Example of CPSing variadic Clojure fn expression with compatibility for non-CPS calls

gistfile1.clj

(fn [w x y & z] z)

(let [empty-k (with-meta identity {:kont true})] 
  (fn foo 
    ;; need a compatibility overload for if someone called
    ;; using only required parameters.
    ([w x y] (foo empty-k w x y)) 
    ;; acts as its own compatibility layer, since we can't
    ;; have another variadic overload
    ([k w x y & z] 
      (if (:kont (meta k)) 
          (k z) 
          ;; funny thing to note about clojure semantics here:
          ;; when using `recur` with a variadic function, the
          ;; last argument to the recur must explicitly be a list.
          ;; you can't simply tack on extra arguments as with a
          ;; non-recur call
          (recur empty-k k w x (conj z y))))))