July 2019 - ghc-devs - Haskell.org

Extended Dependency Generation Proposal
by David Eichmann 30 Jul '19

30 Jul '19

Hello GHC Developers, I've recently been working on a proposal (found here <https://github.com/ghc-proposals/ghc-proposals/pull/245>[1]) for "Extended Dependency Generation". This new feature takes the form of a new build option/mode that outputs comprehensive build dependencies for building Haskell modules. This allows external build tools, such as cabal-install, to implement correct incremental builds with recompilation avoidance using GHC's one shot mode to compile individual modules. All input is appreciated. It would be particularly helpful to hear from the Cabal, Stack, and Shake communities. Looking forward to hearing your comments, David Eichmann [1] https://github.com/ghc-proposals/ghc-proposals/pull/245 -- David Eichmann, Haskell Consultant Well-Typed LLP, http://www.well-typed.com Registered in England & Wales, OC335890 118 Wymering Mansions, Wymering Road, London W9 2NF, England

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Most recent happy and Alex releases can’t build ghc 8.6.x
by Carter Schonwald 27 Jul '19

27 Jul '19

Hey everyone : Is this a known issue / deliberate breaking change / other ? This is also the same Alex and happy that’s needed to build current ghc master Thx! -Carter

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can't checkout ghc 8.6 branch correctly -- something wrong with transformers mirror repo?
by Carter Schonwald 26 Jul '19

26 Jul '19

Hey everyone, whats wrong with the 8.6 branch? when i do a fresh clone, i wind up with this error : $ git submodule update --init --recursive error: Server does not allow request for unadvertised object def8c55d0c47c1c40de985d83f052f3659b40cfd Fetched in submodule path 'libraries/transformers', but it did not contain def8c55d0c47c1c40de985d83f052f3659b40cfd. Direct fetching of that commit failed. 14:17:43 ~/D/r/ghc-8.6.5-series (ghc-8.6|✚6) $

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Try haskell-ide-engine on GHC!
by Matthew Pickering 26 Jul '19

26 Jul '19

Hi all, As some of you know I have been working on getting haskell-ide-engine working on GHC for the last few months. Perhaps now the branch is in a usable state where people can try it and report issues. All the basic features such as, hover, completion, error reporting, go to definition etc should work well. I suspect this will be enough for most developers. I have compiled a list of instructions about how to try out the branch. https://gist.github.com/mpickering/68ae458d2c426a29a7c1ddf798dbc793 In the last few weeks Zubin has been a great help finishing some parts of the patch that I lost steam for and given it a much better chance of getting merged into the main repo before the end of the year. Cheers, Matt

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[ANNOUNCE] GHC 8.8.1 release candidate 1 is now available
by Ben Gamari 26 Jul '19

26 Jul '19

Hello everyone, The GHC team is pleased to announce the release candidate for GHC 8.8.1. The source distribution, binary distributions, and documentation are available at https://downloads.haskell.org/ghc/8.8.1-rc1 This release is the culmination of over 3000 commits by over one hundred contributors and has several new features and numerous bug fixes relative to GHC 8.6: * Profiling now works correctly on 64-bit Windows (although still may be problematic on 32-bit Windows due to platform limitations; see #15934) * A new code layout algorithm for amd64's native code generator * The introduction of a late lambda-lifting pass which may reduce allocations significantly for some programs. * Further work on Trees That Grow, enabling improved code re-use of the Haskell AST in tooling * More locations where users can write `forall` (GHC Proposal #0007) * A comprehensive audit of GHC's memory ordering barriers has been performed, resulting in a number of fixes that should significantly improve the reliability of programs on architectures with weakly-ordered memory models (e.g. PowerPC, many ARM and AArch64 implementations). * A long-standing linker limitation rendering GHCi unusable with projects with cyclic symbol dependencies has been fixed (#13786) * Further work on the Hadrian build system * Numerous bug-fixes As always, if anything looks amiss do let us know. Happy compiling! Cheers, - Ben [1] https://downloads.haskell.org/ghc/8.8.1-rc1/docs/html/users_guide/8.8.1-not…

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Typing rules for Haskell
by Richard Eisenberg 25 Jul '19

25 Jul '19

Hi devs, Simon and I were wondering about a tight specification for the recent action in proposal #253 (https://github.com/ghc-proposals/ghc-proposals/pull/253 <https://github.com/ghc-proposals/ghc-proposals/pull/253>). We needed to see the typing rules. So I made a repo (https://gitlab.haskell.org/rae/haskell <https://gitlab.haskell.org/rae/haskell>) to collect typing rules for source Haskell. I managed to convince the CI infrastructure to produce a PDF at every upload; it is linked from the README. The current version contains the proposed result signatures; it should probably be in a branch, but life is short. Contributions very welcome! Richard

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Any ways to test a GHC build against large set of packages (including test suites)?
by Ömer Sinan Ağacan 25 Jul '19

25 Jul '19

Hi, I'd like to test some GHC builds + some compile and runtime flag combinations against a large set of packages by building them and running test suites. For this I need - A set of packages that are known to work with latest GHC - A way to build them and run their test suites (if I could specify compile and runtime flags that'd be even better) I think stackage can serve as (1) but I don't know how to do (2). Can anyone point me to the right direction? I vaguely remember some nix-based solution for this that was being discussed on the IRC channel, but can't recall any details. Thanks, Ömer

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HIE files?
by Richard Eisenberg 24 Jul '19

24 Jul '19

Hi devs, I recently learned about the code for HIE files. This is quite a substantial new development in GHC, judging from the amount of code. I understand broadly why it's here, but I'd like to learn more specifics. For example, if I'm adding a new bit of syntax, how should I update HIE generation? What if I'm changing a bit of syntax? Is there a primer to all this? Thanks! Richard

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Tracking issues for GHC proposals?
by Ömer Sinan Ağacan 24 Jul '19

24 Jul '19

Hi all, It's currently quite hard to see progress of proposals. For example, I'm looking at the "small primitives" proposal [1]. After some digging I can see that it's mostly (if not completely) implemented [2, 3], but finding all this takes time. I think it'd make sense to create a tracking issue when a proposal is accepted, on GHC's Gitlab, and link to it from the proposal. All related MRs and issues would then be linked from the tracking issue, making seeing progress easier. How does that sound? Ömer [1]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0014-s… [2]: https://phabricator.haskell.org/D5006 [3]: https://phabricator.haskell.org/D4475

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gitlab subject lines
by Richard Eisenberg 23 Jul '19

23 Jul '19

Hi Ben, Since the recent GitLab upgrade, all GitLab emails have "GHC | Glasgow Haskell Compiler | " prefixed to their subject lines. This reduces the bandwidth of information in my mail reader. Is there a way of going back to just "GHC |"? Thanks! :) Richard

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