Issue #16989 has been updated by hsbt (Hiroshi SHIBATA). Status changed from Assigned to Closed `Set` is promoted to Core class at Ruby 4.0. ---------------------------------------- Feature #16989: Sets: need ♥️ https://bugs.ruby-lang.org/issues/16989#change-115993 * Author: marcandre (Marc-Andre Lafortune) * Status: Closed * 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/