#!/usr/bin/env perl

use 5.010;
use strict;
use warnings;

my @test_sites = qw{x.com y.com www.z.com www.y.com};
check_junk($_) for @test_sites;

sub KnownJunkSite {
    my ($key) = @_;

    state $is_junksite = { map +($_, 1), qw{
        x.com www.x.com z.com www.z.com
    } };

    return exists $is_junksite->{$key} ? 1 : 0;
}

sub check_junk {
    my ($key) = @_;

    say "$key: ", KnownJunkSite($key);
}

##</code><code>##

x.com: 1
y.com: 0
www.z.com: 1
www.y.com: 0