// run-pass fn each<'a,T,F:FnMut(&'a T)>(x: &'a [T], mut f: F) { for val in x { f(val) } } fn main() { let mut sum = 0; let elems = [ 1, 2, 3, 4, 5 ]; each(&elems, |val: &usize| sum += *val); assert_eq!(sum, 15); }