As the Haskell community has grown, and emphasis on development has moved from language to libraries, the need for a more formalised process for contributing to libraries has emerged. This page documents our 'best practices' for proposing changes to library interfaces (e.g. new modules or functions, removing functions) in packages that list firstname.lastname@example.org as maintainer. We have been using it since October 2006.
In essence, we don't want proposals to go unnoticed, but changes to basic interfaces also need thorough consideration.
1 Creating a proposal
In order to ensure we have something concrete to discuss, please follow the following guidelines:
- Currency. Make your changes against a copy of the HEAD branch of the relevant library, and make sure it compiles.
- Portability. Code should be portable. If it is not portable, reasons should be given. At the very least ensure the code runs in Hugs and GHC, and on Windows and Linux.
- Style. Follow the conventions in the library you are modifying.
- Documentation. It must include valid Haddock documentation.
- Tests. Code should ideally also come with suitable tests for the testsuite. There's currently some disagreement about what this means. Discussion of where we may want to head is in the library tests page.
2 Submitting the proposal
- Patch. Create a darcs or git patch (depending on what sort of repo the library lives in) of your change using darcs record or git commit -a, including a rationale for the change. Save the patch to a file, using darcs send --output or git format-patch.
- Submission. Start a new thread on the email@example.com mailing list (which you need to subscribe to before posting), with a subject beginning "Proposal:". Include a description of the change and the rationale, and attach the patch. You may wish to include a pointer to updated Haddock documentation, if relevant. You must also include a deadline for the discussion period; it must allow at least 2 weeks for discussion, but you may allow more - particularly if many people are likely to be away during the next 2 weeks. If discussion is still ongoing at the deadline, the discussion period can be extended.
If someone has done all this, they are entitled to expect feedback; silence during the discussion period can be interpreted as consent.
3 At the end of the discussion period
- Determine whether consensus for the change was reached. A deeply held disagreement at this point may require some form of governance (voting, dictatorship, etc). This should be a rare event.
- If consensus was achieved, file a ticket on the GHC trac, attaching the (revised if necessary) patch. As well as the description and rationale, include a link to the discussion in the mailing list archives, as well as a summary of the conversation (the summary is needed for anyone wondering about the change later: it's not reasonable to point people at a 50-message thread (but please do include a link to the thread in the list archives too, so that people can review it if they wish)).
Here is an example of how to summarise a successful submission.