From: andrew@...
Date: 2014-10-08T07:11:09+00:00
Subject: [ruby-core:65513] [ruby-trunk - Feature #7793] New methods on Hash

Issue #7793 has been updated by Andrew Vit.


> the block for these methods should take a hash rather than an array.

Do you mean the input should be a single argument with a hash? I don't think that is very consistent for `|k, v|` expansion.

> That should make more sense since the return value is a hash.

Everything inside the block is a tuple; what type the input/output are transformed from/to happens outside the block. IMHO the array makes more sense than the hash inside the block.

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Feature #7793: New methods on Hash
https://bugs.ruby-lang.org/issues/7793#change-49288

* Author: Dominic Sisneros
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* Category: core
* Target version: next minor
----------------------------------------
It would be nice to have the following methods added to hash

~~~ruby
h = { name: 'dominic', request: 'add the following methods', :why => 'convenience'}

h.map_v{|v| v.upcase}
#=> {:name=>"DOMINIC", :request=>"ADD THE FOLLOWING METHODS", :why=>"CONVENIENCE"}

h.map_k{|k| k.to_s}
#=> { "name"=> 'dominic', "request"=>"add the following methods', "why" => "convenience"}

h.map_kv{|k,v| [k.to_s, v.upcase]}
#=> { "name"=>"DOMINIC", "request"=>"ADD THE FOLLOWING METHODS", "why"=>"CONVENIENCE"}


class Hash

  def map_v
    reduce({}) do |result, array|
      k,v = array
      new_val = yield v
      result.merge( k => new_val)
    end
  end

  def map_k
    reduce({}) do |result, array|
      k,v = array
      new_k = yield k
      result.merge(new_k => v)
    end
  end

  def map_kv
    reduce({}) do |result, array|
      new_k,new_v = yield array
      result.merge(new_k => new_v)
    end
  end

end




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