Re: Do Data Models Need to built on a Mathematical Concept?

Paul Vernon wrote:

>>I tend to agree with Marshall here that there is still room for
>>an imperative component, both inside the implementations of the
>>datatypes and their operators and outside and around the relations.
>>
>>
>
>From what I understand of type theory, you would defiantly want to go the
>functional route for user defined type implementations.
>
>
>
>>This is what I understand is proposed in TTM (www.thethirdmanifesto.com)
>>and implemented in Dataphor by Alphora.
>>
>>
>
>Date & Darwen in The Third Manifesto (TTM) wrote:
> "do not infer from our assumptions of an imperative style that we discount
>the possibility of (e.g.) a "functional programming style" D at the time of
>writing, however, we have not investigated such a possibility in any depth"
>
OK, I am a bit out of my depth here, I have to admit. I don't know the difference between imperative
and procedural - I thought they were the same thing. I would be grateful for any clarification on this...

>>Of course the more we can keep in the relational realm the better,
>>but I believe there will always be parts of the application that
>>will have to be tackled imperatively.
>>
>>
>
>Show me a (useful) algorithm that cannot be performed in a relational algebra
>(hypothetically extended with 'features' from the FP world).
>Why have two languages if we can get away with one?
>
Well, any algorithm can be performed by a Turing machine, and I faintly remember seeing (and learning)
a proof that says that anything that can be expressed with a Turing machine can be expressed
with relations - however, there where some slight performance problems ;-). Does anybody remember
such a proof? It must have been from the early 70's.

regards,
Lauri Pietarinen Received on Mon Apr 28 2003 - 09:59:13 CEST