(local {: contains} (require :lib.contains))

;; Does this move result in a mill?
(fn mill? [rules state move]
  (let [candidates (icollect [_ mill (ipairs rules)] (if (contains mill move) mill))
        candidate->moves (icollect [_ spaces (ipairs candidates)]
                                  (icollect [_ space (ipairs spaces)] (. state space)) )
        candidate-mill? (icollect [_ moves (ipairs candidate->moves)]
                                  (accumulate [acc true
                                              idx m (ipairs moves)]
                                              (and acc (not= 0 m) (= (. moves idx) m)))) ]
    (accumulate [acc true
                 _ x (ipairs candidate-mill?)]
                (and acc x))))

{: mill?}