Perl6 version of http://asq.readthedocs.io/en/latest/narrative.html#key-selector-factory

perl6_sort.pl

use v6;

my $employees = [
    {firstname=>'Joe', lastname=>'Bloggs', grade=>3},
    {firstname=>'Ola', lastname=>'Nordmann', grade=>3},
    {firstname=>'Kari', lastname=>'Nordmann', grade=>2},
    {firstname=>'Jane', lastname=>'Doe', grade=>4},
    {firstname=>'John', lastname=>'Doe', grade=>3},
];

say (
    $employees.sort: {-$^a{'grade'}, $^a{'lastname'}, $^a{'firstname'}}
    ).perl;