Re: object algebra

"Marshall Spight" <mspight_at_dnai.com> wrote in message news:_M90c.144411$uV3.676780_at_attbi_s51...
> "Bob Badour" <bbadour_at_golden.net> wrote in message
news:JMydnSr4AKban9zd4p2dnA_at_golden.net...
> >
> > Since the type designer can implement the equality operation any way the
> > designer wants, why are the colors necessarily equal?
>
> Hmmm. Can the type designer really make equality anything he wants?
> That seems dangerous to me. Java has this mechanism, and it's error
> prone.

Yes, it is error prone and should only be done with the utmost care. However, I assume a type designer for a database has a certain level of competence.

> In a value-oriented world, where variables can only be assigned values
> and not other variables, I don't see the need for user-defined equality.

I do. How else can one properly model unknown? Or the equality of two polar coordinates at zero and 360 degrees? Received on Sun Feb 29 2004 - 05:26:05 CET