Schematron and rule of least power (was Re: [xml-dev] 2007 Predictions)

[Rick Jelliffe <rjelliffe@allette.com.au>]

noah_mendelsohn@us.ibm.com wrote:
> A key point is that information captured in declarative form is typically
> much easier to extract and repurpose than information encoded 
> procedurally.  
>   
..
> These points are all made somewhat more carefully in the recent TAG 
> finding titled: "The Rule of Least Power"[1]. 
>   
Off-topic, but Schematron fits in pretty exactly with the Rule of Least 
Power, at least
if it is understood to be related to Tim Bray's "The Minimum to Declare 
Victory" and the Agile/Extreme "YAGNI" principle.

It comes down to habit of thought. If you made a constraint language for 
the web, what would you do?:

1) Invent the perfect language, allowing all sorts of edge cases and 
computer-theoretical completeness, with your own syntax and higher-order 
logic.  (I think this is the XLinkIt approach.)

2) Refuse to re-invent any wheels: look at XSLT stylesheets made for the 
purpose of validating, then abstract out all the XSLT-specific 
machinery, so that what was left was as declarative as possible. And if 
this means that only low-order logic is used, or there are some 
constraints that cannot be expressed, that is OK.

Cheers
Rick Jelliffe