Rust in the 6.2 kernel

Rust in the 6.2 kernel

> - The argument that "defining your own variant with domain-specific names etc." also applies as a criticism of both Option and Result, and the fact that actually we use Option and Result a lot shows that this criticism only goes so far.

How? Option and Result are domain-specific.

Option is the fix for the billion-dollar mistake: it handles the case where object may or may not be present.

Result is for the case where function may return “normal” result or “error result”. Open POSIX specifications (or practically any API specification) and you'll find many such functions.

It's not enough to have one such function. One function is always better server with ad-hock type. You need series of functions which may share a common type. It's easy to imagine such for Options: lot's of data structures have “leaf nodes”. It even easier to do that with Result: almost all functions which deal with files or network may suffer from the same errors (it doesn't matter whether you are creating file or removing it, if you don't have permission to do that error would be the exact same one).

Just what class of functions do you have in mind where you may have symmetrical two choices and these are the same across the whole range of functions?

Yes, partition_map example makes sense (and that's exactly where itertools are using Either), but Rust is imperative language with for. It's really not clear how often do you even need such thing in Rust.