What is Expressiveness in a Computer Language

[rossberg at ps.uni-sb.de]

Rob Thorpe wrote:
>
> But it differs from latently typed languages like python, perl or lisp.
>  In such a language there is no information about the type the variable
> stores.  The programmer cannot write code to test it, and so can't
> write functions that issue errors if given arguments of the wrong type.
>  The programmer must use his or her memory to substitute for that
> facility.  As far as I can see this is a significant distinction and
> warrants a further category for latently typed languages.

Take one of these languages. You have a variable that is supposed to
store functions from int to int. Can you test that a given function
meets this requirement?

You see, IMO the difference is marginal. From my point of view, the
fact that you can do such tests *in some very trivial cases* in the
languages you mention is an artefact, nothing fundamental.

- Andreas