Why can't we make reference variables?

[Tommi]

On Wednesday, 29 August 2012 at 01:42:36 UTC, Timon Gehr wrote:
> Not exactly the same thing (what you propose would have 
> different
> IFTI behaviour), but works quite well:
>
> import std.stdio;
>
> struct Ref(T){
>     private T* _payload;
>     this(ref T i){_payload = &i; }
>     @property ref T deref(){ return *_payload; }
>     alias deref this;
> }
> auto ref_(T)(ref T arg){return Ref!T(arg);}
>
> void main(){
>     int i,j;
>     auto r = i.ref_;
>     r++;
>     auto q = r;
>     writeln(r," ",q);
>     q++;
>     writeln(r," ",q);
>     q = j.ref_;
>     q++;
>     writeln(r," ",q.deref);
> }

I did figure that that's possible. But, to me, having reference 
variables be implemented in a library instead of them being a 
core language feature, is like having pointers implemented as a 
library. I'd like to have a good answer when some newcomer asks 
me: "why, oh why is this so?".