terminological obscurity

["Martin v. Löwis"]

Arthur wrote:
> Becasue I am not unwilling to see a list as an homogenous context. But
> by placing data within that context we have done nothing to change the
> nature of the data.  If the data was ambiguous, it is still ambiguous.
> 
> The purpose of the list is a perspective on the data. From that
> perspective we view an homogenous aspect of it. 
> 
> Does that do?

Almost. Except, in real life, it is vice versa: First, we have the
perspective, and then we decide to represent the data in a list.

> But if something about type is in the end at the bottom of your view,
> than  I am still a bit lost, I am afraid.

People use the word "type" to mean different things. I try to use it
in what I consider the most generic sense, the one that is also
defined in ISO Open Distributed Processing:

"A type is a predicate"

In that definition "is green" is as much a type as "has used Python
to write software". In that sense, things in a list should share the
same type.

Other people use "type" to mean "class", but, in ODP terminology,
a class is a template: it can be used to create objects. Those
objects all share the same type, namely "is an instance of the
class". So, while classes do imply types, two objects that are
not instances of the same class may still have a same type.

Regards,
Martin