[ruby-core:50563] [ruby-trunk - Feature #6284] Add composition for procs

Issue #6284 has been updated by boris_stitnicky (Boris Stitnicky).


+1 to #*.
+1 to rosenfeld's first 2 paragraphs ( h = f ∘ g as h = f * g, and matrix multiplication analogy).
-1 to "<-". Rationale: It is too easy invent a guitar with one more string. Furthermore, when it comes to operators, I consider design by jury a weak approach.
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Feature #6284: Add composition for procs
https://bugs.ruby-lang.org/issues/6284#change-34401

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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