anchor.diff:      (if slot-list
           `(let ((,name ,init))
              (declare (type (or null vec) ,name) (ignorable ,name))
  -           ;; (declare (ignorable ,name))
              (with-elements ,(expand-vector-arg (list name type) slot-list)
                ,name
                ,@body))
           `(let ((,name ,init))
              (declare (type (or null ,type) ,name) (ignorable ,name))
  -           ;; (declare (ignorable ,name))
              ,@body))))
   
   (defmacro with-vectors ((&rest forms) &body body)
  
positive.code:   (make-array (length args) :element-type 'scalar
                :initial-contents (mapcar #'ensure-scalar args)))
  
  ;;;; ---------------------------------------------------------------------------
  ;;;; ** A square matrix type
  
  
negative.code:   (let ((len (length a)))
      (= (isqrt len) (sqrt len))))
  
  ;;; A square matrix with element type scalar
  (deftype mat (&optional dimension (element-type 'scalar))
    `(and (simple-array ,element-type (,(if (eq '* dimension)
                                            dimension
  