> But what I'm talking about here is genuine runtime exceptions (which NPE is in Java, of course), where the design of the system says that this piece of data c

> But what I'm talking about here is genuine runtime exceptions (which NPE is in Java, of course), where the design of the system says that this piece of data cannot be missing and yet, at runtime, you encounter a case where it is missing, erroneously, because of some bug somewhere. With checked optionals, you'll know that the code differs from the design at compile time. If a piece of data can indeed be missing you can't compile the code without considering that case explicitly.