Snakes and Ladders. #FnConf15

snakes-ladders.clj

(def cells 30) ; Number of cells on the board

; Map of snakes swallowing you at the key and shitting you out at the value
(def snakes {27 1
             21 9
             19 7
             17 4})

; Map of ladders bottom to top cell
(def ladders {3 22
              5 8
              11 26
              20 29})

(def num-of-players 2) ; Number of players in the game
(def initial-state (vec (repeat num-of-players 1))) ; Initialize the state of the game

; Calculate the new position based on whether the user has reached the end
(defn calc-pos
  [moves pos]
  (if (> (+ moves pos) cells)
    pos
    (+ moves pos)))

; Calculate the new state of the game
(defn calc-state
  [state turn new-pos]
  (assoc state turn (or (snakes new-pos) (ladders new-pos) new-pos)))

; Roll the dice and move player with turn those many positions
(defn roll-the-dice
  [state turn]
  (let [new-pos (calc-pos (inc (rand-int 6)) (state turn))]
    (println state (inc turn) new-pos) ; State, Current turn, New position
    (if (= new-pos cells)
      (str "Player " (inc turn) " won!")
      (recur (calc-state state turn new-pos) (mod (inc turn) num-of-players)))))

; Start the game
(defn -main
  []
  (roll-the-dice initial-state 0))

Snakes and Ladders

This is the first Clojure program I've ever written by myself. A code review would be highly appreciated.
The board is based on the image from the slides