Re: [Texmacs-dev] Math codes

[Todd Wilson]

Henri Lesourd wrote:
> This is just a first guess : in texmath.syx, it seems that one defines
> the typesetting characteristics of a group of symbols by means of
> the 'Class' declaration, and then you use a 'Members' declarations
> to add new already existing symbols to the group defined by means
> of 'Class'.
>
> This being said, I don't know if one can change this by means of
> markup, like your '<as-class|...>'. Its rather likely that if the mechanism
> for dynamically extending the functionnality of .syx files is not
> documented, it doesn't exists (yet).

When TeXmacs displays a formula containing ":", it leaves no space to 
the left of ":" and a good deal of space to the right, which is what you 
would do in ordinary text, but not necessarily in math.  By contrast, 
TeX assigns to ":" the default category of "relation", so that is leaves 
the same amount of space on both sides of the symbol as it does for 
other relation symbols like "=" and "<".  And if I want to treat it as a 
binary operator (which still has a good deal of space on either side, 
but less than for a relation), I can prefix it with \mathbin; or if I 
want to treat it as an ordinary symbol (like a variable or a quantifier, 
which has no space around it), I can prefix it with \mathord, etc.

TeXmacs seems to make similar decisions about how to do spacing in math 
mode, so I'd just like to create a "hook" into these algorithms the way 
that TeX has.

> But in any case, one thing you can definitely do is to write macros
> to obtain exactly what you want (but as far as I understand, you
> rether meant using simple symbols and automatically recognizing
> them as being this one particular structurally equivalent markup
> depending on the context).

No, I wasn't looking for automatic decisions based on context, just 
something equivalent to what TeX does:  reasonable defaults for all 
symbols, plus a way to change the default on a per-use basis if necessary.

Anyway, as a workaround, how do I obtain exactly what I want?  Do I take 
a look at what TeXmacs produces and then add the right amount of 
positive or negative space before and after the symbol to compensate? 
Do I create the equivalent of an \hbox, in which the symbol appears as 
an ordinary text symbol with the right amount of space added?  Or what?

--Todd