Evaluate a custom parser for Chroma

[alecthomas]

Is there an existing issue for this?

• I have searched the existing issues

What problem does this feature solve?

I prefer XML to YAML in most cases, but it's also incredibly verbose.

What feature do you propose?

Chroma could use Participle to have its own custom syntax for defining lexers. This should be relatively straightforward, mostly entailing just adding parser tags to the existing data structures.