This is a nice little feature that I’ve missed several times in the past. If you’re still looking for a sponsor, I’m happy to volunteer.
I just read the draft PEP and implementation and I think it’s in good shape already. Two areas where the PEP could be improved:
- There is a lot of discussion of exactly how this would be implemented in the bytecode. Bytecode is a CPython implementation detail that frequently changes, not a part of the language. As such, it shouldn’t be part of the “Specification” section of the PEP. If anything is particularly tricky it could be discussed under “Reference implementation”, but mostly this can be deferred to when you actually implement it in CPython.
- It could be useful to discuss whether other programming languages that have some sort of comprehension support this syntax.