#015 Apr 20, 2022

15. Scan

Iterator adapter similar to fold (see previous bite) - holds some internal state and produces new iterator.

Note that Option is yielded from the closure.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
let nums = [1, 2, 3];

let mut iter = nums.iter().scan(0, |acc, &x| {
    *acc = *acc + x;
    Some((*acc, x))
});

assert_eq!(iter.next(), Some((1, 1)));
assert_eq!(iter.next(), Some((3, 2)));
assert_eq!(iter.next(), Some((6, 3)));

This post is licensed under CC BY 4.0 by the author.