this is just an idea, I'm not sure if I like it though.
I find myself writing the following code a lot:
import 'something' do
dependencies 'other thing'
reference 'other thing', 'field' => :field
end
I thought about adding the dependencies for reference mappings automatically since the table you reference always needs to be loaded. The drawback is, that you don't see all the dependencies on a single line but it would remove some duplication.