but there are other ways to express traits, preconditions, postconditions, etc. besides types You can also put that in the type system, and expressive language

but there are other ways to express traits, preconditions, postconditions, etc. besides types You can also put that in the type system, and expressive languages do. Its just a compiler limitations when we can't. I mean, even in C++ with concepts we can do most of that. And C++ doesn't have the most expressive type system.