Example of using Sets in Perl6

output

Cannot look up attributes in a type object
  in method pairs at src/gen/CORE.setting:11915
  in sub register-arg at src/gen/CORE.setting:11670
  in method new at src/gen/CORE.setting:11677
  in sub set at src/gen/CORE.setting:11708
  in sub infix:<(|)> at src/gen/CORE.setting:11856
  in sub infix:<(|)> at src/gen/CORE.setting:11854
  in block  at ./set.p6:7

set.p6

class A {
    has KeyBag $.people is rw;
}

my $a = A.new();
for 'A', 'B', 'C' -> $name {
    $a.people = $a.people (|) $name;
}

$a.perl.say;