[ruby-core:76135] [Ruby trunk Feature#11653] Add to_proc on Hash

[Ruby-Lang@JoergWMittag.De]

Issue #11653 has been updated by Jörg W Mittag.


Daniel P. Clark wrote:
> Procs can be called the same way a hash is with `[]`.  But a Hash is not mappable as a Proc.
> 
> ~~~ruby
>     my_hash = ->key{{
>       a: 1, b: 2, c: 3, d: 4, e: 5, f: 6
>     }[key]}
> 
>     my_hash[:a]
>     # => 1
> 
>     [:e, :a, :b, :f, :c, :d].map(&my_hash) # hash is now mappable
>     # => [5, 1, 2, 6, 3, 4]
> ~~~
> 
> This seems so straight forward I believe it should be part of the language itself with the `.to_proc` method call.

This is basically a subset of what I proposed a year ago in #11262. I additionally proposed that `Hash` also implement `call`. IMO, it doesn't make much sense to have one without the other: both methods basically say "hey, I'm kinda like a function", and a `Hash` is basically just a function from keys to elements. I proposed the same thing for `Array` and `Set`, which are essentially also just functions from indices to elements (`Array`) or elements to booleans (`Set`). However, so far, there has been no interest in that ticket.

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Feature #11653: Add to_proc on Hash
https://bugs.ruby-lang.org/issues/11653#change-59340

* Author: Daniel P. Clark
* Status: Closed
* Priority: Normal
* Assignee: Nobuyoshi Nakada
----------------------------------------
Procs can be called the same way a hash is with `[]`.  But a Hash is not mappable as a Proc.

~~~ruby
    my_hash = ->key{{
      a: 1, b: 2, c: 3, d: 4, e: 5, f: 6
    }[key]}

    my_hash[:a]
    # => 1

    [:e, :a, :b, :f, :c, :d].map(&my_hash) # hash is now mappable
    # => [5, 1, 2, 6, 3, 4]
~~~

This seems so straight forward I believe it should be part of the language itself with the `.to_proc` method call.



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