turn-has-winner.cljs

(defn- sole-owner
  "Indicates whether all positions are owned by the same player"
  [board positions]
  (let [owners (set (map #(board/get-owner-at board %) positions))]
    (case owners
      #{:owner/circle} :owner/circle
      #{:owner/cross} :owner/cross
      nil)))

(defn get-winner
  "Return the winner, or nil if the game has none"
  [{:keys [board]}]
  (some #(sole-owner board %) winning-cell-sets))