Repetition syntax

Hello,

I think the idea of introducing repetition[1] into Invisible XML has been well received, there just remains the tricky and somewhat subjective question of what syntax to use.

In retrospect, it’s a real shame that we used up single “{“ and “}” for comments. But we did, that’s water under the bridge.

I propose <a,b> and <<a,b>> (parallel to * and **, and + and ++). I think it’s nice to delimit the beginning and the end, so a pair of brackets seems suitable. We can’t use (), [], or {} because those already mean something else. And we can’t use “#” as a delimiter because of hex escapes[2].

I think a single character could work: /a,b/ and //a,b//, for example, but it doesn’t strike me as obviously better.

Liam proposed @(a,b) (and, I assume, @@(a,b)). I think that could work too.

Any more suggestions?

                                        Be seeing you,
                                          norm

[1] https://invisiblexml.org/pr/326/autodiff.html
[2] I mean, technically, I think we probably *could*. I don’t think it would be ambiguous in the grammar, but I think it would be a mistake to make "a"#3 and "a",#3 both be legal and mean very different things. It feels like an invitation to error.

--
Norm Tovey-Walsh
Saxonica

Received on Monday, 1 December 2025 16:14:06 UTC