Cyclic sorted list

praxis_cyclic.clj

;;cyclic list insertion

(def start-node (atom [1 (fn [] start-node)]))

(defn insert-after [node val]
  (let [new-node (atom [val (last @node)])]
    (swap! node (fn [n] [(first n) (fn [] new-node)])))) 

(defn find-insert-spot [node val]
  (loop [cnode node
         ctr 0]
    (let [next-node ((last @cnode))
          cval (first @cnode)
          nval (first @next-node)]
      (if (= next-node node)
        cnode
        (if (or (<= cval val nval)
                (and (> cval nval) (or (>= val cval)
                                       (<= val nval))))
          cnode
          (recur next-node (inc ctr)))))))

(defn insert-val [node val]
  (insert-after (find-insert-spot node val) val))

(defn get-nth-after [start cnt]
  (loop [cnode start i cnt]
    (if (= i 0)
      cnode
      (recur ((last @cnode)) (dec i)))))

(defn ring-vals [start]
  (loop [cnode start
         acc []]
    (let [next-node ((last @cnode))
          cval (first @cnode)]
      (if (= next-node start)
        (conj acc cval)
        (recur next-node (conj acc cval))))))