Population count

Built-in:

say popcount(42)

User-defined:

func population_count(n) { n.as_bin.count('1') }
say "#{0..29 «**« 3 «call« population_count -> join(' ')}"
 
var numbers = 60.of { |i|
    [i, population_count(i)]
}
 
say "Evil:   #{numbers.grep{_[1] %% 2}.map{.first}.join(' ')}"
say "Odious: #{numbers.grep{_[1] &  1}.map{.first}.join(' ')}"

Output:

1 2 2 4 3 6 6 5 6 8 9 13 10 11 14 15 11 14 14 17 17 20 19 22 16 18 24 30 25 25
Evil:   0 3 5 6 9 10 12 15 17 18 20 23 24 27 29 30 33 34 36 39 40 43 45 46 48 51 53 54 57 58
Odious: 1 2 4 7 8 11 13 14 16 19 21 22 25 26 28 31 32 35 37 38 41 42 44 47 49 50 52 55 56 59