From: http://www.digitalmars.com/d/2.0/phobos/std_range.html#stride int[] a = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 ]; assert(equal(stride(a, 3) == [ 1, 4, 7, 10 ][])); The assert should be: assert(equal(stride(a, 3), [ 1, 4, 7, 10 ]));