Excel列名変換をClojureで

excelcol.clj

(defn pow [^long m ^long n]
  (apply * (repeat n m)))

(defn ^long col2row [^String col]
  (apply + (map-indexed (fn [i c] * (- (int c) 64) (pow 26 i))
                        (reverse col))))

(defn ^String row2col [^long row]
  (let [n (mod (- row 1) 26)
        c (char (+ n 1 64))
        r (quot (- row n) 26)]
    (if (zero? r)
      c
      (str (row2col r) c))))

(defn ^String row2col+ [^long row]
  (->> (iterate (fn [[c r]] (let [n (mod (- r 1) 26)]
                             [(inc n) (quot (- r n) 26)]))
                [0 row])
       (partition 2 1)
       (take-while #(not= 0 (second (first %))))
       (reverse)
       (map #(char (+ (first (second %)) 64)))
       (apply str)))