What is Expressiveness in a Computer Language

[Torben Ægidius Mogensen]

"Rob Thorpe" <robert.thorpe at antenova.com> writes:

> Andreas Rossberg wrote:
>
> > No, variables are insignificant in this context. You can consider a
> > language without variables at all (such languages exist, and they can
> > even be Turing-complete) and still have evaluation, values, and a
> > non-trivial type system.
> 
> Hmm.  You're right, ML is no-where in my definition since it has no
> variables.

That's not true.  ML has variables in the mathematical sense of
variables -- symbols that can be associated with different values at
different times.  What it doesn't have is mutable variables (though it
can get the effect of those by having variables be immutable
references to mutable memory locations).

What Andreas was alluding to was presumably FP-style languages where
functions or relations are built by composing functions or relations
without ever naming values.

        Torben