The author talks about how friendly the Clojure community is in the first paragraph but then goes on to take some silly potshots at other languages in the very next paragraph:

I asked around and learned that he wrote a book called "Clean code" and that he likes Ruby, which just makes no sense to me at all - How do you unify a tool as unstable, unpredictable, untamed as Ruby (second only to Perl) with Clean Code?