Checked exceptions really aren't much different from dedicated return type for errors. The Either type in Haskell and its Monad is really not doing anything fun

Checked exceptions really aren't much different from dedicated return type for errors. The Either type in Haskell and its Monad is really not doing anything fundamentally different: Bubbling up errors until the point where someone cares/needs to handle them (though I have to say I hate the whole Left / Right convention thing, just define a dedicated type with proper constructors for value vs. error already). In fact I'd say checked exceptions are a richer formalism since they essentially provide something akin to intersection types for errors. The fact that there are also RuntimeExceptions comes up a lot as an argument against Java/checked exceptions but that doesn't convince me. Haskell also has runtime errors that can happen (division by 0) that are outside the Either or Option/Maybe world. The problem is maybe rather that people are lazy and the trend became to decide that everything should be a RuntimeException because who needs all that noise and checked exception handling, right? I'm fairly certain that people who rejected checked exceptions would also reject the more functional approaches. My argument is that no consensus around using checked exceptions correctly ever developed and so they never really had a chance to shine. Having said that, sure I think having more usage of idioms we find in FP for error handling/propagation or early aborting is great. It's better than just raising runtime exceptions. However we are still in a world where no widely known language actually enforces (!) error handling in that fashion. It's all convention in the end. And so my point was that if you want a language that tries to encourage error handling, with known failure modes communicates in the method signature then Java's checked exceptions sound pretty close. Sure they are not perfect but the question is whether it's worth exploring better formalisms along the lines of first class errors with dedicates language support or piggybacking on the existing type system features and introduce conventions? The latter sort if works but I find it less ...exciting.