What is Expressiveness in a Computer Language

Chris Smith cdsmith at twu.net
Sun Jun 25 20:39:52 CEST 2006

Andrew McDonagh <news at andmc.com> wrote:
> I haven't read all of this thread, I wonder, is the problem to do with 
> Class being mistaken for Type? (which is usually the issue)

Hi Andrew!

Not much of this thread has to do with object oriented languages... so 
the word "class" would be a little out of place.  However, it is true 
that the word "type" is being used in the dynamically typed sense to 
include classes from class-based OO languages (at least those that 
include run-time type features), as well as similar concepts in other 
languages.  Some of us are asking for, and attempting to find, a formal 
definition to justify this concept, and are so far not finding it.  
Others are saying that the definition is somehow implicitly 
psychological in nature, and therefore not amenable to formal 
definition... which others (including myself) find rather unacceptable.

I started out insisting that "type" be used with its correct formal 
definition, but I'm convinced that was a mistake.  Asking someone to 
change their entire terminology is unlikely to succeed.  I'm now 
focusing on just trying to represent the correct formal definition of 
types in the first place, and make it clear when one or the other 
meaning is being used.

Hopefully, that's a fair summary of the thread to date.

Chris Smith - Lead Software Developer / Technical Trainer
MindIQ Corporation

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