Autogenerate the list of modules

[judah]

Currently every proto file needs to be specified twice in the .cabal file: the raw .proto file in extra-src-files, and the Proto.* module in exposed-modules/other-modules.

From very basic experiments with stack, I think it's possible to drop the latter requirement and have our Setup script populate the list of Haskell modules automatically, by changing the PackageDescription and/or LocalBuildInfo.

In addition to less redundancy, this will help with:

• Refactorings such as Separate types into their own module, apart from field lenses. #100
• Integrate better with hpack (in particular, its ability to autodetect the exposed-modules and other-modules)

The exact design of this feature is still an open question: can (should?) we provide control to the user over whether their protos end up in exposed-modules or other-modules? Or in individual components (e.g. tests, executables or benchmarks)? For example, proto-lens-combinators contains a proto test file which is test-only and not intended to be exported from the library.

[judah]

I'm closing this ticket due to lack of progress. Also, in hindsight, it's important to let the user specify which generated modules end up in which package components (libraries,binaries,tests,...) so I don't think there's a good way to automate this.

Additionally, I think globs/wildcards remove most of the noise from the redundancy. For example, in proto-lens-tests we just say:

extra-source-files: tests/*.proto

and then list the modules we actually want to generate in the rest of the .cabal file.