From: non.dmitriy@...
Date: 2019-11-12T19:05:29+00:00
Subject: [ruby-core:95820] [Ruby master Feature#16341] Proposal: Set#to_proc

Issue #16341 has been updated by Nondv (Dmitry Non).


Speaking of hashes, they could implement implicit proc conversion as well:

```ruby
class Hash
  def to_proc
    ->(key) { self[key] }
  end
end

dogs = ['Lucky', 'Trimp', 'Lady']
favourite_food = { 'Lucky' => 'salmon', 'Trimp' => 'pasta', 'Lady' => 'pasta' }

food_to_order = dogs.map(&favourite_food)
```


----------------------------------------
Feature #16341: Proposal: Set#to_proc
https://bugs.ruby-lang.org/issues/16341#change-82647

* Author: Nondv (Dmitry Non)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
``` ruby
class Set
  def to_proc
    -> (x) { include?(x) } # or method(:include?).to_proc
  end
end
```

Usage:

```ruby
require 'set'

banned_numbers = Set[0, 5, 7, 9]
(1..10).reject(&banned_numbers) # ===> [1, 2, 3, 4, 6, 8, 10]
```



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