Leonardo Santiago

When I added this error check, there was really no way to no if a name had been defined before or not (maybe checking if arity was defined for it?...

I believe I've fixed the `nix flake check` issue. When rigille added the nix-filter, he forgot to add it for the tests too.

Thanks for your review! I will address some comments, but I think it is worth going back and rewrite it in a overlay based approach. The main ideas should stay...

But yeah, just to finish up. The `seen` argument present in all the functions is already the `prev:` argument provided in the overlay approach, I would just need to add...

I can, I will get it done next week. The actual code pertaining to that is much much smaller and relatively simple, compared to the resolver.