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Hackathon 2016
This is a page to collect ideas for Cabal/Hackage hacking tasks/mini-projects for the Haskell eXchange Hackathon 2016. It is an updated version of a similar page for the 2015 infrastructure hackathon.
Please use the #hackage
IRC channel on freenode for online discussions.
Feel free to expand individual bullet points into full (linked) pages or tickets/issues.
Mostly Cabal 2.0 and related.
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Package collections in
cabal-install
andhackage-server
The idea here is to support package collections directly in our infrastructure. Currently package collections like Stackage are implemented indirectly by specially crafted
cabal.config
/cabal.project.freeze
files. Collections are also to be distributed via hackage, allowing anyone to define and distribute collections.A specification was posted to the libraries list recently. There is also some prototype code available for cabal-install. The cabal-install code adds solver support and allows for set-like operations on collections. Nothing has been started yet for
hackage-server
.This is an important feature since package collections are one of the two big solutions to cabal hell. This is not a huge project. There's probably enough for two people to work on the client side and two on the server side.
Link to https://github.com/haskell/cabal/issues?q=is%3Aopen+is%3Aissue+label%3A%22meta%3A+easy%22
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Improve
cabal new-build
See Edward's blog post: http://blog.ezyang.com/2016/05/announcing-cabal-new-build-nix-style-local-builds/ for an intro to
new-build
and explanation why it's important.This is not a neat self-contained project. There are lots of parts to this project and it will require people to work together.
List of all open
new-build
issues: https://github.com/haskell/cabal/issues?q=is%3Aissue+is%3Aopen+label%3A%22cabal-install%3A+nix-local-build%22- Get the new-clean PR into shape.
- Building on top of the
cabal new-build
code to supportcabal {run,test,bench}
etc. Relevant ticket: https://github.com/haskell/cabal/issues/3638 cabal new-haddock
- Go through the issues in the Galois meta tracking ticket: https://github.com/haskell/cabal/issues/3577
- UX design for user-wide environments ('cabal new-install'), relevant ticket: https://github.com/haskell/cabal/issues/3737
- UX design for 'cabal new-update' (index freezing by default, interaction with cabal.project.freeze, talk with @ezyang and/or @hvr if they're online), relevant ticket: https://github.com/haskell/cabal/issues/3832
- 'cabal new-install' for binaries. No relevant ticket, but should basically work just like
cabal install foo
does today for binaries modulo using the store for library dependencies. Should be easy to implement (new-build foo
+Setup.hs copy
). - Test Duncan's ghc-environments PR (use GHC 8.0.2 snapshot). PR link: https://github.com/haskell/cabal/pull/3936
- Fix this annoying bug:
ghc-options
applies to all dependencies, not just local packages, https://github.com/haskell/cabal/issues/3883 - Design and implementation of locking the store for concurrent builds: https://github.com/haskell/cabal/issues/3741
- Allow "sandbox without project file" functionality in new Cabal. https://github.com/haskell/cabal/issues/3730 (related to GHC environments, see extra-packages feature)
- Replace new-build's call to
sdist --list-sources
with new command which lists sources of things that will be built, https://github.com/haskell/cabal/issues/3401 (deprecatesdist
hooks, use Stack code as reference, but use Cabal's file globs). - Integration tests for new-build (e.g.: new-build everything on Stackage) https://github.com/haskell/cabal/issues/3322
- Go through the remaining issues in https://github.com/haskell/cabal/issues/3104 (difficulty: moderate)
- Add support for
git
/darcs
/... dependencies, https://github.com/haskell/cabal/issues/2189 (makes sense to start with tarball dependencies before tackling SCM ones -- tarballs are easier to test)
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Cabal documentation.
Cabal's user guide got quite a bit better recently, but there's still a lot of room for improvement. In particular, we want to put more emphasis on the cabal-install tool at the expense of the Setup.hs interface and add a tutorial section. Ideally, the user guide would look like approximately this:
- Intro
- Tutorial, p.1 - how to use cabal-install to build and install existing packages
- Tutorial, p.2 - how to develop programs using cabal-install and write .cabal files -- basically, an updated version of https://wiki.haskell.org/How_to_write_a_Haskell_program.
- .cabal format reference
- cabal-install command reference
- cabal new-build chapter
- Appendix: Cabal spec (i.e., the Setup.hs interface)
Anyone considering this should feel empowered to make decisions. You could decide to start from scratch with a new structure and just pinch material from the existing docs. You might want to fully split into tutorial and reference.
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A new website for cabal-install/Cabal.
Our website hasn't been updated in ages, so a facelift is long due. It doesn't have to be super-advanced, a simple Hakyll-based static page with a blog/news feed would suffice. Start by looking at the https://github.com/haskell/cabal-website repo.
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Improvements in the release process.
This is mainly about automating the process of producing binaries for various platforms (Linux i386/x86-64, OS X, Windows x32/x64). We can either use Travis and AppVeyor or the haskell.org infrastructure. The latter requires extending the code of GHC Builder to support arbitrary Haskell projects besides just GHC, because that's what they (haskell.org) want to use for their build farm. Talk with Gershom (@gbaz/@sclv) if he's online about haskell.org integration.
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Rewrite of the
.cabal
file parser.#2865
@phadej (Oleg Grenrus) is the person to talk to about this issue. This is in a good shape already, and we want to merge the code into mainline soon (but not enable it by default!) to ease the transition. Help Oleg with merging, experiment with using the new parser instead of the old one, write tests.
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New AST for .cabal files (not an easy one!).
Builds on the new parser.
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Include-able Common Stanzas
#2832
Builds on the new parser+AST. Allow to reduce duplication by moving common definitions to include-able
common
stanzas which can then be included from other stanzas.