PersistentArrayMap.createAsIfByAssocComplexPath

(set! (.-createAsIfByAssocComplexPath PersistentArrayMap)
  (fn [init ^boolean has-trailing?]
    (let [init (if has-trailing?
                 (pam-grow-seed-array init
                   ;; into {} in case the final element is not a map but something conj-able
                   ;; for parity with Clojure implementation of CLJ-2603
                   (into {} (aget init (dec (alength init)))))
                 init)
          n    (pam-new-size init)
          len  (alength init)]
      (if (< n len)
        (let [nodups (make-array n)]
          (loop [i 0 m 0]
            (if (< i len)
              (let [dupe? (loop [j 0]
                            (if (< j m)
                              (or
                                (key-test (aget init i) (aget init j))
                                (recur (+ 2 j)))
                              false))]
                (if-not dupe?
                  (let [j (loop [j (- len 2)]
                            (if (>= j i)
                              (if (key-test (aget init i) (aget init j))
                                j
                                (recur (- j 2)))
                              j))]
                    (aset nodups m (aget init i))
                    (aset nodups (inc m) (aget init (inc j)))
                    (recur (+ 2 i) (+ 2 m)))
                  (recur (+ 2 i) m)))))
          (PersistentArrayMap. nil (/ (alength nodups) 2) nodups nil))
        (PersistentArrayMap. nil (/ (alength init) 2) init nil)))))