RFC process

Large and important changes to the Hare programming language are implemented by a formal process of consensus with a “request for comments” (RFC).

When to prepare an RFC?

You may prepare an RFC for any change that you want to have a structured discussion about, large or small. The author of a proposed change may opt-in to the RFC process if they would find it useful for their work, or a maintainer or reviewer may invoke the RFC process for a given change at their discretion.

As a rule of thumb, a change is more likely to require an RFC if any of the following conditions are met:

  • A change is controversial and requires discussion to secure consensus

  • A standard library change breaks a widely-used API

  • A language change requires most Hare users to rewrite their code

  • A large number of subsystems are implicated

0. Prior to submitting an RFC

Ideas can form anywhere, but once you want to turn an idea into action it is important to discuss it in the official community spaces so that you can keep those affected in the loop and prepare people to participate in the consensus process. You can discuss ideas and early proposals, workshop RFC text, and so on, in the Hare IRC channels and mailing lists.

Do some research to see which community members should participate in the discussion, including at a minimum the maintainers of relevant subsystems and a global maintainer. Seek out their feedback and guidance on your propsal.

1. Submitting an RFC

RFCs are formally submitted to the hare-rfc mailing list. The subject line should be “[RFC v1] Subject…”, where v1 increments for each revision of the proposal. Work-in-progress proposals may be submitted to this list with the “[DRAFT RFC]” subject prefix.

The body of the RFC is free-form text, which should be formatted in accordance with typical mailing list etiquette, and should include at a minimum the details of the proposed change, the rationale for the change, and the predicted impact of the change to end-users. Illustrative code samples and other supporting materials are encouraged to be included.

You can start implementing the change proposed by the RFC for research or illustrative purposes, but keep in mind that following the discussion of the RFC much of this code might have to be rewritten.

2. Discussion

The proposal is discussed following its submission, and will likely be refined. Participants will narrow down the details, determine if the implications are completely enumerated, and make plans for the implementation. This process will generally result in the RFC draft being adjusted to incorporate feedback and resubmitted with a new version number.

3. Approval

A RFC does not require explicit approval to proceed to the implementation, though patch authors would be wise to read the room to determine if the potential code reviewers are satisfied with the status of the proposal, lest you write code based on it which will ultimately be rejected for foreseeable reasons.

4. Implementation

Once the discussion participants are satisfied with the proposed RFC, the proposal authors (and/or anyone they convinced to help out during the discussion) should move forward with implementing the proposal and sending out the relevant patches.

Once the implementation is complete, the authors should follow-up on the original proposal thread on the hare-rfc mailing list with details about the implementation (such as links to the relevant patches) to close the proposal and record its implementation for posterity.

Proposal authors are also encouraged during the implementation phase to continue commenting on the RFC thread to record new insights, document deviations from the proposal that occured in practice, or to go back to the drawing board and prepare a new revision with the lessons learned from the code.


Who can submit an RFC?