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From: dwp@willett.pgh.pa.us (Doug Philips)
Newsgroups: comp.lang.forth
Subject: Re: Vocabularies
Message-ID: <1561.UUL1.3#5129@willett.pgh.pa.us>
Date: 20 Aug 90 01:53:07 GMT
References: <1219@acf5.NYU.EDU>
Organization: String, Scotch tape, and Paperclips.  (in Pgh, PA)
Lines: 49

In <1219@acf5.NYU.EDU>, sabbagh@acf5.NYU.EDU (sabbagh) writes:

> CREATE (and other words) can be easily refactored as "take next word from
> input stream then invoke $CREATE" which takes a string argument.  THis
> means that strings would have to be standardized. (Are you listening
> ANSI dudes?).

Agreed!  HERE!  HERE!  :-)
Does it have sufficient existing practice?  I suspect not.  :-( :-(

> I do not have any problems with the mixed-fixed nature of Forth; for those
> who are real purists, check out Postscript which is an entirely postfix
> language.  It uses the concept of anonymous code blocks delimited by {} then
> 
> 	{...(code)...} /foo def
> 
> would define a new word named foo.  This works too, but I like Forth better.

I would agree if the mixed-fixed parts of Forth were actually built from
accessible post-fix forms, as in your CREATE $CREATE example.  I don't think
I'd want to write code in the postscript style (i'm not sure of course, not
having tried it), but I would certainly like to be able to write code that
itself writes code, and that would be much easier with the $CREATE form.

> What are vocabularies?  They are lists of (key,value) pairs!  Why not
> define them abstractly, simply by having each vocabulary provide its own
> words for creation, deletion, listing and finding such pairs in its own
> internal structure?  Also, allow each vocabulary to decide what a number
> is.  Vocabularies could then be kept on a stack, and the inner interpreter
> would call the FIND word for each vocabulary in the stacked order, until
> one of them recognizes the word.  This is the most general solution to
> the vocabulary issue, especially since this would be transparent to the
> user, most of the time.  It also addresses the issue of what to do if
> you want to add new number types, literals, etc. to Forth.

Ok, but how does the inner-interpreter find the FIND words?  Perhaps they
must be the first word in the vocabulary?  (DEFER would be useful in that
case).  I think your earlier point about the history of Forth is relevant
here.  The ANSI "process" is not supposed to be a creative effort, its
supposed to be a consensus making effort.  I think your idea about
vocabularies, which is similar to other ideas I've seen, makes sense on
paper.  I think it would actually work in practice.  But that isn't good
enough for ANSI.  It has to have really been done.

-Doug

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