Mastering Rust - Second Edition

Combinators on Option/Result

As Option and Result are wrapper types, the only way to safely interact with their inner values is either through pattern matching or if let. This paradigm of using matching and then acting on the inner values is a very common operation and, as such, it becomes very tedious having to write them every time. Fortunately, these wrapper types come with lots of helper methods, also known as combinators, implemented on them that allow you to manipulate the inner values easily.

These are generic methods and there are many kinds depending on the use case. Some methods act on success values, such as Ok(T)/Some(T), while some of them act on failed values, such as Err(E)/None. Some methods unwrap and extract the inner value, ...