Passing $ as a function argument

[Michael Coulombe]

On Sunday, 14 October 2018 at 14:35:36 UTC, lngns wrote:
> On Sunday, 14 October 2018 at 13:18:37 UTC, lngns wrote:
>> That would require introducing a new type
>
> Or just use int with a negative number... That's how it's done 
> in some dynamic languages.
> But my point is that it should be compatible with pre-existing 
> code using unsigned indices somehow. I don't think that is 
> possible.

Another way to do this with UFCS:

// write-once library wrapper
struct Indexer(R) {
     R r;
     auto opDollar() { return r.length; }
     auto opIndex(size_t i) { return r[i]; }
}
auto indexer(R)(R r) { return Indexer(r); }

// rewrite index parameter => return wrapped range
auto foo()
{
     auto arr = (...);
     return indexer(arr);
}

// easy-to-use result
auto end = foo[$-1];