> If you add a new type to a sum type in a statically typed language, that's a breaking change for all downstream consumers. Yes, but that's true regardless of

> If you add a new type to a sum type in a statically typed language, that's a breaking change for all downstream consumers. Yes, but that's true regardless of whether the compiler tells you or not. The question is whether adding the value to the set of types that can be returned breaks at compile time or at run time.