In the article and elsewhere Clojure is often used as an example of an anti-OOP language, yet by either Alan Kay's definition (quoted in my previous comment) or by Bertran Meyer's definition^1 Clojure uses the object oriented paradigm. Clojure is more object oriented than PHP or C++ which only provide some OO-inspired data abstraction mechanisms, but are not based around them.

^1 «Object oriented software construction is the building of software systems as structured collections of implementations of abstract data types.» Bertran Meyer. Object Oriented Software Construction, 2nd edition, 1997.