The way I see it, Perl initially (up to version 4) was mostly about compositing various Unix tools and sub-languages (sed, awk, (k|c)*sh) -- and believe me, back in those days that was really needed, as every Unix version out there did it another way.
With Perl 5, some "programming in the large" concepts were added, although it was decided that no definite OO style was needed due to the malleability of the language (if you haven't had a look at Perl5 since CGI days, take a look at the Moose ecosystem these days).
And Perl6 branched out into more "esoteric" topics, which included functional programming. I really need to take a better look at it and it's great that it's now stable enough that writing interesting articles about it doesn't mean that you can't run the code a week later (or that it's horribly slow).
And Damian Conway is always worth a look. Can't wait for 'Perl6 Best Practices'…