From: "trans (Thomas Sawyer)" <transfire@...>
Date: 2012-06-16T07:25:18+09:00
Subject: [ruby-core:45670] [ruby-trunk - Feature #6594] Integrated Functor


Issue #6594 has been updated by trans (Thomas Sawyer).


@resenfeld Well, I thought the examples I provided were pretty good ones. The links I provided also give some examples, though one has to mentally convert their implementations. If you'd like some others:

  $ grep -R "Functor" facets/lib
  lib/core/facets/symbol/as_s.rb:    Functor.new do |op, *a|
  lib/core/facets/enumerator/fx.rb:    Functor.new(&method(:fx_send).to_proc)
  lib/core/facets/hash/recursively.rb:    Functor.new do |op, &yld|
  lib/core/facets/hash/data.rb:    Functor.new do |op, *a|
  lib/core/facets/kernel/not.rb:    Functor.new(&method(:not_send).to_proc)
  lib/core/facets/kernel/eigen.rb:    Functor.new do |op,*a,&b|
  lib/core/facets/kernel/ergo.rb:    @_ergo ||= Functor.new{ nil }
  lib/core/facets/kernel/try.rb:      Functor.new{ nil }
  lib/core/facets/kernel/respond.rb:      Functor.new(&method(:respond).to_proc)
  lib/core/facets/enumerable/ewise.rb:    Functor.new do |op,*args|
  lib/core/facets/enumerable/per.rb:      Functor.new do |enumr_method, *enumr_args|
  lib/core/facets/enumerable/per.rb:        Functor.new do |op, *args, &blk|
  lib/core/facets/enumerable/per.rb:        Functor.new do |enumr_method, *enumr_args|
  lib/core/facets/enumerable/per.rb:          Functor.new do |op, *args, &blk|
  lib/core/facets/enumerable/accumulate.rb:    Functor.new do |op, *args|
  lib/core/facets/enumerable/accumulate.rb:    Functor.new do |op, *args|
  lib/core/facets/string/file.rb:    Functor.new(&method(:file_send).to_proc)
  lib/core/facets/module/method_space.rb:      Functor.new do |op, *args|

And there would be more, but in some cases I opted against it b/c of the efficiency issue mentioned or b/c I created a specialized Functor class instead --mainly to keep support for 1.8.6- b/c Procs couldn't take blocks as arguments before.

----------------------------------------
Feature #6594: Integrated Functor
https://bugs.ruby-lang.org/issues/6594#change-27270

Author: trans (Thomas Sawyer)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 2.0.0


=begin
I know the developers meeting is coming up so I'd like to get a few ideas I've had sitting in the wings out in the air before then.

One the more useful is the idea of integrating Functors directly into the language. "Functor" is the term I use for "higher-order function".

I blogged about this idea and you can read it here: http://trans.github.com/2011-09-07-ruby-heart-higher-order-functions/

The super short version is this:

  def f => op, arg
    arg.send(__op__, arg)
  end

  f + 3  #=> 6
  f * 3  #=> 9

Another example:

  class String
    def file => op, *args
      File.send(__op__, self, *args)
    end
  end

  "README.rdoc".file.mtime  #=> 2012-06-14 12:34:45 -0400

I'm using `=>` as means of indicating a higher-order function. Of course another syntax could be used if this won't fly. The important thing is the idea of higher-order functions being integrated directly into the language. Doing this without that integration requires the creation of an intermediate object for each call which is very inefficient.
=end



-- 
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