utils.lisp

;;;
;;; Utilities 
;;;

(in-package #:closette)

;;; push-on-end is like push except it uses the other end:

(defmacro push-on-end (value location)
  `(setf ,location (nconc ,location (list ,value))))

;;; (setf getf*) is like (setf getf) except that it always changes the list,
;;;              which must be non-nil.

(defun (setf getf*) (new-value plist key)
  (block body
    (do ((x plist (cddr x)))
      ((null x))
      (when (eq (car x) key)
        (setf (car (cdr x)) new-value)
        (return-from body new-value)))
    (push-on-end key plist)
    (push-on-end new-value plist)
    new-value))

;;; mapappend is like mapcar except that the results are appended together:

(defun mapappend (fun &rest args)
  (if (some #'null args)
      ()
      (append (apply fun (mapcar #'car args))
              (apply #'mapappend fun (mapcar #'cdr args)))))

;;; mapplist is mapcar for property lists:

(defun mapplist (fun x)
  (if (null x)
      ()
      (cons (funcall fun (car x) (cadr x))
            (mapplist fun (cddr x)))))