Breadth-first

bfs.clj

(defn bfs [sz ef ff]
  "Initial state sz, expansion function ef [s] and feasibility function ff [s]"
  (loop [queue (conj clojure.lang.PersistentQueue/EMPTY sz)
         ef ef
         ff ff]
  (if (seq queue)
    (let [nx (peek queue)]
      (if (ff nx) nx (recur (into (pop queue) (ef nx)) ef ff)))
    nil)))