Didn't help to learn how to hack Perl.
You already said that, what does that mean?
perlhack DESCRIPTION is
This document explains how Perl development works. It includes details about the Perl 5 Porters email list, the Perl repository, the Perlbug bug tracker, patch guidelines, and commentary on Perl development philosophy.
And perlhack does indeed teach that
So what do you mean?