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PLMW @ ICFP 2026: Funding Call
by conrad.watt＠ntu.edu.sg 29 May '26

29 May '26

APPLICATION FOR PLMW TRAVEL FUNDING Applications for travel funding to PLMW @ ICFP are now open - we will begin awarding funding starting from June 1 AOE until all funding is committed. So long as funding remains, we will continue to consider applications submitted before June 30th AOE. We advise all interested to apply as soon as possible, especially if a visa is required. https://icfp26.sigplan.org/home/PLMW-ICFP-2026#Call-for-Participation The application can be accessed directly at the following URL: https://forms.gle/adtuWjLAbBtGTcCNA PLMW is a workshop co-located with ICFP 2026 (the International Conference on Functional Programming) in Indanapolis, US, from August 24-29. The purpose of this mentoring workshop is to encourage graduate students and senior undergraduate students to pursue careers in programming language research. This workshop will bring together world leaders in programming languages research and teaching from academia and industry to help students imagine how they might contribute to our research community. Topics will range from the abstract (e.g., what is PL research and how does one become involved in it) to the concrete (e.g., how to navigate an academic conference, how to pick a research area) as well as technical talks on cutting-edge topics. See the link below for more details: https://icfp26.sigplan.org/home/PLMW-ICFP-2026

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[ANN] Copilot 4.7.1
by Ivan Perez 28 May '26

28 May '26

Hi café! We are really excited to announce Copilot 4.7.1 [1]. Copilot is a stream-based EDSL in Haskell for writing and monitoring embedded systems, 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 and with rovers. Through the NASA tool Ogma [2] (also written in Haskell), Copilot also serves as a programming language and runtime framework for NASA's Core Flight System, Robot Operating System (ROS 2) and 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 improvements to Copilot: - Fix corner cases in the treatment of special floating point numbers in the Bluespec backend and `copilot-theorem`. - Fix errors in examples in `copilot-theorem` that use Z3. - Add to `copilot-libraries` a module to perform sanity checks of Copilot specifications. - Add to `copilot-libraries` a module to facilitate implementing state machines. Copilot is compatible with versions of GHC from 8.6 to 9.10. Packages are published on Hackage [3], as well as several Linux distributions (e.g., Debian, Fedora). This release has been possible thanks to submissions from Ryan Scott (Galois) and Chris Hathhorn (Galois). We are grateful to them for their contributions, and for making Copilot better every day. For details on this release, see: https://github.com/Copilot-Language/copilot/releases/tag/v4.7.1. As always, we're releasing exactly 2 months since the last release. Our next release is scheduled for Jul 7th, 2026. 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, and formatting the code to meet our coding standards. 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/v4.7.1 [2] https://github.com/nasa/ogma [3] https://hackage.haskell.org/package/copilot [4] https://github.com/Copilot-Language/copilot

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Can't use my hackage account, and "upgrade page" fails too
by Mario Lang 26 May '26

26 May '26

Hi. I just tried to upload a new version of my package chessIO. Apparently, my hackage account (mlang) does no longer work. Last upload was about 2 years ago maybe? Found the upgrade page on Hackage, but that gives me an "authoisation scheme" error, with Firefox and Chrome. Maybe that page is broken? Maybe there is something else wrong with my account? What do I need to do to get it working again? Creating a new one doesn't really solve the problem, as I would still need someone to intervene to get access rights for my package. -- CYa, ⡍⠁⠗⠊⠕

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IFL 2026 First call for papers
by Mart Lubbers 20 May '26

20 May '26

======================================================================= IFL 2026 38th Symposium on Implementation and Application of Functional Languages venue: Aspenäs Herrgård, Gothenburg, Sweden October 28 - 30 2026 https://ifl26.cse.chalmers.se/ ======================================================================= ### 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 2026 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 Following IFL tradition, IFL 2026 will use a post-symposium review process for the formal proceedings. Authors are invited to submit draft papers before the symposium. The program chairs will screen submissions for relevance to IFL, and accepted drafts will be shared with all participants. Each accepted paper must be presented at the symposium by at least one author. If submissions exceed capacity, selection will be based on quality, maturity, and relevance. Authors of accepted presentations will have the opportunity to revise their work in response to symposium feedback and submit a full paper to the post-proceedings. These submissions will be reviewed by the program committee for correctness, novelty, originality, relevance, significance, and clarity. The post-symposium review process is single-blind, with at least three reviews per paper. Camera-ready versions may include minor revisions without further review. ### Important dates Submission of draft papers September 4, 2026 Draft papers notification September 11, 2026 Deadline for early registration September 18, 2026 Deadline for late registration September 25, 2026 IFL symposium October 28-30, 2026 Submission of papers for proceedings November 25, 2026 Notification of acceptance February 12, 2027 Camera-ready version March 12, 2027 Deadlines are end of day Anywhere on Earth (UTC-12). ### 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=ifl26 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: ICPS publishing model FAQ: https://www.acm.org/publications/icps/faq ACM Open program details: https://www.acm.org/publications/openaccess Questions: 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: - Alex Gerdes, Chalmers and University of Gothenburg, Sweden - Koen Claessen, Chalmers and University of Gothenburg, Sweden Publicity Chair: - Mart Lubbers, Radboud University, The Netherlands Local Chairs: - Alex Gerdes, Chalmers and University of Gothenburg, Sweden - Koen Claessen, Chalmers and University of Gothenburg, Sweden Please direct any questions you may have towards alexg(a)chalmers.se. ### Program committee - Abhiroop Sarkar, ETH Zurich - Andres Löh, Well-Typed LLP - Daan Leijen, Microsoft - Dominic Orchard, University of Kent - Fritz Henglein, DIKU - Graham Hutton, University of Nottingham - Guillaume Allais, University of Strathclyde - Jesper Cockx, Delft University of Technology - Mart Lubbers, Radboud University - Nachiappan Valliappan, University of Edinburgh - Nicolas Wu, Imperial College London - Niki Vazou, IMDEA Software Institute The program committee is still being finalized and may be updated. ### Venue IFL 2026 will be held at Aspenäs Herrgård, just outside Gothenburg, Sweden. Aspenäs Herrgård will host the symposium venue and provide a scenic setting for the conference. We will add more information about the venue, accommodation, and travel options soon. ### 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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Conduit missing closing file handles
by Henning Thielemann 14 May '26

14 May '26

I have a pretty simple program for converting ZIP to TAR archives using the 'zip' and 'tar-conduit' packages, both using Conduit for streaming data. In principle the program works, but if the ZIP archive contains a non-trivial number of files, the program breaks because of exceeded limit of open file handles: $ zip2tar /usr/share/libreoffice/share/config/images_colibre.zip >/tmp/images_colibre.tar zip2tar: Uncaught exception ghc-internal:GHC.Internal.IO.Exception.IOException: /usr/share/libreoffice/share/config/images_colibre.zip: openFile: resource exhausted (Too many open files) While handling /usr/share/libreoffice/share/config/images_colibre.zip: openFile: resource exhausted (Too many open files) HasCallStack backtrace: throwIO, called at ./Control/Monad/Trans/Resource.hs:195:13 in resourcet-1.3.0-8b355f9483371034fb75ff40adb2e07157502721c941fbf8a6f607df6dd81546:Control.Monad.Trans.Resource The main function is essentially this one: [1] convertZipToTar :: (Zip.EntrySelector -> Zip.EntryDescription -> CTar.FileInfo) -> Sort -> FilePath -> IO () convertZipToTar fileInfoFromZipEntry_ sortMode zipPath = Zip.withArchive zipPath $ do entries <- Map.toList <$> Zip.getEntries files <- for entries $ \(selector, descr) -> flip fmap (Zip.getEntrySource selector) $ \src -> src .| (C.yield (Left $ fileInfoFromZipEntry_ selector descr) >> C.mapC Right) C.liftIO $ runConduitRes $ sequence_ files .| void CTar.tar .| C.stdoutC 'Zip.getEntrySource selector' generates a conduit for reading a file from the ZIP archive. It opens the archive anew for every accessed file, but it calls Conduit.Binary.sourceIOHandle, which promises to close a file promptly after reading. [2] It seems that files are not immediately closed after reading, but I cannot spot the cause. I suspected that "sequence_ files" might concatenate the Conduits while accumulating open file handles, but I think it should not and I did not find a matching alternative to sequence_. [1] https://hackage-content.haskell.org/package/zip2tar-0.0/src/src/Main.hs [2] https://hackage-content.haskell.org/package/zip-2.2.1/docs/src/Codec.Archiv…

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Subscription management
by Joachim Durchholz 14 May '26

14 May '26

Hi all, I accidentally subscribed two of my mail addresses to Haskell-cafe; here are the pertinent envelope address lines from the incoming mails: Envelope-to: joachim(a)durchholz.org Envelope-to: jo(a)durchholz.org I tried to unsubscribe (both, actually), but https://mailman.haskell.org/accounts/password/reset/ claims to have no knowledge of any of these two addresses. What should I do next? Regards, Jo P.S.: Something is wrong in the appended footer. The HTML version may be fine, but the text version I'm seeing obviously misses a link in the second-to-last line: > _______________________________________________ > Haskell-Cafe mailing list -- haskell-cafe(a)haskell.org > To (un)subscribe, modify options or view archives go to: > Only members subscribed via the mailman list are allowed to post. Sorry for going to the list itself, but I don't know the list administrator's mail address.

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Uploading packages from CLI
by Ivan Perez 08 May '26

08 May '26

Hi, Cabal is getting stuck when I try to upload a package from CLI. My user and password are correct. It this a known problem? Thanks, Ivan

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Journal of Functional Programming - Call for PhD Abstracts
by Graham Hutton (staff) 05 May '26

05 May '26

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 30st May 2026. Please share! Best wishes, Graham Hutton ============================================================ CALL FOR PHD ABSTRACTS Journal of Functional Programming Deadline: 31st May 2026 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 2026 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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Questions about my findings about versioning, dependencies and breakages on Hackage
by Jon Kristensen 04 May '26

04 May '26

Hi! I’m currently wrapping up my master’s thesis, which is about dependencies and breakages on Hackage. In short, I’m analyzing all packages released onto Hackage during a certain window (currently the first quarter of 2025). I’m using the Hackage package index and the Hackage API to collect metadata. I’m using print-api[1] to attempt to detect breaking API changes between these releases and their predecessors. I’m using HIE DB[2] to identify which symbols are actually being used by reverse dependencies. My goal is to investigate versioning and dependency constraint practices, as well as package breakages. I’m now at a point where I would like to evaluate my findings with experts in the Haskell community (such as experienced developers and package maintainers). If you could spare a bit of time I would love to hear your thoughts on my work. I’m thinking the questions could be sent via email, but if you prefer a call we could do that as well. You will be anonymous when any data is presented. Thank you for whatever you can do! All the best, Jon [1]: https://github.com/Kleidukos/print-api [2]: https://github.com/haskell/HieDb

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Two Haskell Talks from Bellroy at Melbourne Compose Group May Meetup
by theghostjw＠gmail.com 02 May '26

02 May '26

We're thrilled to have two Bellroy Haskellers presenting a double-feature at Melbourne Compose Group. Michael Webb (CTO) will share how Bellroy built and scaled a $120M+ brand with a tiny Haskell team. Jack Kelly (Staff Engineer) will walk through deploying Haskell in the cloud with an opinionated guide to Haskell on AWS Lambda. Whether you're using Haskell in production, curious about serverless, or just want to see how a small team moves fast without fear, come along! The Talks Michael Webb - CTO Maximum Agency, Minimum Footguns Lessons from scaling a $120M+ carry brand with a tiny engineering team At Bellroy, we've built a small engineering team that moves fast, ships confidently, and hands real power to the people closest to the work - content editors, ops staff, marketers - without lying awake worrying about what they might break. The secret isn't process, approval chains, or change management theatre. It's that we've encoded the constraints that actually matter directly into our tools - many of them built in Haskell - and trusted our people with everything else. This talk is about the philosophy behind that approach: what it means to design for agency rather than safety, what cultural practices make such an approach practical and why a type system is the most underrated management tool in a company's arsenal. Jack Kelly - Staff Engineer Lambda on Lambda: Running Serverless Haskell Functions on AWS [AWS Lambda]([https://aws.amazon.com/lambda/](https://aws.amazon.com/lambda/)) is AWS's "function-as-a-service" offering, where your code runs in an isolated "microVM" on AWS-managed infrastructure and you pay only for the resources used while your code runs. Fitting your binaries into this model means making your code talk to some internal AWS APIs, and luckily the Haskell ecosystem has some good tools for doing this. In this talk, I'll explain at a high level what AWS Lambda is, how it executes your code, and then provide an opinionated guide and demo for getting your Haskell functions into the cloud. When and Where Format: Strictly IRL When: Thursday 21 May 2026, 6:00pm – 8:00pm Where: Kathleen Syme Centre, Activity Room 2, Carlton (Melbourne Victoria, Australia) RSVP: [luma](https://luma.com/uhdgct1v) About Melbourne Compose Group Melbourne Compose Group is the monthly in-person meetup for functional programmers in Melbourne, every 3rd Thursday of the month in Carlton. As always, newcomers welcome.

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