Re: relations aren't types?
Date: Wed, 7 Jan 2004 22:47:37 -0500
Message-ID: <D6GdnUlrHo-dTmGiRVn-hw_at_golden.net>
"John Jacob" <jingleheimerschmitt_at_hotmail.com> wrote in message
news:72f08f6c.0401061034.73b7ba10_at_posting.google.com...
> > > How do I define a new ... type?
> >
> > Using the type definition productions of the language.
>
> You mean the scalar type generator.
Nope. I mean using the productions of the language. No generator is required because expressions involving no generic types or operations cannot generate any new types.
> > > Where
> > > is the ... type generator?
> >
> > Which type generator? There are several.
>
> Yep, and scalar is one of them.
No, sorry, but your assertion is simply incorrect. Specific declared types do not need generators. Generic types and generic operations define generators.
> > > Do we not need user-defined ...
> > > types?
> >
> > Yes, of course. I have never suggested we do not.
>
> Then we need a type generator that is different from the relation and
> tuple type generators.
We need all kinds of type generators, but user-defined types do not require any particular type generator, per se.
> > > If, as you suggest, scalar is not an important type category, then
> > > isn't it an unnecessary complication to include it in the data model?
> >
> > Yes, I suggest it is an unnecessary complication. I think the
proscription
> > against non-relvar global variables suffices without the scalar
verbiage.
>
> There *are* values that are not relation or tuple values. What should
> we call these kind of values? Hey, how bout scalar.
How about values? I think it absurd to consider array scalar and tuple non-scalar.
> > > So I'll ask you once again, What does a relational language that does
> > > not differentiate between scalar types and relation types look like?
> >
> > Like any relational language.
>
> Sort of like Tutorial D, with a scalar type generator.
Tutorial D creates an artifice in its grammar to account for the requirement that global variables must be relation variables. I suggest using "scalar" in the name of the production was a poor choice that only confuses issues. Received on Thu Jan 08 2004 - 04:47:37 CET