Yup, sorry, I think you're absolutely right. I really don't know why I was absolutely blanking, but I thought I remembered seeing formal parameter lists somewhere, and I guess that was Perl 6. Indeed, perlsub mentions "Perl does not have named formal parameters."

I guess you could change my comment, if you want, to the fact that it's difficult to pass arrays and hashes into functions (with the canonical solution being references and the less typical one prototypes). Thanks for the heads-up.