When are immutable tuples *essential*? Why can't you just use lists *everywhere* instead?

[John Machin]

On Apr 21, 7:09 am, Luis M. González <luis... at gmail.com> wrote:
> On Apr 20, 3:28 pm, Bjoern Schliessmann <usenet-
>
> mail-0306.20.chr0n... at spamgourmet.com> wrote:
> > Luis M. González wrote:
> > > I don't remember exactly where I read about it, but Guido said
> > > once that tuples are being kept mainly for historical reasons.
>
> > Weren't tuples added when lists already existed?
>
> > Regards,
>
> > Björn
>
> > --
> > BOFH excuse #101:
>
> > Collapsed Backbone
>
> I tried googling for these comments, but I couldn't find them.
> Perhaps I never read them and it was just my imagination...
> Anyway, I suggest reading this chapter of "Dive into Python" for a
> good explanation of the differences between tuples and lists:http://diveintopython.org/native_data_types/tuples.html
>
> The article explains that, amongst other things, tuples are faster
> than lists, so if you are working with constant values (inmutables)
> they are more indicated than lists.
>

One inessential but very useful thing about tuples when you have a lot
of them is that they are allocated the minimum possible amount of
memory. OTOH lists are created with some slack so that appending etc
can avoid taking quadratic time.