Instead of flattening out the nested option, as the other answer shows, I’d advocate that you never create an Option<Option<T>>
that you need to flatten in the first place. In the majority of cases I’ve seen, it’s because someone misuses Option::map
when they should have used Option::and_then
:
fn main() {
let input = user_input();
let a = input.map(add1);
// a is Option<Option<i32>>
let b = input.and_then(add1);
// a is Option<i32>
}
fn user_input() -> Option<i32> {
Some(10)
}
fn add1(a: i32) -> Option<i32> {
Some(a + 1)
}
Remember that Rust is a statically typed language; you will always know the exact level of nesting.
See also: