anchor.diff:               (prog1 ucons
                  (cond
                    ((> (length table) 8)
  -                  (setf (ucons-table cdr)
  +                  (setf (utable cdr)
                           (alist-hash-table table :test #'eql :size 16))
  -                  (setf (gethash car (ucons-table cdr)) ucons))
  +                  (setf (gethash car (utable cdr)) ucons))
                    (t
  -                  (push (cons car ucons) (ucons-table cdr)))))))))))
  +                  (push (cons car ucons) (utable cdr)))))))))))
   
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;;;
  
positive.code: (uiop:define-package :petalisp/utilities/ucons
    (:use :closer-common-lisp :alexandria)
    (:export
     #:ucons #:ucar #:ucdr #:ucaar #:ucadr #:ucdar #:ucddr
     #:ulist #:ulist* #:ulength
     #:ulist-shallow-copy #:ulist-deep-copy
     #:map-ulist
     #:do-ulist))
  
  
negative.code:   (declare (type (or null ucons) cdr)
             (type ucar car))
    (let ((alist (and cdr
                      (listp (utable cdr))
                      (utable cdr))))
      (the ucons
           (or
            (loop for cons of-type (cons ucar ulist) in alist
  