typing pandas seems like an r&d-level problem as it seems quite close to tricky areas like row types / dependent types that mostly only work in theory attempti

typing pandas seems like an r&d-level problem as it seems quite close to tricky areas like row types / dependent types that mostly only work in theory attempting manual workarounds like pure nominal typing for it as you describe is against the grain of a type system and pushes a lot of work to the user. We just... don't. We stick with class ('pd DataFrame'), and the one extension we are thinking is Index, while getting into actual columns gets into a mess quite quickly. I tried to engage some PL researchers on this awhile back but no go. IMO would be a great project for most type system research students.