if let expressions

If you want to match a value against a pattern, you can use if let:

fn main() {
let arg = std::env::args().next();
if let Some(value) = arg {
println!("Program name: {value}");
} else {
println!("Missing name?");
}
}
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See pattern matching for more details on patterns in Rust.

Speaker Notes

  • if let can be more concise than match, e.g., when only one case is interesting. In contrast, match requires all branches to be covered.
  • Unlike match, if let does not support guard clauses for pattern matching.