Rust Programming Cookbook

How to do it...

Here are some steps for working with Result and Option:

1. Create a new project with cargo new exceptional-results --lib and open it with VS Code.
2. Open src/lib.rs and add a function before the test module:

/// /// Finds a needle in a haystack, returns -1 on error /// pub fn bad_practice_find(needle: &str, haystack: &str) -> i32 {    haystack.find(needle).map(|p| p as i32).unwrap_or(-1)}

3. As the name suggests, this is not the best way to communicate failure in Rust. What is a better way, though? One answer is to utilize the Option enum. Add another function underneath the first one:

/// /// Finds a needle in a haystack, returns None on error /// pub fn better_find(needle: &str, haystack: &str) -> Option<usize> { haystack.find(needle) ...