Concise Control Flow with if let is a Rust syntax that allows you to combine the if and let keywords into a single statement. This can be used to handle values that match one pattern while ignoring the rest. For example, the following code uses if let to print out the value of a variable if it is Some, but do nothing if it is None:
let config_max = Some(3u8);
if let Some(max) = config_max {
println!("The maximum is configured to be {}", max);
}
The if let syntax is a useful way to write concise and readable code. However, it is important to note that if let does not provide the same exhaustive checking as match. This means that if you use if let, you must be careful to ensure that all possible values are handled. Here is an example of an if let statement with an else clause:
let mut count = 0;
if let Coin::Quarter(state) = coin {
println!("State quarter from {:?}!", state);
} else {
count += 1;
}
In this example, the else clause will be executed if the value of coin does not match the pattern Coin::Quarter(state). In this case, the value of count will be incremented by 1.
