Concrete paths inherit from pure paths - this would be quite strange using antonyms. This isn't like an "abstract" base class. It's a full class on its own, which is extended by another.
Anyway, I think it's meant to be "pure" like pure functions, generally having no side effects or external inputs.
Anyway, I think it's meant to be "pure" like pure functions, generally having no side effects or external inputs.
https://en.wikipedia.org/wiki/Pure_function