JEP draft: Exception handling in switch

Re:JEP draft: Exception handling in switch by bedobi on Friday April 19, 2024 @04:18PM (#40091496)

the difference is that in catch (Error e), you're actually catching the Error type, the superclass of exception

in Either<Error, Foo>, Error is not that, it's usually a sealed class with the full range of things that can go wrong with that thing, no more, no less, eg

    sealed class ChangePasswordErrors {
        class NotAuthenticated() : ChangePasswordErrors()
        class ChangePasswordError() : ChangePasswordErrors()
        class ReusedPassword() : ChangePasswordErrors()
    }

or whatever (but I could have made that clearer)

and no, languages should not add weird syntax to deal with Either, Option, Try etc. Just call map, flatMap, fold.

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Re:JEP draft: Exception handling in switch by ackfoobar on Friday April 19, 2024 @04:26PM (#40091563)

> the Error type, the superclass of exception

> in Either<Error, Foo>, Error is not that

This is confusing. On the JVM `Error` and `Exception` are both subclasses of `Throwable`. If you meant a specific error type, give it another name. (I used `MyError` in the comments above.)

> sealed class ChangePasswordErrors {

If some kind of failure has to be handled, In Kotlin you can write:

    sealed class ChangePasswordResponse {
        class Success(): ChangePasswordResponse()
        class NotAuthenticated() : ChangePasswordResponse()
        ...

> Just call map, flatMap, fold.

Enjoy your callback hell.

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Re:JEP draft: Exception handling in switch by bedobi on Monday April 22, 2024 @04:32PM (#40119914)

Good poit re using MyError, that is indeed what I meant in the Either case

Not sure what you mean by callback hell, I've never experienced that using Either. I just pass the Either from the db layer or whatever to the resource layer or whatever, where I fold it into a 200 with the requested thing or a 4xx or 5xx or whatever depending on the MyError (which is usually a sealed class that lists everything that can go wrong with the thing)

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