Re: RM and abstract syntax trees

On Nov 10, 7:29 am, "David Cressey" <cresse..._at_verizon.net> wrote:

> One of the fundamental properties of a pointer is that you can "dereference"
> it by using it as an address in an address space, in order to retrieve the
> thing pointed to directly. There is no corresponding property in
> sequentially generated arbitrary meaningless identifiers.

The mathematician in me axiomatizes the concept of pointer in terms of its abstract properties, which (ignoring null pointers) are

1. the existence of an associated address space, which is just a set of objects
2. a bijection between objects in the address space and pointer values In one direction this bijection is "address of" and in the other it is "dereference"
3. the ability to compare pointer values

This encompass physical address spaces, virtual address spaces, C++ smart pointers, persistent OIDs and pointer swizzling etc.

It also encompass node identifiers of an AST if we regard the DB as defining an address space of AST nodes, and an appropriate select query represents a dereference that logically binds to precisely one node of the AST.

My perspective conflicts with your statement above. Received on Fri Nov 09 2007 - 18:15:07 CST