- Glasgow-haskell-users

Help inform GHC's development priorities
by Ben Gamari 18 Oct '18

18 Oct '18

tl;dr. Please a take a minute to express your thoughts on GHC's development priorities via this survey [1]. Hello everyone, The GHC developers want to ensure that we are working on problems that of most importance to you, the Haskell community. To this end we are surveying the community [1], asking how our users interact with GHC and which problems need to be addressed most urgently. We hope you will take a few minutes to give us your thoughts [1]. Thanks in advance for your time and, finally, thanks to the financial supporters that make our work GHC possible. Cheers, - Ben and the rest of the GHC developers [1] https://docs.google.com/forms/d/e/1FAIpQLSdh7sf2MqHoEmjt38r1cxCF-tV76OFCJqU…

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[ANNOUNCE] GHC 8.4.4 released
by Ben Gamari 18 Oct '18

18 Oct '18

Hello everyone, The GHC team is pleased to announce the availability of GHC 8.4.4, a patch-level release in the 8.4 series. The source distribution, binary distributions, and documentation for this release are available at https://downloads.haskell.org/~ghc/8.4.4 This release fixes several bugs present in 8.4.3 These include, - A bug which could result in memory unsafety with certain uses of `touch#` has been resolved. (#14346) - A compiler panic triggered by some GADT record updates has been fixed (#15499) - The `text` library has been updated, fixing several serious bugs in the version shipped with GHC 8.4.3 (see `text` issues #227, #221, and #197. - A serious code generation bug in the LLVM code generation, potentially resulting in incorrect evaluation of floating point expressions, has been fixed (#14251) As always, the full release notes can be found in the users guide, https://downloads.haskell.org/~ghc/8.4.4/docs/html/users_guide/8.4.4-notes.… Thanks to everyone who has contributed to developing, documenting, and testing this release! As always, let us know if you encounter trouble. How to get it ~~~~~~~~~~~~~ The easy way is to go to the web page, which should be self-explanatory: https://www.haskell.org/ghc/ We supply binary builds in the native package format for many platforms, and the source distribution is available from the same place. Packages will appear as they are built - if the package for your system isn't available yet, please try again later. Background ~~~~~~~~~~ Haskell is a standard lazy functional programming language. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating efficient code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces. GHC is distributed under a BSD-style open source license. A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page (see below). On-line GHC-related resources ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Relevant URLs on the World-Wide Web: GHC home page https://www.haskell.org/ghc/ GHC developers' home page https://ghc.haskell.org/trac/ghc/ Haskell home page https://www.haskell.org/ Supported Platforms ~~~~~~~~~~~~~~~~~~~ The list of platforms we support, and the people responsible for them, is here: https://ghc.haskell.org/trac/ghc/wiki/Contributors Ports to other platforms are possible with varying degrees of difficulty. The Building Guide describes how to go about porting to a new platform: https://ghc.haskell.org/trac/ghc/wiki/Building Developers ~~~~~~~~~~ We welcome new contributors. Instructions on accessing our source code repository, and getting started with hacking on GHC, are available from the GHC's developer's site run by Trac: https://ghc.haskell.org/trac/ghc/ Mailing lists ~~~~~~~~~~~~~ We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at https://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-tickets There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see https://mail.haskell.org/cgi-bin/mailman/listinfo Some GHC developers hang out on #haskell on IRC, too: https://www.haskell.org/haskellwiki/IRC_channel Please report bugs using our bug tracking system. Instructions on reporting bugs can be found here:

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Call for lightning talks and participation -- Haskell Implementors' Workshop
by Joachim Breitner 16 Sep '18

16 Sep '18

Call for Contributions ACM SIGPLAN Haskell Implementors’ Workshop Sunday, 23 September, 2018 https://icfp18.sigplan.org/track/hiw-2018-papers Co-located with ICFP 2018 St. Louis, Missouri, US https://conf.researchr.org/home/icfp-2018 The Haskell Implementors Workshop is only one week away! Time to look at our great program at https://icfp18.sigplan.org/track/hiw-2018-papers#program and plan your day! Lightning Talks --------------- Like in the previous years, we will have slots for lightning talks. And because they were so successful last year, we will have more! *Topics* Anything related to Haskell implementations, fun uses of Haskell etc. goes. Feel free to tell us about ongoing work, to entertain, to rant, to stir a debate! (If you ever have been to a security or crypto conference, you might have attended their “rump session”. While there will not be alcohol involved at HIW, I hope that we can still match their creativity and insightful fun.) *Rules* * There are 3 sets of 3 lightning talks. * Sign-up is on day of the event, in person, on paper. No prior registration possible. * Lightning talks are 8 mins or less. If you know that your lightning talk takes less time, please say so, and maybe we can put four lightning talks into the slot. * Lightning talks do not count as peer-reviewed publications and are not published in the conference proceedings. Program Committee ----------------- * Edwin Brady (University of St. Andrews, UK) * Joachim Breitner – chair (DFINITY / University of Pennsylvania) * Ben Gamari (Well-Typed LLP) * Michael Hanus (Kiel University) * Roman Leshchinsky (Facebook) * Niki Vazou (University of Maryland) Contact ------- * Joachim Breitner <joachim(a)cis.upenn.edu> -- Joachim Breitner former post-doctoral researcher http://cis.upenn.edu/~joachim

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[ANNOUNCE] GHC 8.6.1-beta1 available
by Ben Gamari 11 Sep '18

11 Sep '18

Hello everyone, The GHC development team is very pleased to announce the first beta leading up to GHC 8.6.1 release. The usual release artifacts are available from https://downloads.haskell.org/~ghc/8.6.1-beta1 This beta fixes most of the bugs reported in the first two alphas and brings all of the core libraries up to their final release versions. The 8.6 release fixes over 300 bugs from the 8.4 series and introduces a number of exciting features. These most notably include: * Significantly better handling of macOS linker command size limits, avoiding linker errors while linking large projects * A new deriving mechanism, `deriving via`, providing a convenient way for users to extend Haskell's typeclass deriving mechanism * Quantified constraints, allowing forall quantification in contexts * An early version of the GHCi `:doc` command * The `ghc-heap-view` package, allowing introspection into the structure of GHC's heap * Valid hole fit hints, helping the user to find terms to fill typed holes in their programs * The BlockArguments extension, allowing the `$` operator to be omitted in some unambiguous contexts * The next phase of the MonadFail proposal, enabling -XMonadFailDesugaring by default A full list of the changes in this release can be found in the release notes: https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/8.6.1-… This will very likely be the last release before the final 8.6.1 so do give it a thorough testing and, as always, report any issues you encounter. Thanks for your help! Cheers, - Ben

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Fwd: Unable to compile ghc-8.2.2 with ghc-8.4.3
by Sven Panne 31 Aug '18

31 Aug '18

Am Fr., 31. Aug. 2018 um 11:11 Uhr schrieb Sam Halliday < sam.halliday(a)gmail.com>: > [...] It would make a lot of sense for the > "unregistered" sources to be made available as an optional download > alongside the source code, if haskell.org were open to that > possibility. IIRC, the generated C code is *not* platform-independent, at least that is what I remember from ancient times. Perhaps I'm wrong and/or this has changed, but if this is really the case, you would need an additional download per target platform. Cheers, S.

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Unable to compile ghc-8.2.2 with ghc-8.4.3
by Sam Halliday 31 Aug '18

31 Aug '18

Hello all, I am unable to compile ghc-8.2.2 with ghc-8.4.3 (which is otherwise working fine, e.g. to compile my own projects and xmonad). Could somebody please help? The error I get is ghc-cabal: Encountered missing dependencies: base >=4.4.1 && <4.11 libraries/hpc/ghc.mk:3: libraries/hpc/dist-boot/package-data.mk: No such file or directory make[1]: *** [libraries/hpc/ghc.mk:3: libraries/hpc/dist-boot/package-data.mk] Error 1 make: *** [Makefile:123: all] Error 2 I should give some background as to why I'm doing this: I am trying to build a back catalogue of ghc installations because the older binary downloads from haskell.org give me linking errors and I've lost faith in Archlinux's ability to package ghc. I plan on using these builds of ghc in stack, instead of their binaries. I don't like downloading binaries. I'd rather build them from source. I will also create a docker image for my own CI purposes. I'm using this script, but it's just a formalisation of the ghc installation instructions to help me automate the process. https://gitlab.com/fommil/ghc-env/blob/master/bin/ghc-env I am on Archlinux, which (I'm sure many of you know) has a very broken concept of ghc. I already lost 2 hours today because Archlinux broke my ~/.ghc, and therefore xmonad was unable to start and this locked me out of my desktop. I plan on using NixOS in the future. From a fresh OS install I do pacman -S ghc-static cabal-install to get me ghc 8.4.3 and the cabal CLI. From here I download and compile ghc 8.4.3 and cabal-install with ghc-env compile 8.4.3 cabal install cabal-install xmonad xmonad-contrib and now I can delete Arch's versions of ghc (yay!). But from here, if I try to compile ghc 8.2.2 (with a view to compile all the way back to the 7.x series) I get the failure at the top. An alternative solution would be if there were instructions for a fabled "phase0" compile, which doesn't require a ghc bootstrap. Does anybody know anything about that? Best regards, Sam

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Constructor as outermost match in RULE under GHC 8.2.2 & 8.4.3
by Conal Elliott 03 Aug '18

03 Aug '18

GHC 8.2.2 and 8.4.3 dislike the following rules: ``` haskell {-# RULES "pair fst snd" forall p. (,) (exl p) (exr p) = p "swap" forall p. (,) (exr p) (exl p) = swap p #-} ``` Error messages: ``` haskell /Users/conal/Haskell/concat/plugin/src/ConCat/Rebox.hs:485:1: warning: A constructor, (,), appears as outermost match in RULE lhs. This rule will be ignored. | 485 | "pair fst snd" forall p. (,) (exl p) (exr p) = p | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ /Users/conal/Haskell/concat/plugin/src/ConCat/Rebox.hs:489:1: warning: A constructor, (,), appears as outermost match in RULE lhs. This rule will be ignored. | 489 | "swap" forall p. (,) (exr p) (exl p) = swap p | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ``` GHC 8.0.2 didn't complain about these rules, though I'm unsure whether they worked as desired. Why disallow such rules (with constructors at the head)? -- Conal

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[ANNOUNCE] GHC 8.6.1-alpha2 available
by Ben Gamari 21 Jul '18

21 Jul '18

The GHC development team is pleased to announce the second alpha release leading up to GHC 8.6.1. The usual release artifacts are available from https://downloads.haskell.org/~ghc/8.6.1-alpha2 This alpha fixes many of the bugs reported in the first alpha and brings many of the core libraries to their (hopefully) final release versions. Unfortunately, the documentation troubles affecting the first alpha haven't quite been resolved in this release. Consequently you will again find there is no documentation uploaded. However, let us know if anything else is amiss. Thanks for your help! Cheers, - Ben

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Final Call for Talks -- Haskell Implementors' Workshop
by Joachim Breitner 16 Jul '18

16 Jul '18

Call for Contributions ACM SIGPLAN Haskell Implementors’ Workshop https://icfp18.sigplan.org/track/hiw-2018-papers Co-located with ICFP 2018 St. Louis, Missouri, US https://conf.researchr.org/home/icfp-2018 Important dates --------------- Proposal Deadline: Friday, 20 July, 2018 Notification: Friday, 3 August, 2018 Workshop: Sunday, 23 September, 2018 Keynote speaker --------------- This year, the Haskell Implementors’ Workshop is proud to present Rahul Muttineni as the keynote speaker. Rahul brough the joys of Haskell to the realm of Java by creating the Eta programming language. Title: Let's Go Mainstream with Eta! Eta is a fork of GHC that focuses on three core principles: user experience, performance, and safety. We'll discuss how we used these principles to guide the re-implementation of the GHC runtime and code generator on the JVM. Moreover, will also cover the inner workings of the FFI and the typechecker support we added for subtyping to make it smooth to interact with Java libraries. Finally, we'll round out with a look at where Eta is headed and how Eta and GHC can collaborate in the future. About the Haskell Implementors’ Workshop ---------------------------------------- The 10th Haskell Implementors’ Workshop is to be held alongside ICFP 2018 this year in St. Louis. 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. Talks and/or demos are proposed by submitting an abstract, and selected by a small program committee. There will be no published proceedings. The workshop will be informal and interactive, with open spaces in the timetable and room for ad-hoc discussion, demos and lightning talks. Scope and Target Audience ------------------------- It is important to distinguish the Haskell Implementors’ Workshop from the Haskell Symposium which is also co-located with ICFP 2018. The Haskell Symposium is for the publication of Haskell-related research. In contrast, the Haskell Implementors’ Workshop will have no proceedings – although we will aim to make talk videos, slides and presented data available with the consent of the speakers. 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 Talks ----- We invite proposals from potential speakers for talks and demonstrations. We are aiming for 20-minute talks with 5 minutes for questions and changeovers. We want to hear from people writing compilers, tools, or libraries, people with cool ideas for directions in which we should take the platform, proposals for new features to be implemented, and half-baked crazy ideas. Please submit a talk title and abstract of no more than 300 words. Submissions can be made via HotCRP at https://icfp-hiw18.hotcrp.com/ until July 20th (anywhere on earth). We will also have lightning talks session. These have been very well received in recent years, and we aim to increase the time available to them. Lightning talks be ~7mins 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. Program Committee ----------------- * Edwin Brady (University of St. Andrews, UK) * Joachim Breitner – chair (University of Pennsylvania) * Ben Gamari (Well-Typed LLP) * Michael Hanus (Kiel University) * Roman Leshchinsky (Facebook) * Niki Vazou (University of Maryland) Contact ------- * Joachim Breitner <joachim(a)cis.upenn.edu> -- Joachim Breitner Post-Doctoral researcher http://cis.upenn.edu/~joachim

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FYI
by Doaitse Swierstra 12 Jul '18

12 Jul '18

> Begin doorgestuurd bericht: > > Van: Job Vranish <jvranish(a)gmail.com> > Onderwerp: Antw.: as far as I can see > Datum: 12 juli 2018 om 3:17:23 CEST > Aan: doaitse(a)swierstra.net > > Wow thanks! > > I’ve updated both. Thanks for letting me know and your help fixing it :) > > - Job > >> On Jul 11, 2018, at 4:44 PM, Doaitse Swierstra <doaitse(a)swierstra.net> wrote: >> >> Dear Job, >> >> I made lenses compatible with the new version of GHC. can you put it on hackage if you approve and update the github too. It still contains an older version. >> >> Best, thanks, >> Doaitse Swierstra >> >> <src-26><lenses.cabal> >

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