(Clojure version) Given an array of integers, determine if any two given elements sum to a given target.

any-pair-make-sum.clj

(defn any-pair-make-sum? [arr target]
  (let [m (frequencies arr)]
    (loop [f (first arr)
           x (- target f)
           r (rest arr)]
     (let [entry (find m x)
           only-needs-one-count (not (= x f))]
       (if (and entry (or only-needs-one-count (> 1 (val entry))))
         true
         (if (empty? r)
           false
           (recur (first r) 
                  (- target (first r)) 
                  (rest r))))))))