Hah, I never have time to blog any more. :-(

However you can just link to the mailman archives if you want to reference it.

On Sat, Dec 19, 2015 at 12:16 AM, Ben Finney <ben+python@benfinney.id.au> wrote:
Guido van Rossum <guido@python.org> writes:

> The link between hashing and immutability is because objects whose
> hash would change are common, e.g. lists, and using them as dict keys
> would be very hard to debug for users most likely to make this
> mistake. […]
>
> […] But the real question here isn't "why aren't all things hashable"
> but "why can't you put mutable values into a set". […]
>
> Hashing comes into play because all of Python's common data structures
> use hashing to optimize lookup -- but if we used a different data
> structure, e.g. something based on sorting the keys, we'd still have
> the mutability problem. And we'd have worse problems, because values
> would have to be sortable, which is a stricter condition than being
> immutable.
>
> In any case, you can't solve this problem by making all values hashable.

That was a great explanation; you answered several points on which I was
vague, and you addressed some things I didn't even know were problems.

I'd love to see that edited to a blog post we can reference in a single
article, if you have the time.

--
 \         “I went to the museum where they had all the heads and arms |
  `\      from the statues that are in all the other museums.” —Steven |
_o__)                                                           Wright |
Ben Finney

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--
--Guido van Rossum (python.org/~guido)