Checking all elements are unique.

[Andrea Fontana via Digitalmars-d-learn]

On Wednesday, 31 August 2016 at 07:40:39 UTC, Dorian Haglund 
wrote:
> Hello,
>
> I have an array of objects of class C which contain a id member.
> I want to figure out if all the id members are unique using 
> functional primitives.
>
> For example, if I have:
>
> class C
> {
>   int id;
> }
>
> and an array of C 'Cs';
>
> My idea was to do:
>
> auto ids = Cs.map!(c => c.id);
> assert(equal(ids.sort().uniq(), ids.sort()));
>
> But it doesn't compile because I can't can call sort on ids.
>
> Any idea why ? and how to solve my initial problem, which is to 
> check all ids are unique.
>
> Regards,
>
> Dorian

Something like this: https://dpaste.dzfl.pl/9fa55b2a7927 ?

Andrea