From: "alexeymuranov (Alexey Muranov)" <redmine@...>
Date: 2012-12-05T20:23:06+09:00
Subject: [ruby-core:50569] [ruby-trunk - Feature #6284] Add composition for procs


Issue #6284 has been updated by alexeymuranov (Alexey Muranov).


rits (First Last) wrote:
> proc composition is not commutative, so the operator should:
> 
> 1. not imply commutativity

In algebra, multiplication is rarely commutative, see for example http://en.wikipedia.org/wiki/Quaternion


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Feature #6284: Add composition for procs
https://bugs.ruby-lang.org/issues/6284#change-34408

Author: pabloh (Pablo Herrero)
Status: Feedback
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: next minor


=begin
It would be nice to be able to compose procs like functions in functional programming languages:

    to_camel = :capitalize.to_proc
    add_header = ->val {"Title: " + val}

    format_as_title = add_header << to_camel << :strip

instead of:

    format_as_title = lambda {|val| "Title: " + val.strip.capitalize }


It's pretty easy to implement in pure ruby:

  class Proc
    def << block
      proc { |*args| self.call( block.to_proc.call(*args) ) }
    end
  end
=end


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