std.v2020.algorithm etc[ WAS: Is run.d going to be expand for runtime and the phobos library?]

[Paul Backus]

On Saturday, 20 June 2020 at 18:34:37 UTC, Johannes Loher wrote:
> On Saturday, 20 June 2020 at 13:07:41 UTC, Paul Backus wrote:
>>
>> For non-forward ranges, there's no promise that the original 
>> range (or any copies of it) will remain valid after calling 
>> `rest`, so you can always implement `rest` like this:
>>
>>     auto rest() {
>>         this.popFront;
>>         return this;
>>     }
>
> Can’t make it const then... also some ranges probably cannot 
> bee const by design, e.g. byLine etc.

Yes, ranges with popFront can't be const. The difference is that, 
with `rest`/`tail` as the default, *some* ranges that are 
currently forced to use popFront unnecessarily can be made 
const-compatible.

Ranges that continue to use popFront, for whatever reason 
(performance, backwards compatibility, etc.) will remain 
mutable-only.