- Haskell-Cafe - Haskell.org

Debugging a test suite freeze
by David Feuer 02 Dec '22

02 Dec '22

The logict-sequence test suite consistently freezes up on the last test when compiled with GHC 9.4.3. logict-sequence and its test suite don't do anything special with that GHC/base version as far as I can see, or anything particularly strange in general, so I'm pretty confident the problem lies elsewhere. My best guesses are hedgehog, tasty, and tasty-hedgehog. Has anyone else run into weird issues with any/all of these on GHC 9.4.3? David

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ANN: hledger 1.28
by Simon Michael 01 Dec '22

01 Dec '22

I'm pleased to announce hledger 1.28 ! https://github.com/simonmichael/hledger/releases/1.28 https://hledger.org/install https://hledger.org/release-notes.html#hledger-1-28 Nothing earth-shaking for users in this release, but internal changes and the usual incremental improvements. Highlights: new hledger-ui screens and default screen; new hledger-move, watchaccounts scripts. Thank you to release contributors Felix Yan, Patrick Fiaux. What is hledger ? - Fast, reliable, free, multicurrency, double-entry, plain text accounting[1] software that runs on unix, mac, windows, and the web - Built around human-readable, version-controllable plain text files - Inspired by and largely compatible with Ledger CLI[2]; convertible to and from Beancount[3] - Written in Haskell for correctness and longevity. For help getting started, or more info, see https://hledger.org and join our chat via Matrix or IRC: https://hledger.org/support Newcomers, experts, contributors, sponsors, feedback are welcome! Aloha, -Simon [1] https://plaintextaccounting.org [2] https://ledger-cli.org [3] https://beancount.github.io

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FOSDEM Haskell devroom: we need proposals!
by Fraser Tweedale 30 Nov '22

30 Nov '22

Previously: https://mail.haskell.org/pipermail/haskell-cafe/2022-November/135674.html **We need more proposals! We need your help!** FOSDEM 2023 will be held on 4 & 5 February 2023, in Brussels. For more information see the [official site](https://fosdem.org/2023/). The Haskell devroom (specialist track) will take place on Sunday 5 February, from 13:10 to 17:00 UTC+1. This is an amazing opportunity to promote Haskell, and functional programming generally, to a legion of free software developers and enthusiasts. But right now, we are not even close to filling our schedule. If we don't fill our ~4 hour schedule, the Haskell devroom will not happen. Therefore we are extending our Call for Proposals until Saturday 2022-12-10. We are also now welcoming proposals for tutorials/workshops and longer presentations (up to 45 minutes). Shorter presentations are still welcome, of course. So if you want to propose an introductory workshop, install fest, hack session, or something similar, have at it. You can also help by sharing our CFP far and wide, and encourage specific people you think might have something interesting to present, to submit a proposal. Thanks, Fraser Tweedale

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Call for Haskell.org Committee Nominations
by Ida Bzowska 29 Nov '22

29 Nov '22

Dear Haskellers, The Haskell.org Committee is happy to announce that we are opening the call for nominations for new members. Details can be found [here <https://discourse.haskell.org/t/call-for-haskell-org-committee-nominations-…> ]. You can nominate yourself or your friend! If you have any questions, don't hesitate to ask. λCheers Ida Bzowska

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Writing and testing a Storable instance for a record wrapping ForeignPtrs
by Hécate 29 Nov '22

29 Nov '22

Hi everyone, In a fit of madness I have found myself writing Haskell code where I need to implement a Storable instance. However, by virtue of not being a C programmer, I'm fairly lost on some of the details, especially the value of the sizeOf and alignment methods. My Haskell-level record is the following: data SignedMessage = SignedMessage { messageLength :: CSize , messageForeignPtr :: ForeignPtr CUChar , signatureForeignPtr :: ForeignPtr CUChar } Here is the code of the Storable instance: https://gist.github.com/Kleidukos/31346d067f309f2a86cbd97a85c0f1e8#file-sig… And so I used `hedgehog-classes` to test the Storable instance. However, all the tests fail with the same reason: Prelude.undefined: https://gist.github.com/Kleidukos/31346d067f309f2a86cbd97a85c0f1e8#file-und… The main problem (and that's certainly a red herring for me) is that the `undefined` call comes frombase:Foreign.Marshal.Array. Which shouldn't be a problem, as it is not supposed to be evaluated! Yet apparently it is. If you're interested to see the full code, it's located here: https://github.com/haskell-cryptography/libsodium-bindings/blob/add-sel-pac… I'm not sure how to proceed from here. What would be a good angle to approach this? Cheers, Hécate -- Hécate ✨ 🐦: @TechnoEmpress IRC: Hecate WWW: https://glitchbra.in RUN: BSD

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PhD and post-doc positions in Mainz, Germany
by Erdweg, Sebastian 25 Nov '22

25 Nov '22

We have multiple open positions for PhD students and post-docs in the PL Group of the University of Mainz in Germany. The available positions include a gross monthly salary of ~4000 Euro. Our team meets and socializes in Mainz; remote work is an option. The PL Group at the University of Mainz was founded in 2019. Our goal is to support developers in creating and maintaining software systems that are easier to write, more secure, run faster, and consume less energy. Our current research topics include: -- Incremental computing: How can a computation react to a change of its input efficiently? We have observed up to 10,000x speedups in prior work, can incrementality help us save as much energy? Can we build a new foundation for incremental computing to support a wider range of computations? -- WebAssembly: How can we discover and prevent security vulnerabilities in WebAssembly? We have built a data-flow analysis platform for WebAssembly to identify properties of WebAssembly programs at compile time. Can this platform be used to protect WebAssembly users while also optimizing the code for performance? -- Datalog: How can the power of Datalog best be exploited in modern software development? How can we abstract over and hide the technicalities of Datalog, for example, by compiling DSLs to Datalog. And how can we optimize Datalog code to provide truly declarative performance, without exposing users to details of the underlying database technology? -- Language engineering: How can we build programming-language tools with modest effort and without duplicating the language's semantics? For example, can we derive type checkers, debuggers, and other editor services from the language’s semantics? And does this require a language workbench or can we support rich services for embedded languages as well? Mainz is part of the Frankfurt Metropolitan Area and only a short train ride away from Frankfurt's international community and culture. Mainz itself lies at the confluence of the Rhine and Main rivers, surrounded by plenty of nature. https://mainz.de/en/worth-seeing/reasons-to-love-mainz.php I'm excited to hear from interested candidates via email. If you know potential candidates, please forward this message to them. Sebastian Erdweg https://www.pl.informatik.uni-mainz.de/erdweg

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Munich Haskell Meeting, 2022-11-30 @ 19:30
by Leah Neukirchen 25 Nov '22

25 Nov '22

Dear all, Next week, our last* monthly Munich Haskell Meeting of the year 2022 will take place again on Wednesday, November 30 at Cafe Puck at 19h30. For details see here: http://muenchen.haskell.bayern/dates.html If you plan to join, please add yourself to this nuudel so we can reserve enough seats! It is OK to add yourself to the nuudel anonymously or pseudonymously. https://nuudel.digitalcourage.de/haskell-munich-nov-2022 Everybody is welcome! *) There will be no meeting in late December due to festivities, but perhaps again in the first week of January, as is tradition. cu, -- Leah Neukirchen <leah(a)vuxu.org> https://leahneukirchen.org/

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Learn Physics with Funtional Programming
by Jonathan Drews 24 Nov '22

24 Nov '22

I got the No starch Press *.pdf book "Learn Physics with Functional Programming" by Scott Walck. It's an easy introduction to coding physics problems in Haskell. It is very well written. I mention it because right now, the week of Thanksgiving, NoStarch Press is having a 35% off sale on all books. -- Kind regards, Jonathan

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KSF Media Ab hiring Senior Developer in Helsinki, Finland
by Kari Pahula 23 Nov '22

23 Nov '22

KSF Media is Finland's largest Swedish language news media group. Our products include Hufvudstadsbladet, Västra Nyland, Östnyland and HBL Junior. KSF Media's digital products are growing fast and our focus is in digital subscription sales and product development. We are now looking for a new member to join our digital development team to create outstanding news media products for our readers. We are a small but capable team with a lean way of working and passion to learn new things every day. Our way of working Kanban Pair Programming, Code Reviews Git, CI/CD (multiple deployments a day), Trunk Based Development Working in the open. Our whole frontend is open source: https://github.com/KSF-Media/affresco and https://github.com/KSF-Media/mosaico Our stack Most new developments happen in Haskell, PureScript and Javascript Cloud Infrastructure as Code (Google Cloud, Kubernetes, Terraform) Microservices environment with REST APIs What we expect from you some relevant work experience and English language. Swedish or Finnish knowledge is a plus Knowledge of the principles behind the modern Web stack: things like MVC, Relational Databases and Testing High motivation, self-steering, willingness to learn and dive into things, good social skills and good sense of humour Interest in functional programming, news media and making the world a better place Awareness of some UX principles, API design (and optionally UI design) and empathy for the users of your code What we can offer Flexible terms, with possibility to remote working Competitive salary and benefits The best co-workers Office in the most central location in Helsinki Interested? Please apply via LinkedIn, https://www.linkedin.com/jobs/view/3373101222 or drop a line at antti.haarala(a)ksfmedia.fi no later than on the 5th of December. Reddit discussion at https://www.reddit.com/r/haskell/comments/z2pupj/ksf_media_ab_hiring_senior…

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Upcoming maintenance on Haskell services
by Bryan Richter 22 Nov '22

22 Nov '22

Hello folks, On Thursday 24 November at 6 AM UTC, I will start a 4-hour maintenance window for the following Haskell services: 1. downloads.haskell.org 2. gitlab.haskell.org In particular, I expect the following outages: 1. downloads.haskell.org will be read-only for the duration of the window. * No uploads 2. gitlab.haskell.org will be read-only for the duration of the window. * No CI pipelines(!) * No git pushes * No commenting on issues or merge requests 3. gitlab.haskell.org will furthermore be entirely inaccessible very briefly. * There will be 1-2 outages. * Each outage will last a few seconds. The reason for the maintenance is that our hosting sponsor, Equinix Metal, is performing a facilities migration. One of our servers, gitlab-storage, is slated for retirement. All data and services that run on that server must be moved to a new server. I'm sending this first notification to a wide audience as an extra precaution in case something goes wrong. :) In reality, I expect this maintenance to only affect GHC developers and a small group of ecosystem maintainers. In particular, web access of https://downloads.haskell.org should *not* be affected by this maintenance. I will send further updates to a smaller audience. Note: The actual migration will be quick. Most of the maintenance window will be spent waiting for DNS propagation. -Bryan Haskell Foundation DevOps

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10 PhD studentships in Nottingham
by Graham Hutton 21 Nov '22

21 Nov '22

Dear all, The School of Computer Science at the University of Nottingham in the UK is seeking applications for 10 fully-funded PhD studentships: https://tinyurl.com/ten-phd-2022 Applicants in the area of the Functional Programming Lab (tinyurl.com/fp-notts) are strongly encouraged! If you are interested in applying, please contact a potential supervisor as soon as possible; the application deadline is 12th Feb 2023: Thorsten Altenkirch - constructive logic, proof assistants, homotopy type theory, category theory, lambda calculus. Ulrik Buchholtz - homotopy type theory, synthetic homotopy theory, proof assistants, constructive mathematics, and related topics. Graham Hutton - functional programming, haskell, category theory, program verification, program calculation. Nicolai Kraus - homotopy type theory, higher category theory, constructive mathematics, and related topics. Dan Marsden - category theory, logic, finite model theory, diagrammatic reasoning, foundations of computer science. These positions are open to students of any nationality. Best wishes, The FP Lab +-----------------------------------------------------------+ 10 Fully-Funded PhD Studentships School of Computer Science University of Nottingham, UK https://tinyurl.com/ten-phd-2022 Applications are invited from international and home students for 10 fully-funded PhD studentships offered by the School of Computer Science, starting on 1st October 2023. The topics for the studentships are open, but should relate to the interests of one the School's research groups: Computational Optimisation and Learning; Computer Vision; Cyber Security; Functional Programming; Intelligent Modelling and Analysis; Mixed Reality; Uncertainty in Data and Decision Making; Visualisation and Computer Graphics; Cyber-Physical Health and Assistive Robotics Technologies. The studentships are fully funded for 3.5 years and include a stipend of £17,668 per year and tuition fees. Applicants are normally expected to have a first-class class bachelors or masters in Computer Science or another relevant area, and must obtain the support of a potential supervisor in the School prior to submitting their application. If you are interested in applying, please contact a potential supervisor as soon as possible, and at least two weeks prior to the closing date. If the supervisor wishes to support your application, they will direct you to make an official application through the MyNottingham system. Closing date for applications: Sunday 12th February 2023. +-----------------------------------------------------------+ 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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Cabal 3.10 last call for contributions
by Mikolaj Konarski 17 Nov '22

17 Nov '22

Hi! Would you like cabal 3.10 to have your favourite bugfix, feature or overall spiffiness? If so, please let us help you help yourself. We are going to soft-freeze cabal 3.10 in a month or two and ship a little later, around the GHC 9.6 release date. There is still time to fix your favourite regression https://github.com/haskell/cabal/issues?q=is%3Aopen+label%3A%22regression+i… or add your high priority feature (or argue for bumping the priority of an existing ticket) https://github.com/haskell/cabal/labels/priority%3A%20high%20%3Afire%3A The friendly team of cabal maintainers is at your disposal whether you need a PR review, a design discussion in a ticket, or you just get stuck or urgently need somebody to chat to (the #hackage IRC/matrix room is open). Cabal 3.10 is going to be mostly a bugfix release, so there may or may not be a release candidate for you to try to break. However, brave people are continuously dogfooding the master branch from github artifacts (at the bottom of 'validate' CI jobs) or gitlab pipelines (more flavours, including statically linked Alpine Linux) https://gitlab.haskell.org/haskell/cabal/-/pipelines/59103 Another way you can contribute is by picking up a newcomer-labelled ticket. Yet another is triaging new tickets, e.g., via https://www.codetriage.com/haskell/cabal Don't worry if you feel you'd need to learn a lot --- cabal is a large and constantly changing system, so most of us are forgetting faster than learning. However, purity, types and tests often permit to focus, code-dive and fix or improve a hot subsystem in relative isolation. See you there, Mikolaj

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[ANN] base16-3.2.1
by Emily Pillmore 16 Nov '22

16 Nov '22

Hi All, I'm announcing `base16-3.2.1`, available on hackage now, which features a QOL contribution from Shea Levy, as well as support for up to GHC 9.4.x. This will be the last in the 3.x series before the next major update, which will feature newtyped Base16 bytestrings and optimized Base16 encoding and decoding loops. The same will happen across the all the BaseN encoding libraries from me. Cheers, Emily

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[ANN] faster-megaparsec
by Olaf Klinke 15 Nov '22

15 Nov '22

Dear Haskellers, megaparsec [1] is a parsing library with excellent error reporting. Being able to emit decent parse error messages is traded off against speed, however. Wouldn't it be nice to have a faster parser for your daily parsing needs, but obtain megaparsec's informative error messages for the rare cases when things go wrong? Thanks to megaparsec's parser type class, MonadParsec, you can have both: I wrote a MonadParsec instance for StateT s Maybe (s being the input stream type such as Text or ByteString) which does not do all the bookkeeping ParsecT needs to do. If you manage to write your parser only using the type class primitives, then you can specialize your parser to StateT s Maybe. Only if that returns Nothing specialize again to ParsecT Void s and parse the input again, thus obtaining a decent error message. The package faster-megaparsec [1,2] provides a convenient function to do just that. Of course StateT s Maybe can not provide all the features ParsecT has: * StateT s Maybe is always backtracking. * It does not know the offset in the stream. * It must hold the entire input stream in memory for a second pass, so no garbage collecting the consumed input while parsing. So if your parsing relies on non-backtracking choice, stream offset or garbage-collecting input while parsing, you can not use faster- megaparsec as a drop-in replacement. Happy parsing! Olaf [1] https://hackage.haskell.org/package/megaparsec [2] https://hackage.haskell.org/package/faster-megaparsec [3] https://hub.darcs.net/olf/faster-megaparsec

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[TFP 2023 2nd Call for Papers] 24th International Symposium on Trends in Functional Programming
by Peter Achten 15 Nov '22

15 Nov '22

# TFP 2023 -- Call for Papers (trendsfp.github.io) ## Important Dates Submission deadline: pre-symposium, full papers, Wednesday 23rd November, 2022 Submission deadline: pre-symposium, draft papers, Friday 16th December, 2022 Notification: pre-symposium submissions, Friday 23rd December, 2022 Registration: Friday 6th January, 2023 TFPIE Workshop: Thursday 12th January, 2023 TFP Symposium: Friday 13th - Sunday 15th January, 2023 Submission deadline: post-symposium review, Friday 17th February, 2023 Notification: post-symposium submissions, Friday 31st March, 2023 The Symposium on Trends in Functional Programming (TFP) is an international forum for researchers with interests in all aspects of functional programming, taking a broad view of current and future trends in the area. It aspires to be a lively environment for presenting the latest research results, and other contributions. This year, TFP will take place in-person at UMass Boston, Massachusetts in the United States. It is co-located with the Trends in Functional Programming in Education (TFPIE) workshop, which will take on the day before the main symposium. Please be aware that TFP has several submission deadlines. The first, November 23, is for authors that wish to have their full paper reviewed prior to the symposium. Papers that are accepted in this way must also be presented at the symposium. The second, December 16, is for authors that wish to present their work or work-in progress at the symposium first without submitting to the full review process for publication. These authors can then take into account feedback received at the symposium and submit a full article for review by the third deadline, February 17. ## Scope The symposium recognizes that new trends may arise through various routes. As part of the Symposium's focus on trends we therefore identify the following five article categories. High-quality articles are solicited in any of these categories: * Research Articles: Leading-edge, previously unpublished research work * Position Articles: On what new trends should or should not be * Project Articles: Descriptions of recently started new projects * Evaluation Articles: What lessons can be drawn from a finished project * Overview Articles: Summarizing work with respect to a trendy subject Articles must be original and not simultaneously submitted for publication to any other forum. They may consider any aspect of functional programming: theoretical, implementation-oriented, or experience-oriented. Applications of functional programming techniques to other languages are also within the scope of the symposium. Topics suitable for the symposium include, but are not limited to: * Functional programming and multicore/manycore computing * Functional programming in the cloud * High performance functional computing * Extra-functional (behavioural) properties of functional programs * Dependently typed functional programming * Validation and verification of functional programs * Debugging and profiling for functional languages * Functional programming in different application areas: security, mobility, telecommunications applications, embedded systems, global computing, grids, etc. * Interoperability with imperative programming languages * Novel memory management techniques * Program analysis and transformation techniques * Empirical performance studies * Abstract/virtual machines and compilers for functional languages * (Embedded) domain specific languages * New implementation strategies * Any new emerging trend in the functional programming area If you are in doubt on whether your article is within the scope of TFP, please contact the TFP 2023 program chair, Stephen Chang. ## Best Paper Awards TFP awards two prizes for the best papers each year. First, to reward excellent contributions, TFP awards a prize for the best overall paper accepted for the post-conference formal proceedings. Second, a prize for the best student paper is awarded each year. TFP traditionally pays special attention to research students, acknowledging that students are almost by definition part of new subject trends. A student paper is one for which the authors state that the paper is mainly the work of students, the students are listed as first authors, and a student would present the paper. In both cases, it is the PC of TFP that awards the prize. In case the best paper happens to be a student paper, then that paper will receive both prizes. ## Instructions to Authors Papers must be submitted at: <https://easychair.org/conferences/?conf=tfp23> Authors of papers have the choice of having their contributions formally reviewed either before or after the Symposium. Further, pre-symposium submissions may either be full (earlier deadline) or draft papers (later deadline). ## Pre-symposium formal review Papers to be formally reviewed before the symposium should be submitted before the early deadline and will receive their reviews and notification of acceptance for both presentation and publication before the symposium. A paper that has been rejected for publication but accepted for presentation may be resubmitted for the post-symposium formal review. ## Post-symposium formal review Draft papers will receive minimal reviews and notification of acceptance for presentation at the symposium. Authors of draft papers will be invited to submit revised papers based on the feedback receive at the symposium. A post-symposium refereeing process will then select a subset of these articles for formal publication. ## Paper categories Draft papers and papers submitted for formal review are submitted as extended abstracts (4 to 10 pages in length) or full papers (20 pages). The submission must clearly indicate which category it belongs to: research, position, project, evaluation, or overview paper. It should also indicate which authors are research students, and whether the main author(s) are students. A draft paper for which all authors are students will receive additional feedback by one of the PC members shortly after the symposium has taken place. ## Format Papers must be written in English, and written using the LNCS style. For more information about formatting please consult the Springer LNCS web site. ## Program Committee Peter Achten, Radboud University Nijmegen, Netherlands Nada Amin, Harvard University, USA Ambrose Bonnaire-Sergeant, Untypable LLC, USA Laura M. Castro, University of A Coruña, Spain Stephen Chang (Chair), University of Massachusetts Boston, US John Clements, Cal Poly, USA Youyou Cong, Tokyo Institute of Technology, Japan Paul Downen, University of Massachusetts Lowell, USA Kathy Gray, Meta Platforms, Inc., UK Ben Greenman, University of Utah, USA Jason Hemann, Seton Hall University, USA Patricia Johann, Appalachian State University, USA Alexis King, Tweag, USA Julia Lawall, Inria-Paris, France Barak Pearlmutter, Maynooth University, Ireland Norman Ramsey, Tufts University, USA Ilya Sergey, National University of Singapore, Singapore Melinda Tóth, Eötvös Loránd University, Hungary Ningning Xie, University of Toronto, Canada

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[ANN] Copilot 3.12
by Ivan Perez 14 Nov '22

14 Nov '22

Dear all, I'm very excited to announce Copilot 3.12. Copilot is a stream-based DSL 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. Among others, Copilot has been used at the Safety Critical Avionics Systems Branch of NASA Langley Research Center for monitoring test flights of drones. It also serves as a runtime monitoring backend for the requirements elicitation tool FRET (https://github.com/NASA-SW-VnV/fret/) via Ogma ( https://github.com/nasa/ogma) The main changes in this release are as follows: - A new library copilot-prettyprinter exposes functions related to the Copilot Core pretty-printing backend. Pre-existing functions included as part of copilot-core are now deprecated. - The C99 backend now produces an additional header file with struct declarations. This file is used by the C implementation file generated by Copilot to define structs before the declarations of the handlers, avoiding potential forward declarations that the C compiler cannot resolve. Users of Copilot can choose to import the same new type declaration header file before the standard Copilot header file in their hand-written code, or use external definitions that declare compatible structs. Note that, in the former case, the header file that declares the structs must be included before the header file that declares the externs, handlers and step function. - The custom type equality module in copilot-core is now deprecated in favour of the definition of type equality in base. - copilot-theorem now includes support for proofs by bisimulation necessary for future extensions to Copilot. - copilot-core now complies with the coding rules established as part of the process of compliance with higher NASA's requirements for software with higher assurance classifications. Current emphasis is on improving the codebase in terms of stability and test coverage, removing unnecessary dependencies, hiding internal definitions, and formatting the code to meet our new coding standards. Users are encouraged to participate by opening issues and asking questions via our github repo (https://github.com/copilot-language/copilot) I'd also like to take this opportunity to announce that Copilot is now available on Debian. As a consequence of this effort, Copilot will also be available to Ubuntu users in the near future. We would like to publicly thank the Debian Haskell Group and, most especially, Scott Talbert, for continued effort making Copilot available on Debian-based distros. This will be extremely useful to a great portion of our users, who need to use Copilot as a runtime verification system targeting C, but do not need to become proficient in Haskell. We hope to continue this effort by making Copilot easily available on other distributions and OSs. Happy Haskelling, The Copilot team

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Sam Staton giving this year's LMS/BCS-FACS Evening Seminar (online) -- registration open until this Wednesday at 5PM, UTC
by Andrei Popescu 14 Nov '22

14 Nov '22

EVENT: Annual LMS/BCS-FACS Evening Seminar SPEAKER: Sam Staton, University of Oxford TITLE: Programming-based foundations for statistics DATE: Thursday, 17 November 2022, Starting time: 18:00 UTC VENUE: Online via Zoom EVENT PAGE: https://www.lms.ac.uk/events/lectures/lms-bcs-facs-evening-seminars REGISTRATION LINK: https://www.lms.ac.uk/civicrm/event/register?id=88&reset=1 Prior registration is required for attendance -- the registration site will close on Wednesday, 16 November, at 17:00 SYNOPSIS Probabilistic programming is a popular tool for statistics and machine learning. The idea is to describe a statistical model as a program with random choices. The program might be a simulation of a system, such as a physics model, a model of viral spread, or a model of electoral behaviour. We can now carry out statistical inference over the system, for example, by running a Monte Carlo simulation – running the simulation 100,000’s of times. As I will discuss in this talk, the idea of treating statistical models as computer programs also has a foundational appeal. If we can understand statistical models as programs, then the foundations of probability and statistics can be discussed in terms of program semantics. There is a chance of new foundational perspectives on statistics, in terms of programming languages and their formal methods. As I will explain, this programming-based foundation for statistics is attractive because there are some intuitively simple scenarios, such as inference over function spaces, which have an easy programming implementation, but for which the traditional mathematical interpretation is complicated. SPEAKER BIOGRAPHY Sam Staton is a Professor of Computer Science and Royal Society University Research Fellow at the University of Oxford. There he currently runs an ERC grant "Better Languages for Statistics". Before arriving in Oxford in 2015, Sam spent time in Nijmegen, Paris, and Cambridge. His PhD was in Cambridge with Marcelo Fiore (2007). Sam's main research is in programming language theory, but he is also interested in logic and category theory. He has recent contributions in probabilistic programming languages, and quantum computing and programming languages. Webpage: https://www.cs.ox.ac.uk/people/samuel.staton/main.html

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[ANN] updated vim's cabal syntax file
by coot＠coot.me 13 Nov '22

13 Nov '22

vim-9.0.0849 comes with an updated cabal syntax file which supports a few more fields. If you want to see the changes, check out the few recent commits: https://github.com/coot/haskell-vim-scripts/commits/master/syntax/cabal.vim… Cheers, Marcin

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Numerical Recipes in Haskell?
by Jonathan Drews 12 Nov '22

12 Nov '22

Hi: New member here. I am looking for a book similar to "Numerical Recioes in C" but for Haskell. https://www.amazon.com/Numerical-Recipes-Scientific-Computing-Second/dp/052… Does such a book exist? I've looked and can't seem to find one. I am new to Haskell and don't have much programming experience. I am using the No Starch press book "Learn Physics with Functional Programming: A Hands-on Guide to Exploring Physics with Haskell". It's very well written. -- Kind regards, Jonathan

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[CFP] FOSDEM Haskell Devroom, Sun 2023-02-05, Brussels
by Fraser Tweedale 12 Nov '22

12 Nov '22

I am thrilled to announce that Europe's largest free software conference, FOSDEM, will in 2023 and for the first time feature a Haskell devroom (specialist track). The Call for Participation is open now, until 2022-11-28. Read on for more info! FOSDEM 2023 will be held on 4 & 5 February 2023, in Brussels. For more information see the official site: https://fosdem.org/2023/. The Haskell devroom will take place on Sunday 5 February, from 13:10 to 17:00 UTC+1. Presentations will be also be streamed live and published afterwards. ## Key Dates 2022-11-28: Submission Deadline 2022-12-12: Announcement of selected talks 2023-02-04..2023-02-05: FOSDEM conference 2023-02-05: Haskell Devroom ## About the Haskell devroom Haskell is a statically typed functional programming language. Its vibrant community spans industry, academia and the hobbyist realm. The Haskell devroom welcomes people new to Haskell or functional programming, as well as intermediate or experienced Haskellers. The Haskell devroom will: - Advocate the Haskell programming language, and its community, to a wide audience of free software developers and users. - Promote and support participation in free software projects that use Haskell. - Teach Haskell (more broadly, functional) programming techniques, and introduce important libraries, frameworks or developer tools. ## Call for Participation We invite proposals for talks, tutorials and demos on topics including: - Introductory talks teaching functional programming concepts and Haskell programming - Practical advice for Haskell programming: developer tools, package ecosystem, Haskell in production. - "Show and tell" session for people to introduce Haskell projects they are involved with, and invite contributions. - Experience reports: share about problems you tackled using Haskell, and the outcomes. - What is going on in the Haskell community? Where and how you can get involved? Sessions will have a maximum duration of 30 minutes, including questions. You are welcome to propose shorter sessions (for example a demo, short talk or Q&A). This is an in-person event. Presenters must be able to attend to deliver their presentation. ## Code of conduct Speakers and attendees must abide by the FOSDEM Code of Conduct[1]. Also, because this is a Haskell community event we expect participants to follow the Haskell Foundation Guidelines for Respectful Communication[2]. [1] https://fosdem.org/2023/practical/conduct/ [2] https://haskell.foundation/guidelines-for-respectful-communication/ If you submit a proposal and it is accepted, you will be required to confirm that you accept the FOSDEM Code of Conduct. If you have any questions about the Code of Conduct or wish to have one of the devroom organizers review your presentation slides or any other content for compliance, please email us and we will do our best to assist you. ## How to submit Submit proposals through the FOSDEM Pentabarf submission tool[3]. If you do not already have an account, you need to create one. [3] https://penta.fosdem.org/submission/FOSDEM23 Go to "Create Event" and select the "Haskell devroom" track. Ensure you fill the following fields: - Event title - Track ("Haskell devroom") - Duration (including questions; <= 30 minutes) - Event type - Short abstract - Full abstract - Submission notes (if any) You can use the Submission notes to mention: - Any special requirements - Anything else you want the organisers/reviewers to know In the "Person" profile section please provide your: - Name, nickname (optional), image - Short Biography - Email address - Phone number (in case we need to contact you during the conference) Presentations will be live-streamed and recordings published under the CC-BY licence. By submitting you consent to having your presentation recorded and broadcast/published under the CC-BY licence. ## People and contacts The Haskell devroom organisers are: - Fraser Tweedale - Troels Henriksen Thanks to David Christiansen and the Haskell Foundation for supporting this event. If you need to reach the Haskell devroom organisers or program committee, email <haskell-devroom-manager(a)fosdem.org>.

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Re: [Haskell-cafe] [ANN] faster-megaparsec
by Olaf Klinke 11 Nov '22

11 Nov '22

Emily wrote: > Do you provide reproducible benchmarks for these claims? I'd love to > see the outcome for various types of projects to make the choice for > myself. > > Unsubstantiated claims of "This is Faster™️" are the path to shame > and treachery. Version 0.1.2 now includes a CSV Benchmark. The benchmark generates random table layouts of up to 50 columns and decodes two named columns in 100000 lines. Speed-up on my machine is roughly 0.7x over ParsecT and 0.6x over Cassava when decoding only few columns of a broad table. In particular, a Text-based ParsecT is faster than (ByteString-based) Cassava in this scenario. This was also the initial reason why I got interested in improving performance of megaparsec parsers in the first place. Cheers, Olaf

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Re: [Haskell-cafe] [ANN] faster-megaparsec
by Olaf Klinke 11 Nov '22

11 Nov '22

> Do you provide reproducible benchmarks for these claims? I'd love to > see the outcome for various types of projects to make the choice for > myself. > > Unsubstantiated claims of "This is Faster™️" are the path to shame > and treachery. > Dear Emily, version 0.1.1 [1] now contains a benchmark suite, where words of randomly generated languages are parsed with both parsers (ParsecT and StateT Text Maybe). For tiny to moderately sized languages, the speed- up is not huge but noticeable. (I need to work on improving test case generation.) I've been using this trick for a long time but only now decided to spin off a dedicated package. My experience with parsing large amounts of tabular data files shows there is a more substantial difference, although that might be due to my lack of understanding how to write optimized megaparsec parsers. Still your point is valid that this is merely anecdotal evidence. If time permits, I shall add a more realistic benchmark with randomly generated CSV data or Finn Bender's haskell-parsing-benchmarks [2]. Cheers, Olaf [1] https://hackage.haskell.org/package/faster-megaparsec-0.1.1.0 [2] https://gitlab.com/FinnBender/haskell-parsing-benchmarks > On Tue, Nov 08, 2022 at 1:31 PM, Olaf Klinke < olf at aatal- > apotheke.de > wrote: > > > > > > > > > Dear Haskellers, > > > > > > > > megaparsec [1] is a parsing library with excellent error reporting. > Being > > able to emit decent parse error messages is traded off against > speed, > > however. Wouldn't it be nice to have a faster parser for your daily > > parsing needs, but obtain megaparsec's informative error messages > for the > > rare cases when things go wrong? > > > > > > > > Thanks to megaparsec's parser type class, MonadParsec, you can have > both: > > I wrote a MonadParsec instance for StateT s Maybe (s being the > input > > stream type such as Text or ByteString) which does not do all the > > bookkeeping ParsecT needs to do. If you manage to write your parser > only > > using the type class primitives, then you can specialize your > parser to > > StateT s Maybe. Only if that returns Nothing specialize again to > ParsecT > > Void s and parse the input again, thus obtaining a decent error > message. > > The package faster-megaparsec [1,2] provides a convenient function > to do > > just that. > > > > > > > > Of course StateT s Maybe can not provide all the features ParsecT > has: > > * StateT s Maybe is always backtracking. > > * It does not know the offset in the stream. > > * It must hold the entire input stream in memory for a second pass, > so no > > garbage collecting the consumed input while parsing. So if your > parsing > > relies on non-backtracking choice, stream offset or garbage- > collecting > > input while parsing, you can not use faster- megaparsec as a drop- > in > > replacement. > > > > > > > > Happy parsing! > > Olaf > > > > > > > > [1] https:/ / hackage. haskell. org/ package/ megaparsec ( > > https://hackage.haskell.org/package/megaparsec ) > > [2] https:/ / hackage. haskell. org/ package/ faster-megaparsec ( > > https://hackage.haskell.org/package/faster-megaparsec ) > > [3] https://hub.darcs.net/olf/faster-megaparsec >

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[ANNOUNCE] GHC 9.4.3 is now available
by Ben Gamari 09 Nov '22

09 Nov '22

The GHC developers are happy to announce the availability of GHC 9.4.3. Binary distributions, source distributions, and documentation are available at downloads.haskell.org: https://downloads.haskell.org/ghc/9.4.3 This release is primarily a bugfix release addressing a few issues found in 9.4.2. These include: * An issue where recursively calls could be speculatively evaluated, resulting in non-termination (#20836) * A code generation issue in the AArch64 native code generator backend resulting in incorrect runtime results in some circumstances (#22282) * A crash on Darwin when running executables compiled with IPE support (#22080) * A long-standing interface-file determinism issue where full paths would leak into the interface file (#22162) * A bug in the `process` library where file handles specified as `NoStream` would still be usable in the child (process#251) Note that, as GHC 9.4 is the first release series where the release artifacts are all generated by our new Hadrian build system, it is possible that there will be packaging issues. If you enounter trouble while using a binary distribution, please open a [ticket]. Likewise, if you are a downstream packager, do consider migrating to [Hadrian] to run your build; the Hadrian build system can be built using `cabal-install`, `stack`, or the in-tree [bootstrap script]. See the accompanying [blog post] for details on migrating packaging to Hadrian. We would also like to emphasize that GHC 9.4 must be used in conjunction with Cabal-3.8 or later. This is particularly important for Windows users due to changes in GHC's Windows toolchain. We would like to thank Microsoft Azure, GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a ticket if you see anything amiss. Happy Haskelling, - Ben [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [bootstrap script]: https://gitlab.haskell.org/ghc/ghc/-/blob/e2520df3fffa0cf22fb19c5fb872832d1… [Hadrian]: https://gitlab.haskell.org/ghc/ghc/-/blob/e2520df3fffa0cf22fb19c5fb872832d1… [blog post]: https://www.haskell.org/ghc/blog/20220805-make-to-hadrian.html

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CIS 194 not compiling under new GHC
by Borys Kopeć 07 Nov '22

07 Nov '22

Hi all, I've been working through the CIS 194 <https://www.cis.upenn.edu/~cis1940/spring13/lectures.html> course recently and unfortunately from lecture 7 onwards the code is not compliant with current compiler. I can still follow the lectures but I'd like to do every homework exercise. Unfortunately most homework exercises provide you with a code framework to work with and this code does not compile. Do any of you know about updated versions or corrections to this course? I believe there could be a repo where someone is keeping the course's homework up to date because this course is still quite popular. Regards Borys

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[Haskell] [ANNOUNCE] GHC 9.2.5 released
by Zubin Duggal 07 Nov '22

07 Nov '22

The GHC developers are very happy to at announce the availability of GHC 9.2.5. Binary distributions, source distributions, and documentation are available at [`downloads.haskell.org`](https://downloads.haskell.org/ghc/9.2.5). Download Page: https://www.haskell.org/ghc/download_ghc_9_2_5.html Blog Post: https://www.haskell.org/ghc/blog/20221107-ghc-9.2.5-released.html This release is primarily a bugfix release addressing a few issues found in 9.2.4. These include: * Code generation issues in the AArch64 native code generator backend resulting in incorrect runtime results in some circumstances (#22282, #21964) * Fixes for a number of issues with the simplifier leading to core lint errors and suboptimal performance (#21694, #21755, #22114) * A long-standing interface-file determinism issue where full paths would leak into the interface file (#22162) * A runtime system bug where creating empty mutable arrays resulted in a crash (#21962) - ... and a few more. See the [release notes] for a full accounting. As some of the fixed issues do affect correctness users are encouraged to upgrade promptly. We would like to thank Microsoft Azure, GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. Happy compiling, - Zubin [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [release notes]: https://downloads.haskell.org/~ghc/9.2.5/docs/html/users_guide/9.2.5-notes.…

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Help with TH trick
by David Feuer 06 Nov '22

06 Nov '22

I remember seeing a package that offered a function used something like this: $(deriveThingy [d| instance Foo a => Thingy a |]) to allow the user to specify the constraint(s) for a generated instance. I'd love to borrow the code for that, but I can't remember what package it was in, what class it derived, etc. Can anyone help?

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Haskell survey 2022
by Henning Thielemann 03 Nov '22

03 Nov '22

It seems there is a survey on Haskell Weekly but I have not seen an announcement on the mailing lists: https://haskellweekly.news/survey/2022.html

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[ANN] mtl-2.3.1
by Emily Pillmore 31 Oct '22

31 Oct '22

Hello Ghosts and Ghouls, After a period of spooky deliberation and well-received release candidate, Koz and I are pleased to announce `mtl-2.3.1`, which features the following hellish changelog: * Add `modifyError` to `Control.Monad.Error.Class`, and re-export from `Control.Monad.Except`. * Make the `MonadCont` instance for `ContT` more polykinded; now, `r` is allowed to be of an arbitrary kind `k`, rather than only `Type`. * Add a generic `liftCallCC` for use with any `MonadTrans`. * Add `modifyError` to `Control.Monad.Error.Class` * Return re-export of `ExceptT` and related functions to `Control.Monad.Except`. * Add `label` function to `MonadCont` If you wish to migrate to `mtl-2.3.x` and have not yet done so, please refer the migration guide in the repo: https://github.com/haskell/mtl/blob/master/docs/Mtl-2.3.x-Migration.md A release has been published on the github repository under the tag v2.3.1. Happy Halloween! Emily + Koz

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Journal of Functional Programming - Call for PhD Abstracts
by Graham Hutton 31 Oct '22

31 Oct '22

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 November 2022. Please share! Best wishes, Graham Hutton ============================================================ CALL FOR PHD ABSTRACTS Journal of Functional Programming Deadline: 30th November 2022 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 30th November 2022. 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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Apply now for maintainership for the `cassava` package
by Andreas Abel 31 Oct '22

31 Oct '22

Looking for maintainer(s) for `cassava`. Please see https://github.com/haskell-hvr/cassava/issues/218 if you are interested in this package. (And answer there.) -- Andreas Abel <>< Du bist der geliebte Mensch. Department of Computer Science and Engineering Chalmers and Gothenburg University, Sweden andreas.abel(a)gu.se http://www.cse.chalmers.se/~abela/

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Package takeover request: webdriver
by Tom McLaughlin 31 Oct '22

31 Oct '22

This package is here: http://hackage.haskell.org/package/webdriver. I opened an issue a few weeks ago asking if a new maintainer was wanted: https://github.com/kallisti-dev/hs-webdriver/issues/188 I've opened various PRs (as has the rest of the community) but there hasn't been a commit by the author since June 2019. Thanks! Tom

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Re: [Haskell-cafe] Mystery: constructor type applications differ from signatures
by Ryan Scott 29 Oct '22

29 Oct '22

I'm inclined to believe that this is a bug in the way that GHC typechecks type applications in patterns. Can you file a GHC issue about this? Ryan

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Mystery: constructor type applications differ from signatures
by Tom Ellis 29 Oct '22

29 Oct '22

I can't understand the different results from three versions of almost exactly the same function. The only difference is whether I bind type variables using type application or with a type signature. In each function isMaybeF, isMaybeG and isMaybeH below I bind three type variables f, g and h: AppK @_ @f @_ t (Proxy @g :: Proxy h) f, g and h ought to be just three different ways of binding exactly the same type. To my surpise, using them gives different results. The only difference between isMaybeF, isMaybeG and isMaybeH is the type variable I apply to `FromType`. I get a type error when I use a variable that was bound by a type application (f or g). The variable that was bound by a type signature (h) works as expected. It seems that when using f or g the type checker is too eager and looks at `FromType @f` (respectively g), decides that f must be of the form `Type -> Type`, a constraint which it can't satisfy at the site of the `AppK` pattern match, so it fails. When using h, by contrast, it seems to be able to wait to dispatch that constraint until it has seen `IsType`. Subsequently I discovered a simpler example with similar behaviour, except the type checker succeeds for g as well as h. What is going on here? (This all originally arose from my investigations into https://github.com/haskell/core-libraries-committee/issues/99#issuecomment-…) Tom {-# LANGUAGE GADTs #-} {-# LANGUAGE LambdaCase #-} -- | Requires GHC >= 9.2 and the issue appears in both 9.2 and 9.4 module Puzzle where import Data.Kind (Type) import Data.Typeable (eqT, Proxy(Proxy)) import Type.Reflection (Typeable, (:~:) (Refl)) -- | @FunRep (f b)@ witnesses that @b :: Type@. data FunRep a where AppK :: forall (k :: Type) (f :: k -> Type) (b :: k). IsType k -> Proxy f -> FunRep (f b) -- | @IsType k@ witnesses that @k ~ Type@. data IsType k where IsType :: IsType Type data FromType where FromType :: forall (f :: Type -> Type). FromType -- Could not deduce: k ~ * isMaybeF :: forall (a :: Type). FunRep a -> FromType isMaybeF = \case AppK @_ @f @_ t (Proxy @g :: Proxy h) -> case t of IsType -> FromType @f -- Could not deduce: k ~ * isMaybeG :: forall (a :: Type). FunRep a -> FromType isMaybeG = \case AppK @_ @f @_ t (Proxy @_ @g :: Proxy h) -> case t of IsType -> FromType @g -- Works fine isMaybeH :: forall (a :: Type). FunRep a -> FromType isMaybeH = \case AppK @_ @f @_ t (Proxy @_ @g :: Proxy h) -> case t of IsType -> FromType @h {-# LANGUAGE GADTs #-} {-# LANGUAGE LambdaCase #-} -- | Requires GHC >= 9.2 and the issue appears in both 9.2 and 9.4 module Puzzle2 where import Data.Kind (Type) import Data.Typeable (eqT, Proxy(Proxy)) import Type.Reflection (Typeable, (:~:) (Refl)) -- | @FunRep (f b)@ witnesses that @b :: Type@. data FunRep a where AppK :: forall k (b :: k). IsType k -> Proxy k -> FunRep b -- | @IsType k@ witnesses that @k ~ Type@. data IsType k where IsType :: IsType Type data FromType where FromType :: forall (b :: Type). FromType -- Works fine isMaybeF :: forall k (a :: k). FunRep a -> FromType isMaybeF = \case AppK @_ @f t (Proxy @_ @g :: Proxy h) -> case t of IsType -> FromType @f -- Works fine isMaybeG :: forall k (a :: k). FunRep a -> FromType isMaybeG = \case AppK @_ @f t (Proxy @_ @g :: Proxy h) -> case t of IsType -> FromType @g -- Works fine isMaybeH :: forall k (a :: k). FunRep a -> FromType isMaybeH = \case AppK @_ @f t (Proxy @_ @g :: Proxy h) -> case t of IsType -> FromType @h

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Re: [Haskell-cafe] Updating the description of the mailing list?
by Douglas McIlroy 25 Oct '22

25 Oct '22

> Could the description be changed to simply be the first sentence? > "This mailing list is for the discussion of topics related to Haskell." Yes. Like definitions in a modern dictionary, it tells how the list is actually used rather than how some ancient authority thought it ought to be. Doug

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Updating the description of the mailing list?
by Bryan 25 Oct '22

25 Oct '22

At https://mail.haskell.org/mailman/listinfo/haskell-cafe, the description states: This mailing list is for the discussion of topics related to Haskell. The volume may at times be high, as the scope is broader than the main Haskell mailing list. Discussions on the Haskell mailing list which have drifted off topic, or are only of interest to a small number of subscribers, will be asked to move to Haskell-Cafe. This implies that Haskell-Cafe is a place for off-topic discussions. In practice, haskell(a)haskell.org is unused and haskell-cafe(a)haskell.org *is* the Haskell mailing list. Could the description be changed to simply be the first sentence? "This mailing list is for the discussion of topics related to Haskell." --- This request comes from an effort to point potential new contributors to Haskell resources. Specifically, I'm editing https://gitlab.haskell.org/ghc/ghc/-/wikis/mailing-lists-and-irc. I wanted to add a link to haskell-cafe. While sanity-checking the URL, I read the description of the list and got momentarily confused: Should I actually be subscribed to haskell@ instead? But then after checking the archives, I remembered why I unsubscribed from that list many years ago. If it was confusing for me, I assume it would be confusing for newcomers as well. -Bryan

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[ANN] - Hugs for MacOS (x86) - via Nix Flakes
by Justin Bailey 24 Oct '22

24 Oct '22

I spent some time with the last public release of the Hugs sources, making them compile on a modern Mac (x86 chipset). I used Nix's flakes feature to manage the build and install. If you'd like to run the hugs interpreter directly using the flake, just type: `nix run github:m4dc4p/hugs#hugs` If you'd like to execute a Haskell file, try: `nix run github:m4dc4p/hugs <file.hs>` Or alternately: `nix run github:m4dc4p/hugs#runhugs <file.hs>` (That is, `runhugs` is the default app provided by the flake.) See the README at https://github.com/m4dc4p/hugs for more details (including other binaries available). I don't have much of a use case for Hugs, so I got the flake to the point where I could start the interpreter and run simple programs. I'm glad to accept pull requests or bug reports. You can find the source and submit any issues at https://github.com/m4dc4p/hugs. Note: I don't have access to Apple silicon, so this build has only been tested under x86. If it works for M1 please let me know, or if you are able to submit a PR I'd welcome it! Enjoy! Justin

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Munich Haskell Meeting, 2022-10-25 @ 19:30
by Leah Neukirchen 23 Oct '22

23 Oct '22

Dear all, Next week, our monthly Munich Haskell Meeting will take place again on Tuesday, October 25 at Cafe Puck at 19h30. For details see here: http://muenchen.haskell.bayern/dates.html If you plan to join, please add yourself to this dudle so we can reserve enough seats! It is OK to add yourself to the dudle anonymously or pseudonymously. https://nuudel.digitalcourage.de/haskell-munich-oct-2022 Everybody is welcome! cu, -- Leah Neukirchen <leah(a)vuxu.org> https://leahneukirchen.org/

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Re: [Haskell-cafe] Announcing the Haskell Error Index
by Olaf Klinke 21 Oct '22

21 Oct '22

David, the Haskell error index is an awesome idea and the existing entries of high quality. Are there plans to tap the already quite enormous online resources about GHC errors, e.g. this mailing list, reddit and stackoverflow? One can imagine there are numerous brilliant explanations to be found. How did the other languages you mentioned handle the initial populatuion with content? (A general problem knowledge bases suffer: To be useful, a critical mass of knowledge must be accumulated, otherwise users won't be likely to contribute.) Regards, Olaf

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TFPIE 2023 call for submissions (deadline Dec 27th)
by Elena Machkasova 21 Oct '22

21 Oct '22

Please consider submitting and spread the word! TFPIE 2023 Call for papers https://wiki.tfpie.science.ru.nl/TFPIE2023 (January 12th 2023, Boston, MA, USA, co-located with TFP 2023 and POPL 2023) TFPIE 2023 welcomes submissions describing techniques used in the classroom, tools used in and/or developed for the classroom and any creative use of functional programming (FP) to aid education in or outside Computer Science. Topics of interest include, but are not limited to: FP and beginning CS students FP and Computational Thinking FP and Artificial Intelligence FP in Robotics FP and Music Advanced FP for undergraduates FP in graduate education Engaging students in research using FP FP in Programming Languages FP in the high school curriculum FP as a stepping stone to other CS topics FP and Philosophy The pedagogy of teaching FP FP and e-learning: MOOCs, automated assessment etc. Best Lectures - more details below In addition to papers, we are requesting best lecture presentations. What's your best lecture topic in an FP related course? Do you have a fun way to present FP concepts to novices or perhaps an especially interesting presentation of a difficult topic? In either case, please consider sharing it. Best lecture topics will be selected for presentation based on a short abstract describing the lecture and its interest to TFPIE attendees. The length of the presentation should be comparable to that of a paper. In addition, the speaker can provide commentary on effectiveness or student feedback. Submissions Potential presenters are invited to submit an extended abstract (4-6 pages) or a draft paper (up to 20 pages) in EPTCS style. The authors of accepted presentations will have their preprints and their slides made available on the workshop's website. Papers and abstracts can be submitted via easychair at the following link: https://easychair.org/conferences/?conf=tfpie2023 After the workshop, presenters are invited to submit (a revised version of) their article for the formal review. The PC will select the best articles for publication in the Electronic Proceedings in Theoretical Computer Science (EPTCS). Articles rejected for presentation and extended abstracts will not be formally reviewed by the PC. Important Dates Submission deadline: December 27th 2022, Anywhere on Earth. Notification: December 30th 2022 (Note: earlier submissions will receive earlier response) TFPIE Registration Deadline: TBA Workshop: January 12th 2023 Submission for formal review: April 19th 2023, Anywhere on Earth. Notification of full article: May 24th 2023 Camera ready: July 1st 2023 Program Committee Christopher Anand - McMaster University, Canada Attila Egri-Nagy - Akita International University, Japan Jason Hemann - Seton Hall University, USA Kevin Kappelmann - Technical University of Munich, Germany Elena Machkasova (Chair) - University of Minnesota Morris, USA Kristina Sojakova - INRIA, France Jørgen Villadsen - Technical University of Denmark, Denmark Registration information See https://wiki.tfpie.science.ru.nl/TFPIE2023 for updated information. Registration and attendance are mandatory for at least one author of every paper that is presented at the workshop. Presenters will have their registration fee waived. Only papers that have been presented at TFPIE may be submitted to the post-reviewing process. Best regards, Elena Machkasova (program committee chair) -- Dr. Elena Machkasova Associate Professor of Computer Science Division of Science and Mathematics University of Minnesota, Morris Office: Sci 2325 (320) 589-6308 http://cda.morris.umn.edu/~elenam/ Pronouns: she/her/hers or any other

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Re: [Haskell-cafe] Announcing the Haskell Error Index
by Douglas McIlroy 21 Oct '22

21 Oct '22

(comment mostly for entertainment) The announcement of the Haskell error index conjured memories of the Fortran I stop book. On an error, the original Fortran compiler executed a halt instruction. To find the cause, one would read the memory address of the halt from the console lights and manually look the address up in the stop book, a thick 11"x17" computer printout. In the Haskell error index, the codes are permanent identifiers for evolving diagnostic explanations. In contrast, Fortran stop numbers varied with compiler version, while the explanations were essentially static. The stop book was indispensable, but far from user-friendly. If reasonably curated, the error index could be a big advance in the latter respect. Doug McIlroy

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Bogotá Functional Programming Interest Group
by Jeffrey Brown 20 Oct '22

20 Oct '22

I imagine people who read Haskell Cafe and live in Colombia might be interested in this new group. It's the closest thing I'm aware of to a Haskell user group in the country. https://www.meetup.com/functional-programming-interest-group-at-puj/ -- Jeff Brown | Jeffrey Benjamin Brown LinkedIn <https://www.linkedin.com/in/jeffreybenjaminbrown> | Github <https://github.com/jeffreybenjaminbrown> | Twitter <https://twitter.com/carelogic> | Facebook <https://www.facebook.com/mejeff.younotjeff>

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Announcing the Haskell Error Index
by David Christiansen 20 Oct '22

20 Oct '22

The Haskell Error Index (https://errors.haskell.org/) is a community-driven web site for improving the documentation of Haskell tooling. In the upcoming release of GHC, each error message or warning includes a unique code. This code can be looked up on the index to find user-contributed explanations and examples. As the specific phrasing of messages in GHC is improved over time, the codes will remain constant, which allows the documentation on the site to retain its value and its search-engine usefulness. The site is run off of a Git repo full of Markdown files and example programs at https://github.com/haskellfoundation/error-message-index/ , so you don't need to be an expert to contribute. Contributions of documentation as well as technical improvements to the site generator, HTML, and CSS are all very welcome. Most of the current content and infrastructure was contributed by volunteers at Zurihac this year. Right now, it only covers an unreleased version of GHC, but the system is set up to also work with other tools. If you're an author of Haskell-related tooling and would like to have it included, please write to me at david(a)haskell.foundation. The site is inspired by the Rust error index and by the excellent user-contributed sections in the PHP documentation. It's part of the Haskell Foundation's technical agenda, arising from a Haskell Foundation Technical Proposal ( https://github.com/haskellfoundation/tech-proposals/blob/main/proposals/acc…) If you'd like to have influence on what we at the HF do, please submit a proposal! All the best, David Thrane Christiansen Executive Director The Haskell Foundation

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PhD positions at Binghamton University
by William Hallahan 19 Oct '22

19 Oct '22

Dear all, I am a new faculty member at Binghamton University, looking for PhD students (starting in Spring 2023 or Fall 2023) to work on formal verification, analysis, and/or synthesis. A common aim of my work is to ease the process of verifying programs, either by improving the debugging experience when verification fails, or by automating the verification process. Much of my work revolves around functional languages, with a particular focus on debugging and verifying Haskell programs. I am also interested in verification and synthesis of systems in domains such as networking and machine learning. You can find more information about me on my website: https://billhallahan.github.io <https://billhallahan.github.io/> Please reach out if you are interested or if you have any questions. Best, William Hallahan

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Haskell language model
by Jorrit Willaert 19 Oct '22

19 Oct '22

Dear all, For my thesis, I will try to offer Haskell coding assignments for a course in a more dynamic way, where the next assignment is based on the knowledge gap of the learner. For this, I will use a neural network, which will have to process a submission of a learner. Therefore, I want to use a language model that extracts features from the submission. I was planning to use BERT in a first phase, since this model creates embeddings from a document. However, this model is not trained on any programming language, so this may turn out to be insufficient. Moreover, models such as CodeBERT are trained on source code, but only on very well known programming languages. I was wondering if someone had an idea if there already exists a language model that can create meaningful representations for Haskell. More general models such as Codex (paying API) or GPT-Code-Clippy (free and opensource) could also be tried out, but if there exists a model that has been trained on Haskell specific data, that would of course be the most beneficial option. If you want to read more about my thesis, you can read more about it in the attachment. Thanks in advance! Kind regards, Jorrit Willaert https://www.linkedin.com/in/jorrit-willaert-166a64198/ https://github.com/JorritWillaert

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What's different about quantified constraints since GHC 9.2?
by Li-yao Xia 19 Oct '22

19 Oct '22

Dear Café, There's a trick [1] involving quantified constraints (and usually type families) where a function has a quantified constraint (forall a. CF a) and which is explicitly instantiated with a well-placed type annotation (_ :: CF x => ...). Since GHC 9.2, this trick works without that type annotation. How did GHC get smarter at instantiating this quantified constraint? Below is a minimized example which compiles on GHC 9.2.1 but not 9.0.1 (haven't tested 9.0.2), unless you uncomment the last line. Cheers, Li-yao [1]: an Iceland_jack trick https://gitlab.haskell.org/ghc/ghc/-/issues/14860#note_151394 {-# LANGUAGE TypeFamilies, FlexibleInstances, FlexibleContexts, QuantifiedConstraints, ScopedTypeVariables #-} module A where type family F a class C a class C (F a) => CF a f :: C (F a) => a f = undefined g :: (forall a. CF a) => a g = f -- :: forall a. CF a => a -- needed until GHC 9.0.1 but not GHC 9.2.1 (and later)

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FOSDEM 2023 Haskell devroom proposal - co-organiser needed!
by Fraser Tweedale 19 Oct '22

19 Oct '22

Greetings, I decided to propose a Haskell devroom (like a one/half-day specialist track or miniconf) for FOSDEM 2023, to be held February 4--5 in Brussels. It would be great to promote Haskell among this audience and hopefully attract new contributors / community members. Unfortunately I left it quite late (deadline submission is today). I only just realised I need a secondary contact (i.e. co-organiser) to submit the proposal. So... any volunteers? Ideally you are located in Europe or definitely planning to attend FOSDEM. If you are willing, please reply! I think I all need right now is your name and email address (and enthusiasm). The text of my proposal may be found at https://github.com/frasertweedale/talks/blob/master/2022-02-xx-fosdem-haske…. I have experience organising and host FP miniconfs at linux.conf.au including running the CFP etc. I expect FOSDEM will be similar, except y'know, the other side of the world from Australia, where I live. Thanks, Fraser

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Package takeover request: utf8-light
by Francesco Ariis 18 Oct '22

18 Oct '22

Hello list, I would like to take over `utf8-light`: https://hackage.haskell.org/package/fgl as it currently breaks compilation for a game I wrote: https://github.com/haskell-infra/hackage-trustees/issues/347 There is no repository, I contacted the maintainer via email on october 2, without receiving any answer —F

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Call for Contributions: BOB 2023 [March 17, Deadline Nov 21]
by Stefan Wehr 18 Oct '22

18 Oct '22

================================================================================ BOB Conference 2023 "What happens when we use what's best for a change?" https://bobkonf.de/2023/cfc.html Berlin, Mar 17 Call for Contributions Deadline: November 21, 2022 ================================================================================ You are actively engaged in advanced software engineering methods, solve ambitious problem with software and are open to cutting-edge innovation? Attend this conference, meet people that share your goals, and get to know the best software tools and technologies available today. We strive to offer a day full of new experiences and impressions that you can use to immediately improve your daily life as a software developer. If you share our vision and want to contribute, submit a proposal for a talk or tutorial! NOTE: The conference fee will be waived for presenters. Travel expenses will not be covered (for exceptions see "Speaker Grants"). Online or Onsite ---------------- We expect we'll be able to hold BOB 2023 in Berlin. Note that we intend to provide a safe environment for all participants. There will be space outside to eat and chat. We may ask you to wear a mask indoors when not presenting or eating, and may also ask you to take a COVID test on-site before the event. If an on-site BOB is not possible, we'll make BOB a successful online event, like BOB 2021 and BOB 2022. Should BOB happen online, we will likely ask for pre-recorded talks to make room for questions and social interactions during the actual conference day. (Of course, we'll provide assistance making those recordings.) Tutorials will likely happen as a live-session. Shepherding ----------- The program committee offers shepherding to all speakers. Shepherding provides speakers assistance with preparing their sessions. Specifically: - advice on structure and presentation - review of talk slides - assistance with recording - review of recording, if applicable Speaker Grants -------------- BOB has Speaker Grants available to support speakers from groups under-represented in technology. We specifically seek women speakers, speakers of color, and speakers who are not able to attend the conference for financial reasons. Topics ------ We are looking for talks about best-of-breed software technology, e.g.: - functional programming - persistent data structures and databases - event-based modelling and architecture - "fancy types" (dependent types, gradual typing, linear types, ...) - formal methods for correctness and robustness - abstractions for concurrency and parallelism - metaprogramming - probabilistic programming - math and programming - controlled side effects - program synthesis - next-generation IDEs - effective abstractions for data analytics - … everything really that isn’t mainstream, but you think should be - … includeing rough ideas worth discussing. Presenters should provide the audience with information that is practically useful for software developers. Challenges ---------- Furthermore, we seek contributions on successful approaches for solving hard problems, for example: - bias in machine-learning systems - digital transformation in difficult settings - accessibiltity - systems with critical reliability requirements - ecologically sustainable software development We're especially interested in experience reports. Other topics are also relevant, e.g.: - introductory talks on technical background - overviews of a given field - demos and how-tos Requirements ------------ We accept proposals for presentations of 45 minutes (40 minutes talk + 5 minutes questions), as well as 90 minute tutorials for beginners. The language of presentation should be either English or German. Your proposal should include (in your presentation language of choice): - An abstract of max. 1500 characters. - A short bio/cv - Contact information (including at least email address) - A list of 3-5 concrete ideas of how your work can be applied in a developer's daily life - additional material (websites, blogs, slides, videos of past presentations, …) - Don't be confused: The system calls a submission event. Organisation ------------ - Direct questions to konferenz at bobkonf dot de - Proposal deadline: November 21, 2022 - Notification: December 5, 2022 - Program: December 12, 2022 Submit here: https://pretalx.com/bob-2023/submit/ Program Committee ----------------- (more information here: https://bobkonf.de/2023/programmkomitee.html) - Matthias Fischmann, Wire - Matthias Neubauer, SICK AG - Nicole Rauch, Softwareentwicklung und Entwicklungscoaching - Michael Sperber, Active Group - Stefan Wehr, Hochschule Offenburg Scientific Advisory Board - Annette Bieniusa, TU Kaiserslautern - Torsten Grust, Uni Tübingen - Peter Thiemann, Uni Freiburg

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Haskell merchandise
by Borys Kopeć 14 Oct '22

14 Oct '22

Hey all, Do you know where to find official (if there is one) merch on Haskell? I'm talking stickers, clothes and gadgets. Regards Borys

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Ph.D. position at Radboud University Nijmegen, The Netherlands
by Pieter Koopman 14 Oct '22

14 Oct '22

Dear all, we are looking for a PhD candidate in Software Technology <https://www.ru.nl/en/working-at/job-opportunities/phd-candidate-in-software…>. As a PhD candidate in the Software Technology Group, you will actively contribute to the research group's IoT activities, spearheading research on swarm computing in the IoT: intelligent cooperating nodes that are dynamically connected in an ever-changing network. You will contribute to our research in swarm computing, working with dynamically changing networks of cooperating intelligent nodes. You have a Master's degree in computer science or mathematics with a background in declarative/functional programming. Experience with code generation, run-time systems, the internet of things, edge computing, language design, or low-power computing is a plus. Please contact me for details. Pieter Koopman

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