sub split_it_this_a_way {
    my $string = shift || die "die, die, kill you all!";
    my ( $second, $first ) = split '\.', reverse($string), 2;
    ( ~~reverse($first), $second );
}

my $str = "x.z.y";
print $str, " -> ", join(" + ", split_it_this_a_way($str)), $/;