You can define what happens for an object when an operator is applied (like +, /, or -) so that you can obj+obj. I wonder if there’s a way to override “tab” such that it acts like a “:”, but from inside the language (this is trivial if you edit the language itself like you suggest). Thinking about it more, I’m guessing not since “:” isn’t an operator and this doesn’t have a corresponding __operator__ function.