Have you used typescript? Because to my eyes, that's a massively successful "bolted on" type system.
Sure there're holes in the system, but the utility is significant, especially relative to the cost.
Sure there're holes in the system, but the utility is significant, especially relative to the cost.
And then the expressiveness of the type system there is also really pragmatic. You can't natively express union types in Java and many other static languages without writing your own Either monad implementation. Instead, you often wind up with code that has objects with a hodge-podge of field sets that are nullable.
It's nothing short of miraculous how well the null-safety situation is in TypeScript. It's built on the back of community-driven types in DefinitelyTyped where the maintainers of libs often aren't the ones writing and keeping types up to date. Nowadays, types are becoming more and more first-party, but it still amazes me how we got to this point.