Conversion to ANSI Common Lisp via FUTURE-COMMON-LISP

[Hornig@RIVERSIDE.SCRC.Symbolics.COM (Charles Hornig)]

    Date: Mon, 10 Dec 1990 11:59 EST
    From: lgm@iexist.att.com

    I am about to convert our group's software to CLOS, and would like to
    convert to ANSI Common Lisp at the same time, at least to the extent of
    its implementation in FUTURE-COMMON-LISP in Genera 8.0.1.  That is, I
    would USE-PACKAGE both SCL and FUTURE-COMMON-LISP but prefer the latter
    in symbol conflicts.  Are people using FUTURE-COMMON-LISP extensively
    yet?  What pitfalls should I watch out for?  Offhand, the following seem
    to be the major points of caution:

...

	    DEFSTRUCT -- I assume that FUTURE-COMMON-LISP:DEFSTRUCT is
		    upward-compatible with LISP:DEFSTRUCT, including its
		    physical representation of structures.

Thew new DEFSTRUCT's physical representation is not compatible with the
old one if you do not specify the :TYPE argument.  The old one used an
array with the named structure bit set, the new one uses an instance.