Joseph Wright writes:
 > > 
 > > if we accept that the current xparse is really xparse-2e (whether we call
 > > it that or not) then one consequence from this for me is that xparse-2e
 > > should offer the possibility to define commands with a syntax that fits
 > > current 2e.
 > 
 > Not quite sure I follow the paragraph!

sorry not very clear I agree. This remark was largely due to a
misunderstanding on my part from reading the current documentation For example

   \foo {[}bar]{baz}

shouldn't be interpreted as \foo[bar]{baz} (which it isn't, except in a
special extension).

So I guess current xparse does provide the right level of mimicking 2e syntax
(even if the optional arg magic is a slight deviation from current practice) -
in short ignore the remark


 > > I would expect that once we have a clearer picture of how to do the separation
 > > between layer -1 and layer 0 all this needs rewriting anyway
 > > 
 > > I also hope (and expect) that once we are clear on how to write specifications
 > > for layer 0 properly, that other interfaces for layer -1 will be written, both
 > > because more than one might be needed and because we need some trials to
 > > settle on what we want to promote as that standard layer -1 for latex3
 > 
 > As you probably realise, my overall feeling is that for many (most?) end
 > users, a LaTeX2e-like syntax will remain the best way to use LaTeX
 > whatever we deliver as LaTeX3. 

agreed, but that doesn't mean that it (the final standard syntax) is equal to 2e syntax

 > So xparse having a mainly LaTeX2e-like focus does not worry me too
 > much. I'd say that I think the underlying idea is a bit more flexible than
 > just forming LaTeX syntax (as we use abstract concepts such as "optional
 > argument" in preference to more concrete ones such as "argument delimited
 > by "[" ... "]").

it doesn't worry me at all, as far as my sentiments are going I'm not really
concerned about the precise layer -1 syntax at all at this stage - any will
do.  But I also see the need for experiments and a clean separation (which we
don't have yet) between layer -1 and layer 0 would make this easier.


This does not prohibit us to provide a stable version for now even if
imperfect. On the contrary, I agree that it is needed to allow using the more
interesting parts and I also agree that it looks like xparse is fitting that
bill.

On the other hand I would probably prefer the current state to be called
xparse-2e and run with that as stable. Then Bill, for example, could easily
build a matching xparse-gellmu and promote using this document level syntax
for accessing the other latex3 layers, etc. And we can leave the name xparse
for a more "final" interface version.

frank