Kris Nuttycombe

What’s your ideal look like in Scala?

What is the point of *forcing* the user to handle the exception in a place down the call stack where maybe it is not yet appropriate to make a decision? And while on sum types, why just not return the sum type like Either<Left, ErrorSumType>

Declare it to be rethrown. Using Either is *fantastic* for errors that are relevant to the semantic domain - incorrect user input, serialization problems, etc - but call stacks are better for genuinely exceptional conditions.

I would agree, given a language that lets me declare "this function rethrows whatever its function parameters throws". Otherwise you get Java where you can't call `map` with any function that throws, which, at least in Java, ends up being most of them.

There are many problems with Java's checked exceptions and among those, the issue of sum types versus modeling inheritance hierarchies is a actually a minor one. And we don't have to guess. We can see how checked exceptions have been (mis)used in major Java projects.

More important problems: 1. error recovery doesn't happen often, "finally" is more important than "catch", checked exceptions make people ignore important errors in dangerous ways 2. error type is an encapsulation leak