At long last, Steven D'Aprano and I have pushed a second draft of PEP 584 (dictionary addition): https://www.python.org/dev/peps/pep-0584/ The accompanying reference implementation is on GitHub: https://github.com/brandtbucher/cpython/tree/addiction This new draft incorporates much of the feedback that we received during the first round of debate here on python-ideas. Most notably, the difference operators (-/-=) have been dropped from the proposal, and the implementations have been updated to use "new = self.copy(); new.update(other)" semantics, rather than "new = type(self)(); new.update(self); new.update(other)" as proposed before. It also includes more background information and summaries of major objections (with rebuttals). Please let us know what you think – we'd love to hear any *new* feedback that hasn't yet been addressed in the PEP or the related discussions it links to! We plan on updating the PEP at least once more before review. Thanks! Brandt