how to get top N distinct elements from range?

[bearophile]

Andrea Fontana:

> But i think "front" was "cached", but it seems not...	

The caching of map front was recently removed.


More test code:


import std.stdio, std.range, std.algorithm, std.traits, 
std.random;

void main() {
     5.iota.map!((_) {
         auto x = uniform(0, 10);
         write("*");
         return x;
     }).filter!(_ => true).array;
}


Prints:

**********

Bye,
bearophile