tictactoe-refactor.clj

;; tictactoe.core.clj

(defn -main []  
 (play (new-board 9) (get-player (first piece)) (get-player (second piece))))

;; tictactoe.game.clj

(defn get-player [piece]
  (let [player-type (get-player-type piece)]
     (if (valid-type? player-type) 
        (do {:piece piece :player-type player-type})       
        (recur piece))))