Sets: officially ordered
Officially, set elements have uncertain order. This predades when Hash started being ordered (Ruby 1.9.0, Xmas 2007). Sets have since been de-facto insertion-ordered. FYI, in those 13 years, there have been about 70 commits to
I have the impression that a non-negligible amount of code in the wild rely on sets being ordered, at least under most circumstances. I feel that this should be officialized.
If sets are truly unordered, then why do we hesitate to make an optimization of
See also: https://bugs.ruby-lang.org/issues/14069
Updated by Eregon (Benoit Daloze) about 1 year ago
+1 from me. Hash if officially ordered.
Making Set unordered would likely break many things.
In practice I would think many Set usages already assume it ordered.
Similar to what I said in https://bugs.ruby-lang.org/issues/15281#note-9
Having unordered elements does not feel Ruby-like, it introduces non-determinism in things as simple as
If super high performance is wanted and being unordered helps, then using a separate class or external gem for that makes sense I think.