Clojure is a functional lisp, reportedly not at all object-oriented, even though it runs on the JVM, a VM designed for an object oriented language. Clojure provides identical interfaces for iterating over lists and vectors by abstracting them to an interface called seq. This is even implemented internally using a Java interface called ISeq. Is this not an example of object-oriented abstraction? How can it be claimed that Clojure is not object-oriented?
I guess a corollary to this question--- when can polymorphism be considered distinct from object orientation?