Re: more on BOGUS-FIXNUMS

[Jeff Dalton <jeff%aiai.edinburgh.ac.uk@NSS.Cs.Ucl.AC.UK>]

> From: sandra <(Sandra J Loosemore)sandra%cdr@edu.utah.cs>
> Date: Fri, 22 Jul 88 10:56:40 MDT

> I think this is probably just a misunderstanding of terminology --
> what Stan Shebs described to me as being "fixnums" are clearly not the
> same beasties that you call "fixnums".  

Yes, but the advantage of my position is that the beasties I call
"fixnums" are the same beasties Franz, MacLisp, and most CL's call
"fixnums".  (So there.)

> I could play devil's advocate here and point out that the confusion
> over terminology tends to support my argument for getting rid of the
> name "fixnum" from the language entirely;

No, it supports clarification of the terminology, not its elimination.

> when an implementation has several different classes of numbers,
> which one(s) do you call "fixnum"?

The ones that are like "ints" (or maybe "longs"): that is, the ones
that are like machine integers (modulo type tags).  Of course, we
already know an implementation might pick a losing implementation of
fixnums, but there are lots of ways a CL can lose and still be CL.

> In PSL and its derivatives, for example, the class of
> numbers which are called "inums" (represented as immediate data) are
> more "fixnum"ish than the class of numbers called "fixnums"!

Actually (looking at PSL documentation), I suppose either could be
called fixnums if PSL were a Common Lisp; but PSL's "fixnums" are
closer to what I mean by "fixnums", espectially where inums are 19 bit
and fixnums are 36 (DEC-20).

What I want from fixnums is that proper declarations will get me
compiled code not much less efficient than for other languages on
the same machine, and using numbers with similar range.  (I'm willing
to allow type information and for fixnums to be immediate.)

Perhaps we should add somethng to CL for integers are are represented
immediately.  In some implementations, this would be the same set as
fixnums, but would not have to be.

BTW, my "real" address is below.

Cheers,
Jeff

Jeff Dalton,                      JANET: J.Dalton@uk.ac.ed             
AI Applications Institute,        ARPA:  J.Dalton%uk.ac.ed@nss.cs.ucl.ac.uk
Edinburgh University.             UUCP:  ...!ukc!ed.ac.uk!J.Dalton