🚀 go-pugleaf

In <KERS.91May10092912@cdollin.hpl.hp.com> kers@hplb.hpl.hp.com (Chris Dollin) writes:

>Clearly if the new definition does not ascribe the same type as the old one,
>the inconsistency must be resolved some way; for example, the definition could
>be disallowed (yuk) or a new variable could be created (and the old one
>assigned a value such as "\x. error 'obsolete function called", and maybe all
>using functions tagged as obsolete).

Disallowing the definition is obviously not a good idea. Discarding the old 
binding is better, but static scoping (like ML does) improves on this, by not 
binding the old definition to "\x. error", but hiding it.

>Clearly redefining "sin" (Nico's later example) would be a Bad Thing. This just
>means that we need some way of annotating those names no longer available for
>redefinition - no big deal.

But sometimes I really want to redefine a definition. One of the features
of teX (which supports dynamic scoping through macro substitution) which
drives me crazy is that I sometimes cannot define a command by
\newcommand{\name}{body}
because it already exists --- it is annotated as "no longer available for
definition".
I then have to use \renewcommand{\name}{body}
but that is potentially dangerous. 
Suppose I am a novice LaTeX user, writing a paper on scoping in ML, and I
want to define a command \let for typesetting programs which use 
let ... = ... in ... ;
LaTeX complains when the I say \newcommand{\let}{...}.
Now I know much about ML (remember this is only an example!) but little 
about TeX (he I don't even know about the difference between TeX/LaTeX).
I therefore say \renewcommand{\let}{...}, with disastrous results.
The problem is that TeX uses its own \let, which I don't need, and that I
want to use my own \let, and I don't want to give it another name.
Marking the old \let is just as bad as \renewcommand-ing it.
The only solution here really is static scoping!

There is a discussion about scoping in TeX on comp.text.tex at the moment.
If only TeX would scope like ML...
-- 
Nico Verwer                                       | nico@cs.ruu.nl
Dept. of Computer Science, University of Utrecht  | phone: +31 30 533921
p.o. box 80.089, 3508 TB Utrecht, The Netherlands | fax:   +31 30 513791