Whoa! I have an uneasy feeling about this PEP. AFAIK the usual procedure for adding a new feature to Python is: An idea is raised and attracts some support. Someone sufficiently motivated writes a PEP. The PEP is thoroughly discussed. Eventually a consensus (or at least an "agree to differ" stalemate) is reached. The PEP is accepted (if it is). (Then and only then) Someone works on the implementation. etc. However, PEP 622 only seems to have been presented to the Python community only *after* a well-developed (if not finalised) implementation was built. A fait accompli. So there will inevitably be resistance from the developers to accept changes suggested on python-dev. And since the PEP has Guido's authority behind it, I think it is likely that it will eventually be accepted pretty much as it was originally written. This means that most of the discussion we have seen on python-dev (and there has been a lot) will end up being just pissing in the wind. (I don't mean to be vulgar or disrespectful; I just can't think of another phrase that conveys my meaning so well.) And Guido's 2nd email ("PEP 622: Structural Pattern Matching -- followup") already to me (YMMV) reads rather like "OK, you've had your fun, now try not to joggle our elbows too much while we get on with the work". I don't know how many of the decisions made in the PEP are right and how many could be improved (it is of course a subjective question anyway). I do think it's a pity that the Python community did not have the chance to supply feedback earlier down the road (when IMO it would have been taken more seriously). While Guido and the other developers have obviously already put a huge amount of work into this PEP (and by now probably have a significant emotional investment in it), I do hope that they will take the time to consider seriously and on their merits most/all suggested changes, rather than being tempted to rush through the acceptance and implementation of the PEP. Best wishes Rob Cliffe