March 2023 - Haskell-Cafe

Re: [Haskell-cafe] dynamic web form generation for algebraic data types
by Olaf Klinke 14 Mar '23

14 Mar '23

> > From briefly reading the wiki page > https://wiki.haskell.org/Tangible_Value, it looks like it relies on > Applicative functors for combining values. > So maybe the missing piece for sum-types was Selective functors > https://hackage.haskell.org/package/selective? > > Gustavo Bicalho > Well spotted! I did not know selective applicative functors (SAFs), thanks for mentioning! Indeed `branch` seems to be all that is necessary to get forms for sum types going. In the talk [1] Andrey mentions that SAFs have a bind, but only for enumerable inputs. The papers state that "all effects are declared statically". If we equate "effect" with "form input" then for recursive types like lists this would mean to pre-define an infinite number of fields and have the user select a finite number of them. I wonder whether that is feasible with html forms. Maybe forms (in the html sense) are a red herring for what I am after. Both the Grace and tangible values demos immediately process changes to inputs, there is no distinction between inputting the data and having the data processed: they are event-driven systems. As is JavaScript with its `oninput` and `onchange` functions. So there are two sub-problems here: The first problem is to programmatically generate html elements by JavaScript functions that can build all finite values of a given Generic Haskell type, and nothing else. The second problem is to scrape the thusly generated elements and re-assemble them into a Haskell value on the server side. The second problem is usually solved by html forms, but there may be other means. Olaf [1] https://dl.acm.org/doi/abs/10.1145/3341694#

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Just released: cabal 3.10.1.0
by Mikolaj Konarski 13 Mar '23

13 Mar '23

Dear cabal users and contributors, The cabal team is proud to announce the release of cabal 3.10.1.0. This is mainly a bugfix release, but it has some new features and enhancements as well. The thread about the release, including troubleshooting and porting discussions, is at https://discourse.haskell.org/t/just-released-cabal-3-10-1-0/5978 The changelogs and release notes are at https://github.com/haskell/cabal/blob/master/release-notes/cabal-install-3.… and, if your code depends on the Cabal library, at https://github.com/haskell/cabal/blob/master/release-notes/Cabal-3.10.1.0.md Two backward (in)compatibility notes may be of particular interest: the XDG Base Directory Specification (conditionally) replacing ~/.cabal and the `--enable-documentation` option by default added to all `cabal haddock` invocations. Please look them up at the links above. Let me finish by thanking our esteemed benefactors, past and present, contributing code, devops, testing, feedback, comments. Representing these are the authors of all PRs included in the 3.10.1.0 release, honourably mentioned in the list of fame below. Abastro Alexander Biehl Alexey Radkov amigalemming Andrea Bedini Andreas Abel Andreas Klebinger Artem Pelenitsyn Ben Gamari Bodigrim Brandon Chinn Bryan Richter Byron Johnson Cheng Shao chowells79 Cmdv Colton Clemmer cydparser Daniel Gröber deltaspace0 Evgenii Akentev fendor Francesco Ariis Francesco Gazzetta Gautier DI FOLCO Georgi Lyubenov Gershom Bazerman Guillaume Genestier Hécate Moonlight Ikko Ashimine instinctive Jade Lovelace James Hobson Jan Synáček Jappie Klooster Javier Neira John Ericson Kobayashi Marcin Szamotulski Martijn Bastiaan Matthew Pickering Max Amanshauser Miezhiko Mike Pilgrem Musab Guma'a Patrick Dougherty Paweł Dybiec Pierre Le Marre Robert Vollmert Ross Paterson Saad Ahmed Sergey Vinokurov sheaf Sören Tempel Sylvain Henry Tom McLaughlin Troels Henriksen Vilius Panevėžys Vladislav Zavialov Wismill

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[ANNOUNCE] GHC 9.6.1 is now available
by Ben Gamari 12 Mar '23

12 Mar '23

The GHC team is very pleased to announce the availability of GHC 9.6.1. As usual, binaries and source distributions are available at downloads.haskell.org: https://downloads.haskell.org/ghc/9.6.1/ Beginning with GHC 9.6.1, GHC can be built as a cross-compiler to WebAssembly and JavaScript. This is an important step towards robust support for compiling Haskell to the Web, but there are a few caveats to be aware of in the 9.6 series: - Both the Javascript and WebAssembly backends are still at an early stage of development and are present in this release as a technology preview - Using GHC as a cross-compiler is not as easy as we would like it to be; in particular, there are challenges related to Template Haskell - GHC is not yet run-time retargetable; a given GHC binary targets exactly one platform, and both WebAssembly and JavaScript are considered platforms for this purpose. Cross-compilers must be built from source by their users We hope to lift all of these limitations in future releases. Additionally, 9.6.1 includes: - Significant latency improvements in the non-moving garbage collector - Efficient runtime support for delimited continuations - Improvements in compiler error messages - Numerous improvements in the compiler's memory usage See the [release notes] for a comprehensive accounting of changes in this release. As always, one can find a migration guide to aid in transitioning from older releases on the [GHC Wiki][migration-guide]. We have also recently started extending our release process to cover a wider set of Linux distributions. In particular, we now offer Rocky 8 and Ubuntu 20.04 binary distributions which cover RedHat-derivative and distributions using older glibc releases (namely 2.27), respectively. Thanks to everyone who has contributed code, documentation, testing, and tickets to this release process. As this release represents upstream GHC's first step towards supporting web targets, we are very excited to have this release out the door! Cheers, - Ben [ticket]: https://gitlab.haskell.org/ghc/ghc/issues/ [migration-guide]: https://gitlab.haskell.org/ghc/ghc/-/wikis/migration/9.6 [release notes]: https://downloads.haskell.org/ghc/9.6.1/docs/users_guide/9.6.1-notes.html

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ANN: hledger-1.29
by Simon Michael 11 Mar '23

11 Mar '23

I'm pleased to announce hledger 1.29 ! https://github.com/simonmichael/hledger/releases/1.29 https://hledger.org/install https://hledger.org/release-notes.html#hledger-1-29 Highlights: Tag checking, flexible multi-period start dates, flexible cost/conversion posting combining, new commands list, hledger manual reorg, easier close command, 10% more Ledger file compatible. Thank you to release contributors Chris Lemaire, Caleb Maclennan, Jonathan Dowland, J. B. Rainsberger, Michael Grünewald, Robert Nielsen, and Yann Büchau. 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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ANN: Haskell Tiny Game Jam 2023 Results
by Simon Michael 10 Mar '23

10 Mar '23

We are very pleased to announce.. the results of Haskell Tiny Game Jam 2023 ! Congratulations and thanks to all participants! - 55 entries in 4 categories from 28 entrants in 3 weeks - 109 reviews, 5 winners and 6 honourable mentions from 2 judges - Shell script to browse and play the games on all major platforms (single binary coming later maybe) - Readable source versions, useful development tips, informative blog posts This was the first Haskell game dev contest. The prize.. glory! Also fun, learning, and advancing Haskell's suitability for game dev and programming in the small. We invite you to come and play, read, and get inspired for the next one! https://github.com/haskell-game/tiny-games-hs

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ANN: atomic-modify-general
by David Feuer 10 Mar '23

10 Mar '23

I just put together a new package, atomic-modify-general, for generalizations of the `atomicModifyIORef` operation. In particular: 1. Versions that allow a result of an arbitrary type (not necessarily a pair), where the caller passes in an extraction function. These work with `Array` and `SmallArray` from `primitive` as well as `IORef`. 2. A version that works with record types (not just pairs) whose first field is the new value to install in the `IORef`. This uses implementation details of the `atomicModifyMutVar#` primop as well as GHC's heap object layout to achieve better performance. Please try it out and let me know how it goes, and what extras you may want! Hackage: https://hackage.haskell.org/package/atomic-modify-general-0.1.0.0

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Nearly lens examples
by Geraldus 10 Mar '23

10 Mar '23

Dear all! Do you have good usage examples of *nearly* lens, especially in composition with other lenses / prisms? Sincerely yours, Arthur.

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PhD or Postdoc Position at LMU Munich about Verified Modal Logics
by Andrei Popescu 09 Mar '23

09 Mar '23

We are looking for a PhD student (4 years) or postdoctoral researcher (3 years) to work on the Isabelle formalization of modal model theory. The work will take place within the Chair of Theoretical Computer Science at LMU Munich under Jasmin Blanchette's supervision with the participation of two external experts: Cláudia Nalon (University of Brasília) and Sophie Tourret (Inria Nancy). Modal logics are extensions of classical logics with operators that allow for the qualification of truth. Model theory for modal logics is concerned with the interplay between the language (syntax, i.e., the set of its formulas) and its meaning (semantics, i.e., the structures over which the language is interpreted). There are, however, different ways of characterizing meaning for modal sentences and also several (well-established) results that allow for restriction on the sets of structures being considered. This project concerns the formalization in Isabelle of those results for general Kripke structures for generalized modal operators (i.e., of any arity). The goal is to produce a library that could then be used (and possibly extended) for specific applications, in particular those related to proof theory. The position is categorized as TV-L E13 according to the German salary scale. It includes some teaching obligations. The starting date is flexible. Please contact Jasmin Blanchette (jasmin.blanchette(a)ifi.lmu.de) for more information or if you want to apply. The application deadline is 15 April 2023.

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Alpha Release of Keelung, the New Haskell DSL Designed for Secure and Fast Application Development
by Ting Wang 09 Mar '23

09 Mar '23

Hello developers, I'm Ting with BTQ. We are thrilled to announce the alpha release of Keelung, a new domain-specific language (DSL) designed to make fast, private, and secure application development easy for developers.Both Keelung and its compiler have been implemented in Haskell, enabling you to produce high-level zero-knowledge proofs protected by Haskell's cutting-edge type system while leveraging Haskell's extensive ecosystem and tooling. What's more, Keelung will be 100% open-source, aligning with our values of transparency, collaboration, and community-driven development.Check out our blog post <https://www.btq.com/en/blog/keelung-alpha-release> of Keelung alpha release for more detail. If you're interested in using Keelung to build privacy-preserving applications, please visit our GitHub repository <https://github.com/btq-ag/keelung> and Hackage <https://hackage.haskell.org/package/keelung>. Our documentation <https://btq.gitbook.io/keelung/> also provides detailed information on how to use Keelung, including installation instructions, examples, and tutorials.If you have any questions about Keelung or would like to contribute to the project, please start a thread on our GitHub discussions <https://github.com/btq-ag/keelung/discussions> page or reach out to us via email at desk(a)btq.li. We're always happy to help and would love to hear from you!Thank you and we can't wait to see what you build with it! Ting Wang (Ms.) Product Manager ty.wang(a)btq.li www.btq.com [image: twitter] <https://twitter.com/btq_ag> [image: linkedin] <https://www.linkedin.com/company/btqag/about/>

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[ANN] Copilot 3.14
by Ivan Perez 08 Mar '23

08 Mar '23

(Apologies if you see this through multiple channels.) Hi everyone, I’m very excited to announce Copilot 3.14. Copilot is a stream-based EDSL in Haskell for writing and monitoring embedded C programs, with an emphasis on correctness and hard realtime requirements. Copilot is typically used as a high-level runtime verification framework, and supports temporal logic (LTL, PTLTL and MTL), clocks and voting algorithms. Copilot has been used at NASA in drone test flights. Through the NASA tool Ogma [1] (also written in Haskell), Copilot also serves as a runtime monitoring backend for the requirements elicitation tool FRET [4], and can target NASA’s Core Flight System and the Robot Operating System (ROS2) applications. This new version provides up-to-date compiler support, simplifies the API, and improves the documentation. For details, see [2]. As always, we’re releasing exactly 2 months since the last release. Our next release is scheduled for May 7th, 2023. We have almost completed the C99 unit tests, and plan to include those in the next version. Copilot is currently undergoing the qualification process necessary for NASA Class D Software. Current emphasis is on increasing 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 [3] There’s been many more updates on the Copilot front in the last few months. We’ll be able to announce more soon. Stay tuned. Happy Haskelling! Ivan [1] https://github.com/nasa/ogma [2] https://github.com/Copilot-Language/copilot/releases/tag/v3.14 [3] https://github.com/Copilot-Language/copilot [4] https://github.com/NASA-SW-VnV/fret

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