[olavk]

S-expressions are nice but not superior to XML for all use cases. S-expression syntax are optimized for lists of names and numbers. XML-syntax is optimized for structured documents. Since XML is used just as much for data as for documents these days, s-expressions would perhaps be just as good as XML for a common data exchange meta format. But that train left the station a decade ago.

I suspect a reason XML catched on and s-expressions didn't (outside of the Lisp-niche) is that XML tackled difficult internationalization issues like different encodings and character sets head on.

[anamax]

And strings, I forgot strings. (For some reason, XML folk often confuse strings with sequences of atoms. They also confuse numbers and numerals.)

And numbers in different bases.

S-expressions predate unicode. However, unicode support was added in. It's not that big a deal.

[anamax]

> S-expression syntax are optimized for lists of names and numbers.

Nope. Structs, tables, vectors, and arrays all work just fine.

And there's also support for dags and circular structures.