- ghc-devs - Haskell.org

GHC 9.14.1-alpha2 is now available
by Ben Gamari 16 Sep '25

16 Sep '25

The GHC developers are very pleased to announce the availability of the second alpha prerelease of GHC 9.14.1. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org] GHC 9.14 will bring a number of new features and improvements, including: * Significant improvements in specialisation: * The `SPECIALISE` pragma now allows use of type application syntax * The `SPECIALISE` pragma can be used to specialise for expression arguments as well as type arguments. * Specialisation is now considerably more reliable in the presence of `newtype`s * Significant improvements in the GHCi debugger * Record fields can be defined to be non-linear when `LinearTypes` is enabled. * `RequiredTypeArgments` can now be used in more contexts * SSE/AVX2 support in the x86 native code generator backend * A major update of the Windows toolchain * ... and many more A full accounting of changes can be found in the [release notes]. Given the many specialisation improvements and their potential for regression, we would very much appreciate testing and performance characterisation on downstream workloads. Observant readers of these prerelease announcements will note that polymorphic specialisation has been dropped from alpha 2. This measure was taken out of an abundance of caution after finding a miscompilation during testing of alpha 1. While this bug will be fixed in the next alpha, we expect to keep polymorphic specialisation disabled by default in the final release. Users needing more aggressive specialisation can explicitly enable this feature with the `-fpolymorphic-specialisation` flag. Depending upon our experience with 9.14.1, we may enable this feature by default in a later minor release. This is the second of three expected alpha prereleases. We expect the next (third) alpha will come 23 Sept. 2025, with the release candidate coming 7 Oct. 2025. We would like to thank the Zw3rk stake pool, Well-Typed, Mercury, Channable, Tweag I/O, 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 have made the Haskell ecosystem what it is today. As always, do give this release a try and open a [ticket] if you see anything amiss. [downloads.haskell.org] https://downloads.haskell.org/ghc/9.14.1-alpha2 [release notes]: https://downloads.haskell.org/ghc/9.14.1-alpha2/docs/users_guide/9.14.1-not… [ticket]: https://gitlab.haskell.org/ghc/homepage/-/issues/new

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

15 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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AArch64/Linux CI runners
by Ben Gamari 12 Sep '25

12 Sep '25

Hi all, Last night we brought up the new AArch64/Linux runners in their temporary home. They are now serving jobs, seemingly successfully. If you observe any suspicious failures do let us know. At some point in the near future we will need to bring the runners back down for a day or so to move them to their final home at OpenCape. We will communicate plans for this as they are formed. Cheers, - Ben

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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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gitlab.haskell.org is now behind Cloudflare
by Ben Gamari 07 Sep '25

07 Sep '25

Hi all, In response to reports of Anubis breaking some page loads and the LLM crawling load, I have put gitlab.haskell.org behind Cloudflare proxying. My hope is that this allows us to both mitigate some of the spam problem, avoid the crawling load, and avoid the issues with Anubis. Naturally, let me know if you observe anything amiss. Cheers, - Ben

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Marge
by Simon Peyton Jones 05 Sep '25

05 Sep '25

Friends Is Marge stalled. Look at !14742. 16 hrs ago marge said "I'll try this", but no further news since then Thanks Simon

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Gitlab down?
by Simon Peyton Jones 02 Sep '25

02 Sep '25

Friends Is https://gitlab.haskell.org/ down? I'm getting this, which leaves me rather stalled. Thanks Simon HTTP 502: Waiting for GitLab to boot

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Is master broken?
by Oleg Grenrus 28 Aug '25

28 Aug '25

My build fails Configuring ghci-9.15... Error: [Cabal-8010] Encountered missing or private dependencies: ghc-internal >=9.1001.0 && <=9.1500.0 `ghci.cabal` indeed has ghc-internal >= 9.1001.0 && <=9.1500.0, and `ghc-internal.cabal` has version: 9.1500.0 So what is happening? My invocation is ./hadrian/build --build-root=_build_wip --flavour=default+no_profiled_libs+omit_pragmas

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Documenting and improving cmm regular update
by Diego Antonio Rosario Palomino 27 Aug '25

27 Aug '25

Hello. from now on, i would like to provide regular updates about my project: documenting and improving cmm. In the past few days, i have: 1. implemented the bones for a cmm ast serialization https://github.com/GunpowderGuy/cmm-documentation/blob/master/myproject/src… 2. improved the writing / redaction on the cmm documentation i wrote that goes over how features are implemented https://github.com/GunpowderGuy/cmm-documentation/blob/master/Exploded_view… To elaborate on those points: in that document, i want to explain for each feature: * how textual cmm code gets parsed (what parser code handles an example feature) * what part of the ast (haskell data type) handles that feature * what part of the pretty printer handles the ast feature about the cmm ast (de)serializer: i have been deriving generic for the cmm datatypes, and the aeson typeclasses for said types. i started doing so with the top level type the cmm parser outputs. when implementing fromjson, ghc complains about its subtypes not implementing fromjson. i implement fromjson for those. this has been going well, but now i hit a blocker. some of the types use type level features such as gadts, which prevent generic from being derived for them. there are many ways i could work around this. generic is used for automatically deriving serialization in aeson. i could implement the methods manually for gadts types and the like, but i would prefer not doing so since going the generic way allows me to easily add more (de)serialization formats. for example, i can use a non aeson framework with fewer dependencies and the instances will be derived from generic. i could support that and conditionally not use aeson. given that, i think i could manually write generic instances or use a workaround like this: ( https://hackage.haskell.org/package/kind-generics )

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Mail migration status
by Ben Gamari 26 Aug '25

26 Aug '25

Hi all, Yesterday I completed the last task of the OpenCape migration, moving our mail services from our previous, ancient Rackspace box to their new home. This was a fairly invasive process, requiring migrating to a new Mailman version and a completely new delivery configuration. As with any migration, there is a chance that something isn't quite right. If you notice any delivery or reception issues of mailing list traffic from haskell.org please do let me know. Cheers, - Ben

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