> Is that feature actually needed for projects like Django, FastAPI, numpy, etc? Yes. FastAPI depends on really slow pydantic (disclaimer: I'm the author of t

> Is that feature actually needed for projects like Django, FastAPI, numpy, etc? Yes. FastAPI depends on really slow pydantic (disclaimer: I'm the author of the faster typedload). All those dynamic typechecking modules rely on the dynamic nature of the language. The alternative would be to having to generate code at compile time instead. pydantic is also in the process of being rewritten in rust to be not so slow any longer, and in the process it will become incompatible with anything else than cpython (the normal python runtime). Which in turns means fastapi won't be able to run on anything else (unless they decouple from pydantic… which probably won't be easy).