What is Expressiveness in a Computer Language

[Anton van Straaten]

Chris Smith wrote:
> Dr.Ruud <rvtol+news at isolution.nl> wrote:
...
>>The 'dynamic type' is just another type.
> 
> 
> That's essentially equivalent to giving up.  I doubt many people would 
> be happy with the conclusion that dynamically typed languages are typed, 
> but have only one type which is appropriate for all possible operations.  

I'm not sure if this is what you're getting at, but what you've written 
is precisely the position that type theorists take.  Having "only one 
type which is appropriate for all possible operations" is exactly what 
the term "untyped" implies.

> That type system would not be implemented, since it's trivial and 
> behaves identically to the lack of a type system, and then we're back 
> where we started.

This is why I've suggested that "untyped" can be a misleading term, when 
applied to dynamically-typed languages.

Anton