BEGIN {
    package MyCow;
    use Moose; # or Mouse

    has "guernsey" =>
        is => "rw",
        isa => "Bool",
        ;
}

my $cow = MyCow->new;
$cow->guernsey(1);
print "How now, ",
    $cow->guernsey ? "brown" : "purple",
    " cow?", $/;

my $attr = $cow->meta->get_attribute("guernsey");
print "Attribute does Bool? ", $attr->does("Bool") ? "Yes!" : "No...", $/;