- From: Dave Peterson <davep@iit.edu>
- Date: Tue, 8 Jul 2008 22:02:14 -0400
- To: Michael Kay <mike@saxonica.com>, paul@sparrow-hawk.org, "'Alan Ruttenberg'" <alanruttenberg@gmail.com>
- Cc: "'Rob Shearer'" <rob.shearer@comlab.ox.ac.uk>, public-webont-comments@w3.org, public-owl-wg@w3.org, www-xml-schema-comments@w3.org
At 7:54 PM +0100 2008-07-08, Michael Kay wrote: >(b) it claims the existence of a "principle that if a string >maps to a given value in a particular type then it should map to the same >value >in all supertypes". I don't see that principle as being in any way >fundamental, and I certainly don't see it as "fundamental to subtyping in >programming languages". It's also violated within XML Schema itself - " xx " >as an instance of xs:token maps to a different value from " xx " as an >xs:string. Not so. ' xx ' is not in the lexical space of token. The literal that is considered for lexical space membership is the one that is obtained by whitespace processing. Whether this is good or bad is a matter of opinion, I suppose. But that's the way whitespace works. (Took me a few years to really internalize this, myself.) Whether the primciples themselves are good is a matter of opinion. But I hope we don't change things from one version of the spec to the next without serious thought. (E.g., there was serious thought given to the decision to allow equality to differ from identity, to have two zeros in float and double, and to retain timezone information in the date/time datatypes.) -- Dave Peterson SGMLWorks! davep@iit.edu
Received on Wednesday, 9 July 2008 02:59:12 UTC