list of proposed changes to Common Lisp

[Rob MacLachlan <RAM@>]

    Date: Monday, 16 December 1985  12:34-EST
    From: Guy Steele <gls at THINK-AQUINAS.ARPA>
    Re:   list of proposed changes to Common Lisp

    Presumably COPY-PERSON, when applied to an ASTRONAUT, returns
    something that is a PERSON but not an ASTRONAUT; that is, it makes a
    copy of just the PERSON part of an ASTRONAUT?

Well, so maybe it's not so clear-cut.  I thought the obvious
interpretation was that COPY-PERSON was the same thing as
COPY-ASTRONAUT when applied to an astronaut.  It now seems we have
three possible interpretations:
 1] It is illegal to use a copier for an included structure on an
    instance of the including structure.
 2] The copier for the included structure returns an object of the
    same type as the included structure, containing only the included
    slots.
 3] The copier for the included structure also copies instances of any
    structure which include it.
If there are three modedately reasonable interpretations, is even more
important to specify which applies.  One thing worth considering is
how well the interpretation fits into possible object-oriented
programming systems such as Common Loops.

  Rob