General question about Python design goals

[Rocco Moretti]

Fredrik Lundh wrote:
> Rocco Moretti wrote:
> 
>>>>I'm sure Antoon wouldn't object if lists were to be allowed as
>>>>dictionary keys, which would eliminate the multiple castings for
>>>>that situation. I wouldn't, either.
>>>
>>>so what algorithm do you suggest for the new dictionary im-
>>>plementation?
>>
>><devil's_advocate> One option is to create a new "frozen list" type, a`
>>la frozen sets.
> 
> doesn't frozenset make a copy?

As does the current "cast as tuple" technique. (I'm certainly not 
advocating it, but ...) Certain implementations of "frozen list" could 
possibly do the list->frozenlist conversion without a copy. (e.g. by 
flipping an "immutable" bit)

>     http://www.python.org/peps/pep-0351.html
> 
>     This PEP describes a simple protocol for requesting a frozen,
>     immutable copy of a mutable object. 

Perhaps Barry has been borrowing Guido's time machine?