> Turns out monomorphization isn't all you need. Turns out that it is, in fact, occasionally useful to unify an object and its behavior in a runtime-polymorphic way.
This actually gets the history backwards. Ancient Rust tried to do generics in a fully polymorphic way using intensional type analysis, like Swift does. We switched to monomorphization reluctantly because of the code bloat, complexity of implementation, and performance problems with intensional type analysis. "dyn Trait" was always intended to be an alternative that code could opt into for runtime polymorphism.
This actually gets the history backwards. Ancient Rust tried to do generics in a fully polymorphic way using intensional type analysis, like Swift does. We switched to monomorphization reluctantly because of the code bloat, complexity of implementation, and performance problems with intensional type analysis. "dyn Trait" was always intended to be an alternative that code could opt into for runtime polymorphism.