(defclass r-vector-sfp (generic-vector)
  ()
  (:default-initargs
   :segment-width 4
   :element-type 'single-float
   :initial-element 0.0)
  (:documentation "Vector with single-float elements"))

(defmethod initialize-instance :after ((vector r-vector-sfp) &key)
  (setf (slot-value vector 'segments)
	(map-into (make-array (number-of-segments vector))
		  (lambda () (make-array (segment-width vector)
					 :element-type (element-type vector)
					 :initial-element (initial-element vector))))))
;;;

(defmethod (setf vref-seg) ((value single-float) (vector r-vector-sfp) &optional indexes)
  (declare
   (type (element-type vector) value)