August 2021 - Haskell-Cafe

The second day of the 2021 Haskell Symposium is now streaming on YouTube
by Hage, J. (Jurriaan) 27 Aug '21

27 Aug '21

Haskellers, Today is the 2nd day of the 2021 Haskell Symposium and it is being streamed on Youtube. If you want a taste of it join us while it is still public. After the invited talk of Mathieu Boespflug yesterday (we maxed out at about a 100 viewer on Youtube and some 74 people in Airmeet) we will have yet another invited talk on Linear Haskell today by Jean-Philippe Bernardy, and one of the five research talks will be on Linear Haskell as well. On top of that there are four more research talks on your favorite programming language. Here’s the link: https://youtu.be/6pJKIjn95eU Do not miss out, and no need to register for ICFP. Best, Jurriaan Hage Chair

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[Haskell] [ANNOUNCE] GHC 8.10.7 released
by Zubin Duggal 26 Aug '21

26 Aug '21

The GHC team is very pleased to announce the availability of GHC 8.10.7. Source and binary distributions are available at the [usual place](https://downloads.haskell.org/ghc/8.10.7/). Download Page: https://www.haskell.org/ghc/download_ghc_8_10_7.html Blog Post: https://www.haskell.org/ghc/blog/20210827-ghc-8.10.7-released.html This is a small bugfix release, fixing one linking portability issue (#19950) present in GHC 8.10.5 and GHC 8.10.6 on some x86_64 macOS toolchains, which resulted in undefined symbol errors for `___darwin_check_fd_set_overflow`. Issue #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). We claimed to have fixed this in GHC 8.10.6, but alas this wasn't the case. The fix was originally tested on the master branch, which uses a different build configuration from the 8.10 branch. We have now tested the fix on the GHC 8.10 branch and finally squashed the bug. We would like to thank 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. We would also like to thank the hundreds of open-source contributors whose work makes GHC possible. A complete list of bug fixes and improvements can be found in the [release notes](https://downloads.haskell.org/ghc/8.10.7/docs/html/users_guide/8. 10.7-notes.html). 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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Magical Haskell book preview: Haskell and type theory in pictures and in a fun and accessible way
by Anton Antich 26 Aug '21

26 Aug '21

Dear all, I started "Magical Haskell" 3 years ago with the goal to fill the void of explaining typed functional programming from the first principles, but in a fun and accessible way. Imperative patterns really mess with learning Haskell, while alternative top-down approaches are usually too technical and math-heavy, so that the beauty and elegance of the concepts involved is lost on many. So I tried to use the latter, but build it up gradually, from intuition and functional thinking, so that a high school student could understand. Now the book is about 50% ready as I came back to writing it after a sabbatical break, now covers the foundations, functional thinking, different types, typeclasses, and specific examples gently building up from Maybe and List through Monoid and up to Functor and Bifunctor. Applicative, Monad and real world programs via Monad Transformer Stacks are coming up. It is available here: https://leanpub.com/magicalhaskell - free to read online. Would very much appreciate your feedback - what is missing, what do you think of such a style, what is maybe too much, etc. Also, if anyone is ready to contribute a public testimonial - will gladly give a free copy of the ebook and all future updates in offline formats! Thank you very much!

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Haskell Symposium starts right now!
by Hage, J. (Jurriaan) 26 Aug '21

26 Aug '21

Hi all at Haskell Cafe, Just in case you had not registered for ICFP and its workshops, you can still follow the talks of the Haskell Symposium in a live stream. These recordings are currently public, but that may not last for long. Here’s the link: https://www.youtube.com/watch?v=sVrlaF7sCU4 Best, Jur

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IFL'21 call for participation
by Pieter Koopman 25 Aug '21

25 Aug '21

================================================================================ IFL 2021 33rd Symposium on Implementation and Application of Functional Languages venue: online 1 - 3 September 2021 https://ifl21.cs.ru.nl <https://ifl21-publicity-dot-yamm-track.appspot.com/Redirect?ukey=1NdKhGOLpm…> *Registration* Registration is free of charge, but required for participation! Use the below link to register for IFL 2021: https://docs.google.com/forms/d/e/1FAIpQLSdMFjo-GumKjk4i7szs7n4DhWqKt96t8of… <https://ifl21-publicity-dot-yamm-track.appspot.com/Redirect?ukey=1NdKhGOLpm…> *Scope* 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 2021 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. *Program* The program is now available at https://ifl21.cs.ru.nl/Program <https://ifl21-publicity-dot-yamm-track.appspot.com/Redirect?ukey=1NdKhGOLpm…> . *Organisation* IFL 2021 Chairs: Pieter Koopman and Peter Achten, Radboud University, The Netherlands IFL Publicity chair: Pieter Koopman, Radboud University, The Netherlands *PC* Peter Achten (co-chair) - Radboud University, Netherlands Thomas van Binsbergen - University of Amsterdam, Netherlands Edwin Brady - University of St. Andrews, Scotland Laura Castro - University of A Coruña, Spain Youyou Cong - Tokyo Institute of Technology, Japan Olaf Chitil - University of Kent, England Andy Gill - University of Kansas, USA Clemens Grelck - University of Amsterdam, Netherlands John Hughes - Chalmers University, Sweden Pieter Koopman (co-chair) - Radboud University, Netherlands Cynthia Kop - Radboud University, Netherlands Jay McCarthey - University of Massachussetts Lowell, USA Neil Mitchell - Facebook, England Jan De Muijnck-Hughes - Glasgow University, Scotland Keiko Nakata - SAP Innovation Center Potsdam, Germany Jurriën Stutterheim - Standard Chartered, Singapore Simon Thompson - University of Kent, England Melinda Tóth - Eötvos Loránd University, Hungary Phil Trinder - Glasgow University, Scotland Meng Wang - University of Bristol, England Viktória Zsók - Eötvos Loránd University, Hungary [image: beacon]

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Munich Virtual Haskell Meeting, 2021-08-26 @ 19:30
by Leah Neukirchen 24 Aug '21

24 Aug '21

Dear all, This week, our monthly Munich Haskell Meeting will take place again on Thursday, August 26 on Jitsi at 19:30 CEST. **Due to bad weather for meetings outside this meeting will take place online!** For details see here: https://muenchen.haskell.bayern/dates.html A Jitsi link to join the room is provided on the page. Everybody is welcome, especially the Haskellers from Bavaria that do not usually come to our Munich meetings due to travel distance! cu, -- Leah Neukirchen <leah(a)vuxu.org> https://leahneukirchen.org/

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Some tooling questions
by Sven Panne 23 Aug '21

23 Aug '21

Just 2 quick questions to see if I understand things correctly: * Current Haddock versions have the ability to render hyperlinked coloured source code built-in, there is no need for a separate HsColour executable anymore (IIRC, this was required in ancient times), correct? * The haskell-language-server executables have all their "plugins" compiled and linked into them, correct? So there is e.g. no need for an external ormolu, hlint, ... executable. This would be a good thing, but using the word "plugin" for this is quite confusing for the end user IMHO. For me, plugins are something which you can install in addition to something else. This doesn't seem to be the case here, if I understand the source code correctly. And some final questions regarding the Haskell Language Server: Why are there separate haskell-language-server-X.Y executables plus a wrapper? Why are the executables tied to a fixed GHC version and what exactly does the wrapper do? Which of these executables is used e.g. by Emacs' lsp-mode? This looks quite complicated, at least compared to all the other LSP backends I know: For C++, just point to any clangd; for Groovy, just point to a JAR; for Python just install a single python-lsp-server package (which has real plugins as separate packages BTW), etc. Slightly confused, S.

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Fwd: Unlock instructions
by Henk-Jan van Tuyl 23 Aug '21

23 Aug '21

L.S., Did anyone else get a message like the one below? I did not try to log on to GitLab, as far as I can remember I do not have an account there. Is this some kind of physhing-attempt? Regards, Henk-Jan van Tuyl ------- Forwarded message ------- From: GitLab <gitlab(a)gitlab.haskell.org> To: hjgtuyl(a)chello.nl Subject: Unlock instructions Date: Wed, 18 Aug 2021 13:26:41 +0200 Hello, Henk-Jan! 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 -- Message from Stanford University: Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. https://foldingathome.org/ -- http://Van.Tuyl.eu https://HenkJanvanTuyl.werkaandemuur.nl/ https://sfeeraandemuur.nl/winkel/nekutimo/ https://github.com/HJvT https://web.archive.org/web/20201109033750/members.chello.nl/hjgtuyl/tourde… https://web.archive.org/web/20201111212601/http://members.chello.nl/hjgtuyl… Haskell programming --

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[ANNOUNCE] GHC 9.2.1-rc1 now available
by Ben Gamari 22 Aug '21

22 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 22 Aug '21

22 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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