anchor.diff:                       (unknown-coercion-object condition)
                        (unknown-coercion-type condition)))))
   
  -(defun coerce-vector-element-type (type)
  +(eval-when (:compile-toplevel :load-toplevel :execute)
  +(defun coerce-vector-element-type (type &optional environment)
     "Figure out the element type of the vector type TYPE."
     (cond
  -    ((or (subtypep type 'base-string)
  -         (subtypep type 'simple-base-string))
  +    ((or (subtypep type 'base-string environment)
  +         (subtypep type 'simple-base-string environment))
        'base-char)
  -    ((or (subtypep type 'string)
  -         (subtypep type 'simple-string))
  +    ((or (subtypep type 'string environment)
  +         (subtypep type 'simple-string environment))
        'character)
  -    ((or (subtypep type 'bit-vector)
  -         (subtypep type 'simple-bit-vector))
  +    ((or (subtypep type 'bit-vector environment)
  +         (subtypep type 'simple-bit-vector environment))
        'bit)
  -    (t (let* ((expanded-type (typeexpand type))
  +    (t (let* ((expanded-type (typeexpand type environment))
                 (element-type (cond ((and (consp expanded-type)
                                           (member (first expanded-type) '(array simple-array)))
                                      (parse-array-type expanded-type))
  -                                  ((subtypep expanded-type 'vector)
  +                                  ((subtypep expanded-type 'vector environment)
                                      ;; Some generic vector type?
                                      't)
                                     (t
  
positive.code:         ((subtypep result-type 'character)
           (character object))
          (t (error 'unknown-coercion :object object :type result-type))))
  
negative.code:          (map 'list 'identity object))
          ((subtypep result-type 'vector)
           (check-type object sequence)
           (let ((element-type (coerce-vector-element-type result-type nil)))
             (if element-type
                 (make-array (length object)
                             :element-type element-type
  