July 2024 - Haskell-Cafe

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

04 Nov '24

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

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Haskell Implementors' Workshop - Change of date
by Matthew Pickering 29 Jul '24

29 Jul '24

This year the decision has been taken to combine together Haskell Implementors' Workshop and Haskell Symposium. Therefore the workshop will now take place on the dates September 6/7 (the dates of the Haskell Symposium). Please email me if you have any questions. Cheers, Matt

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[ANN] streamly-0.10 with fast binary serialization
by Harendra Kumar 29 Jul '24

29 Jul '24

Streamly is a concurrent stream and array library supporting a wide range of functionality. Important features in the new release include: (1) fast binary serialization to arrays with an option to serialize record field names; (2) the array type can now represent pinned as well unpinned memory, unifying the representations used by bytestring, text and vector; and (3) concurrency support for folds. For more details, see this post: https://blog.composewell.com/v0/posts/streamly-release-0.10.0.html . -harendra

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Call for Participation, Functional Software Architecture (Sep 6, Milan)
by Michael Sperber 29 Jul '24

29 Jul '24

====================================================================== *** FUNARCH 2024 -- CALL FOR PARTICIPATION *** The Second ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large 6th September 2024, Milan, Italy Co-located with ICFP 2024 https://www.functional-architecture.org/events/funarch-2024/ ====================================================================== 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. Reduced fees are available until 5th August. http://icfp24.sigplan.org/attending/registration KEYNOTE: Architecting Functional Programs Marco Sampellegrini ACCEPTED SUBMISSIONS: F3: A Compiler For Feature Engineering Weixi Ma, Arnaud Venet, Junhua Gu, Subbu Subramanian, Siyu Wang, Rocky Liu (Meta) Daniel Friedman, Yafei Yang (Indiana University) Design and implementation of a verified interpreter for additive manufacturing programs Matthew Sottile, Mohit Tekriwal (Lawrence Livermore National Laboratory) Applying Continuous Formal Methods to Cardano James Chapman, Arnaud Bailly, Polina Vinogradova (IOHK) Continuations: what have they ever done for us? Marc Kaufmann (Austriae Central European University), Bogdan Popa Bidirectional Data Transformations Marcus Crestani, Markus Schlegel, Marco Schneider (Active Group) PROGRAM CHAIRS: Mike Sperber (Active Group, Germany) Perdita Stevens (University of Edinburgh, UK) PROGRAM COMMITTEE: Annette Bieniusa (University of Kaiserslautern) Jeffrey Young (IOG) Will Crichton (Brown University) Isabella Stilkerich (Schaeffler Technologies AG) Kiko Fernandez-Reyes (Ericsson) Ryan Scott (Galois) Satnam Singh (Groq) Facundo Dominguez (Tweag) Ilya Sergey (University of Singapore) Martin Elsman (University of Copenhagen) Benjamin Pierce (University of Pennsylvania) Matthew Flatt (University of Utah) Nada Amin (Harvard University) Richard Eisenberg (Jane Street) WORKSHOP VENUE: The workshop will be co-located with the ICFP 2024 conference at the Milano Convention Centre, Milan, Italy. ======================================================================

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Functional Conf 2024 - Bengaluru, India
by John Sinclair 25 Jul '24

25 Jul '24

===================================================================== Call for Proposals Functional Conf 2024 21-23 November Bengaluru, India https://functionalconf.com <https://igafnl.com/click?redirect=https%3A%2F%2Ffunctionalconf.com&dID=1721…> ===================================================================== You are invited to join us for 3 days in-person for Functional Conf, Asia's Premier Functional Programming Conference. Immerse yourself in thought-provoking sessions led by top-notch speakers, engage in hands-on workshops to elevate your coding skills, and network with like-minded professionals. Whether you’re a seasoned pro or a curious beginner, this conference promises to ignite your passion for Functional Programming and revolutionize the way you approach software development. Don’t miss out on this exciting opportunity to be a part of the future of technology. *Call for Proposals is currently open* The stage is set for you to showcase your expertise at our upcoming event through our Call for Proposals. Whether you’re eager to deliver a captivating talk, lead a dynamic demonstration, present a compelling case study, offer an insightful tutorial, share an experience report, or facilitate an engaging workshop of Functional Programming in action, we welcome your submissions with open arms. * Submit a Proposal (deadline: 1 September 2024) https://confengine.com/conferences/functional-conf-2024/proposals <https://igafnl.com/click?redirect=https%3A%2F%2Fconfengine.com%2Fconference…> * Registration: https://confengine.com/conferences/functional-conf-2024/register/selection <https://igafnl.com/click?redirect=https%3A%2F%2Fconfengine.com%2Fconference…> Early bird tickets still available! We hope to see you there!

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Strange kind error when using Lens.traverseOf
by Henning Thielemann 23 Jul '24

23 Jul '24

I have this simplified module: module Ganeti.LensPlain where import Control.Lens (LensLike, traverseOf) import Data.Functor.Compose (Compose(..)) traverseOf2 :: LensLike (Compose f g) s t a b -> (a -> f (g b)) -> s -> f (g t) traverseOf2 k f = getCompose . traverseOf k (Compose . f) With ghc-9.2 and later I get this kind error: src/Ganeti/LensPlain.hs:8:32: error: [GHC-25897] • Couldn't match kind ‘k2’ with ‘*’ When matching types Compose f g0 :: * -> * Compose f g :: k2 -> * Expected: s -> Compose f g t Actual: s -> Compose f g0 t0 ‘k2’ is a rigid type variable bound by the type signature for: traverseOf2 :: forall {k1} {k2} (f :: k1 -> *) (g :: k2 -> k1) s (t :: k2) a (b :: k2). LensLike (Compose f g) s t a b -> (a -> f (g b)) -> s -> f (g t) at src/Ganeti/LensPlain.hs:7:1-79 • In the second argument of ‘(.)’, namely ‘traverseOf k (Compose . f)’ In the expression: getCompose . traverseOf k (Compose . f) In an equation for ‘traverseOf2’: traverseOf2 k f = getCompose . traverseOf k (Compose . f) • Relevant bindings include f :: a -> f (g b) (bound at src/Ganeti/LensPlain.hs:8:15) k :: LensLike (Compose f g) s t a b (bound at src/Ganeti/LensPlain.hs:8:13) traverseOf2 :: LensLike (Compose f g) s t a b -> (a -> f (g b)) -> s -> f (g t) (bound at src/Ganeti/LensPlain.hs:8:1) | 8 | traverseOf2 k f = getCompose . traverseOf k (Compose . f) | ^^^^^^^^^^^^^^^^^^^^^^^^^^ GHC-9.0 accepts the code. Also GHC-9.2 accepts it when the module is compiled as part of a larger Cabal project! I thought that (.) would cause the problem, but manually inlining it does not help. I compiled with: $ ghc-9.6.6 -package lens -c src/Ganeti/LensPlain.hs

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ICFP 2024: Call for Participation
by ICFP Publicity 22 Jul '24

22 Jul '24

===================================================================== Call for Participation The 29th ACM SIGPLAN International Conference on Functional Programming (ICFP 2024) and affiliated events https://icfp24.sigplan.org Milan, Italy; Sep 2-7, 2024 ===================================================================== ICFP is a celebration of the art and science of functional programming, providing a forum for researchers and developers to engage on a variety of topics, from foundations to features, and from abstraction to application. You are invited to participate in a full week dedicated to functional programming, featuring the ICFP main conference as well as several other related events. * Accepted Papers: https://icfp24.sigplan.org/track/icfp-2024-papers#event-overview * Registration: https://icfp24.sigplan.org/attending/registration The early-bird deadline is August 3, 2024 * Venue: Allianz MiCo (Milano Convention Centre) https://icfp24.sigplan.org/venue/icfp-2024-venue There are several events affiliated with ICFP: September 2 HOPE - https://icfp24.sigplan.org/home/hope-2024 PLMW - https://icfp24.sigplan.org/home/PLMW-ICFP-2024 HIW - https://icfp24.sigplan.org/home/hiw-2024 Erlang - https://icfp24.sigplan.org/home/erlang-2024 FARM - https://icfp24.sigplan.org/home/farm-2024 September 3-5 ICFP - Main conference September 6 Tutorials (Sep 6-7) - https://icfp24.sigplan.org/track/icfp-2024-tutorials FProPer - https://icfp24.sigplan.org/home/fproper-2024 ML - https://icfp24.sigplan.org/home/mlworkshop-2024 Haskell (Sep 6-7) - https://icfp24.sigplan.org/home/haskellsymp-2024 TyDe - https://icfp24.sigplan.org/home/tyde-2024 miniKanren - https://icfp24.sigplan.org/home/minikanren-2024 FUNARCH - https://icfp24.sigplan.org/home/funarch-2024 September 7 Tutorials (Sep 6-7) - https://icfp24.sigplan.org/track/icfp-2024-tutorials Scheme - https://icfp24.sigplan.org/home/scheme-2024 OCaml - https://icfp24.sigplan.org/home/ocaml-2024 Haskell (Sep 6-7) - https://icfp24.sigplan.org/home/haskellsymp-2024 Conference organizers: https://icfp24.sigplan.org/committee/icfp-2024-organizing-committee =====================================================================

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POPL 2025: Final Call for Workshops and Co-located Events (July 26 AOE)
by Ningning Xie 19 Jul '24

19 Jul '24

FINAL CALL FOR WORKSHOPS AND CO-LOCATED EVENTS POPL 2025 52nd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages Sun 19 - Sat 25, January 2025 Denver, Colorado, United States https://popl25.sigplan.org The 52nd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages (POPL 2025) will be held in Denver, Colorado, United States. POPL provides a forum for the discussion of fundamental principles and important innovations in the design, definition, analysis, transformation, implementation and verification of programming languages, programming systems, and programming abstractions. Events focusing on experimental and theoretical topics are welcome. Proposals are invited for workshops and other events to be co-located with POPL 2025. All co-located events are sponsored by SIGPLAN ( http://acm.org/sigplan/) Workshops should be more informal and focused than POPL itself, and include sessions that enable interaction among the workshop attendees. The preference is for one-day workshops, but other schedules can also be considered. --------------------------------------------------------------------- Submission details Deadline for submission: 26 July 2024 Notification of acceptance: 2 August 2024 A workshop proposal should provide the following information: * Name of the workshop. * Duration of the workshop. * Whether the workshop will be Conference-approved or SIGPLAN-approved (see below). * Organizers: names, affiliation, contact information, brief (100 words) biography. * A short description (150-200 words) of the topic. * Event format: workshop; type of submissions if any; review process; results dissemination. * Expected attendance and target audience. * Potential PC members - please do not contact them before the workshop is approved. * History of the workshop. * Plans for remote participation Proposals must be submitted in PDF form by email with the subject POPL 2025 Workshop Proposal: [workshop name], to the workshop co-chairs: Christoph Matheja (chmat(a)dtu.dk) and Robert Rand (rand(a)uchicago.edu) --------------------------------------------------------------------- SIGPLAN Sponsorship POPL co-located events are sponsored by SIGPLAN (http://sigplan.org/) There are two kinds of co-located events: Conference-approved (no proceedings) and SIGPLAN-approved (proceedings in the ACM Digital Library). See http://www.sigplan.org/Resources/Guidelines/Workshops/ for more information, including a full listing of prescriptions for Conference-approved and SIGPLAN-approved workshops. SIGPLAN-approved workshops must respect the SIGPLAN Diversity Policy. Proposals for SIGPLAN-approved workshops must additionally include the gender, country of affiliation, and professional status of potential PC members. See https://www.sigplan.org/Resources/Policies/Diversity/ for more details. --------------------------------------------------------------------- Selection committee All submissions will be evaluated by a committee comprising the workshops co-chairs, the general chair, and the program chair. --------------------------------------------------------------------- Further information Any questions regarding POPL 2025 co-located event proposals should be addressed to the workshops chairs Christoph Matheja (chmat(a)dtu.dk) and Robert Rand (rand(a)uchicago.edu)

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Call for Papers: Scheme ‘24 (extended deadline: July 25th)
by Kristopher K Micinski 15 Jul '24

15 Jul '24

-------------------------------------------------------------------------------- CALL FOR PAPERS The 2024 Workshop on Scheme and Functional Programming Co-located with ICFP 2024 (Milan, Italy) https://icfp24.sigplan.org/home/scheme-2024 -------------------------------------------------------------------------------- The 2024 Scheme and Functional Programming Workshop is calling for submissions. We invite high-quality papers and talk proposals about novel research results, lessons learned from practical experience in an industrial or educational setting, and even new insights on old ideas. We welcome and encourage submissions that apply to any dynamic functional language, especially those that can be considered a Scheme: from strict subsets of RnRS to other "Scheme" implementations, to Racket, to Lisp dialects including Clojure, Emacs Lisp, Common Lisp, to functional languages with continuations and/or macros (or extended to have them) such as Dylan, ECMAScript, Hop, Lua, Scala, Rust, etc. The elegance of the paper and the relevance of its topic to the interests of Schemers will matter more than the surface syntax of the examples used. * Topics Topics of interest include (but are not limited to): - Interaction: program-development environments, debugging, testing, refactoring - Implementation: interpreters, compilers, tools, garbage collectors, benchmarks - Extension: macros, hygiene, domain-specific languages, reflection, and how such extension affects interaction - Expression: control, modularity, ad hoc and parametric polymorphism, types, aspects, ownership models, concurrency, distribution, parallelism, non-determinism, probabilism, and other programming paradigms - Integration: build tools, deployment, interoperation with other languages and systems - Formal semantics: theory, analyses and transformations, partial evaluation - Human factors: past, present and future history, evolution and sociology of the language Scheme, its standard and its dialects - Education: approaches, experiences, curricula - Applications: industrial uses of Scheme - Scheme pearls: elegant, instructive uses of Scheme * Dates - Submission deadline is Thursday July 25, 2024 (extended). - Authors will be notified by Monday August 12, 2024. - Camera-ready versions are due Thursday August 29, 2024. - Workshop will be held in Milan, Italy on Saturday September 7, 2024. All deadlines are 23:59 UTC-12, anywhere on Earth. * Submission Information We encourage all kinds of submissions, including full papers, experience reports, and lightning talks. Papers and experience reports are expected to be 10–24 pages in length using the single-column SIGPLAN acmart style. (For reference, this is about 5–12 pages of the older SIGPLAN 2-column 9pt style.) Abstracts submitted for lightning talks should be limited to 192 words. Authors of each accepted submission are invited to attend and be available for the presentation of that paper at the conference. The schedule for presentations will be determined and shared with authors after the full program has been selected. The size limits above exclude references and any optional appendices. There are no size limits on appendices, but the papers should stand without the need to read them, and reviewers are not required to read them. Authors are encouraged to publish any code associated to their papers under an open source license, so that reviewers may try the code and verify the claims. Proceedings will be uploaded to arXiv.org (https://arXiv.org/) Publication of a paper at this workshop is not intended to replace conference or journal publication, and does not preclude re-publication of a more complete or finished version of the paper at some later conference or in a journal. Please submit papers through the workshop's HotCRP site (https://scheme2024.hotcrp.com/) * Lightweight double-blind reviewing Scheme 2024 will use lightweight double-blind reviewing. Submitted papers must omit author names and institutions and reference the authors’ own related work in the third person (e.g., not “we build on our previous work…” but rather “we build on the work of…”). The purpose is to help the reviewers come to an initial judgment about the paper without bias, not to make it impossible for them to discover the authors if they were to try. Nothing should be done in the name of anonymity that weakens the submission or makes the job of reviewing the paper more difficult (e.g., important background references should not be omitted or anonymized). * Formatting Information Full papers and experience reports should use the SIGPLAN acmsmall option to acmart. We recommend using the anonymous and review options to acmart when submitting a paper; these options hide the author names and enable line numbers for easy reference in review. LaTeX and Microsoft Word templates for this format are available through SIGPLAN (https://www.sigplan.org/Resources/Author/) Lightning talks can be submitted as either a text file or a PDF file. * Workshop Organization Organizing Committee: Kristopher Micinski (Syracuse University, United States) Youyou Cong (Tokyo Institute of Technology, Japan) Program Committee: Julia Belyakova (Purdue University, United States) Kimball Germane (Brigham Young University, United States) Yuki Nishida (Tohoku University, Japan) Gabriel Scherer (Inria Saclay, France) Philipp Schuster (University of Tübingen, Germany) Taro Sekiyama (National Institute of Informatice, Japan) Michael Sperber (Active Group GmbH, Germany)

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