Function difference 

pub fn difference<T, L, R>(a: L, b: R) -> impl Iterator<Item = T>
where
    T: Ord,
    L: IntoIterator<Item = T>,
    R: IntoIterator<Item = T>,

Take the difference of two sets (elements in a but not in b) represented by sorted, deduplicated iterators.

Time complexity: O(a.len() + b.len()).

Examples

use iter_set::difference;

let a = [1, 2];
let b = [2, 3];

assert!(difference(&a, &b).eq(&[1]));