Improper-consp
Recognizer for improper (non-nil-terminated) non-empty lists
Improper-consp is the function that checks whether its
argument is a non-empty list that ends in other than nil. See proper-consp and also see true-listp.
Function: improper-consp
(defun improper-consp (x)
(declare (xargs :guard t))
(and (consp x) (not (true-listp x))))
