 Jul 2025: Submission of camera-ready papers to ACM * Sun 12 Oct 2025: Workshop ### Proceedings and Copyright ### We will have formal proceedings for full-length papers, published by the ACM. Accepted papers will be included in the ACM Digital Library. Authors must grant ACM publication rights upon acceptance, but may retain copyright if they wish. Authors are encouraged to publish auxiliary material with their paper (source code, test data, and so forth). The proceedings will be freely available for download from the ACM Digital Library from one week before the start of the conference until two weeks after the conference. 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. ### Submission Details ### Submissions should fall into one of two categories: * regular research papers (12 pages); * extended abstracts (3 pages). The bibliography will not be counted against the page limits for either category. Regular research papers are expected to present novel and interesting research results, and will be included in the formal proceedings. Extended abstracts should report work in progress that the authors would like to present at the workshop. Extended abstracts will be distributed to workshop attendees but will not be published in the formal proceedings. We welcome submissions from PC members (with the exception of the two co-chairs), but these submissions will be held to a higher standard. Submission is handled through HotCRP: > https://tyde25.hotcrp.com All submissions should be in portable document format (PDF) and formatted using the ACM SIGPLAN style guidelines: > https://www.sigplan.org/Resources/Author/ Note that submissions should use the new ‘acmart’ format and the two-column ‘sigplan’ subformat (not to be confused with the one-column ‘acmsmall’ subformat). Extended abstracts must be submitted with the label ‘Extended Abstract’ clearly in the title. ### Presentations ### We expect that each accepted submission is presented at the workshop. Presentations are around 20 minutes plus questions. Remote presentation is possible. ### Participant Support ### Student attendees with accepted papers can apply for a SIGPLAN PAC grant to help cover participation-related expenses. PAC also offers other support, such as for child-care expenses during the meeting or for accommodations for members with physical disabilities. For details on the PAC program, see its web page: > https://www.sigplan.org/PAC/ ### Workshop Organization ### Organizing Committee: - András Kovács (University of Gothenburg and Chalmers University of Technology) - Yuting Wang (Shanghai Jiao Tong University, China) Program Committee: - Nathan Corbyn (University of Oxford, United Kingdom) - Stephen Dolan (Jane Street, United Kingdom) - Paul Downen (University of Massachusetts at Lowell, United States) - Brandon Hewer (University of Nottingham, United Kingdom) - Hongwei Xi (Boston University, United States) - Wen Kokke (University of Edinburgh, United Kingdom) - Yao Li (Portland State University, United States) - Hidehiko Masuhara (Institute of Science Tokyo, Japan) - Stefan Monnier (Université de Montréal, Canada) - Steven Ramsay (University of Bristol, United Kingdom) - Di Wang (Peking University, China) - Zhixuan Yang (Imperial College London, United Kingdom)

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Non-linear patterns.
by Serguey Zefirov 06 May '25

06 May '25

There are artifacts of old Haskell standards that are a matching against integer value (2 + 2 = 5) and a matching against arithmetic expression (f (n+1) = f n). Both are interesting in requiring a class over type to match. f 10 = 11 has type f :: (Eq a1, Num a1, Num a2) => a1 -> a2 f (n+1) = f n has type f :: Integral t1 => t1 -> t2 In that vein it is possible to add non-linear patterns by adding an equality constraint on the non-linear matches. E.g., f x x = x would have type f :: Eq a => a -> a -> a For example: data Logic = True | False | Not Logic | Or Logic Logic | And Logic Logic deriving Eq simplify (And x x) = simplify x simplify (Or x x) = simplify x simplify (Not (Not x)) = simplify x simplify x = x Patterns like that are common in simplification/optimization rules. Also, by making them legal, it would be possible to use them in Template Haskell to make better embedded languages. On the implementation side, it can be implemented much like the (n+k) pattern. I also think that pattern matching completeness checker should not change. What would you say?

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Journal of Functional Programming - Call for PhD Abstracts
by Graham Hutton 06 May '25

06 May '25

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 30th May 2025. Please share! Best wishes, Graham Hutton ============================================================ CALL FOR PHD ABSTRACTS Journal of Functional Programming Deadline: 30th May 2025 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 29th November 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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GHC 9.10.2 is now available
by Zubin Duggal 03 May '25

03 May '25

The GHC developers are very pleased to announce the availability of the release candidate for GHC 9.10.2. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.2 is a bug-fix release fixing over 50 issues of a variety of severities and scopes, including: * Significantly improved performance when dynamically loading Haskell symbols (#23415). * Fixing a bug where the simplifier sometimes destroyed join points during float out, which could impact performance (#24768). * Reduced memory fragmentation in the non-moving GC's segment allocator, improving resident set size by up to 26% for some applications (#24150). * Added new flags to control speculative evaluation (-fspec-eval and -fspec-eval-dictfun) to work around performance regressions (#25606). * Fixed several platform-specific issues, including segfaults with FFI on PowerPC (#23034) and improved code generation for AArch64 with multiway branches now using jump tables (#19912) * And many more! A full accounting of these fixes 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 Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, 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/9.10.2/docs/users_guide/9.10.2-notes.html [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.2 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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Haskell Symposium 2025 Second Call for Papers
by Ningning Xie 02 May '25

02 May '25

======================================================================== Haskell Symposium 2025 Call for Papers Thu 16 - Fri 17 Oct 2025, Singapore https://conf.researchr.org/home/icfp-splash-2025/haskellsymp-2025 ======================================================================== The ACM SIGPLAN Haskell Symposium 2025 will be co-located with the 2025 International Conference on Functional Programming (ICFP) and the 2025 International Conference on Systems, Programming, Languages and Applications: Software for Humanity (SPLASH). The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. Submission deadline: 9 June 2025 (Mon) Notification: 17 July 2025 (Thu) Deadlines are valid anywhere on Earth. Papers should be submitted through HotCRP at: https://haskell25.hotcrp.com/ Topics of interest include: * Language design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, such as formal semantics of the present language or future extensions, type systems, effects, metatheory, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management, as well as foreign function and component interfaces; * Libraries, that demonstrate new ideas or techniques for functional programming in Haskell; * Tools, such as profilers, tracers, debuggers, preprocessors, and testing tools; * Applications, to scientific and symbolic computing, databases, multimedia, telecommunication, the web, and so forth; * Functional Pearls, being elegant and instructive programming examples; * Experience Reports, to document general practice and experience in education, industry, or other contexts; * Tutorials, to document how to use a particular language feature, programming technique, tool or library within the Haskell ecosystem; * System Demonstrations, based on running software rather than novel research results. Keynote Speakers ================= * Richard A. Eisenberg * Simon Peyton Jones Program Committee ================= Andreas Abel Gothenburg University Patrick Bahr IT University of Copenhagen Matthew Fluet Rochester Institute of Technology Adam Gundry Well-Typed LLP Xuejing Huang IRIF Hideya Iwasaki Meiji University Patricia Johann Appalachian State University Hsiang-Shang 'Josh' Ko Institute of Information Science, Academia Sinica András Kovács University of Gothenburg and Chalmers University of Technology Andres Löh Well-Typed LLP J. Garrett Morris (co-chair) University of Iowa Liam O'Connor Australian National University Maciej Piróg University of Wrocław Arnaud Spiwack Tweag Meng Wang University of Bristol Li-yao Xia Inria Ningning Xie (co-chair) University of Toronto Gergő Érdi Standard Chartered Bank

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Utrecht Summer School on Advanced Functional Programming
by Wouter Swierstra 02 May '25

02 May '25

Second Call for Participation SUMMER SCHOOL ON ADVANCED FUNCTIONAL PROGRAMMING Utrecht, the Netherlands, 07 July – 11 July 2025 http://afp.school **Please register before June 15th** ## ABOUT The Advanced Functional Programming summer school has been running for more than fifteen years. We aim to educate aspiring Haskell programmers beyond the basic material covered by many textbooks. The lectures will cover several more advanced topics regarding the theory and practice of Haskell programming, including topics such as: * lambda calculus; * lazy evaluation; * generalized algebraic data types; * type families and type-level programming; * concurrency and parallelism. The summer school will be held in Utrecht and consists of a mix of lectures, labs, and a busy social program. ## PREREQUISITES We expect students to have a basic familiarity with Haskell already. You should be able to write recursive functions over algebraic data types, such as lists and trees. There is a great deal of material readily available that covers this material. If you've already started learning Haskell and are looking to take your functional programming skills to the next level, this is the course for you. ## DATES Registration deadline: June 15th, 2025 School: 07 July – 11 July 2025 ## COSTS € 950 euro - Profession registration fee € 500 euro - Student registration fee € 200 euro - Housing fee We will charge a registration fee of €950 (or €500 for students) to cover our expenses. This fee includes all lunches, dinners, and coffee breaks - you won't need to budget much else besides your travel. If this is problematic for you for any reason at all, please email the organisers and we can try to offer you a discounted rate or a fee waiver. We have a limited number of scholarships or discounts available for students that would not be able to attend otherwise, especially for women and under-represented minorities. ## FURTHER INFORMATION Further information, including instructions on how to register, is available on our website: http://afp.school

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IFL 2025: First call for papers
by Mart Lubbers 29 Apr '25

29 Apr '25

===================================================================== IFL 2025 37th Symposium on Implementation and Application of Functional Languages Montevideo, Uruguay October 1-3, 2025 https://www.fing.edu.uy/inco/congresos/ifl2025 ===================================================================== ### Scope The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2025 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. ### Topics of interest Topics of interest to IFL include, but are not limited to: - language concepts - type systems, type checking, type inferencing - compilation techniques - staged compilation - run-time function specialisation - run-time code generation - partial evaluation - (abstract) interpretation - meta-programming - generic programming - automatic program generation - array processing - concurrent/parallel programming - concurrent/parallel program execution - embedded systems - web applications - (embedded) domain specific languages - security - novel memory management techniques - run-time profiling performance measurements - debugging and tracing - virtual/abstract machine architectures - validation, verification of functional programs - tools and programming techniques ### Peer-review process Differently from previous editions of IFL, IFL 2025 solicits two kinds of submissions: * Regular papers (12 pages including references) * Draft papers for presentations ('weak' limit between 8 and 15 pages) Regular papers will undergo a rigorous review by the program committee, and will be evaluated according to their correctness, novelty, originality, relevance, significance, and clarity. A set of regular papers will be conditionally accepted for publication. Authors of conditionally accepted papers will be provided with committee reviews along with a set of mandatory revisions. Regular papers not accepted for publication will be considered as draft papers, at the request of the author. Draft papers will be screened to make sure that they are within the scope of IFL, and will be accepted for presentation or rejected accordingly. Prior to the symposium: Authors of conditionally accepted papers and accepted presentations will submit a pre-proceedings version of their work that will appear in the draft proceedings distributed at the symposium. The draft proceedings does not constitute a formal publication. We require that at least one of the authors present the work at IFL 2025. After the symposium: Authors of conditionally accepted papers will submit a revised versions of their paper for the formal post-proceedings. The program committee will assess whether the mandatory revisions have been adequately addressed by the authors and thereby determines the final accept/reject status of the paper. Our interest is to ultimately accept all conditionally accepted papers. If you are an author of a conditionally accepted paper, please make sure that you address all the concerns of the reviewers. Authors of accepted presentations will be given the opportunity to incorporate the feedback from discussions at the symposium and will be invited to submit a revised full article for the formal post-proceedings. The program committee will evaluate these submissions according to their correctness, novelty, originality, relevance, significance, and clarity, and will thereby determine whether the paper is accepted or rejected. ### Important dates Submission of regular papers: June 16, 2025 Regular papers notification: August 4, 2025 Submission of draft papers: August 4, 2025 Draft papers notification: August 11, 2025 Deadline for early registration: September 5, 2025 Submission of pre-proceedings version: September 8, 2025 IFL Symposium: October 1-3, 2025 Submission of papers for post-proceedings: December 15, 2025 Notification of acceptance: February 28, 2026 Camera-ready version: March 30, 2026 Deadlines are end of day Anywhere on Earth (UTC-12) (https://www.timeanddate.com/time/zones/aoe) ### Submission details All contributions must be written in English. Papers must use the ACM two columns conference format, which can be found at: http://www.acm.org/publications/proceedings-template Submit your paper here: https://easychair.org/conferences/?conf=ifl20240 Important note to authors about the new ACM open access publishing model ACM has introduced a new open access publishing model for the International Conference Proceedings Series (ICPS). Authors based at institutions that are not yet part of the ACM Open program and do not qualify for a waiver will be required to pay an article processing charge (APC) to publish their ICPS article in the ACM Digital Library. To determine whether or not an APC will be applicable to your article, please follow the detailed guidance here: https://www.acm.org/publications/icps/author-guidance. Further information may be found on the ACM website, as follows: - Full details of the new ICPS publishing model: https://www.acm.org/publications/icps/faq - Full details of the ACM Open program: https://www.acm.org/publications/openaccess - Please direct all questions about the new model to icps-info(a)acm.org. ### Peter Landin Prize The Peter Landin Prize is awarded to the best paper presented at the symposium every year. The honoured article is selected by the program committee based on the submissions received for the formal review process. The prize carries a cash award equivalent to 150 Euros. ### Organisation PC Chairs: Alberto Pardo, Universidad de la República, Montevideo, Uruguay Marcos Viera, Universidad de la República, Montevideo, Uruguay Local Chairs: Alberto Pardo, Universidad de la República, Montevideo, Uruguay Marcos Viera, Universidad de la República, Montevideo, Uruguay ### Program committee: Matteo Cimini, University of Massachusetts Lowell Facundo Domínguez, Tweag João Paulo Fernandes, Universidade do Porto Jeremy Gibbons, Oxford University Jurriaan Hage, Heriot Watt University Jason Hemann, Seton Hall University Maja Hanne Kirkeby, Roskilde University Mart Lubbers, Radboud University Bruno C. D. S. Oliveira, The University of Hong Kong Rinus Plasmeijer, Radboud University Andre Rauber Du Bois, Universidade Federal de Pelotas Rodrigo Ribeiro, Universidade Federal de Ouro Preto Alejandro Russo, Chalmers University of Technology João Saraiva, University of Minho Wenhao Tang, University of Edinburgh Zhixuan Yang, Imperial College London Brent Yorgey, Hendrix College Beta Ziliani, Manas.Tech Viktória Zsók, Eötvös Loránd University ### Venue IFL 2025 will be held physically in Montevideo, Uruguay. See the website for more information. https://www.fing.edu.uy/inco/congresos/ifl2025 ### Acknowledgments This call-for-papers is an adaptation and evolution of content from previous instances of IFL. We are grateful to prior organisers for their work, which is reused here.

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Is there a way to make this code compose generic ?
by PICCA Frederic-Emmanuel 25 Apr '25

25 Apr '25

Hello, I have this data DataSourceShape = DataSourceShape ([HSize], [Maybe HSize]) | DataSourceShape'Range !DIM1 !DIM1 a function which combine 2 DataSourceShape and produce an new one (monoid operation ?) combine'Shape ∷ DataSourceShape → DataSourceShape → DataSourceShape I use this in this class with familly types. class DataSource a where data DataSourcePath a ∷ Type data DataSourceAcq a ∷ Type ds'Shape ∷ MonadSafe m ⇒ DataSourceAcq a → m DataSourceShape withDataSourceP ∷ (Location l, MonadSafe m) ⇒ ScanFile l → DataSourcePath a → (DataSourceAcq a → m r) → m r and here an instance for one of my type DataFrameQCustom (I have plenty of them). they are all constructed the same way. data DataSourceAcq DataFrameQCustom = DataSourceAcq'DataFrameQCustom (DataSourceAcq Attenuation) (DataSourceAcq Geometry) (DataSourceAcq Image) (DataSourceAcq Mask) (DataSourceAcq Timestamp) (DataSourceAcq Timescan0) (DataSourceAcq Scannumber) ds'Shape(DataSourceAcq'DataFrameQCustom a g i m idx t0 s) = do sa ← ds'Shape a sg ← ds'Shape g si ← ds'Shape i sm ← ds'Shape m sidx ← ds'Shape idx st0 ← ds'Shape t0 ss ← ds'Shape s pure $ foldl1 combine'Shape [sa, sg, si, sm, sidx, st0, ss] withDataSourceP f (DataSourcePath'DataFrameQCustom a g i m idx t0 s) gg = withDataSourceP f a $ λa' → withDataSourceP f g $ λg' → withDataSourceP f i $ λi' → withDataSourceP f m $ λm' → withDataSourceP f idx $ λidx' → withDataSourceP f s $ λs' → withDataSourceP f t0 $ λt0' → gg (DataSourceAcq'DataFrameQCustom a' g' i' m' idx' t0' s') My question is, how should avoid writting by hand all these ds'Shape / withDatasourceP implementations, which seems quite mechanical. thanks for your help Frederic

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ICFP 2025 Student Research Competition Call for Submissions
by Kimball Germane 24 Apr '25

24 Apr '25

ICFP 2025 invites students to participate in the Student Research Competition in order to present their research and get feedback from prominent members of the programming language research community. The SRC consists of three rounds: * Submission of an extended abstract * Poster session at ICFP 2025 * Finalists' presentations at ICFP 2025 During the first round students submit an extended abstract detailing their research to be reviewed by the program committee. Those students whose abstracts get accepted advance to the poster session round which will take place during ICFP 2025. Winners of the poster session advance to the next round, where they will give a 5-minute presentation about their work on the ICFP main stage in front of a live audience. Please note that a work cannot be simultaneously submitted to multiple SRCs, including both the ICFP SRC and the SPLASH SRC which are co-located this year. ### IMPORTANT DATES AND TIMES * Submission Deadline: 19 June 2025 (Thursday) * Author Notification: 14 July 2025 (Monday) * ICFP 2025 Conference in Singapore: 12 October 2025 (Sunday) - 18 October 2025 (Saturday) ### SUBMISSION OF EXTENDED ABSTRACTS * Submission Website: https://icfp25src.hotcrp.com Each submission (referred to as "abstract" below) should include the student author's name and e-mail address; institutional affiliation; research advisor's name; ACM student member number; category (undergraduate or graduate); research title; and an extended abstract addressing the following: * Problem and Motivation: Clearly state the problem being addressed and explain the reasons for seeking a solution to this problem. * Background and Related Work: Describe the specialized (but pertinent) background necessary to appreciate the work in the context of ICFP areas of interest. Include references to the literature where appropriate, and briefly explain where your work departs from that done by others. * Approach and Uniqueness: Describe your approach in addressing the problem and clearly state how your approach is novel. * Results and Contributions: Clearly show how the results of your work contribute to programming language design and implementation in particular and to computer science in general; explain the significance of those results. * Submissions must be original research that is not already published at ICFP or another conference or journal. One of the goals of the SRC is to give students feedback on ongoing, unpublished work. Furthermore, the abstract must be authored solely by the student. If the work is collaborative with others and/or part of a larger group project, the abstract should make clear what the student's role was and should focus on that portion of the work. * 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. For authors using LaTeX, a lighter-weight package, including only the essential files, is available from http://sigplan.org/Resources/Author/#acmart-format. The submission must not exceed 3 pages in PDF format. Reference lists do not count towards the 3-page limit. Further information is available at the ICFP SRC website: https://icfp25.sigplan.org/track/icfp-2025-student-research-competition

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"Magical Haskell" book is finally finished and available :)
by Anton Antich 22 Apr '25

22 Apr '25

Dear all, I have started working on this book almost 10 years ago, wrote about a third and then took a big pause until last year, when I got approached by Springer and finished the book in another 6 months, dedicating the 2nd part to Agentic AI and now it's finally out and available and I would really love to get the community's feedback :) I tried to introduce Haskell from the first mathematical principles, but very gently, so that it is accessible to a much wider audience as we all know the learning curve can be a bit steep. Here is a sample free chapter on medium: https://medium.com/superstringtheory/functor-bifunctor-trifunctor-c1424f962… The book itself is available on Springer: https://link.springer.com/book/10.1007/979-8-8688-1282-8 And there is a 20% discount with the code APAUT - or just scan the QR code below. I put a lot of effort into this book, being passionate about the language we all love and do hope it will help more people to become proficient and fluent in Haskell! Best wishes, Anton Antich, CPO and founder, Integrail.ai [image: image.png]

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Release: webdriver-precore
by John Walker 21 Apr '25

21 Apr '25

Hi All, We are happy to announce the release of [webdriver-precore]( https://hackage.haskell.org/package/webdriver-precore) ~ *A typed wrapper for [W3C WebDriver](https://www.w3.org/TR/2025/WD-webdriver2-20250306/) protocol* This library is intended to be used as a base for other libraries that provide a WebDriver client implementation and higher level functions for browser automation. More details can be found in the [project README]( https://github.com/pyrethrum/webdriver) John & Adrian

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type-class and subclasses
by lloyd allison 16 Apr '25

16 Apr '25

I have a general question: I would like to have a type-class C in which types that are instances of C have some type parameters and then a subclass S of C where some of the type parameters of an instance of S are more constrained in some way -- perhaps by being equal and/or being instances of some other class. I have an entirely artificial example (att.) that illustrates this situation and struggled (it's a while since I wrote much Haskell) to get it past the ghc type checker until stumbling across GADTs which do seem to do the trick, so I could leave it at that but... ...I am very far from sure that this is the correct way to look at the problem and am hoping for some illumination. regards Lloyd. -- No AI was used in composing this message.

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TyDe 2025 - Call for Papers & Extended Abstracts
by Andras Kovacs 11 Apr '25

11 Apr '25

========================================================================= The Tenth International Workshop on TYPE-DRIVEN DEVELOPMENT Call for papers and extended abstracts Singapore, 12 October 2025 https://icfp25.sigplan.org/home/tyde-2025 ========================================================================= The Workshop on Type-Driven Development (TyDe) aims to show how static type information may be used effectively in the development of computer programs. Co-located with ICFP and SPLASH, this workshop brings together leading researchers and practitioners who are using or exploring types as a means of program development. We welcome all contributions, both theoretical and practical, on a range of topics including: * dependently typed programming; * generic programming; * design and implementation of programming languages, exploiting types in novel ways; * exploiting typed data, data dependent data, or type providers; * static and dynamic analyses of typed programs; * tools, IDEs, or testing tools exploiting type information; * pearls, being elegant, instructive examples of types used in the derivation, calculation, or construction of programs. ### Important dates ### * Mon 9 Jun 2025 (AoE): Submission deadline for papers and extended abstracts * Wed 16 Jul 2025: Notification of acceptance * Wed 30 Jul 2025: Submission of camera-ready papers to ACM * Sun 12 Oct 2025: Workshop ### Proceedings and Copyright ### We will have formal proceedings for full-length papers, published by the ACM. Accepted papers will be included in the ACM Digital Library. Authors must grant ACM publication rights upon acceptance, but may retain copyright if they wish. Authors are encouraged to publish auxiliary material with their paper (source code, test data, and so forth). The proceedings will be freely available for download from the ACM Digital Library from one week before the start of the conference until two weeks after the conference. 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. ### Submission Details ### Submissions should fall into one of two categories: * regular research papers (12 pages); * extended abstracts (3 pages). The bibliography will not be counted against the page limits for either category. Regular research papers are expected to present novel and interesting research results, and will be included in the formal proceedings. Extended abstracts should report work in progress that the authors would like to present at the workshop. Extended abstracts will be distributed to workshop attendees but will not be published in the formal proceedings. We welcome submissions from PC members (with the exception of the two co-chairs), but these submissions will be held to a higher standard. Submission is handled through HotCRP: > https://tyde25.hotcrp.com All submissions should be in portable document format (PDF) and formatted using the ACM SIGPLAN style guidelines: > https://www.sigplan.org/Resources/Author/ Note that submissions should use the new ‘acmart’ format and the two-column ‘sigplan’ subformat (not to be confused with the one-column ‘acmsmall’ subformat). Extended abstracts must be submitted with the label ‘Extended Abstract’ clearly in the title. ### Presentations ### We expect that each accepted submission is presented at the workshop. Presentations are around 20 minutes plus questions. Remote presentation is possible. ### Participant Support ### Student attendees with accepted papers can apply for a SIGPLAN PAC grant to help cover participation-related expenses. PAC also offers other support, such as for child-care expenses during the meeting or for accommodations for members with physical disabilities. For details on the PAC program, see its web page: > https://www.sigplan.org/PAC/

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Extended deadline - CFP - Haskell Implementors' Workshop 2025
by Andreas Herrmann 07 Apr '25

07 Apr '25

Extended deadline to April 18, 2025 Call for proposals for the Haskell Implementors' Workshop https://haskell.foundation/events/2025-haskell-implementors-workshop.html June 6, 2025 Organized by the Haskell Community Co-located with ZuriHac 2025 and Haskell Ecosystem Workshop 2025 Hosted by the Haskell Foundation at Eastern Switzerland University of Applied Sciences (OST) https://www.ost.ch/en/university-of-applied-sciences/campus/rapperswil-jona… ## Overview * Extended Deadline: April 18, 2025 * Notification: May 5, 2025 * Workshop: June 6, 2025 The 17th Haskell Implementors' Workshop is to be held alongside ZuriHac 2025 this year near Zurich. It is a forum 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. Talks and/or demos are proposed by submitting an abstract, and selected by a small program committee. There will be no published proceedings. The workshop will be informal and interactive, with open spaces in the timetable and room for ad-hoc discussion, demos, and lightning talks. In the past the Haskell Implementors’ Workshop was co-located with ICFP (International Conference on Functional Programming). However, in recent years it has become more and more challenging to attract a large enough audience and sufficiently many speakers for an appealing program. ZuriHac and the Haskell Ecosystem Workshop have become an important annual gathering of a large part of the Haskell community. This year the Haskell Implementors’ Workshop will be co-located with these events to be accessible to a broader audience. ## Scope and Target Audience The Haskell Implementors' Workshop is an ideal place to describe a Haskell extension, describe works-in-progress, demo a new Haskell-related tool, or even propose future lines of Haskell development. Members of the wider Haskell community are encouraged to attend the workshop - we need your feedback to keep the Haskell ecosystem thriving. Students working with Haskell are especially encouraged to share their work. The scope covers any of the following topics. There may be some topics that people feel we've missed, so by all means submit a proposal even if it doesn't fit exactly into one of these buckets: * Compilation techniques * Language features and extensions * Type system implementation * Concurrency and parallelism: language design and implementation * Performance, optimization and benchmarking * Virtual machines and run-time systems * Libraries and tools for development or deployment ## Talks We invite proposals from potential speakers for talks and demonstrations. We are aiming for 20-minute talks with 5 minutes for questions and changeovers. We want to hear from people writing compilers, tools, or libraries, people with cool ideas for directions in which we should take the platform, proposals for new features to be implemented, and half-baked crazy ideas. Submissions can be made via the form linked below until April 18, 2025 (anywhere on earth). https://docs.google.com/forms/d/e/1FAIpQLSdczGbxJYGc4eusvPrxwBbZl561PnKeYno… We will also have a lightning talks session. Lightning talks should be ~7mins and are scheduled on the day of the workshop. Suggested topics for lightning talks are to present a single idea, a work-in-progress project, a problem to intrigue and perplex Haskell implementors, or simply to ask for feedback and collaborators. ## Program Committee * Luite Stegeman * Jaro Reinders * Emily Pillmore * Rodrigo Mesquita * Ian-Woo Kim * Andreas Herrmann (chair) ## Contact * Andreas Herrmann

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Re: [Haskell-cafe] type level function with different return kinds
by Barak A. Pearlmutter 06 Apr '25

06 Apr '25

Can a type level function have different return kinds depending on its arguments? I think this question is best answered by quoting https://aphyr.com/posts/342-typing-the-technical-interview “Haskell is a dynamically-typed, interpreted language.”

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type level function with different return kinds
by Zoran Bošnjak 06 Apr '25

06 Apr '25

Dear haskellers, is it possible to write a type/kind level function that returns types of different kinds for different inputs. Either by using open/closed type families, a typeclass, extensions or any other type level magic. Something like this: {-# LANGUAGE DataKinds #-} {-# LANGUAGE TypeFamilies #-} import GHC.TypeLits data A = A1 | A2 data B = B1 | B2 type family F (n :: Nat) where F 0 = 'A1 F 1 = 'A2 F 2 = 'B1 F 3 = 'B2 The problem with this approach is that (F 0) and (F 1) are ok, but not in combination with (F 2). The error says: • Expected kind ‘A’, but ‘'B1’ has kind ‘B’ If I instead write: type family F (n :: Nat) :: k where ... I get compile error already on the (F 0) line • Expected kind ‘k’, but ‘'A1’ has kind ‘A’ Any ideas how to remove the "same kind" restriction or how to workaround it? I am using ghc 9.6.6. regards, Zoran

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dumping ByteArray#
by Kazu Yamamoto 29 Mar '25

29 Mar '25

Hello, For debugging, I need to dump the inside of `ByteArray#`. Are there any utility functions for this purpose? --Kazu

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implementing a class using superclasses?
by Mark McConnell 28 Mar '25

28 Mar '25

Here is a simplified, self-contained version of some code I'm working on. I have a Ord type Foo that I want to be ordered primarily by comp1, and, in case of ties, secondarily by comp2. It is important to my users to know that the primary sorting will always be by comp1. Therefore, I am trying to use to the type system to articulate that Foo must be ordered in a two-fold lexicographic way. My code is module Lex2Test where class Ord a => Primary a where comp1 :: a -> a -> Ordering comp1 = compare class Ord a => Secondary a where comp2 :: a -> a -> Ordering comp2 = compare class (Primary a, Secondary a) => Lex2 a instance Lex2 a => Ord a where compare x y = comp1 x y <> comp2 x y However, when I load the code into ghci, I get Lex2Test.hs:13:10: error: • The constraint ‘Lex2 a’ is no smaller than the instance head ‘Ord a’ (Use UndecidableInstances to permit this) • In the instance declaration for ‘Ord a’ |13 | instance Lex2 a => Ord a where | ^^^^^^^^^^^^^^^ I feel I must be missing something. UndecidableInstances seems too extreme for what I am trying to do. (I have never said that I want to go backwards in class inference from Ord to Lex2.) If this were C++, I would be just trying to implement some virtual functions in terms of other virtual functions. Any comments would be appreciated.

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Call for Nominations: SLE 2025 - Artifact Evaluation Committee, Nominations Wanted
by Andrei Chis 27 Mar '25

27 Mar '25

18th ACM SIGPLAN International Conference on Software Language Engineering (SLE 2025) 12-13 June 2025 Koblenz, Germany https://conf.researchr.org/home/sle-2025 https://www.sleconf.org/2025/ https://x.com/sleconf ------------------------------------------------------------------------ The SLE 2025 Artifact Evaluation Committee (AEC) is looking for nominations and self-nominations for committee members. If you are a PhD student, postdoctoral researcher, associate, or professor working in software language engineering, we encourage you to apply. Serving on the AEC is an excellent opportunity to contribute to the community and gain valuable experience in artifact evaluation. -------------------------------------- Important Dates (All deadlines are AoE) -------------------------------------- Artifact submission deadline: April 23, 2025 Artifact bidding: April 24–26, 2025 Camera-ready deadline for SLE papers: May 1, 2025 Kick-the-tires review deadline & rebuttal phase: May 2, 2025 Final review deadline: May 24, 2025 Artifact discussion: May 25–31, 2025 Artifact notification: June 1, 2025 ------------------------------------------------------------------------ To nominate yourself or someone else, please complete the following form by April 6, 2025 Form: https://docs.google.com/forms/d/15Q-9i1tCwHzrtdtRqfJbWqZs4hV7DnJfwBSZuop75b… For any questions, please do not hesitate to contact us. SLE 2025 Artifact Evaluation Co-Chairs, Idriss Riouak and Jeff Smits Idriss Riouak: idriss.riouak(a)cs.lth.se Jeff Smits: j.smits-1(a)tudelft.nl

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Haskell Symposium 2025 First Call for Papers
by Ningning Xie 27 Mar '25

27 Mar '25

======================================================================== Haskell Symposium 2025 Call for Papers Thu 16 - Fri 17 Oct 2025, Singapore https://conf.researchr.org/home/icfp-splash-2025/haskellsymp-2025 ======================================================================== The ACM SIGPLAN Haskell Symposium 2025 will be co-located with the 2025 International Conference on Functional Programming (ICFP) and the 2025 International Conference on Systems, Programming, Languages and Applications: Software for Humanity (SPLASH). The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. Submission deadline: 9 June 2025 (Mon) Notification: 17 July 2025 (Thu) Deadlines are valid anywhere on Earth. Papers should be submitted through HotCRP at: https://haskell25.hotcrp.com/ Topics of interest include: * Language design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, such as formal semantics of the present language or future extensions, type systems, effects, metatheory, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management, as well as foreign function and component interfaces; * Libraries, that demonstrate new ideas or techniques for functional programming in Haskell; * Tools, such as profilers, tracers, debuggers, preprocessors, and testing tools; * Applications, to scientific and symbolic computing, databases, multimedia, telecommunication, the web, and so forth; * Functional Pearls, being elegant and instructive programming examples; * Experience Reports, to document general practice and experience in education, industry, or other contexts; * Tutorials, to document how to use a particular language feature, programming technique, tool or library within the Haskell ecosystem; * System Demonstrations, based on running software rather than novel research results. Program Committee ================= Andreas Abel Gothenburg University Patrick Bahr IT University of Copenhagen Matthew Fluet Rochester Institute of Technology Adam Gundry Well-Typed LLP Xuejing Huang IRIF Hideya Iwasaki Meiji University Patricia Johann Appalachian State University Hsiang-Shang 'Josh' Ko Institute of Information Science, Academia Sinica András Kovács University of Gothenburg and Chalmers University of Technology Andres Löh Well-Typed LLP J. Garrett Morris (co-chair) University of Iowa Liam O'Connor Australian National University Maciej Piróg University of Wrocław Arnaud Spiwack Tweag Meng Wang University of Bristol Li-yao Xia Inria Ningning Xie (co-chair) University of Toronto Gergő Érdi Standard Chartered Bank If you have questions, please contact the chairs at: ningningxie(a)cs.toronto.edu and garrett-morris(a)uiowa.edu.

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CFP - Haskell Implementors' Workshop 2025
by Andreas Herrmann 27 Mar '25

27 Mar '25

Call for proposals for the Haskell Implementors' Workshop https://haskell.foundation/events/2025-haskell-implementors-workshop.html June 6, 2025 Organized by the Haskell Community Co-located with ZuriHac 2025 and Haskell Ecosystem Workshop 2025 Hosted by the Haskell Foundation at Eastern Switzerland University of Applied Sciences (OST) https://www.ost.ch/en/university-of-applied-sciences/campus/rapperswil-jona… ## Overview * Deadline: April 4, 2025 * Notification: May 5, 2025 * Workshop: June 6, 2025 The 17th Haskell Implementors' Workshop is to be held alongside ZuriHac 2025 this year near Zurich. It is a forum 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. Talks and/or demos are proposed by submitting an abstract, and selected by a small program committee. There will be no published proceedings. The workshop will be informal and interactive, with open spaces in the timetable and room for ad-hoc discussion, demos, and lightning talks. In the past the Haskell Implementors’ Workshop was co-located with ICFP (International Conference on Functional Programming). However, in recent years it has become more and more challenging to attract a large enough audience and sufficiently many speakers for an appealing program. ZuriHac and the Haskell Ecosystem Workshop have become an important annual gathering of a large part of the Haskell community. This year the Haskell Implementors’ Workshop will be co-located with these events to be accessible to a broader audience. ## Scope and Target Audience The Haskell Implementors' Workshop is an ideal place to describe a Haskell extension, describe works-in-progress, demo a new Haskell-related tool, or even propose future lines of Haskell development. Members of the wider Haskell community are encouraged to attend the workshop - we need your feedback to keep the Haskell ecosystem thriving. Students working with Haskell are especially encouraged to share their work. The scope covers any of the following topics. There may be some topics that people feel we've missed, so by all means submit a proposal even if it doesn't fit exactly into one of these buckets: * Compilation techniques * Language features and extensions * Type system implementation * Concurrency and parallelism: language design and implementation * Performance, optimization and benchmarking * Virtual machines and run-time systems * Libraries and tools for development or deployment ## Talks We invite proposals from potential speakers for talks and demonstrations. We are aiming for 20-minute talks with 5 minutes for questions and changeovers. We want to hear from people writing compilers, tools, or libraries, people with cool ideas for directions in which we should take the platform, proposals for new features to be implemented, and half-baked crazy ideas. Submissions can be made via the form linked below until April 4, 2025 (anywhere on earth). https://docs.google.com/forms/d/e/1FAIpQLSdczGbxJYGc4eusvPrxwBbZl561PnKeYno… We will also have a lightning talks session. Lightning talks should be ~7mins and are scheduled on the day of the workshop. Suggested topics for lightning talks are to present a single idea, a work-in-progress project, a problem to intrigue and perplex Haskell implementors, or simply to ask for feedback and collaborators. ## Program Committee * Luite Stegeman * Jaro Reinders * Emily Pillmore * Rodrigo Mesquita * Ian-Woo Kim * Andreas Herrmann (chair) ## Contact * Andreas Herrmann

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Call for Papers, Functional Software Architecture (Deadline June 16)
by Michael Sperber 25 Mar '25

25 Mar '25

====================================================================== *** FUNARCH 2025 -- CALL FOR PAPERS *** Third ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large 17th October 2025, Singapore Co-located with ICFP 2025 https://functional-architecture.org/events/funarch-2025/ ====================================================================== TIMELINE: Paper submission 16th June 2025 Author notification 21st July 2025 Camera ready copy 25th August 2025 Workshop 17th October 2025 BACKGROUND: "Functional Software Architecture" refers to methods of construction and structure of large and long-lived software projects that are implemented in functional languages and released to real users, typically in industry. The goals for the workshop are: - To assemble a community interested in software architecture techniques and technologies specific to functional programming; - To identify, categorize, and document topics relevant to the field of functional software architecture; - To connect the functional programming community to the software architecture community to cross-pollinate between the two. The workshop follows on from the Functional Software Architecture open space that was held at ICFP 2022 in Slovenia. SCOPE: The workshop seeks submissions in a range of categories: - You're a member of the FP community and have thought about how to support programming in the large, for example by framing functional ideas in architectural terms or vice verse, comparing different languages in terms of their architectural capabilities, clarifying architectural roles played by formal methods, proof assistants and DSLs, or observing how functional concepts are used in other language and architecture communities. Great, submit a research paper! - You're a member of the architecture community, and have thought about how your discipline might help functional programmers, for example by applying domain-driven design, implementing hexagonal architecture, or designing self-contained systems. Excellent, submit a research paper! - You've worked on a large project using functional programming, and it's worked out well, or terribly, or a mix of both; bonus points for deriving architectural principles from your experience. Wonderful, submit an experience report! - You know a neat architectural idiom or pattern that may be useful to others developing large functional software systems. Fabulous, submit an architectural pearl! - You have something that doesn't fit the above categories, but that still relates to functional software architecture, such as something that can be written up, or that could be part of the workshop format like a panel debate or a fishbowl. Superb, submit to the open category! Research papers should explain their research contributions in both general and technical terms, identifying what has been accomplished, explaining why it is significant, and relating it to previous work, and to other languages where appropriate. Experience reports and architectural pearls need not necessarily report original research results. The key criterion for such papers is that they make a contribution from which others can benefit. It is not enough simply to describe a large software system, or to present ideas that are specific to a particular system. Open category submissions that are not intended for publication are not required to follow the formatting guidelines, and can submit in PDF, word or plain text format as preferred. Not knowing what kinds of submissions we will receive, we cannot be specific as to how they will be evaluated. However, submissions that seem likely to stimulate discussion around practices in functional architecture are encouraged. If you are unsure whether your contribution is suitable, or if you need any kind of help with your submission, please email the program chairs (Jeff (jmy6342(a)gmail.com) and Christine (christine.rizkallah(a)unimelb.edu.au)) Papers must be submitted by 16th June 2025 using the hotcrp submission page (https://funarch25.hotcrp.com/) Formatting: submissions intended for publication must be in PDF format and follow the ACM SIGPLAN style guidelines, using the acmart format and the sigplan sub-format. Please use the review option when submitting, as this enables line numbers for easy reference in reviews. For further details, see SIGPLAN's author information: http://www.sigplan.org/Resources/Author/#acmart-format If your submission is not a research paper, please mark this using a subtitle (Experience Report, Architectural Pearl, Open Category). Length: submissions must adhere to the limits specified below. However, there is no requirement or expectation that all pages are used, and authors are encouraged to strive for brevity. Research papers 5 to 12+ pages Architectural pearls 5 to 12 pages Experience reports 3 to 6 pages Open category 1 to 6 pages Publication: The proceedings of FUNARCH 2024 will be published in the ACM Digital Library, and authors of accepted papers are required to agree to one of the standard ACM licensing options. Accepted papers must be presented at the workshop by one of the authors, but in special cases we may consider remote presentation. 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. PROGRAM CHAIRS: Jeffrey Young (Unaffiliated) Cristine Rizkallah (University of Melbourne) PROGRAM COMMITTEE: Isabella Stilkerich (Schaeffler Technologies) Ryan Scott (Galois) Facundo Dominguez (Tweag) J. Garrett Morris (University of Iowa) Nada Amin (Harvard University) Tom Ellis (Groq) KC Sivaramakrishnan (IIT Madras and Tarides) Hidehiko Masuhara (Institute of Science Tokyo) WORKSHOP VENUE: Room to be determined. The workshop will be co-located with the ICFP 2025 conference at the Marina Bay Sands Convention Centre, Singapore.

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Call for Participation, Functional Software Architecture (Oct. 17th, Singapore)
by Michael Sperber 25 Mar '25

25 Mar '25

====================================================================== *** FUNARCH 2025 -- CALL FOR PARTICIPATION *** The Third ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large 17th October 2025, Singapore Co-located with ICFP 2025 https://www.functional-architecture.org/events/funarch-2025/ ====================================================================== BACKGROUND: The ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large aims to disseminate and enable the use of functional programming in the large and long-lived software projects. We specifically want: - To assemble a community interested in software architecture techniques and technologies specific to functional programming; - To identify, categorize, and document topics relevant to the field of functional software architecture; - To connect the functional programming community to the software architecture community to cross-pollinate between the two. We'd love for you to be part of this effort. Whatever your background, you're welcome at FUNARCH - to listen to talks, report on your experience, and interact with others that share our goals. See you at FUNARCH! REGISTRATION: You can register for the workshop via the registration page for the ICFP conference, but there's no need to also register for the conference. KEYNOTE: TBD ACCEPTED SUBMISSIONS: TBD PROGRAM CHAIRS: Jeffrey Young (Active Group, Germany) Christina Rizkallah (University of Edinburgh, UK) PROGRAM COMMITTEE: Isabella Stilkerich (Schaeffler Technologies) Ryan Scott (Galois) Facundo Dominguez (Tweag) J. Garrett Morris (University of Iowa) Nada Amin (Harvard University) Tom Ellis (Groq) KC Sivaramakrishnan (IIT Madras and Tarides) Hidehiko Masuhara (Institute of Science Tokyo) WORKSHOP VENUE: The workshop will be co-located with the ICFP 2025 conference at the Marina Bay Sands Convention Centre, Singapore. ======================================================================

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GHC 9.6.7 is now available
by Luite Stegeman 24 Mar '25

24 Mar '25

The GHC developers are very pleased to announce the availability of GHC 9.6.7. Binary distributions, source distributions, and documentation are available at https://downloads.haskell.org/ghc/9.6.7 We hope to have this release available via ghcup shortly. GHC 9.6.7 brings number of fixes, including: - GHC’s internal Unique type has been widened to 64-bits on 32-bit architectures, avoiding potential miscompilations on large projects. - Fix a runtime crash when using the compacting GC, caused by black holes in large objects. - Added new flags -fspec-eval and -fspec-eval-dictfun to allow switching off speculative evaluation. The following libraries have been updated since GHC 9.6.6: - base-4.18.3.0 - filepath-1.4.301.0 - unix-2.8.6.0 - bytestring-0.11.5.4 - array-0.5.8.0 A more detailed description can be found in the [release notes] and a full list of changes in [GHC!13841] and [GHC!13891] Note about Haskell Language Server and building GHC 9.8+: The change of Unique to 64 bit [GHC#22010] adds the exported symbol ghc_unique_counter64 to the RTS. Unfortunately it's impossible to avoid this without breaking other things. If you encounter a linker error related to ghc_unique_counter64 when building GHC (or building a GHC-derived package like ghc-lib-parser) with GHC 9.6.7, you probably have to add this [fix] to the program you're building. 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. Please give this release a try and open a [ticket] if you see anything amiss. ~ Luite [release notes]: https://downloads.haskell.org/ghc/9.6.7/docs/users_guide/9.6.7-notes.html [GHC!13841]: https://gitlab.haskell.org/ghc/ghc/-/merge_requests/13841 [GHC!13891]: https://gitlab.haskell.org/ghc/ghc/-/merge_requests/13891 [GHC#22010]: https://gitlab.haskell.org/ghc/ghc/-/issues/22010 [fix] https://gitlab.haskell.org/ghc/ghc/-/merge_requests/13743 [ticket] https://gitlab.haskell.org/ghc/ghc/-/issues/new

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Thesis-Job: Find the best specification method
by lists0＠freea2a.de 22 Mar '25

22 Mar '25

Dear haskell-list, at Siemens Mobility I would like to improve our specifications. For that, I have the opportunity to teach the properties of our product to a student, and ask him/her to specify the product with more or less of the full power of current specification techniques. The goal for me is, to evaluate existing methods and find the best method. We work intensively with specifications, thus a big level of mathematical formalism can count, as long as the technical team likes to learn and use it. The job offering for a final thesis is at the end of the post. Beside that: What does the list think are methods that are fruitful in a commercial high-quality setting ? The implementation shall not or almost not be changed, we just want a system for test generation and analysis of the required (and hopefully correctly implemented) system. Thank you for your answers! #### Job-offering (German): https://jobs.siemens.com/careers?query=440671&pid=563156121392428&organizat… As part of your work, you can do the following tasks: Search and justify a selection of an existing textual specification method (Domain Specific Language or Framework in a proven programming language). Specify parts of our existing system with the selection and apply the specification, e.g. for test case generation or for the detection of system properties. Examine the practicality of the specification method for daily use. What do you bring? You are studying computer science or a similar field. You already have knowledge of syntax and semantics / specification methods. Ideally, you have knowledge of several imperative languages and knowledge of functional programming (e.g. Haskell, OCaml, ...). Knowledge of machine proving is an advantage. You have good German and English language skills. You can write the work in German, English or bilingual. If you would like to complete a mandatory internship in advance, this is also possible after consultation. -- Mein PGP-Schlüssel-Fingerabdruck: B3CD 2CB8 EC08 B6BD D82C 9BE1 F702 BF50 C4AF 179D oder 88E6 D1E7 9276 BC56 849C CF02 9F96 BE18 43FA 2CC0

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Haskell.org mailing list status
by Ben Gamari 20 Mar '25

20 Mar '25

Hi all, As you may have noticed, yesterday brought an unexpected influx of traffic from haskell.org's mailing lists. This was the result of fixing an interruption in mailing list message delivery which began in late February as a result of on-going infrastructure migration efforts. We are monitoring the situation to ensure that this issue does not recur but if you see anything amiss don't hesitate to contact admin(a)haskell.org. Thank you for your understanding and help! Cheers, - Ben

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Utrecht Summer School on Advanced Functional Programming
by Wouter Swierstra 20 Mar '25

20 Mar '25

# Call for Participation SUMMER SCHOOL ON ADVANCED FUNCTIONAL PROGRAMMING Utrecht, the Netherlands, 07 July – 11 July 2025 http://www.afp.school **Please register before June 15th ** ## ABOUT The Advanced Functional Programming summer school has been running for more than fifteen years. We aim to educate aspiring Haskell programmers beyond the basic material covered by many textbooks. The lectures will cover several more advanced topics regarding the theory and practice of Haskell programming, including topics such as: * lambda calculus; * lazy evaluation; * generalized algebraic data types; * type families and type-level programming; * concurrency and parallelism. The summer school will be held in Utrecht and consists of a mix of lectures, labs, and a busy social program. ## PREREQUISITES We expect students to have a basic familiarity with Haskell already. You should be able to write recursive functions over algebraic data types, such as lists and trees. There is a great deal of material readily available that covers this material. If you've already started learning Haskell and are looking to take your functional programming skills to the next level, this is the course for you. ## DATES Registration deadline: June 15th, 2025 School: 07 July – 11 July 2025 ## COSTS € 950 euro - Profession registration fee € 500 euro - Student registration fee € 200 euro - Housing fee We will charge a registration fee of €950 (or €500 for students) to cover our expenses. This fee includes all lunches, dinners, and coffee breaks - you won't need to budget much else besides your travel. If this is problematic for you for any reason at all, please email the organisers and we can try to offer you a discounted rate or a fee waiver. We have a limited number of scholarships or discounts available for students that would not be able to attend otherwise, especially for women and under-represented minorities. ## FURTHER INFORMATION Further information, including instructions on how to register, is available on our website: http://www.afp.school

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ZuriHac 2025 takes place 7-9 June, Registration Open
by Farhad D. Mehta 20 Mar '25

20 Mar '25

Dear Friends of Haskell, It is our pleasure to announce that ZuriHac 2025 will take place Saturday 7 June – Monday 9 June 2025 as a physical event at the Rapperswil-Jona campus of the OST Eastern Switzerland University of Applied Sciences. ZuriHac is the biggest Haskell community event in the world: a completely free, three-day grassroots coding festival co-organized by the Zürich Friends of Haskell and the OST Eastern Switzerland University of Applied Science. It is not your standard conference with papers and presentations, but features fantastic keynotes, hands-on tracks, hacking on many of your favourite projects, and of course lots of socializing! This year’s keynote speakers currently include Lennart Augustson (current holder of the record for most number of Haskell compiler implementations), Rebecca Skinner (author of “Effective Haskell”), and Brent Yorgey (of “Diagrams” and “Swarm” fame). Further keynote speaker and track announcements will be made on our website. For an idea of what to expect, have a look at last year’s schedule on https://zfoh.ch/zurihac2024/ and a video impression of last year’s event at https://youtu.be/SMIdDqZxrUk?si=Jvl1LpuanFJHglSC . We also welcome beginners or people unfamiliar to Haskell who are curious to learn more. There will be an organised beginners’ track as well as many mentors from the Haskell community happy to answer all your questions. ZuriHac Prelude: Two days prior to ZuriHac, the Haskell Foundation and OST will organize the Haskell Ecosystem Workshop (HEW) and the Haskell Implementors’ Workshop (HIW - formerly co-located with the ICFP) at the same venue. Details will be posted to the ZuriHac website as they become available. You can find more information about the event and register at https://zurihac.info <https://zurihac.info/>. The event is free for participants. This is only possible with the help of our generous supporters, who are currently: - The Haskell Foundation - IOHK - OST - Tweag - Well-Typed In case you would like to support ZuriHac, as a company or as an individual, please get in touch with us. We would be grateful. Bank details for monetary donations can be found at https://zfoh.ch/#donations. We hope to see you there! The Zurich Friends of Haskell

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CfP: GPCE 2025
by Jeremy Yallop 20 Mar '25

20 Mar '25

[GPCE is co-located with ECOOP rather than SPLASH this year, so the deadline is earlier than usual.] ========================================================= GPCE 2025 24th International Conference on Generative Programming: Concepts & Experiences -- 3-4 July, 2025, co-located with ECOOP Bergen, Norway CALL FOR PAPERS https://2025.ecoop.org/home/gpce-2025 ========================================================= The ACM SIGPLAN International Conference on Generative Programming: Concepts & Experiences (GPCE) is a programming languages conference focusing on techniques and tools for code generation, language implementation, and product-line development. This is the 24th edition of the conference, co-located with the ECOOP 2025 conference in Bergen, Norway. ================== Topics of Interest =================== GPCE seeks conceptual, theoretical, empirical, and technical contributions to its topics of interest, which include but are not limited to: * program transformation, staging, * macro systems, preprocessors, * program synthesis, * code-recommendation systems, * domain-specific languages, * generative language workbenches, * language embedding, language design, * domain engineering, * software product lines, configurable software, * feature interactions, * applications and properties of code generation, * language implementation, * AI/ML techniques for generative programming, * generative programming for AI/ML techniques, * low code / no code approaches. GPCE promotes cross-fertilization between programming languages and software development and among different styles of generative programming in its broadest sense. Authors are welcome to check with the PC chair whether their planned papers are in scope. =================== Paper Categories ==================== GPCE solicits four kinds of submissions: Full Papers: reporting original and unpublished results of research that contribute to scientific knowledge for any GPCE topics. Full paper submissions must not exceed 12 pages excluding the bibliography. Short Papers: presenting unconventional ideas or new visions in any GPCE topics. Short papers do not always contain complete results as in the case of full papers, but can introduce new ideas to the community and get early feedback. Note that short papers are not intended to be position statements. Accepted short papers are included in the proceedings and will be presented at the conference. Short paper submissions must not exceed 6 pages excluding the bibliography, and must have the text “(Short Paper)” appended to their titles. Tool Demonstrations: presenting tools for any GPCE topics. Tools must be available for use and must not be purely commercial. Submissions must provide a tool description not exceeding 6 pages excluding bibliography and a separate demonstration outline including screenshots also not exceeding 6 pages. Tool demonstration submissions must have the text “(Tool Demonstration)” appended to their titles. If they are accepted, tool descriptions will be included in the proceedings. The demonstration outline will only be used for evaluating the submission. Generative Pearls: are elegant essays about generative programming. Examples include but are not limited to an interesting application of generative programming and an elegant presentation of a (new or old) data structure using generative programming (similar to Functional Pearl in ICFP and Pearl in ECOOP). Accepted Generative Pearl papers are included in the proceedings and will be presented at the conference. Generative Pearl submissions must not exceed 12 pages excluding the bibliography, and must have the text “(Generative Pearl)” appended to their titles. =================== Paper Selection ===================== The GPCE program committee will evaluate each submission according to the following selection criteria: Novelty. Papers must present new ideas or evidence and place them appropriately within the context established by previous research in the field. Significance. The results in the paper must have the potential to add to the state of the art or practice in significant ways. Evidence. The paper must present evidence supporting its claims. Examples of evidence include formalizations and proofs, implemented systems, experimental results, statistical analyses, and case studies. Clarity. The paper must present its contributions and results clearly. ==================== Important Dates ==================== Abstract Submission: Wed 26 Mar 2025 Paper Submission: Wed 2 Apr 2025 Review Notification: Fri 9 May 2025 Author Response: Mon 12 May 2025 Final Notification: Mon 19 May 2025 Conference: Thu 3 - Fri 4 July, 2025 ===================== Organization ====================== PC Chair: Nada Amin, Harvard General Co-Chair: Sebastian Erdweg, JGU Mainz General Co-Chair: Amir Shaikhha, University of Edinburgh Publicity Chair: Jeremy Yallop, University of Cambridge ======================= PC Members ====================== Bernhard Rumpe, RWTH Aachen University Casper Bach Poulsen, University of Southern Denmark Cyrus Omar, University of Michigan Eli Tilevich, Virginia Tech Elisa Gonzalez Boix, Vrije Universiteit Brussel Geoffrey Mainland, Drexel University Georg Ofenbeck Guillaume Allais, University of Strathclyde Jeremy Yallop, University of Cambridge Judith Michael, RWTH Aachen University Julia Lawall, Inria Kenichi Asai, Ochanomizu University Klaus Ostermann, University of Tuebingen L. Thomas van Binsbergen, University of Amsterdam Lionel Parreaux, The Hong Kong University of Science and Technology Malte Lochau, University of Siegen Maryam Mehri Dehnavi, University of Toronto Michel Steuwer, Technische Universität Berlin Ondřej Lhoták, University of Waterloo Parisa Ataei, Cornell University Philiip Wadler, University of Edinburgh Robert Glück, DIKU, Dept. of Computer Science, Univ. of Copenhagen Ruby Tahboub, University of Illinois Urbana-Champaign Sandro Stucki, Amazon Prime Video Automated Reasoning Sheng Chen, UL Lafayette Shigeru Chiba, University of Tokyo Shoaib Kamil, Adobe Research Simon Fowler, University of Glasgow Tijs van der Storm, CWI Ulrik Pagh Schultz Lundquist, University of Southern Denmark Vadim Zaytsev, Universiteit Twente Walter Binder, Università della Svizzera italiana (USI) Yukiyoshi Kameyama, University of Tsukuba Zena Ariola, University of Oregon

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Midlands Graduate School - registration now open
by Graham Hutton 18 Mar '25

18 Mar '25

Dear all, Registration is now open for the Midlands Graduate School (MGS) in the Foundations of Computing Science, 7-11 April 2025, Sheffield, UK. Eight fantastic courses on category theory, type theory, coalgebra, semantics and more. Spaces are limited, so please register early to secure your place. Please share in your communities! 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 - Four Lectures on 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: The registration fee is £300 for academic participants, and £500 for industry participants. The fee includes all lecture courses and example classes, lunch and coffee breaks. The registration deadline is ** Monday 17th March **. Spaces are limited, so please register early to secure your place. 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. ========================================================== — Professor Graham Hutton School of Computer Science University of Nottingham, UK http://www.cs.nott.ac.uk/~pszgmh 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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[ANN] Copilot 4.3
by Ivan Perez 17 Mar '25

17 Mar '25

Hi everyone!! We are really excited to announce Copilot 4.3 [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 updates, bug fixes and improvements to Copilot: - Specifications now produce information about counterexamples when copilot-theorem is able to prove the property false. - We introduce a new Prop construct in copilot-core that captures the quantifier used in a property. - The What4 backend of Copilot theorem now produces an exception when trying to prove an existential property. The restriction of not being able to handle existentially quantified properties already existed, but due to information loss during the reification process, the quantifier was being lost and all properties to be proved via what4 were being treated as a universally quantified. - Several deprecated functions have been removed. - The installation instructions have been updated. - Compatibility with GHC 9.10 is now explicitly listed in the README. - Several typos have been fixed in comments and documentation. The new implementation is compatible with versions of GHC from 8.6 to 9.10. This release has been made possible thanks to key submissions from Ryan Scott (Galois) and Esther Conrad (NASA), 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. For details on this release, see [1]. https://github.com/Copilot-Language/copilot/releases/tag/v4.3. As always, we're releasing exactly 2 months since the last release. Our next release is scheduled for May 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 using Copilot for full data processing applications (e.g, system control, arduinos, rovers, drones), improving usability, performance, and stability, increasing 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/v4.3 [2] https://hackage.haskell.org/package/copilot [3] https://github.com/nasa/ogma [4] https://github.com/Copilot-Language/copilot

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GHC 9.12.2 is now available
by Ben Gamari 15 Mar '25

15 Mar '25

The GHC developers are happy to announce the release of GHC 9.12.2. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org] We hope to have this release available via `ghcup` shortly. This is a small release fixing a critical code generation bug, #25653, affecting some subword division operations. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status]. We would like to thank 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 who contribute their code, tickets, and energy to the GHC project. As always, do give this release a try and open a [ticket] if you see anything amiss. [release notes]: https://downloads.haskell.org/ghc/9.12.2/docs/users_guide/9.12.2-notes.html [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.2 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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Internship opportunity at NASA Ames Research Center -- Deadline Feb 28
by Ivan Perez 27 Feb '25

27 Feb '25

All, We have an opening for an internship opportunity at NASA Ames Research Center working on a Haskell project. The deadline is tomorrow Friday, Feb 28. I've posted the details here: https://www.reddit.com/r/haskell/comments/1ixmlei/haskell_internship_openin… Please have any students who qualify apply ASAP. Thanks, Ivan

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GHC API stability initiative
by Facundo Domínguez 20 Feb '25

20 Feb '25

Dear all, At the end of last year I started collecting feedback from tool maintainers about the costs of dealing with GHC as a library. Eventually the feedback will be used to propose some actions to reduce these costs. Here's the last update on the initiative [1]. [1] https://discourse.haskell.org/t/ghc-api-stability-update-3/11407 This message is to broadcast the invitation for tool maintainers to share their feedback. I can be reached at facundo.dominguez(a)tweag.io, or you can reach me in the discourse thread as well. Best, Facundo

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Midlands Graduate School 2025 hosted by the University of Sheffield
by Andrei Popescu 18 Feb '25

18 Feb '25

Dear Colleagues, This year's Midlands Graduate School in the Foundations of Computing Science will take place at the University of Sheffield. We have some great lecturers and topics. (Below you can also find information about fees. The registration site will open soon.) Best wishes, Andrei 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 - Four Lectures on 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 FEES AND REGISTRATION The fees for MGS 25, which also cover catering (including coffee, pastries and lunch) during the day and optionally the conference dinner, are as follows. - Academic participant: £300, plus an optional £30 dinner ticket for Wednesday evening. - Industry participant: £500, plus an optional £30 dinner ticket for Wednesday evening. Registration will be open shortly. 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.

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using the same data structure on a type level and as a value
by Zoran Bošnjak 15 Feb '25

15 Feb '25

Dear haskellers, I would like to reuse some (complex) data structures at a type level and as a regular value. The intention is to have the original specification on the type level (something like web API in Servant). But the idea is also to be able to convert the same structure to the value (of the same shape) and print it for example. There is no need to go from values back to types. I am not sure if Generic could help me do the conversion or do I need Typeable or even something else. I would like to avoid template haskell if possible, but please do advice if TH is the way to go in such cases. In my case, the data type structure is suppose to be the same, with the only difference being the 2 "primitives", which is: number is (Nat or Integer, depending on the usecase) and text is (Symbol or String). My attempt was something like this. import GHC.Generics -- not sure if this is required, but deriving works OK import GHC.TypeLits data Usecase = TypeLevel | ValueLevel -- Generic Int is 'Nat' or 'Integer'. type family GInt (u :: Usecase) where GInt 'TypeLevel = Nat GInt 'ValueLevel = Integer -- Generic Text is 'Symbol' or 'Text'. type family GText (u :: Usecase) where GText 'TypeLevel = Symbol GText 'ValueLevel = String -- Positive/zero or negative value. data PlusMinus = Plus | Minus deriving (Generic, Show) -- Now we can define generic plus/minus number. data PMInt (u :: Usecase) = PMInt PlusMinus (GInt u) deriving (Generic) deriving instance Show (PMInt 'ValueLevel) -- And we also define some more complex structure. data GNumber (u :: Usecase) = GNumInt (PMInt u) | GNumDiv (GNumber u) (GNumber u) | GNumPow (PMInt u) (PMInt u) deriving (Generic) deriving instance Show (GNumber 'ValueLevel) data GTest (u :: Usecase) = GTest [GInt u] [GText u] deriving (Generic) deriving instance Show (GTest 'ValueLevel) -- This does not work, but the idea is to define some type aliases -- In real application, this will be a huge list of structure descriptions (as types) type Example1 = 'PMInt 'Plus 3 -- GHC does not like '3' here?? type Example2 = 'PMInt 'Minus 4 type Example3 = 'GNumInt Example1 type Example4 = 'GNumDiv Example3 Example3 type Example5 = 'GTest '[ 1, 2, 3 ] '[ "Test1", "Test2"] -- 'convert' implementation ?? -- ... and be able to convert types to values, something like this val1 :: PMInt 'ValueLevel val1 = convert @Example1 -- ... or print it directly f :: IO () f = print ( convert @Example1, convert @Example2, convert @Example3 , convert @Example4, convert @Example5) Appreciate your suggestions. regards, Zoran

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Re: [Haskell-cafe] Course-of-value recursion by defining a sequence as a self-referential infinite list
by Douglas McIlroy 10 Feb '25

10 Feb '25

> catalanNumbers :: Num a => [a] > catalanNumbers = > let xs = 1 : PowerSeries.mul xs xs > in xs This example of a generating function come to life as a program deserves to be better known. Bill Burge presented it 50 years ago in "Recursive Programming Techniques", Addison-Wesley, 1975. I revisited it in "Power series, power serious", JFP 9 (1999) 323-335, where, with overloadied arithmetic, it became ts = 1 : ts^2 The technique is laid bare in ten one-liners at https://www.cs.dartmouth.edu/~doug/powser.html. Doug

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A Conversation With Sandy Maguire - Melbourne Haskell Users' Group - 28-03-2024
by John Walker 10 Feb '25

10 Feb '25

Hi All, Our interview with Sandy Maguire at Melbourne Haskell Users' Group, (now Melbourne Compose Group) is now on [YouTube](https://youtu.be/dnHIsr6gGnE). Sandy is well known in the Haskell and broader FP community, particularly as the author of: - [Thinking With Types](https://leanpub.com/thinking-with-types) - [Algebra Driven Design](https://leanpub.com/algebra-driven-design) - [Certainty By Construction](https://leanpub.com/certainty-by-construction) John

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Re: [Haskell-cafe] Course-of-value recursion by defining a sequence as a self-referential infinite list
by Douglas McIlroy 09 Feb '25

09 Feb '25

>> Karczmarczuk’s solution via the Haskell prelude: >> >> part = 1 : b 1 >> where b n = (1 : b (n + 1)) + (replicate n 0 ++ b n) >> > This is broken code, no?, just 2 reasons I can spot why: > - function 'b n' calls 'b n' unconditionally (infite loop) > - What is the reutrn type of 'b'? It seems like it returns list, but the > return value is in the form 'a + b' , where (+) is instance of num so > I don't think prelude contains any ad-hoc definition of (+) that > returns list Not broken, just insufficiently documented. "part "is supposed to produce an infinite stream whose nth element is the number of distinct representations of n as a sum of positive integers. The "infinite loop" is deliberate, quite like ones = 1 : ones which generates an infinite sequence of 1s. It is not stated, but the (+) is understood to have been overloaded to handle lists of Nums in the natural way Doug

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[ANN] NASA's Ogma 1.6.0
by Ivan Perez 05 Feb '25

05 Feb '25

Hi everyone! I'm thrilled to announce the release of Ogma 1.6.0! NASA's Ogma is a mission assurance tool that facilitates integrating runtime monitors or runtime verification applications into other systems. Use cases supported by Ogma include producing Robot Operating System (ROS 2) packages [3], NASA Core Flight System (cFS) applications [4], and components for FPrime [1] (the software framework used for the Mars Helicopter). Ogma is also one of the solutions recommended for monitoring in Space ROS applications [2]. Ogma is fully written in Haskell, and leverages existing Haskell work, like the Copilot language [5] (also funded by NASA) and BNFC [6]. For more details, including videos of monitors being generated and flown in simulators, see: https://github.com/nasa/ogma * What's changed This major release includes the following improments: - Update Ogma to be able to extract data from XML files, including standard formats used in MBSE tools. - Provide a new diagram command capable of generating state machine implementations from diagrams. - Make the ROS and F' backend able to use any JSON- or XML files as input, makes the ROS, F', standalone backends capable of using literal Copilot expressions in requirements and state transitions. - Extend Ogma to be able to use external tools to translate requirements, including LLMs. - Make the F' backend able to use templates. - Allow users to provide custom definitions for XML and JSON formats unknown to the tool. - Fixes several other smaller maintenance issues. - Upgrades the README to include instructions for external contributors. This constitutes the single largest release of Ogma in number of new features added, since its first release. For details about the release, see: https://github.com/nasa/ogma/releases/tag/v1.6.0 * Releases Ogma is released as a collection of packages in Hackage. The entry point is https://hackage.haskell.org/package/ogma-cli. * Code The github repo is located at: https://github.com/nasa/ogma. * What's coming The next release is planned for Mar 21st, 2025. We are currently working on a GUI for Ogma that facilitates collecting all mission data relative to the design, diagrams, requirements and deployments, and help users refine designs and requirements, verify them for correctness, generate monitors and full applications, follow live missions, and produce reports. We also want to announce that both Ogma and Copilot can now accept contributions from external users, and we are also keen to see students use them for their school projects, their final projects and theses, and other research. If you are interested in collaborating, please reach out to ivan.perezdominguez(a)nasa.gov. We hope that you are as excited as we are and that our work demonstrates that, with the right support, Haskell can reach farther than we ever thought possible. Happy Haskelling! Ivan [1] https://github.com/nasa/fprime [2] https://space.ros.org/ [3] https://www.ros.org/ [4] https://github.com/nasa/cFS [5] https://github.com/Copilot-Language/copilot [6] https://github.com/BNFC/bnfc

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