map.pl

#!/usr/bin/env perl

use Modern::Perl;
use Data::Dump qw/pp/;

my @neighbourhood = (
    {
        name      => 'Donald',
        age       => 3,
        behaviour => 'naughty',
        stocking  => [],
    },
    {
        name      => 'Theresa',
        age       => 5,
        behaviour => 'nice',
        stocking  => [],
    },
    {
        name      => 'Angela',
        age       => 17,
        behaviour => 'nice',
        stocking  => [],
    },
);

map {
    push @{$_->{stocking}},
        $_->{behaviour} eq 'nice' ? 'lollipop' : 'coal';
}
grep { $_->{age} < 16 } @neighbourhood;

say pp(@neighbourhood);