Comment by rossant
17 hours ago
If I'm not mistaken, CPython's dict preserved insertion order as an implementation detail at first, but because too many users came to rely on it, it was made part of the language specification starting in Python 3.7.
17 hours ago
If I'm not mistaken, CPython's dict preserved insertion order as an implementation detail at first, but because too many users came to rely on it, it was made part of the language specification starting in Python 3.7.
I don't think that's quite right. CPython dicts only started preserving insertion order in 3.6. There were concerns that other Python implementations might not be able to do this or it would be a performance bottleneck, but by Python 3.7 these were satisfied enough to make it part of the spec.