[wyager]

You can manipulate value-level things like EitherT in ways that are not convenient or possible in Java.

EitherT and friends also force you to handle exceptions explicitly before getting a value out. In Java, you can usually just ignore it and "let it bubble up" as someone suggested earlier.

[jstimpfle]

"Manipulate", that's what I meant by "transformations by higher order functions". The point is acknowledged, but I feel in practice it's not always beneficial. There are typically not many more points of use than different transformations. Doing the stuff inline (with catch blocks) is often better since there's less conceptual overhead.

"Bubbling up", that's exactly what the monad instance gives you. How EitherT is supposed to be used. That's why I said there's not much difference from a practical standpoint. So no, EitherT does not force any better style than checked exceptions (but it makes it really inconvenient to traverse regions of code with differing sets of exceptions).

I still feel that the C-style way of handling error codes is superior in most situations, from a writeability and readability perspective. The big problem is it doesn't enforce error handling. Another problem is it's totally unsuited for quick and dirty scripts like I can write with Python "unchecked" exceptions: Just do it, and tell me if there were errors (I might or might know which ones are possible) only at runtime.