Re: Scalars & atomic values & variables

"Bob Badour" <bbadour_at_golden.net> wrote in message <news:eICdnT6fXqHX2Gqi4p2dnA_at_golden.net>...

> "Adrian Kubala" <adrian_at_sixfingeredman.net> wrote in message
> news:slrnbvebrd.ta3.adrian_at_sixfingeredman.net...

> > The definition I proposed elsewhere (for types the values of which are
> > atomic), is that subtypes are non-atomic. What constitutes a subtype
> > depends on the type system, I guess. Using the "set of values and
> > associated functions" definition, my original guess is that A is a
> > subtype of B if its values and functions are supersets of those of B.
>
> Nope. A is a subtype of B if its values are a subset and its operations are
> a superset. A is a proper subtype of B if its values are a proper subset and
> its operations are a proper superset.

And then there's Liskov's notion of subtypes:

 URL:http://en2.wikipedia.org/wiki/Liskov_substitution_principle

Perhaps the notions of "subtype" and "derived type" should be distinct.

--
Joe Foster <mailto:jlfoster%40znet.com>  Sacrament R2-45 <http://www.xenu.net/>
WARNING: I cannot be held responsible for the above        They're   coming  to
because  my cats have  apparently  learned to type.        take me away, ha ha!