Perl prototype is too difficult to understand

prototype.pl

#!/usr/bin/env perl
use strict;
use warnings;

sub with_prototype ($) {
    print "@_\n";
}

with_prototype(());         # OK, pass undef
with_prototype(("a", "b")); # OK, pass 'b', ignore 'a'
with_prototype("a", "b");   # Compile Error