Re: Nested Relations / RVAs / NFNF

From: Kenneth Downs <>
Date: Wed, 27 Oct 2004 15:47:56 -0400
Message-ID: <>

Laconic2 wrote:

> "Marshall Spight" <> wrote in message
> news:17Rfd.316248$MQ5.24677_at_attbi_s52...

>> I note that in the type theory world, attention is paid to the

> appropriateness
>> of associated operations. For example, one might choose to have separate
>> *types* for metric units and for English units, and allow the type system
>> to either prevent invalid crossovers or convert for you. Also, you can do
>> things like have a separate numeric type for speed, distance, and time,
>> or even things like length, area, and volume. The type of the multipy
>> operation for (length, length) is area; for (length, area) is volume,
>> etc.

> I'm following this with interest, although it's kinda unfamiliar ground to
> me.
> So, could you have two distinct types that share a common domain? That
> is, they both have exactly the same
> possible values, with the same semantics, but they don't allow the same
> operations on them?

Wouldn't an overlap of allowed values be an artifact of the underlying storage type? If two types are both stored as int32 and have the range of -infinity to +infinity, they both share the same virtual domain and the same physical limited domain.

But methinks we'd be encouraged to think of that as a coincidence, and not to make much of it.

Kenneth Downs
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Received on Wed Oct 27 2004 - 21:47:56 CEST

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