> Well, since the extra code will be autogenerated, guess it wouldn't be much problematic. But I see about the PEG thing.


On the other hand, having explicit types for the sequences will allow us to get compile errors instead of runtime errors for the standard types, so this may be a good possibility. Maybe some mixture of both:

* asdl_seq objects can contain an enum describing what they are.
* We have specific specializations for adding to ASDL types.