merge-plists

merge-plists.lisp

;; I'm sure this could be improved a lot! I'm still a lisp newbie.

(defun merge-plists (&rest plists)
  "Merge all the given plists into a new plist. The new plist has all
the keys from each plist, with values of keys in later lists
overriding the values of the same keys in earlier plists.
No particular order of key/value pairs is guaranteed.
E.g.:
  > (afw/util:merge-plists '(:a 1 :b 2) '(:a 3 :c 4) '(:d 5))
  (:D 5 :C 4 :A 3 :B 2)"

  (let ((result (copy-list (first plists))))
    (dolist (plist (rest plists))
      (do* ((prop  (first plist)  (first plist))
            (value (second plist) (second plist))
            (oldpl plist          plist)
            (plist plist          (cddr plist)))
           ((not oldpl))
        (setf (getf result prop) value)))
    result))

;; A more clear and concise version, using loop instead of do*.

(defun merge-plists2 (&rest plists)
  (let ((result (copy-list (first plists))))
    (dolist (plist (rest plists))
      (loop for (key value) on plist by #'cddr
         do (setf (getf result key) value)))
    result))