Re: GNU eqn clarifications and reforms (was: EQN - special words)

[Damian McGuckin]

Hi Richard,

On Fri, 9 Jun 2023, Richard Morse wrote:

> > On Jun 9, 2023, at 5:01 AM, Damian McGuckin <damianm@esi.com.au> wrote:
> >
> > On Fri, 9 Jun 2023, G. Branden Robinson wrote:
> >
> > > > How should I define 'thing' before I start talking about it?
> > >
> > > My solution (of recent vintage) in eqn(1) has been to leave our CS
> > > brains exposed and use the word "token".
> >
> > The original User Guide has no CS brains within earshot so I was hoping to 
> > avoid that word.
>
> - element
> - part (of the equation)
> - symbol

Thanks for your input. Always good to get feedback.

Hopefully my brain is still working at this late hour.

The words I have

        thing, entity, item or element, ..... or ..... (hmmm) token

because

        symbol  has a very specific meaning to eqn/troff
                - they are single character mathematical and unicode symbols
                - multiple character symbols like times and +-
                - troff special symbols like \(mo - element of
                - groff special symbols like \[fa] - for all
                - unicode specifial symbols
        term    is again probably multiple things, e.g. 'a sub 2'
        part    is probably multiple things, ditto

and keyword is obviously any one of the 'eqn' keywords.

By the way, Branden's is the most technically correct.

But the big question is, even with 'token' ... what is the definition of 
element, entity, thing, or token, a tight one.

As far as I see it, EQN input is made of things where a thing is one of

        mathematical or troff or eqn symbol
        mathematical punctuation
        delimiter, these being space, '~', '^', '{', '}', or newline
        a character surrounded by punctuation or delimiters
        - with/without users errors
        a word surrounded by punctuation or delimiters
        - with/without users errors
        EQN keywords (which are special words???)

That is way too long winded!! I want something tight.

Also remember that

        left {
        right }

removes the special meaning from the braces, i.e. as a way to group 
multiple things into what can then be treated as a single thing. In
that context, those braces are also then no longer delimiters.

Thanks - Damian