How to recursively remove all keys with empty values from (YAML) hash?

Question

I have been trying to get rid of all hash keys in my YAML file that have empty (blank) values or empty hashes as values.

This earlier post helped me to get it almost

Answer 1

hash = {"x"=>{"m"=>{"n"=>{}}}, 'y' => 'content'}
clean = proc{ |k,v| !v.empty? ? Hash === v ? v.delete_if(&clean) : false : true }
hash.delete_if(&clean)
#=> {"y"=>"content"} 

or like @sawa suggested, you can use this proc

clean = proc{ |k,v| v.empty? or Hash === v && v.delete_if(&clean) }