# Your's:
sub make_call { goto $_[0] }

# Anonymonk's(slightly rearranged):
sub Y { $_[0]->(@_) }

##</code><code>##

make_call (sub {
        my $factor = $_[1];
   
        return $factor > 1
            ? $_[0]->($_[0], $factor-1) * $factor
            : 1;
    }, $_);