Correction: Conway says don't use postfix unless, for, while or until

So last example should be:

    for my $i (@list) {
        next if not $i % 2 == 0;
        do_something();
    }

Personally I don't follow the bible to the letter :) I do use prefix & postfix unless but only with simple truth conditions like this:

    unless ($this) { ... }

    next unless $this;