Python from Wise Guy's Viewpoint

[Pascal Costanza]

Dirk Thierbach wrote:
> Pascal Costanza <costanza at web.de> wrote:
> 
>>No, other people are claiming that one should _always_ use static type 
>>sytems, and my claim is that there are situations in which a dynamic 
>>type system is better.
>>
>>If you claim that something (anything) is _always_ better, you better 
>>have a convincing argument that _always_ holds.
>>
>>I have never claimed that dynamic type systems are _always_ better.
> 
> To me, it certainly looked like you did in the beginning. Maybe your
> impression that other people say that one should always use static
> type systems is a similar misinterpretation? 

Please recheck my original response to the OP of this subthread. (How 
much more "in the beginning" can one go?)

> Anyway, formulations like "A has less expressive power than B" aresvery
> close to "B is always better than A". It's probably a good idea to
> avoid such formulations if this is not what you mean.

"less expressive power" means that there exist programs that work but 
that cannot be statically typechecked. These programs objectively exist. 
By definition, I cannot express them in a statically typed language.

On the other hand, you can clearly write programs in a dynamically typed 
language that can still be statically checked if one wants to do that. 
So the set of programs that can be expressed with a dynamically typed 
language is objectively larger than the set of programs that can be 
expressed with a statically typed language.

It's definitely a trade off - you take away some expressive power and 
you get some level of safety in return. Sometimes expressive power is 
more important than safety, and vice versa.

It's not my problem that you interpret some arbitrary other claim into 
this statement.

Pascal

-- 
Pascal Costanza               University of Bonn
mailto:costanza at web.de        Institute of Computer Science III
http://www.pascalcostanza.de  Römerstr. 164, D-53117 Bonn (Germany)