refinements cannot do recursion

gistfile1.rb

class Literal < Struct.new(:number)
  def show
    print number
  end
end

class Add < Struct.new(:a, :b)
  def show
    a.show
    print ' + '
    b.show
  end
end

module Evalution
  refine Literal do
    def eval
      number
    end
  end

  refine Add do
    def eval
      a.eval + b.eval
    end
  end
end

def run1
  using Evalution

  Add.new(Literal.new(3), Literal.new(4)).show
  puts
  p Add.new(Literal.new(3), Literal.new(4)).eval
end
run1

class Negate < Struct.new(:expression)
  def show
    print '- ('
    expression.show
    print ')'
  end
end

module NegativeEvaluation
  refine Negate do
    def eval
      - expression.eval
    end
  end
end

def run2
  using Evalution
  using NegativeEvaluation

  Add.new(Literal.new(5), Negate.new(Add.new(Literal.new(2), Literal.new(2)))).show
  puts
  p Add.new(Literal.new(5), Negate.new(Add.new(Literal.new(2), Literal.new(2)))).eval
end
run2

3 + 4
7
5 + - (2 + 2)
refinements.rb:24:in `eval': private method `eval' called for #<Negate:0x000000021009a8> (NoMethodError)
    from refinements.rb:60:in `run2'
    from refinements.rb:62:in `<main>'