opNext: Simplified ranges

[Joseph Rushton Wakeling]

On Sunday, 6 November 2022 at 01:48:04 UTC, Walter Bright wrote:
> We didn't use the "next" protocol for ranges because one cannot 
> test for existence of the next element without consuming it.

Aren't there cases (e.g. some kinds of IO) where that's 
unavoidable in any case?

The "next" approach is surely the most information-limited case, 
where you really can't separate between checking for existence of 
the next element, and consuming it.  Other possibilities, such as 
the presence of a check whether the range is `empty`, or the 
possibility to `peek`, would then be less information-limited 
options on top of that.

I apologize if I'm out of date on some discussions which have 
already taken place around the range design, and so forcing you 
to re-explain something that's already been worked through.