Re: [xacml] Bags of structured type

[Seth Proctor <Seth.Proctor@Sun.COM>]

On Fri, 2004-03-05 at 10:57, Polar Humenn wrote:
> I think you can replace "primitive type(s)"  with "datatype(s)" in that
> paragraph. The notion of "primitive" is kind of vague anyway, since you
> can introduce new 'primitive' types, which are data types.

Right. The "primitive type" description is just saying "not a bag or
set." Or, as Polar aptly puts it, any types that are representable. For
a clear explination of this, look at the last paragraph of A.5. Structed
types are certainly allowed in bags.

> Unfortunately our Bag function(s) are defined for only primitive types.
> So, when you introduce a new data type, you must introduce all functions
> that deal with it, such as any "*-set"  operations, or any other
> "primitive" functions dealing with the types.

I don't see how we could do better here. We can only define the type-*
function identifiers for the known, standard types. Then you have to
hope that the system you use provides the right functionality. In my
code, for example, the type-* functions are specifically designed so
it's trivial to get them to support any new datatypes you define.

The alternative would be to redefine the type-* functions without the
type qualifier, so there is only a single is-in (for example) function
that operates over all types. This has benefits and drawbacks that we
discussed at length before 1.0 came out (this focused around the map
function, I think).


seth