my @results = foreach (@data) {
    $_ = $_ * 13;
    # some command to add the element to the resulting list
    # kind of push(), but how to get the reference
    # to the resulting array?
}

##</code><code>##

@results = eval {
    my @r;
    foreach (@data) {
        $_ = $_ * 13;
        push(@r);
    }
    return(@r);
}