Hi Johan, Not sure if this mail is a request for comments, but on the story for large projects one thing that I would like to see is the ability to add packages that aren't in hackage to the depends list. I agree that adding some scanning and auto add ability is definitely sorely needed, but this information goes into add-source-timestamps in the sandbox folder, and if you blow away the sandbox, it's gone. Or you can try and version a file that contains ever changing timestamps. Right now I have a shell script that maintains a list of added sources and I keep that versioned in the project. It would be nice to have git dependencies in there as well, and then disallow a hackage upload for any cabal file with a non-hackage dependency listed. I would be happy to contribute time to both design and implementation.
Ben On Thu Apr 24 2014 at 10:53:59, Johan Tibell <johan.tib...@gmail.com> wrote: > Hi all, > > While I'm sure we still have a bugfix release or two to make on the 1.20 > branch, I thought it'd be worth looking at what we want to accomplish for > 1.22. Here are my thoughts on what we should focus on: > > ## A dependency solver that always works > > As Hackage has grown so have the requirements of the dependency solver. > There are three distinct problems I'm seeing now that we should tackle: > > * Treat each sections (i.e. library, test suite, benchmark, and > executable) in the .cabal file separately for the purpose of dependency > resolution. Today all the sections' dependencies are merged and used as the > constraints of the package as a whole. This is troublesome for all packages > that are dependencies of QC, HUnit, test-framework, and criterion, as > there's a dependency cycle if you treat e.g. the containers package and its > test suite as one unit. > > The solution here is to treat each unit as a mini package for the > purpose of dependency resolution. This would also allow you to have e.g. > several executables with conflicting dependencies. > > * Improve performance. Some packages (e.g. yesod) can take over 10 > seconds to run over. This problem will get worse as Hackage grows and we > build bigger applications on top of it, so we need to tackle this now > before it becomes a real problem. > > * Fix Hackage package blacklisting. Users can blacklist packages on > Hackage e.g. if they know them to be broken. However, this doesn't really > work as the Hackage blacklist translates to a soft preference in the > dependency solver and is thus often ignored. See > https://github.com/haskell/cabal/issues/1792 for the gory details. > > ## Do the right thing automatically > > This is a carry-over from the 1.20 goals, as we didn't make much progress > here. > > The focus here should be on avoiding manual steps the cabal could do > for the user. > > * Automatically install dependencies when needed. When `cabal build` > would fail due to a missing dependency, just install this dependency > instead of bugging the user to do it. This will probably have to be > limited to sandboxes where we can't break the user's system > > * GHCi support could be improved by rebinding :reload to rerun e.g. > preprocessors automatically. This would enable the users to develop > completely from within ghci (i.e. faster edit-save-type-error cycle). > We have most of what we need here (i.e. GHC macro support) but someone > needs to make the final change to generate a .ghci file to pass in the > ghci invocation. > > ## Faster builds > > I think we're almost done here. There's really only one remaining thing to > do: > > * Build components and different ways (e.g. profiling) in parallel. > We could build both profiling and non-profiling versions in parallel. > We could also build e.g. all test suites in parallel. The key > challenge here is to coordinate all parallel jobs so we don't spawn > too many. > > ## Support large projects > > This is also a carry-over from the 1.20 goals. > > We still don't have a good story for large projects. Sandboxes are too > annoying to use if there are 100 add-source deps. We need more automation > and more opinionated defaults (e.g. scan the sub-directories from in which > cabal was run to find source packages.) > > What we need most of all here is a design. Perhaps we could try to get > together at some Hackathon/ICFP and discuss. > > ## Issue tracker spring cleaning and test suite improvements > > The issue tracker is out-of-hand. It's too unwieldy to use for planning > our work and get an overview of the most important issues. We should try to > close down bugs that haven't had updates in years with extreme prejudice. > If the issue is important it will pop up again. > > We're also severely lacking in the testing department. There are two > problems: > > * There aren't enough tests: the cabal user facing surface is quite > larger (lots of features and flags) and many of them are not tested at all, > which will lead to regressions as we keep fixing bugs and adding features. > > * The tests take too long to run: we have too many end-to-end style tests > (i.e. build a whole package) and not enough unit style tests. We need to > add more of the latter kind. > > Cheers, > Johan > > _______________________________________________ > cabal-devel mailing list > cabal-devel@haskell.org > http://www.haskell.org/mailman/listinfo/cabal-devel >
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