Composing with Procs

proc_compose.rb

class Proc
  class << self
    def compose *others
      others.map(&:to_proc).inject :*
    end
  end

  def * other
    proc { |*args| other.call self.call *args }
  end
end

doubled = ->(n) { n + n }
squared = ->(n) { n * n }

doubled_then_squared = doubled * squared
squared_then_doubled = squared * doubled

doubled_then_squared[5]
#=> 100
squared_then_doubled[5]
#=> 50

do_some_stuff_then_print = Proc.compose doubled_then_squared,
                                        :next,
                                        squared_then_doubled,
                                        method(:puts)
do_some_stuff_then_print[5]
#>> 20402
#=> nil