Typescript’s optional and unsound type system also does nothing for a JIT beyond what it could already do for JavaScript, you can’t do optimization if your types are unreliable. However, I really really like how Typescript’s type system super charges developer productivity (type errors via the compiler and feedback via the IDE), and don’t mind this part of the design at all.

You can use typescript types to compile functions. You just might need to deoptimize when you actually hit the function.

I don’t know if Vortex-style compilation ever worked in practice.