Implement method into_ok_or_err for Result<T, T>

[Edwin]

I think it'd be nice to be able to write something like

val a = res.map { it.joinToString("\n") }.into_ok_or_err()

instead of

val a = when (res) {
    is Ok -> res.unwrap().joinToString("\n") // -> String
    is Err -> res.unwrapError() // -> String
}

This feature already exists in Rust Nightly.

[Michael Bull]

Can you describe the receiver type and the return type more precisely? Struggling to understand what this is meant to take and produce with the implicit type in your examples

[Edwin]

Yes, sorry.

val res: Result<List<String>, String> = fetchList()
val output: String = res.map { it.joinToString("\n") }.into_ok_or_err()

Another example:

val res: Result<String, String> = fetchString()
val output: String = res.into_ok_or_err()

Essentially just takes the ok value if ok and err value if not ok.

[Michael Bull]

Does this differ from merge?

[Edwin]

Nope, I just totally missed that method.

Thank you!

[Michael Bull]

No worries, here's the wiki entry for it if that helps.