Issue #16989 has been updated by marcandre (Marc-Andre Lafortune). matz (Yukihiro Matsumoto) wrote in #note-17: > I agree with some of your proposals (#16990, #16991, #16993, #16995). I want @knu to work on this. If I missed something, he will tell us. Thank you for reviewing these :-) > I strongly disagree with #16994. There's no evidence we need frozen sets of strings or symbols that much. Even if we do, I think frozen arrays should come first. Right, I agree that there is a larger discussion about frozen & static literals to be had. Would a non-frozen notation for Set of strings / symbols have a chance of being accepted? I would like to avoid `Set.new(%w[a list of words])` as can be currently seen in `RuboCop` or in Rails: https://github.com/rails/rails/blob/master/actionpack/lib/action_dispatch/http/cache.rb#L128 https://github.com/rails/rails/blob/master/actionpack/lib/action_dispatch/http/headers.rb#L25-L44 I think that many gems have simply not really taken care about `Sets`. For example, this file in `Bundler` defines a 40-element array constant, only to call `include?` on it... https://github.com/rubygems/rubygems/blob/master/bundler/lib/bundler/settings.rb#L9 I feel that a builtin way to write this might help. ---------------------------------------- Feature #16989: Sets: need https://bugs.ruby-lang.org/issues/16989#change-87434 * Author: marcandre (Marc-Andre Lafortune) * Status: Assigned * Priority: Normal * Assignee: knu (Akinori MUSHA) ---------------------------------------- I am opening a series of feature requests on `Set`, all of them based on this usecase. The main usecase I have in mind is my recent experience with `RuboCop`. I noticed a big number of frozen arrays being used only to later call `include?` on them. This is `O(n)` instead of `O(1)`. Trying to convert them to `Set`s causes major compatibility issues, as well as very frustrating situations and some cases that would make them much less efficient. Because of these incompatibilities, `RuboCop` is in the process of using a custom class based on `Array` with optimized `include?` and `===`. `RuboCop` runs multiple checks on Ruby code. Those checks are called cops. `RuboCop` performance is (IMO) pretty bad and some cops currently are in `O(n^2)` where n is the size of the code being inspected. Even given these extremely inefficient cops, optimizing the 100+ such arrays (most of which are quite small btw) gave a 5% speed boost. RuboCop PRs for reference: https://github.com/rubocop-hq/rubocop-ast/pull/29 https://github.com/rubocop-hq/rubocop/pull/8133 My experience tells me that there are many other opportunities to use `Set`s that are missed because `Set`s are not builtin, not known enough and have no shorthand notation. In this issue I'd like to concentrate the discussion on the following request: `Set`s should be core objects, in the same way that `Complex` were not and are now. Some of the upcoming feature requests would be easier (or only possible) to implement were `Set`s builtin. -- https://bugs.ruby-lang.org/ Unsubscribe: <mailto:ruby-core-request / ruby-lang.org?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>