list filtering

list_filtering.clj

(let [candidates [{:udicode 1} {:udicode 2} {:udicode 3} {:udicode 4} {:udicode 1} {:udicode 9} {:udicode 20}]
      result (atom #{})
      filters [#(not (@result %))
               #(< (:udicode %) 10)]
      include? (fn [h]
                 (if (every? #(% h) filters)
                   (swap! result conj h)))]
  (take 7 (filter include? candidates)))

;; using juxt and reduce for applying the filters:
(reduce #(and %1 %2) ((apply juxt [nil? keyword? (constantly true)]) nil))