words (RE: extensibility in XSchema?)
cowan at locke.ccil.org
Mon Jun 22 23:13:14 BST 1998
Peter Murray-Rust wrote:
> Now compare MIME:
> If I get sent a file of type image/gif I can:
> - determine that 'image/gif' is a MIME type
> - see if it is in the central IETF registry. If so I can read the formal
> definition, etc.
> - *and most important for me* I can associate the MIME type with a program
> through the mailcap file, *even if the MIME type is not registered*.
> This is all I am asking for, but there seems to be no way to do a similar
> thing for an XML element or attribute.
The trouble, IMHO, is not so much that an "elemcap" file couldn't
be created; it's what to put in it. MIME types describe fairly
large objects with little structure, except for the multipart/*
types, and their structure is just a list of objects with
MIME types, so simple recursion does it all. When you've got
down to the non-multipart level, you can reasonably run a program
on each resulting MIME object.
In XML documents, though, you can't reasonably run a program on
each element, unless the programs are very lightweight. That
seems to me to be what DS+L (I can't remember the number of S's)
is all about: associate a Scheme program with every element
according to a hierarchical rule, and then run that program
to interpret the element.
Unfortunately, people seem to have fallen into the "report-generator"
syndrome: the desire to do everything that's possible in a programming
language, using something that's simpler than a (Turing-complete)
programming language. Hard to do.
John Cowan http://www.ccil.org/~cowan cowan at ccil.org
You tollerday donsk? N. You tolkatiff scowegian? Nn.
You spigotty anglease? Nnn. You phonio saxo? Nnnn.
Clear all so! 'Tis a Jute.... (Finnegans Wake 16.5)
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