What is Expressiveness in a Computer Language

[David Hopwood]

Chris F Clark wrote:
> Chris Smith <cdsmith at twu.net> writes: 
>  
>>Unfortunately, I have to again reject this idea.  There is no such
>>restriction on type theory.  Rather, the word type is defined by type
>>theorists to mean the things that they talk about. 
> 
> Do you reject that there could be something more general than what a 
> type theorist discusses?  Or do you reject calling such things a type?
>  
> Let you write: 
> 
>>because we could say that anything that checks types is a type system,
>>and then worry about verifying that it's a sound type system without
>>worrying about whether it's a subset of the perfect type system. 
> 
> I'm particularly interested if something unsound (and perhaps 
> ambiguous) could be called a type system.

Yes, but not a useful one. The situation is the same as with unsound
formal systems; they still satisfy the definition of a formal system.

-- 
David Hopwood <david.nospam.hopwood at blueyonder.co.uk>