Ranges, constantly frustrating

[Jesse Phillips]

On Tuesday, 11 February 2014 at 13:00:19 UTC, Regan Heath wrote:
> import std.stdio;
>
> struct S1 {
>    private int[] elements = [9,8,7];
>    int opApply (int delegate (ref uint, ref int) block) {
>        foreach (uint i, int n ; this.elements)
>            block(i, n);
>        return 0;
>    }
> }
>
> void main()
> {
> 	S1 range;

S1 is not a range. But this is a correct response to "Is 
foreach(i, val; aggregate) even defined if aggr is not an array 
or associated array?"