Function Composition

composition.rb

class Proc
  def +(other)
    ->(*a1, &b1) do
      ->(*a2, &b2) do
        inner = other.to_proc.call(*a1, &b1)
        outer = self         .call(inner, *a2, &b2)
      end
    end
  end
end

class Symbol
  def +(other)
    self.to_proc + other
  end
end

(:<< + :to_s + :- + :*).(20,5).(1).().(' bottles')
"99 bottles"