assoc-in.clj

;; The core function assoc-in
(defn my-assoc-in
  [m [& ks] v]
  (let [sorted-keys (reverse ks)]
    (loop [curr-key (first sorted-keys)
           rem-keys (rest sorted-keys)
           curr-map (get-in m (reverse rem-keys))
           acc-val  (assoc curr-map curr-key v)]
      (if (empty? rem-keys)
        acc-val
        (let [next-key (first rem-keys)
              next-rem (rest rem-keys)
              next-map (get-in m next-rem)
              next-val (assoc next-map next-key acc-val)]
          (recur next-key next-rem next-map next-val))))))