> Says who? You can totally do code reuse using manually-written dynamic dispatch in "rust without traits". That's how C does it, and it works just fine.

Rust can monomorphize functions when you pass in types that adhere to specific traits. This is super-handy, because it avoids a bounce through a pointer.

The C++ equivalent would be a templated function call with concept-enforced constraints, which was only well-supported as of C++20 (!!!) and requires you to move your code into a header or module.

Zig can monomorphize with comptime, but the lack of trait-based constraint mechanism means you either write your own constraints by hand with reflection or rely on duck typing.

C doesn't monomorphize at all, unless you count preprocessor hacks.