> 99% of the time 99% of whose time? Where does this estimate come from? Definitely not my case, and definitely not the case for lots of programmers I know an

> 99% of the time 99% of whose time? Where does this estimate come from? Definitely not my case, and definitely not the case for lots of programmers I know and/or work with. Python has its own place (for example, in DS/ML) and while I use it myself on daily basis for what's it's best at, statements like "you should be programming just about 99% of your time in Python" make no sense at best. And, note, it's not only about speed/performance; after writing lots of Rust (or even F#), it's hard to get back to Python because of missing expressiveness and basic language tooling. Finally, speaking of Python (CPython in particular), part of why it's so attractive is all the fast binary extensions libraries written for it... in C++/Rust, not Python. > Sum types and traits are not getting things done. Disagreed, sum types are exactly what gets things done, regardless of language performance and other features. This kind of logic exists everywhere. That's why languages with proper (or even semi-proper) sum types like Rust, F# are a lot easier to express 'business logic' in. And e.g. that's exactly why serialization/deserialization can get so weird in Python where values can be of multiple types and you have to invent crutches to work around that, to simulate sum types in this way or another.