fn iter_vec(v: [T], f: block(T)) { for x: T in v { f(x); } } fn main() { let v = [1, 2, 3, 4, 5]; let sum = 0; iter_vec(v, {|i| iter_vec(v, {|j| log(error, i * j); sum += i * j; }); }); log(error, sum); assert (sum == 225); }