Yarn RFCs

Many changes, including bug fixes and documentation improvements can be implemented and reviewed via the normal GitHub pull request workflow.

Some changes though are "substantial", and we ask that these be put through a bit of a design process and produce a consensus among the Yarn core team.

The "RFC" (request for comments) process is intended to provide a consistent and controlled path for new features to enter the project.

Active RFC List

As a new project, Yarn is still actively developing this process, and it will still change as more features are implemented and the community settles on specific approaches to feature development.

When to follow this process

You should consider using this process if you intend to make "substantial" changes to Yarn or its documentation. Some examples that would benefit from an RFC are:

A new feature that creates new API surface area, and would require a feature flag if introduced.
The removal of features that already shipped as part of the release channel.
The introduction of new idiomatic usage or conventions, even if they do not include code changes to Yarn itself.

The RFC process is a great opportunity to get more eyeballs on your proposal before it becomes a part of a released version of Yarn. Quite often, even proposals that seem "obvious" can be significantly improved once a wider group of interested people have a chance to weigh in.

The RFC process can also be helpful to encourage discussions about a proposed feature as it is being designed, and incorporate important constraints into the design while it's easier to change, before the design has been fully implemented.

Some changes do not require an RFC:

Rephrasing, reorganizing or refactoring
Addition or removal of warnings
Additions that strictly improve objective, numerical quality criteria (speedup, better browser support)
Additions only likely to be noticed by other implementors-of-Yarn, invisible to users-of-Yarn.

What the process is

In short, to get a major feature added to Yarn, one usually first gets the RFC merged into the RFC repo as a markdown file. At that point the RFC is 'active' and may be implemented with the goal of eventual inclusion into Yarn.

Fork the RFC repo http://github.com/yarnpkg/rfcs
Copy 0000-template.md to accepted/0000-my-feature.md (where 'my-feature' is descriptive. don't assign an RFC number yet).
Fill in the RFC. Put care into the details: RFCs that do not present convincing motivation, demonstrate understanding of the impact of the design, or are disingenuous about the drawbacks or alternatives tend to be poorly-received.
Submit a pull request. As a pull request the RFC will receive design feedback from the larger community, and the author should be prepared to revise it in response.
Build consensus and integrate feedback. RFCs that have broad support are much more likely to make progress than those that don't receive any comments.
Eventually, the team will decide whether the RFC is a candidate for inclusion in Yarn.
RFCs that are candidates for inclusion in Yarn will enter a "final comment period" lasting 7 days. The beginning of this period will be signaled with a comment and tag on the RFC's pull request.
An RFC can be modified based upon feedback from the team and community. Significant modifications may trigger a new final comment period.
An RFC may be rejected by the team after public discussion has settled and comments have been made summarizing the rationale for rejection. A member of the team should then close the RFC's associated pull request.
An RFC may be accepted at the close of its final comment period. A team member will merge the RFC's associated pull request, at which point the RFC will become 'active'.

The RFC life-cycle

Once an RFC becomes active, then authors may implement it and submit the feature as a pull request to the Yarn repo. Becoming 'active' is not a rubber stamp, and in particular still does not mean the feature will ultimately be merged; it does mean that the core team has agreed to it in principle and are amenable to merging it.

Furthermore, the fact that a given RFC has been accepted and is 'active' implies nothing about what priority is assigned to its implementation, nor whether anybody is currently working on it.

Modifications to active RFC's can be done in followup PR's. We strive to write each RFC in a manner that it will reflect the final design of the feature; but the nature of the process means that we cannot expect every merged RFC to actually reflect what the end result will be at the time of the next major release; therefore we try to keep each RFC document somewhat in sync with the language feature as planned, tracking such changes via followup pull requests to the document.

Implementing an RFC

The author of an RFC is not obligated to implement it. Of course, the RFC author (like any other developer) is welcome to post an implementation for review after the RFC has been accepted.

If you are interested in working on the implementation for an 'active' RFC, but cannot determine if someone else is already working on it, feel free to ask (e.g. by leaving a comment on the associated issue).

Reviewing RFC's

Each week the team will attempt to review some set of open RFC pull requests.

We try to make sure that any RFC that we accept is accepted at the Friday team meeting, and reported in [core team notes]. Every accepted feature should have a core team champion, who will represent the feature and its progress.