条件をどんどん付けてフィルタリングするのを簡単にするための何か

conditions_filter.clj

;; macroで書く必要がなかった...
;; (defmacro gen-bool-fns
;;   [key-value-pairs]
;;   `(loop [fns# []
;; 	  pairs# (partition 2 ~key-value-pairs)]
;;      (if (empty? pairs#)
;;        fns#
;;       (recur
;;        (conj fns# (let [[k# v#] (first pairs#)]
;; 		    (fn [x#] (= (k# x#) v#))))
;;        (rest pairs#)))))

(defn gen-bool-fns
  [key-value-pairs]
  (loop [fns []
	 pairs (partition 2 key-value-pairs)]
    (if (empty? pairs)
      fns
      (recur
       (conj fns (let [[k v] (first pairs)]
		   (fn [x] (= (k x) v))))
       (rest pairs)))))

(defstruct employee :name :a :b :c)

(defn conds-filter [lists & conds]
  (->> lists
       (filter
	(fn [x] (reduce 'and (map (fn [f] (f x))
				  (gen-bool-fns conds)))))))

(def employee-a (struct-map employee :name :a :a 1 :b 2 :c 3))
(def employee-b (struct-map employee :name :b :a 1 :b 2 :c 3))
(def employee-c (struct-map employee :name :c :a 1 :b 2 :c 1))
(def employees [employee-a employee-b employee-c])

(conds-filter employees :a 1 :b 2 :c 3) ; ({:name :a, :a 1, :b 2, :c 3} {:name :b, :a 1, :b 2, :c 3})
(conds-filter employees :b 2) ; ({:name :a, :a 1, :b 2, :c 3} {:name :b, :a 1, :b 2, :c 3} {:name :c, :a 1, :b 2, :c 1})