Rust for C-Programmers

21.16 If Let Chains (Planned for Rust 2024)

If-let chains are a new feature planned for Rust 2024. They allow combining multiple if let conditions with logical AND (&&) or OR (||) in a single if statement, reducing unnecessary nesting.

21.16.1 Why If Let Chains?

Without if-let chains, you might end up nesting if let statements or writing separate condition checks that clutter your code. If-let chains provide a concise way to require multiple patterns to match at once (or match any of a set of patterns).

21.16.2 Example Usage (Nightly Rust Only)

#![feature(let_chains)]

fn main() {
    let some_value: Option<i32> = Some(42);
    let other_value: Result<&str, &str> = Ok("Success");

    if let Some(x) = some_value && let Ok(y) = other_value {
        println!("Matched! x = {}, y = {}", x, y);
    } else {
        println!("No match!");
    }
}

Compile on nightly:

rustup override set nightly
cargo build
cargo run

21.16.3 Future Stabilization

If-let chains are expected to become part of the stable language in Rust 2024, removing the need for the feature flag. Once stabilized, they will further streamline pattern-based branching.