if let Expressions

The if let expression lets you execute different code depending on whether a value matches a pattern:

# // Copyright 2025 Google LLC
# // SPDX-License-Identifier: Apache-2.0
#
use std::time::Duration;

fn sleep_for(secs: f32) {
    let result = Duration::try_from_secs_f32(secs);

    if let Ok(duration) = result {
        std::thread::sleep(duration);
        println!("slept for {duration:?}");
    }
}

fn main() {
    sleep_for(-10.0);
    sleep_for(0.8);
}

• Unlike match, if let does not have to cover all branches. This can make it more concise than match.
• A common usage is handling Some values when working with Option.
• Unlike match, if let does not support guard clauses for pattern matching.
• With an else clause, this can be used as an expression.