There is a pretty big error in here, trying to return a tuple
comperhension: (a for a in []) is not a tuple, it's a generator. This
has profound type annotations: generators don't support most tuple or
list methods, and they can only be iterated once. Beyond that tuples are
meant for heterogenous types, ie, position matters for types. I've
converted the output to a list in all cases.
The compilers module is rather large and confusing, with spaghetti
dependencies going every which way. I'm planning to start breaking out
the internal representations into a mixins submodule, for things that
shouldn't be required outside of the compilers module itself.