// run-pass fn each(x: &[T], mut f: F) where F: FnMut(&T) { for val in x { f(val) } } fn main() { let mut sum = 0_usize; let elems = [ 1_usize, 2, 3, 4, 5 ]; each(&elems, |val| sum += *val); assert_eq!(sum, 15); }