anchor.diff:                        (dotimes (n this-dim retv)
                           (setf (aref retv n)
                                 (frob m rest-dim 
  -                                    ;; FIXME: much consing
  -                                    (append upper-offsets
  -                                            (list n)))))))
  +                                    (* upper-offset n))))))
                      (t 
                       (let ((retv
                              (make-array this-dim
  
positive.code: 
  ;; (compute-array-vector* #3A(((1 2 3 4) (4 3 2 1)) ((4 3 2 1) (1 2 3 4))))
  ;; => #(#(#(1 2 3 4) #(4 3 2 1)) #(#(4 3 2 1) #(1 2 3 4)))
  
  (defun row (m i)
    (declare (type array-dimension-designator i)
  
negative.code:   (declare (type array m)
             (values (simple-array * (*))))
    (let ((dims (array-dimensions m)))
      (labels ((frob (m dims &optional (upper-offset 1))
                 (let ((this-dim (car dims))
                       (rest-dim (cdr dims)))
                   (cond 
  