tic-tac-zipper

core.clj

(ns ticzip.core
  (:require [clojure.zip :as z]))

(def game {:board (vec (repeat 9 nil))
           :player :x})

(def next-player {:x :o, :o :x})

(defn- free-tiles [{:keys [board]}]
  (->> board
       (keep-indexed (fn [idx itm] (when (nil? itm) idx)))
       (seq)))

(defn- play-move [{:keys [board player]} move]
  {:board  (assoc board move player)
   :player (next-player player)})

(defn- children [game]
  (reduce #(assoc %1 %2 (play-move game %2))
          {}
          (free-tiles game)))

(defn- children [game]
  (map (partial play-move game) (free-tiles game)))

(defn- make-node [game children]
  (assoc game :children children))

(def ticzip (z/zipper free-tiles children make-node game))

(-> ticzip
    z/down
    z/right
    z/down
    z/down
    z/down
    z/children)