sass-specis a suite of implementation-agnostic test cases for verifying that a Sass implementation behaves correctly. It's the best way to track your implementation's compatibility with the Sass reference implementation.
@extendWorks is a fairly comprehensive run-down of the algorithm used by Sass's trickiest feature. Natalie still says that the implementation of
@extendis the hardest code she's ever had to write, but luckily you don't have to figure it out from scratch.
Reach out! If you're working on a new implementation, we want to hear about it. Send an email to Natalie and Chris, tell us about the cool work you're doing, and ask about any corners of the language that don't quite make sense.
We whole-heartedly love new implementations of Sass, but we do have a few restrictions that we ask those implementations to follow in order to call themselves "Sass", "Sass implementations", or the like. Sass is a community as much as it is a language, and it's important that all implementations are willing to work for the good of the community.
First, we ask that every implementation adopt the Sass community guidelines for their own implementation-specific communities. Much of what makes the Sass community strong is a culture of kindness and respect, and having clear and explicit guidelines helps produce that culture.
Second, we ask that implementations not extend the language without agreement from the other major implementations and from the language designers, Natalie and Chris. The only reason a Sass community exists at all is because the language enables styles and frameworks to be shared among designers, and it's crucial for sharing that Sass code that works for one implementation works the same for all of them. In addition, it's important that there be a unified vision for the language design.
Making Language Changes
Sass can still evolve as a language, of course. We have a process for proposing and iterating on new language features that anyone can participate in. Language changes are discussed collaboratively, with particular weight given to the maintainers of mature Sass implementations. Attempts will be made to reach consensus with all stakeholders. However, this may be impossible in some circumstances, and the ultimate say lies with the lead designer of Sass, Natalie.