Re: MAKE-LOAD-FORM can handle circularities [was Compilation implications]

[David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>]

    Date: Wed, 11 Jan 89 09:11:57 MST
    From: sandra%defun@cs.utah.edu (Sandra J Loosemore)

    Just to set the record straight:

    > Date: Tue, 10 Jan 89 19:03:49 PST
    > From: jrose@Sun.COM (John Rose)
    > 
    > File-level EQ preservation works to restore the embedded
    > object reference "for free".

    Unfortunately, we don't know yet if file-level EQ preservation works;
    see issue CONSTANT-CIRCULAR-COMPILATION.  KCL is one implementation
    where COMPILE-FILE/LOAD does not now preserve EQness of structures. 

If file-level EQ preservation is punted, MAKE-LOAD-FORM only returns one
value, and this whole discussion is punted.  So it doesn't actually
matter that we don't know yet (except that we might be wasting our
time).

Personally, I think file-level EQ preservation is important and would
hate to see it excluded from the language specification.

To throw a digression into the discussion, the only thing I know of
that's hard about file-level EQ preservation is EQness of CDRs in
implementations with cdr-coding of lists.  Even that's only "hard" in
the sense that it is difficult to convince implementors to do EQness
checking by treating each individual cons as a separate object, rather
than treating the whole list as a single object, because it seems (and
in fact is) less efficient.  Symbolics Genera 7.x gets this wrong.  What
about the TI Explorer?