Issue #16155 has been reported by connorshea (Connor Shea).
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Feature #16155: Add an Array#intersection method
https://bugs.ruby-lang.org/issues/16155
* Author: connorshea (Connor Shea)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
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`Array#union` and `Array#difference` were added in Ruby 2.6 ([see this bug](https://bugs.ruby-lang.org/issues/14097)), but an equivalent for `&` (intersection) was not.
I'd like to propose `Array#intersection`. This would essentially just be a more readable alias for `Array#&`, in the same way that `Array#|` and `Array#-` have `Array#union` and `Array#difference`.
I think it'd make sense for Ruby to have a more readable name for this method :)
Current syntax:
``` ruby
[ 1, 1, 3, 5 ] & [ 3, 2, 1 ] #=> [ 1, 3 ]
[ 'a', 'b', 'b', 'z' ] & [ 'a', 'b', 'c' ] #=> [ 'a', 'b' ]
```
What I'd like to see added:
```ruby
[ 1, 1, 3, 5 ].intersection([ 3, 2, 1 ]) #=> [ 1, 3 ]
[ 'a', 'b', 'b', 'z' ].intersection([ 'a', 'b', 'c' ]) #=> [ 'a', 'b' ]
```
mame asks about `intersection` [in this comment](https://bugs.ruby-lang.org/issues/14097#note-26) on the `union`/`difference` bug, but as far as I can tell it was never addressed.
[`Set#intersection`](http://ruby-doc.org/stdlib-2.6.2/libdoc/set/rdoc/Set.html#method-i-intersection) already exists and is an alias for `Set#&`, so there's precedent for such a method to exist.
Thanks for Ruby, I enjoy using it a lot! :)
Related links:
- [PR for `union`](https://github.com/ruby/ruby/pull/1747)
- [PR for `difference`](https://github.com/ruby/ruby/pull/1758)
- [Bug for adding `union` and `difference` methods](https://bugs.ruby-lang.org/issues/14097)
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