Produces Excel like column names

iterate_example.clj

(defn column-names-seq
  "Given an alphabet string generate a lazy sequences of column names
  e.g.
  `(column-names-seq \"abcdefghijklmnopqrstuvwxyz\") ;; => (\"a\" \"b\" \"c\" ... \"aa\" \"ab\")`"
  [alphabet]
  (->> (map str alphabet)
       (iterate (fn [chars]
                  (for [x chars
                        y alphabet]
                    (str x y))))
       (apply concat)))

(defn alphabetical-column-names
  "Returns an infinite sequence of alphabetized column names.  If more
  than 26 are required the sequence will count AA AB AC ... BA BB BC
  ... ZZZA ... etc"
  []
(column-names-seq "abcdefghijklmnopqrstuvwxyz"))