Optional values

Optional<T> is either some(value) or none; T? is equivalent type shorthand. none needs context from an annotation, branch, argument, or return type.

Match both cases for explicit control. Inside a function returning another optional, postfix ? unwraps some or returns none early.

fn label(name: Optional<string>) -> string {
  match name {
    some(value) => value,
    none => "unknown",
  }
}

fn main() {
  println(label(some("Ada")))
  println(label(none))
}