;;; not improper and which is not circular?
(defun list-with-length-p (x)
(values (ignore-errors (list-length x))))
+
+;;; not used in 0.7.8, but possibly useful for defensive programming
+;;; in e.g. (COERCE ... 'VECTOR)
+;;;(defun list-length-or-die (x)
+;;; (or (list-length x)
+;;; ;; not clear how to do this best:
+;;; ;; * Should this be a TYPE-ERROR? Colloquially that'd make
+;;; ;; lots of sense, but since I'm not sure how to express
+;;; ;; "noncircular list" as a Lisp type expression, coding
+;;; ;; it seems awkward.
+;;; ;; * Should the ERROR object include the offending value?
+;;; ;; Ordinarily that's helpful, but if the user doesn't have
+;;; ;; his printer set up to deal with cyclicity, we might not
+;;; ;; be doing him a favor by printing the object here.
+;;; ;; -- WHN 2002-10-19
+;;; (error "can't calculate length of cyclic list")))