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:         (satisfies square-matrix-p)))
  
  (setf (get 'mat 'element-type) 'scalar)
  
  (declaim (inline mat))
  (defun mat (&rest args)
    (if (square-matrix-p args)
        (apply #'vec args)
        (error 'simple-error
               :format-control "arglist must fit a square matrix
  and be of length (* dimension dimension)")))
  
  ;;;; ---------------------------------------------------------------------------
  ;;;; * Macro definitions
  