To kinda follow up on marto's reply, it really comes down to: were they taught "programming" or a language. It's encouraging that he has been exposed to both C and Python (my knowledge of R is very limited). Perl in a lot of ways is Cish and Python shares its scripting nature with Perl so once the sygils have been properly appreciated, Perl's type permissiveness understood and the power of Perl hashes, arrays, grep and map fully groked, he should have no trouble. Oh, and the fact that Perl classes are a blessing should get shoehorned in there somewhere too.