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On Thu, Dec 21, 2017 at 7:51 PM, Stephen J. Turnbull <turnbull.stephen.fw@u.tsukuba.ac.jp> wrote:

I understand the motivation to guarantee order, but it's a programmer
convenience that has nothing to do with the idea of mapping, and the
particular (insertion) order is very special and usually neither
relevant nor reproducible. I have no problem whatsoever with just
documenting any failure to preserve order while reproducing dicts,
\*except\* that a process that inserts keys in the same order had better
result in the same insertion order.

​json, pickle == png, i.e., guaranteed lossless.

repr, pprint == jpg, lossy for very specific motivating reasons.​

In particular, I use pprint output in regression baselines, and if the long documented sort-by-key behavior changed, I would not be happy.

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