On Tue, 21 Nov 2006, Paul Eggert wrote: > "Joel E. Denny" <[EMAIL PROTECTED]> writes: > > > I suspect that using [] in a grammar to mean optional is not nearly as > > common. > > It's pretty common, I'm afraid. It's in the ISO standard for EBNF, > for example. > > http://www.cl.cam.ac.uk/~mgk25/iso-ebnf.html > > Characters unused by ISO EBNF include .:!+_%@&#$<>/\^`~.
Ok, thanks. Nevertheless, surely it's not as common as () used for grouping. And it's still not clear to me what's wrong with "(...)?" instead of "[...]". > I sort of liked the notation a.b to denote the b component of a, as > it's a common notation in many languages. But I admit I haven't been > following this discussion too closely. Are you referring to this? exp.sum: exp.term1 '+' exp.term2
