core.clj

(defmacro defrecord-with-ctor
  "Declare a record with the given fields, as well as a
make-x (lower-case) taking a map instead of ordered fields"
  [name field-vec]
  (let [ctor-name (->> name str .toLowerCase (str "make-") symbol)
		nil-args (repeat (count field-vec) nil)]
	`(do
	   (defrecord ~name ~field-vec)
	   (let [template# (new ~name ~@nil-args)]
		 (defn ~ctor-name [arg-map#]
		   (into template# arg-map#))))))

(defrecord-with-ctor Card [suit rank owner])
;; expands to:
(do
  (defrecord Card [suit rank owner])
  (let [template (new Card nil nil nil)]
    (defn make-card [arg-map] 
      (into template arg-map))))