[nilved]

It depends on how you implement the gradual typing as well. Through contracts is one way (probably the bad way, since they still apply at runtime) and static analysis with type annotations is another way. There isn't any reason a sufficient static analyzer couldn't be as powerful as an inbuilt static type system.

This is effectively dragging some of the benefits of static typing to dynamic typing. I wonder why you'd pay the cost of dynamic types though, instead of going the other direction. With type inference you don't need to explicitly write types the entire codebase, and you can opt-in to dynamic types in controlled, explicit scenarios.