Help understanding the decisions *behind* python?

[Hendrik van Rooyen]

On Wednesday 22 July 2009 16:36:51 Inky 788 wrote:
> On Jul 22, 2:36 am, Hendrik van Rooyen <hend... at microcorp.co.za>
>
> wrote:

> > The good reason is the immutability, which lets you use
> > a tuple as a dict key.  
>
> Thanks for the reply Hendrik (and Steven (other reply)). Perhaps I'm
> just not sophisticated enough, but I've never wanted to use a list/
> tuple as a dict key. This sounds like obscure usage, and a bit
> contrived as a reason for having *both* lists and tuples.

Steven showed why you cannot have a mutable thing
as a key in a dict.

if you think it is contrived, then please consider how you would 
keep track of say the colour of a pixel on a screen at position
(x,y) - this is about the simplest "natural" tuple format and
example.

There are other equally valid examples, as has been pointed
out.  (may have been in another thread - am a bit confused
about that right now)

- Hendrik