What's wrong with my usage of std.algorithm.map in this code example?

[Chris via Digitalmars-d-learn]

On Wednesday, 25 May 2016 at 19:07:32 UTC, Era Scarecrow wrote:
> On Wednesday, 25 May 2016 at 13:27:28 UTC, Chris wrote:
>> Why can the tuple be iterated with foreach, as in my quick 
>> fix, and indexed with tuple[0..], but is not accepted as a 
>> range? What are the differences? Is there a way to rangify a 
>> tuple?
>
>  The tuple is identified/used at compile-time, as such it's a 
> compiler primitive and not a range. Foreach in this case will 
> unroll the loop regardless how it looks. So...
>
>   test(Args...)(Args args) {
>   ...
>   foreach (const ref i; items)
>     itemstrings ~= i.to!string;
>
>   Will become: (const and ref are pointless in this example, 
> unless the args are referenced)
>
>   test(int arg1, int arg2, int arg3, int arg4) {
>   ...
>     itemstrings ~= arg1.to!string;
>     itemstrings ~= arg2.to!string;
>     itemstrings ~= arg3.to!string;
>     itemstrings ~= arg4.to!string;
>
>
>  Trying to use map on it was literally expanding the entire 
> input to map.

Ah, I didn't know that it was just unrolled. That makes sense, of 
course.

[snip]