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Re: exit-to-system

    Date: Tue, 15 Jul 86 12:03 EDT
    From: Daniel L. Weinreb <DLW@QUABBIN.SCRC.Symbolics.COM>
    I feel the same way about the BYE function.  Common Lisp would need a
    concept of "returning to the operating system" or something like that.
    Some implementations do not have any such thing.  It is out of the scope
    of Common Lisp.

    The only way I can imagine that such functions would be acceptable would
    be if their definition said something like "In some implementations,
    this function is allowed to do absolutely nothing".  They would
    therefore have to be considered part of a "user interface" rather than
    part of the language, since no portable program could sensibly call
    them.  I think we should try to confine ourselves to the language
    business.  We have more than enough work ahead of us in that department!

Well, we do have ED, which is clearly a user-interface thing.
Here is a stab at defining QUIT:

QUIT								[Function]

This function is intended to terminate the running Lisp system in some
appropriate manner.  In some implementations or under some circumstances
the Lisp system and all data contained within it may be destroyed, more
or less irretrievably, in which case the user might be left in
communication with the ``operating system'' or ``command shell,'' or
might be ``logged out.''  In other implementations or under other
circumstances this function might do nothing, in which case the call to
QUIT returns NIL (to indicate that the call ``failed'').

 /   \	  This was a serious attempt.  I happened to think that QUIT
|   / |	  is a reasonable thing to standardize, but I find it very
| :/) |	  difficult to come up with a definition that is portable
| /   |	  without seeming tongue-in-cheek.