Thanks a lot for making this. I've been keeping excited since I heard this several hours ago!
I'm a researcher(and also a student) in some field dedicated in the study of programming language constructs, including pattern matching.
**Python Pattern Matching** is something special to me, which finally shaped the route of my life. I'd say the design is quite clean and impressive, however still, I found many issues, and I wrote a blog post for this, in order to present my points clearly to you promoters and developers of PEP 622: https://thautwarm.github.io/Site-32/Design/PEP622-1.html
The summary of the key points in my blog post:
1. There is a scoping issue which is not specified to be solved in the specification of PEP 622, and can be a dangerous bug. 2. The reason for accepting AND patterns, and its use case for enhancing the composability of programs. 3. Guards as patterns can be useful for pattern matching in Python. 4. An alternative '__match__' protocol which can be beneficial. 5. Reason for voting 'else' clause, just like Ethan and other kind people proposed.
I also feel like to implement PEP 622, and I'm familiar with steps concerning the implementation.