if you go through the files in the repo they are very easy to read (I would recommend starting with the test/ folder): https://github.com/jcoglan/jit

obviously the lib folder requires a lot of git-specific knowledge but I didn't see any use of features that don't have exact or very similar equivalent in more popular programming languages.

I think the most "complex" might be things like Struct.new(*Inputs::ATTRS) where it's creating a new anonymous class from a list of attributes which becomes the class instance attributes (nothing crazy :) )