Why functional Python matters

[Paul Wallich]

In article <3E9F1FE8.5030409 at removethis.free.fr>,
 laotseu <bdesth at removethis.free.fr> wrote:

> Florian Weimer wrote:

>  > In the strictest sense, the language has to be purely
>  > applicative (or free of side effects).  Common Lisp satisfies the
>  > first definition, but not the second.
> 
> Do you mean that it is *absolutely not possible* to write a whole 
> program in CL whithout any side effect ? Or that many features in the 
> language, that you can choose to use or not, are not side effect free ?

It's the second. In a strictest-sense functional language, it is 
impossible to write a whole program that *does* have side effects. 
This leads to the usual amusements such as passing the universe to a 
function that then returns a similar-but-not-identical universe with one 
property differing...

paul