- From: Jeremy Carroll <jeremy@topquadrant.com>
- Date: Mon, 02 Nov 2009 23:39:15 -0800
- To: public-rdf-dawg-comments@w3.org
- CC: Holger Knublauch <holger@topquadrant.com>, Jeremy Carroll <jcarroll@topquadrant.com>
PS My example come from putting together the following thoughts ... A suggestion that what people don't like about LET is that it is 'procedural'. However single-assignment is declarative, and that perceiving LET as procedural is a failure of understanding. Ordering constraints can be declarative or procedural, LET introduces declarative ordering constraints. The ordering constraints appear because of the shape of the problem: for example if you compute an end date from a start date and a duration, you need to know the start date and the duration. Each LET declaratively but concisely introduces an ordering constraint. The alternative SELECT AS WHERE construct declaratively and verbosely introduces an ordering constraint. There is a natural ordering to do with the flow of information. This isn't necessarily the order of computation, but it is an order in which it is easier for the query author to think about the query. The LET syntax follows this natural ordering, the AS syntax does not.
Received on Tuesday, 3 November 2009 07:39:43 UTC