Syntax highlighting for the Reason language. If you're using Atom and have already installed Nuclide, this one's unnecessary.
This is the source of truth for our syntax regex-based highlighting. Hopefully Sublime, Atom, VSCode and the rest all use this same one or derive the highlighting from it. The latter two already do so.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.