Soln to 119

4clojure119.clj

(fn [player board]
    (let [column
          (fn [[x y]]
            (for [newy [0 1 2]]
              [x newy]))
 
          row
          (fn [[x y]]
            (for [newx [0 1 2]]
              [newx y]))
 
          diags
          (fn [[x y :as pos]]
            (let [up [[0 2] [1 1] [2 0]]
                  down [[0 0] [1 1] [2 2]]]
              (filter #(some (partial = pos) %) [up down])))
 
          triples
          (fn [pos]
            (into (diags pos) [(row pos) (column pos)]))
 
          winning?
          (fn [board triple]
            (every? #(= player (get-in board %)) triple))
 
          empties
          (fn [board]
            (for [x [0 1 2]
                  y [0 1 2]
                  :when (= :e (get-in board [x y]))]
              [x y]))
          ]
      (apply hash-set
             (filter
              (fn [pos]
                (let [new-board (assoc-in board pos player)
                      lines (triples pos)]
                  (some #(winning? new-board %) lines)))
               
              (empties board)))))