If your language is not purely functional it is imperative. There is really no conceptual difference between Clojure and Python, except for syntax/macros and that Clojure has immutable data structures in clojure.core.
You could use mutable arrays in Clojure the same way you could use immutable arrays in Python (yet nobody is calling Python a functional language.)
Still, I agree that functional mostly means "language with closures and immutable data" in the mainstream, but in the context of this post I'd say it's not that hard to guess that the authors meant purely functional.
You could use mutable arrays in Clojure the same way you could use immutable arrays in Python (yet nobody is calling Python a functional language.)
Still, I agree that functional mostly means "language with closures and immutable data" in the mainstream, but in the context of this post I'd say it's not that hard to guess that the authors meant purely functional.