cl-tree (cons a d))))
(t cl-tree)))
-(defun acons (a b c) (cons (cons a b) c))
-(defun pairlis (a b &optional c) (nconc (mapcar* 'cons a b) c))
+(defun acons (key value alist)
+ "Add KEY and VALUE to ALIST.
+Return a new list with (cons KEY VALUE) as car and ALIST as cdr."
+ (cons (cons key value) alist))
+
+(defun pairlis (keys values &optional alist)
+ "Make an alist from KEYS and VALUES.
+Return a new alist composed by associating KEYS to corresponding VALUES;
+the process stops as soon as KEYS or VALUES run out.
+If ALIST is non-nil, the new pairs are prepended to it."
+ (nconc (mapcar* 'cons keys values) alist))
;;; Miscellaneous.