Digital Root Clojure Solution 1

digital-root.clj

(ns digital-root
  (:require [clojure.string :as str]))

(defn split-numbers [n]
  (str/split (str n) #""))

(defn sum-numbers [numbers]
  (reduce (fn [sum number]
            (+ (int sum) (Integer/parseInt number))) 
          0 numbers))

  (defn digital-root [n]
    (let [splited-numbers (split-numbers n)
          result (sum-numbers splited-numbers)]
    (if (< result 10) result 
    (recur result))))