Re: no names allowed, we serve types only

From: Tegiri Nenashi <>
Date: Sun, 21 Feb 2010 11:33:19 -0800 (PST)
Message-ID: <>

On Feb 21, 3:05 am, Jan Hidders <> wrote:
> On 20 feb, 03:40, David BL <> wrote:
> ... E.g. a relation has an attribute
> > containing circles and you must allow it to be addressed using either
> > circle or ellipse.
> Indeed. But the header would contain only Ellipse, and all subtypes,
> including Circle, would be implied. ...

Ellipse-Circle example is unconvincing. Both are conic sections and it is natural to suggest that the design would greatly benefit from introducing a single class instead of many. The only objection is that certain methods being constrained to subtypes (such as Circle) might greatly benefit in performance. However, this is rarely a concern in practice with so called "object-oriented design" methodology, where not much thought is put into creating a wealth of new classes.

The situation is mirrored for physical units. Here in the US the debate is still imperial vs. metric, where "more educated" crowd points out that metric is certainly superior because scientists are using it. Which scientists? It is as early as at physics undergraduate level that one learns that SI is not used in physics anymore and a system with 3 basic units (cm-gm-sec) is certainly superior. Later on, on theoretical physics level, this system is dumped in favor of dimensionless units where all fundamental constants are set equal to 1.

Therefore, both types and units are seems to be artifacts of our limited perspective. As soon as we get better knowledge we get rid of them.

Math is different story. Types were created as a vehicle to avoid certain paradoxes. A typical view of somebody working in applied sciences is that borrowing a tool designed to avoid some obscure theoretical constructions is ridiculous. To cite E.T.Jaynes, Appendix B Formalities and Mathematical Style who quotes Henri Poincare (1909):

""In the old days when people invented a new function they had some useful purpose in mind: now they invent them deliberately just to invalidate our ancestors' reasoning, and that is all they are ever going to get out of them."

Indeed, this fad of artificially contrived mathematical pathology seems nearly to have run its course, and for just the reason that Poincare foresaw; nothing useful can be done with it."

A similar situation happened in mathematical foundation area where a wealth of paradoxes were created, and, unlike analysis, these pathologies were instrumental for axiomatizing set theory. It is remarkable that a construction, which was created in such peculiar circumstances, is one of the most profound ideas in CS. Received on Sun Feb 21 2010 - 20:33:19 CET

Original text of this message