Using trampoline to process a long sequence of mutually recursive function calls.

trampoline.clj

(letfn [(m-even [v]
          (if (zero? v) v
            (fn [] (m-odd (dec v)))))
        (m-odd [v]
          (if (zero? v) v
            (fn [] (m-even (dec v)))))]
  (trampoline m-even 100000))
;; => 0
(letfn [(m-even [v]
          (if (zero? v) v
            (m-odd (dec v))))
        (m-odd [v]
          (if (zero? v) v
            (m-even (dec v))))]
  (trampoline m-even 100000))        
; StackOverflowError   clojure.lang.Numbers.isZero (Numbers.java:90)