Range Redesign: Copy Semantics

[Paul Backus]

On Sunday, 21 January 2024 at 05:00:31 UTC, Jonathan M Davis 
wrote:
> From what I can see, the main negative is simply that you can't 
> then write code that works on both a basic input range and a 
> forward range (though you can obviously still create function 
> overloads so that the caller can use either)

With the proposed design, it would be possible to implement 
next() for forward ranges as a UFCS function:

     auto next(FR)(FR fr)
         if (std.v2.range.isForwardRange!FR)
     {
         if (fr.empty)
         {
             return Nullable!(ElementType!FR).init;
         }
         else
         {
             scope(success) fr.popFront;
             return nullable(fr.front);
         }
     }

So, a function written to operate on basic input ranges would be 
able to accept any kind of range, same as today.