Python from Wise Guy's Viewpoint

[Pascal Costanza]

Dirk Thierbach wrote:
> Andreas Rossberg <rossberg at ps.uni-sb.de> wrote:
> 
>>Pascal Costanza wrote:
> 
> 
>>Anyway, you are right of course that any type system will take away some 
>>expressive power (particularly the power to express bogus programs :-) 
>>but also some sane ones, which is a debatable trade-off).
> 
> 
> Yep. It turns out that you take away lots of bogus programs, and the
> sane programs that are taken away are in most cases at least questionable
> (they will be mostly of the sort: There is a type error in some execution
> branch, but this branch will never be reached)

No. Maybe you believe me when I quote Ralf Hinze, one of the designers 
of Haskell:

"However, type systems are always conservative: they must necessarily 
reject programs that behave well at run time."

found at 
http://web.comlab.ox.ac.uk/oucl/research/areas/ap/ssgp/slides/hinze.pdf

Could you _please_ just accept that statement? That's all I am asking for!


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)