3 trait DigitCollection: Sized {
4 type Iter: Iterator<Item = u8>;
5 fn digit_iter(self) -> Self::Iter;
7 fn digit_sum(self) -> u32 {
9 .map(|digit: u8| digit as u32)
10 .fold(0, |sum, digit| sum + digit)
14 impl<I> DigitCollection for I where I: Iterator<Item=u8> {
17 fn digit_iter(self) -> I {
23 let xs = vec![1, 2, 3, 4, 5];
24 assert_eq!(xs.into_iter().digit_sum(), 15);