(defmethod (setf foreign-struct-slot-value)
    (value ptr (slot aggregate-struct-slot))
  "Set the value of an aggregate SLOT to VALUE in PTR."
  (let* ((type (slot-type slot))
         (output-ptr (inc-pointer ptr (slot-offset slot)))
         (elt-size (foreign-type-size type)))
    (loop for i below (slot-count slot)
          for v in value
          do (setf (mem-ref output-ptr type (* i elt-size))
                   (translate-to-foreign v type)))))