- Haskell-Cafe - Haskell.org

GHC 9.12.3-rc1 is now available
by Zubin Duggal 22 Sep '25

22 Sep '25

The GHC developers are very pleased to announce the availability of the release candidate for GHC 9.12.3. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.12.3 is a bug-fix release fixing several issues of a variety of severities and scopes. A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 2 October 2025. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. [release notes]: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.12/docs/users_guide/9.12.3-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.3-rc1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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Haskell Symposium 2025 Last Call for Talks (deadline Sept 15th)
by Ningning Xie 14 Sep '25

14 Sep '25

======================================================== Haskell Symposium 2025 Call for Talks Thu 16 - Fri 17 Oct 2025, Singapore https://conf.researchr.org/home/icfp-splash-2025/haskellsymp-2025 ======================================================== The ACM SIGPLAN Haskell Symposium 2025 will be co-located with the 2025 International Conference on Functional Programming (ICFP) and the 2025 International Conference on Systems, Programming, Languages and Applications: Software for Humanity (SPLASH). The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. We invite proposals from potential speakers for talks. Talk proposals should report work in progress relevant to Haskell language design, theory, tools, or applications. Talks are proposed by submitting an abstract. Please submit a talk title and abstract of no more than 300 words. There will be no published proceedings. Papers should be submitted through HotCRP at: https://haskell25.hotcrp.com/ Submission deadline: 15 September 2025 (Mon) Deadlines are valid anywhere on Earth. Talk proposals will go through a lightweight reviewing process, evaluated by the PC for relevance to the Haskell community, but are not expected to include finished results. Talk proposals will not be distributed to attendees, but authors of talk proposals may provide links to materials to be included on the program. Topics of interest include: * Language design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, such as formal semantics of the present language or future extensions, type systems, effects, metatheory, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management, as well as foreign function and component interfaces; * Libraries, that demonstrate new ideas or techniques for functional programming in Haskell; * Tools, such as profilers, tracers, debuggers, preprocessors, and testing tools; * Applications, to scientific and symbolic computing, databases, multimedia, telecommunication, the web, and so forth; * Experience Reports, to document general practice and experience in education, industry, or other contexts; * System Demonstrations, based on running software rather than novel research results.

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[Call for participation]: North American Haskell Hackathon in New York
by Jose Calderon 13 Sep '25

13 Sep '25

Hello Haskell Cafe, The Haskell Foundation is proud to announce the inaugural AmeriHac, a two day haskell hackathon, with this iteration being in New York City! Jane Street has kindly offered to host the Haskell Foundation’s first North American Haskell event. The event will take place on Feb 7th and Feb 8th 2026 within Jane Street’s New York premises (https://maps.app.goo.gl/eHweQfEGkRJiYkct6) Registration will be free, thanks to Jane Street’s generosity as hosts. ## Organization Much like ZuriHac, there will be dedicated space for specific projects (GHC, cabal, stack, etc.), with the full details being determined by registrant interest. The webpage, https://haskell.foundation/events/2026-amerihac.html, will be updated with more information as we finalize keynote speakers and the schedule. ## Summary: - Who: Haskell Foundation and Jane Street - What: Weekend Haskell hackathon - Where: Jane Street NYC (https://maps.app.goo.gl/eHweQfEGkRJiYkct6) Register here: https://forms.gle/3dZvn3VAvwa3JgJK8 We look forward to seeing you there! -Jose

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GHC 9.10.3 is now available
by Zubin Duggal 11 Sep '25

11 Sep '25

The GHC developers are very pleased to announce the availability of the final release for GHC 9.10.3. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][]. GHC 9.10.3 is a bug-fix release fixing many issues of a variety of severities and scopes, including: * Fix a number of crashes in the compiler frontend (#25960, #25004, #25056) * Fix incorrect results in the NCG (#25601, #26061) * Support for far jumps in the AArch64 NCG (#24648) * A fix for a segfault in the RTS when running certain code involving STM (#26205) * And many more! A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. [release notes]: https://downloads.haskell.org/~ghc/9.10.3/docs/users_guide/9.10.3-notes.html [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.3 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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CGO 2026 - Call For Tutorials
by Luisa Cicolini 10 Sep '25

10 Sep '25

Dear all, This is a reminder that only one week is left to submit tutorial proposals<https://2026.cgo.org/track/cgo-2026-workshops-and-tutorials> for CGO 2026 (deadline 17th September). The International Symposium on Code Generation and Optimization (CGO) provides a premier venue to bring together researchers and practitioners working at the interface of hardware and software on a wide range of optimization and code generation techniques and related issues. The conference spans the spectrum from purely static to fully dynamic approaches, and from pure software-based methods to specific architectural features and support for code generation and optimization. CGO will be held in Sydney, Australia from 31st January – 4th February 2026 and tutorials (half- or full-day) will be held before the main conference. Best, Luisa

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[ANN] Copilot 4.5.1
by Ivan Perez 09 Sep '25

09 Sep '25

Hi everyone!! We are really excited to announce Copilot 4.5.1 [1,2]. Copilot is a stream-based EDSL in Haskell for writing and monitoring embedded C programs, with an emphasis on correctness and hard realtime requirements. Copilot is typically used as a high-level runtime verification framework, and supports temporal logic (LTL, PTLTL and MTL), clocks and voting algorithms. Compilation to Bluespec, to target FPGAs, is also supported. Copilot is NASA Class D open-source software, and is being used at NASA in drone test flights. Through the NASA tool Ogma [3] (also written in Haskell), Copilot also serves as a programming language and runtime framework for NASA's Core Flight System, Robot Operating System (ROS2), FPrime (the software framework used in the Mars Helicopter). Ogma now supports producing flight and robotics applications directly in Copilot, not just for monitoring, but for implementing the logic of the applications themselves. Since the last announcement, the major updates and improvements are: - Copilot maintream now includes the verification, FPGA and visualization backends. - Copilot now includes a tutorial showing how to generate code for FPGA and run it (thanks to Sukhman Kahlon!). - Compatibility with newer versions of dependencies has been extended. - Cleaning efforts in `copilot-theorem`, and `copilot-core`. A picture of the Copilot visualizer can be seen at [5]. The new implementation is compatible with versions of GHC from 8.6 to 9.12. This release has been made possible thanks to key submissions from Sukhman Kahlon (NASA). We also thank Corey Carter (NASA), Ryan Scott (Galois) and Kaveh Zare (NASA) for their input. We are grateful to them for their contributions, and for making Copilot better every day. For details on this release, see [1]. As always, we're releasing exactly 2 months since the last release. Our next release is scheduled for Nov 7th, 2025. We want to remind the community that Copilot is now accepting code contributions from external participants again. Please see the discussions and the issues in our github repo [4] to learn how to participate. Current emphasis is on using Copilot for full data processing applications (e.g, system control, arduinos, rovers, drones), improving usability, performance, and stability, increasing test coverage, removing unnecessary dependencies, hiding internal definitions, and formatting the code to meet our coding standards. Users are encouraged to participate by opening issues, asking questions, extending the implementation, and sending bug fixes. Happy Haskelling! Ivan -- [1] https://github.com/Copilot-Language/copilot/releases/tag/v4.5.1 [2] https://hackage.haskell.org/package/copilot [3] https://github.com/nasa/ogma [4] https://github.com/Copilot-Language/copilot [5] https://www.reddit.com/r/haskell/comments/1nci0u6/ann_copilot_451/

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IFL2025 Call for Participation
by Mart Lubbers 05 Sep '25

05 Sep '25

========================================================== Call for Participation IFL 2025 37th Symposium on Implementation and Application of Functional Languages Montevideo, Uruguay October 1-3, 2025 (Tutorials September 29-30) https://www.fing.edu.uy/inco/congresos/ifl2025 ========================================================== The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2025 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. ### Registration The registration fee covers use of facilities, participation in the tutorials and symposium, lunches, coffee breaks, social outing, symposium dinner and access to draft proceedings. Early Bird Registration Deadline is Sep 5, 2025. https://www.fing.edu.uy/inco/congresos/ifl2025/register.html If you choose online payment at registration, you will receive payment instructions during the week. ### Keynote speakers Roberto Ierusalimschy Departamento de Informática, PUC-Rio, Río de Janeiro, Brazil Functions in Lua Iván Pérez NASA Ames Research Center, California, USA Making Haskell Fly https://www.fing.edu.uy/inco/congresos/ifl2025/keynotes.html ### Tutorials On September 29 and 30, the two days prior to the symposium, four tutorials will be held: Gradual typing Éric Tanter, University of Chile, Chile Type Based Static Analysis Jurriaan Hage, Heriot-Watt University, UK Development of dApps in the UTxO model TxPipe, Argentina Programming-Based Automata Theory Marco T. Morazán, Seton Hall University, USA https://www.fing.edu.uy/inco/congresos/ifl2025/tutorials.html ### Accepted Papers Regular Papers: Compilation of the Stochastic Language ALEA, Baltasar Trancón Y Widemann and Markus Lepper. Design and Implementation of DSLs for Unit Testing, Marco T. Morazán and Andres Garced. Recipe-Based Errors: Methodology, Implementation, and Evaluation, Marco T. Morazán, Shamil Dzhatdoyev, Josephine Des Rosiers, Rose Bohrer, Andres Garced and David Anthony Fields. Refinement-Types Driven Development: A study, Facundo Domínguez and Arnaud Spiwack. Draft Papers: AI-Assisted Program Design Using Structural Recursion, Marco T. Morazán. A Quantum-Control Lambda-Calculus with Multiple Measurement Bases, Nicolas A. Monzon and Alejandro Díaz-Caro. Automatic Testing for Finite-State Machines, Marco T. Morazán, Sophia G. Turano, Andres Garced and David Anthony Fields. Closures in a Higher-Order Polymorphic DSL for GPU programming, Andre Rauber Du Bois, Henrique Gabriel Rodrigues and Rodrigo Geraldo Ribeiro. Energy-aware Data-Parallel Functional Array Processing for Heterogeneous Platforms, Clemens Grelck. Formalizating System I with type Top in Agda, Agustín Séttimo, Cristian Sottile and Cecilia Manzino. Foundations of Gradual Abstract Interpretation, Gaspar Ricci, Sebastian Erdweg, Éric Tanter and Matías Toro. Heuristics-based Type Error Diagnosis for Haskell: the case of type families, Niels Kwadijk and Jurriaan Hage. Higher-ranked region inference for polymorphic, lazy languages, Ivo Gabe de Wolff and Jurriaan Hage. Improving a Group Membership Protocol Implementation using Liquid Haskell and QuickCheck, Jianhao Li and Viktoria Zsok. List Fold Operators in Dafny, Juan Michelini, Nora Szasz and Alvaro Tasistro. Reducibility candidates modulo isomorphisms, Cristian Sottile and Alejandro Díaz-Caro. Type Checking Dependently Sorted Nominal Signatures, Maribel Fernandez, Miguel Pagano, Nora Szasz and Alvaro Tasistro. Unrestricted Grammar Design and Visualization: A Design Recipe and Dynamic Visualization Tool, Marco T. Morazán, Andres Garced and Tijana Minić.

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Haskell Symposium 2025 Call for Talks (deadline Sept 15th)
by Ningning Xie 02 Sep '25

02 Sep '25

======================================================== Haskell Symposium 2025 Call for Talks Thu 16 - Fri 17 Oct 2025, Singapore https://conf.researchr.org/home/icfp-splash-2025/haskellsymp-2025 ======================================================== The ACM SIGPLAN Haskell Symposium 2025 will be co-located with the 2025 International Conference on Functional Programming (ICFP) and the 2025 International Conference on Systems, Programming, Languages and Applications: Software for Humanity (SPLASH). The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. We invite proposals from potential speakers for talks. Talk proposals should report work in progress relevant to Haskell language design, theory, tools, or applications. Talks are proposed by submitting an abstract. Please submit a talk title and abstract of no more than 300 words. There will be no published proceedings. Papers should be submitted through HotCRP at: https://haskell25.hotcrp.com/ Submission deadline: 15 September 2025 (Mon) Deadlines are valid anywhere on Earth. Talk proposals will go through a lightweight reviewing process, evaluated by the PC for relevance to the Haskell community, but are not expected to include finished results. Talk proposals will not be distributed to attendees, but authors of talk proposals may provide links to materials to be included on the program. Topics of interest include: * Language design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, such as formal semantics of the present language or future extensions, type systems, effects, metatheory, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management, as well as foreign function and component interfaces; * Libraries, that demonstrate new ideas or techniques for functional programming in Haskell; * Tools, such as profilers, tracers, debuggers, preprocessors, and testing tools; * Applications, to scientific and symbolic computing, databases, multimedia, telecommunication, the web, and so forth; * Experience Reports, to document general practice and experience in education, industry, or other contexts; * System Demonstrations, based on running software rather than novel research results.

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Takeover of AvlTree and COrdering
by Andrew Lelechenko 22 Aug '25

22 Aug '25

I’d like to take over Hackage packages https://hackage.haskell.org/package/COrdering and https://hackage.haskell.org/package/AvlTree. Last uploads were in 2008. Both packages fail to compile with modern GHCs; my intention is to bring them back to life. There are no maintainer contacts and no source code repository linked, so I cannot reach out to the maintainer to offer my services. Best regards, Andrew

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GHC 9.10.3-rc4 is now available
by Zubin Duggal 18 Aug '25

18 Aug '25

The GHC developers are very pleased to announce the availability of the fourth release candidate for GHC 9.10.3. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.3 is a bug-fix release fixing over 50 issues of a variety of severities and scopes. A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. The changes from the third release candidate are: - A fix for a rare segfault with code involving STM (#26205) - A fix for the `naturalAndNot` returning bogus results (#26205) - A fix for a crash in the renamer (#25056) This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 1 September 2025. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. [release notes]: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.10/docs/users_guide/9.10.3-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.3-rc4 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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