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[RFC] TcPlugin changes in GHC 9.4: what would you like to see?
by Sam Derbyshire 23 Aug '21

23 Aug '21

Hi all, As you may recall, the API for type-checking plugins is changing (ever so slightly) in GHC 9.4. It was pointed out to me that this might be a good opportunity to make further changes to accommodate other needs of type-checking plugin authors. For the moment, I have one concrete change in mind: changing the TcPluginSolveResult datatype to be a flat record, where one can separately return solved constraints, new constraints and insoluble constraints. This allows plugin authors to return contradictions at the same time as they return solved constraints, which (I have been told) can significantly improve the quality of the error messages. Pattern synonyms can be provided for compatibility, so the impact to plugin authors should be very minimal. I would love to hear other suggestions for improvements. Note however that I believe it is best if we keep the GHC API quite sparse, leaving more elaborate design choices to libraries. Thanks, Sam

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[ANNOUNCE] GHC 9.2.1-rc1 now available
by Ben Gamari 23 Aug '21

23 Aug '21

Hi all, The GHC developers are very happy to announce the availability of the release cadidate of the 9.2.1 release. Binary distributions, source distributions, and documentation are available at https://downloads.haskell.org/ghc/9.2.1-rc1 GHC 9.2 will bring a number of exciting features including: * A native code generation backend for AArch64, significantly speeding compilation time on ARM platforms like the Apple M1. * Many changes in the area of records, including the new `RecordDotSyntax` and `NoFieldSelectors` language extensions, as well as Support for `DuplicateRecordFields` with `PatternSynonyms`. * Introduction of the new `GHC2021` language extension set, giving users convenient access to a larger set of language extensions which have been long considered stable. * Merge of `ghc-exactprint` into the GHC tree, providing infrastructure for source-to-source program rewriting out-of-the-box. * Introduction of a `BoxedRep` `RuntimeRep`, allowing for polymorphism over levity of boxed objects (#17526) * Implementation of the `UnliftedDataTypes` extension, allowing users to define types which do not admit lazy evaluation ([proposal]) * The new [-hi profiling] mechanism which provides significantly improved insight into thunk leaks. * Support for the `ghc-debug` out-of-process heap inspection library [ghc-debug] * Support for profiling of pinned objects with the cost-centre profiler (#7275) * Introduction of Haddock documentation support in TemplateHaskell (#5467) Finally, thank you to Microsoft Research, GitHub, IOHK, the Zw3rk stake pool, Tweag I/O, Serokell, Equinix, SimSpace, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Moreover, 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 testing, - Ben [apple-m1]: https://www.haskell.org/ghc/blog/20210309-apple-m1-story.html [proposal]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0265-u… [-hi profiling]: https://well-typed.com/blog/2021/01/first-look-at-hi-profiling-mode/ [ghc-debug]: http://ghc.gitlab.haskell.org/ghc-debug/ [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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The State of GHC 8.10
by Zubin Duggal 21 Aug '21

21 Aug '21

Hi all, GHC 8.10.6 was released last week, with high hopes of finally putting an end to the long running saga of the GHC 8.10 series. Unfortunately, this was not to be the case as we soon discovered #19950, an issue that we claimed to have fixed in the 8.10.6 release, was still affecting the released compiler. #19950 is caused by a bug in newer Apple toolchains (specifically XCode 12) where programs compiled with affected versions of XCode are not backwards compatible with configurations running older version of XCode (certain versions of XCode 11). It surfaced in GHC 8.10.5 since we upgraded the toolchain on our Darwin builders to one of the affected versions. The original fix/workaround for #19950 was tested on the master and GHC-9.2 branches and found to be working, and so backported to the 8.10 branch. Unfortunately, Darwin releases for 8.10 are still done using the Make build system, which did not pick up the extra linker options needed to work around the issue. It places a heavy burden on developers to have so many active branches of the compiler to keep in mind, and the current situation with 4 active branches is simply not sustainable. As the oldest currently active branch, it is currently a priority to retire the 8.10 branch of GHC from active development as soon as possible. We have now fixed and verified the fix for #19950 on the 8.10 branch and prepared a GHC 8.10.7 release including it. As of now, the only change in GHC 8.10.7 is to link the x86_64 darwin release build with a few extra linker options to work around #19950. If you have any other critical issues that prevent you from using GHC 8.10(.6), please raise them soon by either pointing to existing tickets on the tracker or creating a new one. We are planning to cut the new release as soon as early next week, and we are really hoping that this would be the final release in the 8.10 series. Cheers, Zubin.

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Call for Participation: Haskell Implementors' Workshop 2021
by Ningning Xie 20 Aug '21

20 Aug '21

Call for Participation ACM SIGPLAN Haskell Implementors' Workshop Sunday 22 Aug 20:00-05:00 (Seoul) https://icfp21.sigplan.org/home/hiw-2021 We are happy to announce that Haskell Implementors' Workshop is taking place this Sunday, co-located with ICFP 2021. The workshop will be live streamed on Youtube. We invite you to watch the talks, and attend the workshop. The program features 11 exciting talks, along with 4 lightning talks. The keynote is given by Bengt Marten Agren (Standard Chartered Bank), on "Haskell reinterpreted – large-scale real-world experience with the Mu compiler in Financial Markets". Program details: https://icfp21.sigplan.org/home/hiw-2021#program Keynote details: https://icfp21.sigplan.org/details/hiw-2021-papers/14/Haskell-reinterpreted… Program Committee ----------------- * Dominique Devriese (Vrije Universiteit Brussel) * Daan Leijen (Microsoft Research) * Andres Löh (Well-Typed LLP) * Julie Moronuki (Typeclass Consulting) * John Wiegley (DFINITY) * Ningning Xie (the University of Hong Kong) * Edward Z. Yang (Facebook AI Research) Contact ------- * Ningning Xie <xnningxie(a)gmail.com>

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Fwd: Unlock instructions
by Bryan Richter 17 Aug '21

17 Aug '21

Hey all, I got this message from gitlab, which makes me think someone is trying to attack the system. I have not tried to log in recently. I have 2FA and unique passwords so I'm not too worried, but just FYI. ---------- Forwarded message --------- From: GitLab <gitlab(a)gitlab.haskell.org> Date: Sat, 14 Aug 2021, 16.42 Subject: Unlock instructions To: <b(a)chreekat.net> Hello, Bryan R! Your GitLab account has been locked due to an excessive amount of unsuccessful sign in attempts. Your account will automatically unlock in 10 minutes or you may click the link below to unlock now. Unlock account <https://gitlab.haskell.org/users/unlock?unlock_token=oeTBsanKDc7a2VUteWUs>

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[Haskell] [ANNOUNCE] GHC 8.10.6 released
by Zubin Duggal 14 Aug '21

14 Aug '21

The GHC team is very pleased to announce the availability of GHC 8.10.6. Source and binary distributions are available at the [usual place](https://downloads.haskell.org/ghc/8.10.6/). Download Page: https://www.haskell.org/ghc/download_ghc_8_10_6.html Blog Post: https://www.haskell.org/ghc/blog/20210814-ghc-8.10.6-released.html This is a bugfix release, fixing many issues present in GHC 8.10.5, including: - A fix for segmentation faults in GHCi on `aarch64-darwin` due to an incorrect foreign import in `haskeline`. See [this blog post](https://www.haskell.org/ghc/blog/20210709-capi-usage.html) by Ben Gamari for more details on how your library could be affected. - A fix for a critical bug affecting Haskell Language Server (HLS) among other applications caused by missing RTS symbols required for statically linked builds of the GHC library (#19763). - No longer emitting spurious warnings for LLVM versions (LLVM 9-12) that were actually supported (#19973, #19829, #19959). - Numerous bug fixes for the new LLVM based `aarch64-darwin` backend (#20132). - Fixes and stability improvements for the non-moving GC (#19715). - Many other bug fixes for the RTS (#18033, #20132, #20093, #19421). - Many packaging related fixes, including versioned `ghc-pkg` executables (#20087), and actually distributing GHC versions linked against the `integer-simple` big integer backend (#18967, #19953) on both Windows and Alpine Linux. Previous releases were still linked against the `GMP` library due to a misconfiguration of the builders. - A significant refactoring of `process` fixing numerous bugs mostly on Apple platforms (#19994, [process refactoring](https://github.com/haskell/process/pull/208)) - A FreeBSD release after fixing issues that caused GHC 8.10.5 to be unable to build (#19958, #19948). - Bug fixes for the linker on Darwin platforms (#20004, #19968, #19950). A complete list of bug fixes and improvements can be found in the [release notes](https://downloads.haskell.org/ghc/8.10.6/docs/html/users_guide/8.10.…. As always, feel free to report any issues you encounter via [gitlab.haskell.org](https://gitlab.haskell.org/ghc/ghc/-/issues/new).

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Fwd: GHC Module change database
by Ari Fordsham 09 Aug '21

09 Aug '21

AF ---------- Forwarded message --------- From: Ari Fordsham <arifordsham(a)gmail.com> Date: Sun, 8 Aug 2021 at 16:43 Subject: Re: GHC Module change database To: Vaibhav Sagar <vaibhavsagar(a)gmail.com> That's where I generated it from :-) It would be nice to generate that from the new database. My main motivation was as follows: There are two possible paradigms for GHC API compatibility: - Export old names for new modules - as in ghc-api-compat <https://gitlab.haskell.org/haskell/ghc-api-compat> This allows existing code to (kind of) 'just work' - but it doesn't help in managing that code as it gets extended to use new features - Export new names to old modules I am thinking of working on a tool that does this. You need to rewrite code to use current modules (maybe https://github.com/facebookincubator/retrie/issues/33 will help), but then you can just target the latest API, and have compatibility built in. This seems to me better for active codebases. Having a 'single source of truth' database will help with this. AF On Sun, 8 Aug 2021 at 16:36, Vaibhav Sagar <vaibhavsagar(a)gmail.com> wrote: > Hi Ari, > > Have you seen https://gitlab.haskell.org/haskell/ghc-api-compat? > > Thanks, > Vaibhav > > On Mon, Aug 9, 2021 at 1:34 AM Ari Fordsham <arifordsham(a)gmail.com> wrote: > >> I've made a database of GHC API module changes. >> >> https://github.com/AriFordsham/ghc-module-renames >> >> This might be useful for automatic tooling. >> >> It would be nice if this would be moved into the GHC Gitlab, and kept >> up-to-date. >> >> Ari Fordsham >> _______________________________________________ >> ghc-devs mailing list >> ghc-devs(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >> >

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Fwd: GHC Module change database
by Ari Fordsham 08 Aug '21

08 Aug '21

I've made a database of GHC API module changes. https://github.com/AriFordsham/ghc-module-renames This might be useful for automatic tooling. It would be nice if this would be moved into the GHC Gitlab, and kept up-to-date. Ari Fordsham

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How to Collect Type Errors?
by Guanda Yuan 06 Aug '21

06 Aug '21

Hello all, I want to write a plugin for Haskell Language Server, to collect type errors in the code. I'm new to GHC API, so I need some help. My current thought is, I can collect diagnostics or the error messages and extract the type error infos. I have tried to referred to the Haddock documentation for GHC API, but I'm still not sure which function should I use. Thanks, Guanda

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Call for Lightning Talks: Haskell Implementors' Workshop @ ICFP'21
by Ningning Xie 06 Aug '21

06 Aug '21

Call for Lightning Talks ACM SIGPLAN Haskell Implementors' Workshop https://icfp21.sigplan.org/home/hiw-2021 Virtual, 22 Aug, 2021 Co-located with ICFP 2021 https://icfp21.sigplan.org/ Important dates --------------- Deadline: Thursday, 19 Aug, 2021 (or when slots are full, whichever is sooner) Workshop: Sunday, 22 Aug, 2021 The 13th Haskell Implementors' Workshop is to be held alongside ICFP 2021 this year virtually. It is a forum for people involved in the design and development of Haskell implementations, tools, libraries, and supporting infrastructure, to share their work and discuss future directions and collaborations with others. We will have a number of slots for lightning talks. Lightning talks will be ~7 minutes and are scheduled on the day of the workshop. Suggested topics for lightning talks are to present a single idea, a work-in-progress project, a problem to intrigue and perplex Haskell implementors, or simply to ask for feedback and collaborators. Lightning talks are proposed by submitting a title and an abstract. Submissions will not be part of the peer-review process. Notification of acceptance will be continuous until slots are full. Submissions should be made via Google form: https://forms.gle/BmUSyWWTXt1AMTec8 Accepted lightning talks will be posted on the workshop’s website. Scope and target audience ------------------------- The Implementors' Workshop is an ideal place to describe a Haskell extension, describe works-in-progress, demo a new Haskell-related tool, or even propose future lines of Haskell development. Members of the wider Haskell community encouraged to attend the workshop -- we need your feedback to keep the Haskell ecosystem thriving. Students working with Haskell are specially encouraged to share their work. The scope covers any of the following topics. There may be some topics that people feel we've missed, so by all means submit a proposal even if it doesn't fit exactly into one of these buckets: * Compilation techniques * Language features and extensions * Type system implementation * Concurrency and parallelism: language design and implementation * Performance, optimisation and benchmarking * Virtual machines and run-time systems * Libraries and tools for development or deployment Logistics --------- Due to the on-going COVID-19 situation, ICFP (and, consequently, HIW) will be held remotely this year. However, the organizers are still working hard to provide for a great workshop experience. While we are sad that this year will lack the robust hallway track that is often the highlight of HIW, we believe that this remote workshop presents a unique opportunity to include more of the Haskell community in our discussion and explore new modes of communicating with our colleagues. We hope that you will join us in making this HIW as vibrant as any other. Contact ------- * Ningning Xie <xnningxie(a)gmail.com>

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