What is Expressiveness in a Computer Language

[Pascal Costanza]

Matthias Blume wrote:
> "Rob Thorpe" <robert.thorpe at antenova.com> writes:
> 
>> I don't think dynamic typing is that nebulous.  I remember this being
>> discussed elsewhere some time ago, I'll post the same reply I did then
>> ..
>>
>>
>> A language is statically typed if a variable has a property - called
>> it's type - attached to it, and given it's type it can only represent
>> values defined by a certain class.
> 
> By this definition, all languages are statically typed (by making that
> "certain class" the set of all values).  Moreover, this "definition",
> when read the way you probably wanted it to be read, requires some
> considerable stretch to accommodate existing static type systems such
> as F_\omega.
> 
> Perhaps better: A language is statically typed if its definition
> includes (or ever better: is based on) a static type system, i.e., a
> static semantics with typing judgments derivable by typing rules.
> Usually typing judgmets associate program phrases ("expressions") with
> types given a typing environment.

How does your definition exclude the trivial type system in which the 
only typing judgment states that every expression is acceptable?


Pascal

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