filters

filters.clj

;; a function that provides the ability to filter a collection using multiple predicate functions, *lazily*.
;; The predicate functions must accept 2 args:
;;   - the first arg is the accumulating collection (think "reduce").
;;   - the second arg is the current item in the collection.
;; The return value is a reduced version of the input
;;
(defn filters [res items & fns]
  (last (reductions
         (fn [r i]
           (if (every? #(% r i) fns) (conj r i) r))
         res
         items)))

(take 100
      (filters #{}
               (concat (range -250000 250000) (range -250000 250000))
               (fn [r i] (not (r i)))
               (fn [_ i] (pos? i))))