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It seems people dont realize that you can have your cake and eat it too. You can have both orderered and unordered maps in the same language: https://yaml.org/

It seems people dont realize that you can have your cake and eat it too. You can have both orderered and unordered maps in the same language: https://yaml.org/type/map https://yaml.org/type/map https://yaml.org/type/omap https://yaml.org/type/omap No reason to argue about which one to make "dict". In fact it would be better to have both because youre taking a performance hit (a significant one) by ordering the entries.

lvh 7y ago
The new dict does not come with a performance hit, let alone a significant one. It’s much more memory efficient and generally slightly faster.
- svnpenn 7y ago
  pretty strong evidence to the contrary https://apps.dtic.mil/dtic/tr/fulltext/u2/a627127.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/a627127.pdf do you have any references to back your claim that its actually faster?
  - joshuamorton 7y ago
    https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html https://morepypy.blogspot.com/2015/01/faster-more-memory-eff... The new python dict implementation is benchmarked as faster in both microbenchmarks and in practice for almost all real-world workloads. Note that this isn't a sorted map, like C++'s "Ordered Map", but an Ordered map. C++ get's the name wrong. Items aren't ordered by key comparison, but ordered by insertion time.
    - svnpenn 7y ago
      Good link, thanks
masklinn 7y ago
Python has had both ordered and unordered maps in the same languages for 10 years or so (OrderedDict was added to the stdlib in 2009). In 2016, the standard dict was moved to a new and more efficient implementation (more compact & faster to iterate). It was naturally ordered, and so as a side-effect of this change and since the CPython devs did not explicitly scramble it, iteration on dicts became both deterministic and specific (it would always follow insertion order). This was considered both a boon because conserving iteration order is strictly more useful than not doing it and a woe because it would cause compatibility issues with third-party implementations or further changes down the line as users would absolutely start relying on the iteration order even if it was still considered unspecified. So in the next major release they decided to resolve the issue by making this behaviour part of the language. It restricts future design space, but they can always add an unordered dict as part of the stdlib if that ever truly becomes useful so meh.

lvh 7y ago

The new dict does not come with a performance hit, let alone a significant one. It’s much more memory efficient and generally slightly faster.

svnpenn 7y ago
pretty strong evidence to the contrary https://apps.dtic.mil/dtic/tr/fulltext/u2/a627127.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/a627127.pdf do you have any references to back your claim that its actually faster?
- joshuamorton 7y ago
  https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html https://morepypy.blogspot.com/2015/01/faster-more-memory-eff... The new python dict implementation is benchmarked as faster in both microbenchmarks and in practice for almost all real-world workloads. Note that this isn't a sorted map, like C++'s "Ordered Map", but an Ordered map. C++ get's the name wrong. Items aren't ordered by key comparison, but ordered by insertion time.
  - svnpenn 7y ago
    Good link, thanks

masklinn 7y ago

Python has had both ordered and unordered maps in the same languages for 10 years or so (OrderedDict was added to the stdlib in 2009). In 2016, the standard dict was moved to a new and more efficient implementation (more compact & faster to iterate). It was naturally ordered, and so as a side-effect of this change and since the CPython devs did not explicitly scramble it, iteration on dicts became both deterministic and specific (it would always follow insertion order). This was considered both a boon because conserving iteration order is strictly more useful than not doing it and a woe because it would cause compatibility issues with third-party implementations or further changes down the line as users would absolutely start relying on the iteration order even if it was still considered unspecified. So in the next major release they decided to resolve the issue by making this behaviour part of the language. It restricts future design space, but they can always add an unordered dict as part of the stdlib if that ever truly becomes useful so meh.