Help understanding the decisions *behind* python?

Duncan Booth duncan.booth at invalid.invalid
Mon Jul 20 21:54:02 CEST 2009

Phillip B Oldham <phillip.oldham at> wrote:

> On Jul 20, 6:08 pm, Duncan Booth < at invalid.invalid> wrote:
>> The main reason why you need both lists and tuples is that because a
>> tuple of immutable objects is itself immutable you can use it as a
>> dictionary key.
> Really? That sounds interesting, although I can't think of any real-
> world cases where you'd use something like that.

How about a multi-dimensional sparse array?

>>> d = {}
>>> d[1,2] = 'a'
>>> d[5,7] = 'b'

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