Re: a proposal about compatibility

[HEDRICK at RUTGERS (Mngr DEC-20's/Dir LCSR Comp Facility)]

This is a response to a couple of requests to justify my comments.  Based
on one of these, I feel it necessary to say that nothing in this message
(nor in the previous one) should be taken to be sarcasm.  I am trying to
speak as directly as possible.  I find it odd when people take me as
being sarcastic when I start with the assumption that CL should be a
dialect of Lisp, and then give what I think is a fairly conservative
explanation of what I think that should mean.  However once I get into
the mode of looking for sarcasm, I see how easy it is to interpret
things that way.  Almost any of the statements I make below could be
taken as sarcasm.  It depends upon what expression you imagine being on
my face.  The rest of this message was typed with a deadpan expression.

I thought what I said was that if CL used a name in the set I mentioned,
that the use should be consistent with the old use.  I didn't say that
CL should in fact implement all of the old functions, although I would
not be opposed to such a suggestion.  But what I actually said was that
CL shouldn't use the old names to mean different things.

As for justification, consider the following points:
  - now and then we might like to transport code from one major family
	to another, i.e. not just Maclisp to CL, etc., but Interlisp to
	CL.  I realize this wouldn't be possible with code of some
	types, but I think at least some of our users do write what I
	would call "vanilla Lisp", i.e. Lisp that uses mostly common
	functions that they expect to be present in any Lisp system.  I
	admit that such transportation is not going to be easy under any
	circumstance and for that reason will not be all that common,
	but we should not make it more complicated than necessary.
  - I would like to be able to teach students Lisp, and then have them
	be able to use what they learned even if they end up using a
	different implementation.  Again, some reorientation is
	obviously going to be needed when they move to another
	implementation, but it would be nice not to have things that
	look like they ought to be the same, and aren't.  Further, it
	would be helpful for there to be enough similarity that we can
	continue to have textbooks describe Lisp.
  - I find myself having to deal with several dialects.  Of course I am
	probably a bit unusual, in that I am supporting users, rather
	than implementing systems.  Presumably most of the users will
	spend their time working on one system.  But I would like for
	the most common functions to do more or less the same thing in
	in all of these systems.
  - Now and then we write papers, journal articles, etc.  It would be
	helpful for these to be readable by people in other Lisp
	communities.
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