用其他哈希值构造一个哈希值

ruby-1.9.2-p136 :001 > {:es => {:hello => \"You\" } }.deep_merge({:es => {:bye => \"Man\"}})
=> {:es=>{:hello=>\"You\", :bye=>\"Man\"}}

irb(main):001:0> h1 = {:es => {:hello => \"You\"}}
=> {:es=>{:hello=>\"You\"}}
irb(main):002:0> h2 = {:es => {:bye => \"Man\"}}
=> {:es=>{:bye=>\"Man\"}}
irb(main):003:0> h1.each_key {|x| h1[x].merge! h2[x]}
=> {:es=>{:bye=>\"Man\", :hello=>\"You\"}}

class Hash
  def inner_merge(other_hash)
    other_hash.inject(self) do |acc, (key, value)|
      if (acc_value = acc[key]) && acc_value.is_a?(Hash) && value.is_a?(Hash)
        acc.merge(key => acc_value.inner_merge(value))
      else
        acc.merge(key => value)
      end
    end       
  end
end

h1.inner_merge(h2) #=> {:es=>{:hello=>\"You\", :bye=>\"Man\"}}

dm = lambda {|l,r| l.merge(r) {|k,ov,nv| l[k] = ov.is_a?(Hash) ? dm[ov, nv || {}] : nv} }
dm[h1,h2]
#  => {:es=>{:hello=>\"You\", :bye=>\"Man\"}}