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RFC-2: sbt 2.0 RFC process

problem space

There are various technical decisions around sbt and Zinc that impact the Scala ecosystem, but currently the process of adding new features or changes to existing feature is not well defined. For the most part, the contributors like Scala Center and I come up with ideas and execute them.

RFC process

At the Tooling Summit in Lausanne this week, Iulian Dragos suggested we adopt “a lightweight process based on RFC (request for comments) docs that can serve as a design document.” In general, it would be a good idea to capture motivations and design intent of major changes.

goal of the RFC process

To quote “Why wasn’t I consulted” - How Rust does OSS:

The goal isn’t that everyone’s opinion gets the same weight. It’s not a voting democracy. It’s more that we are collectively exploring the space of tradeoffs. First the process is what are the options, what are the tradeoffs. At some point it reaches a steady state. That doesn’t mean that everyone in the thread has reached the same concensus. In fact that usually doesn’t happen. At that point the team would head towards making a decision, rejecting or accepting the RFC.


status and outcome

The status transitions in the following flow (happy path).

                ┌────────┐    ┌───────────┐
┌────────┐ │    └────────┘    └───────────┘
│ Review ├─┤
└────────┘ │    ┌────────┐
           └───►│ Closed │

Comments are open during Review state, and during this period the document will be actively updated to reflect the discussion. After some point, the core devs will either move the proposal to Accepted/Closed state. We’ll update the decision in the outcome section. An accepted RFC should then transition to Implemented, but depending on the situation it could also move back to Review or Closed as well.

continuum of continuity

During the sbt 2.0 discussion in the Tooling Summit I drew something like this on the whiteboard:

┌───────────────┐           ┌────────────────────────┐
│               │           │                        │
│ Don't Change  │◄─────────►│ Change Everything      │
│ (stability)   │           │ (perf, UX improvements,│
│               │           │  simplicity etc)       │
└───────────────┘           └────────────────────────┘

Given that sbt has many builds out in the wild, my general philosophy is to avoid making huge jumps conceptually from sbt 1 (see also how long we kept bincompat for sbt 0.13). The iron rule is to bring the ecosystem forward together.

At the same time, since there already is sbt 1 for users who do not want any changes, sbt core devs shouldn’t be too afraid of changes if that could improve sbt’s user experience, performance, or the long-term maintainability of sbt etc.

who is going to work on it?

It bears repeating that my job is not maintaining sbt. I work on sbt in my free time, like many others who work on open source. When I write an RFC, I may work on it, or not if I am busy. But hopefully outlining the ideas would help other contributors and organizations plan for what may happen, participate in the design, or join the implementation effort.

If someone else writes an RFC, and we accept it, it should also be presumed that they work on it (or find someone to work on it), not me.

alternatives considered: Google Docs?

I generally like Google docs for internal memos, but for public RFCs there are some issues:


I created a discussion thread Let me know what you think there.