Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ucbvax!MITCH.ENG.SUN.COM!wmb
From: wmb@MITCH.ENG.SUN.COM (Mitch Bradley)
Newsgroups: comp.lang.forth
Subject: Re: Re-inventing the wheel
Message-ID: <9102211533.AA22502@ucbvax.Berkeley.EDU>
Date: 21 Feb 91 00:20:47 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: Mitch Bradley <wmb%MITCH.ENG.SUN.COM@SCFVM.GSFC.NASA.GOV>
Organization: The Internet
Lines: 33

> I'm bothered a little by the rationale for the use of WORDSET in lieu
> of VOCABULARY; what I heard of of the reasons given for the change there
> simply didn't seem to be enough for my liking...

If the word VOCABULARY exists in the standard, then the upgrade path
for several important commercial implementations is made considerably
more difficult.  In particular, polyForth, LMI Forth, MacForth, and
MVP Forth all have the word VOCABULARY in different forms.  Any definition
of VOCABULARY that you choose will break at least 3 of those 4 systems.

This seems like a strong argument to me.  Those systems represent many
thousands of Forth programmers between them.

> Not to mention the forms of signed division (We now need the code for
> both forms in the dictionary instead of one- or so I understand it to
> be);

Remember, the code *doesn't have to be in the dictionary*.  It just has
to be available.  It could even be a paper listing that the user could
type in, defining, for instance, FM/MOD in terms of SM/MOD or UM/MOD .

> they both give incorrect answers in the third quadrant (both numbers
> negative...) the MOD part of /MOD for either algorithm is NEGATIVE when
> it should be positive (which is mathematically wrong...).

Is it?  Knuth Vol. 1, Page 38, says:

        if  y < 0 , then  0 >=  x mod y  >  y

Also see Robert Berkey's excellent discussion of division in the
proceedings of the 1982 FORML conference.

Mitch Bradley, wmb@Eng.Sun.COM