terminological obscurity

["Martin v. Löwis"]

Arthur wrote:
> Donn. who I think we agree, brought some light to this discussion did
> state clearly, I think, that the use of the "homogenous data" (in
> describing for example  None and a module) is bad and misleading
> terminolgy.  Perhaps, because it supports too well a supposition that
> we are only talking in tautologies. What can be said be homogenous
> about such data, outside of the membership in a list?

It is obvious that a single piece of data, in itself, cannot be
homogenous. You have to pick a set of objects to determine whether
they are homogenous. However, they are NOT homogenous by the mere
fact that they are in set, and they are NOT homogenous by the fact
that they share all the same type. Instead, they share the same
semantical properties (whatever those are).

So: No, "homogenous data" is *NOT* a tautology. It refers to
inherent properties of the elements of the list, not to the
fact that they are members of the list. It is possible to create
a heterogenous list; the Python style suggests that you should
not do that.

If "lists are for homogenous data" was a tautology, the term
"heterogenous lists" would be a contradiction. However, it is
not: it is a meaningful term indeed.

> Yet you insist, with a fresh start on all this, on using the
> terminology "homogenous data".
> 
> I don't understand Martin any better thatn I understand Guido.

I don't see where I use the term in any new way in which
it hasn't been used before.

I *also* mentioned that Guido has talked about typing, and
explained how a list of differently-typed objects may still
get a single static type. However, static typing of lists
and homogenous lists (i.e. lists of homogenous data) are
different (although related) issues.

Regards,
Martin