digest.rb

# Quick and dirty script to compare builtin methods between two rubyies
# Usage:
#
#   ruby_old digest.rb | ruby_new digest.rb

def class_signature(klass)
  Hash[
    {instance: klass, singleton: klass.singleton_class}.to_a
    .product([:private, :public, :protected])
    .map{ |(level, obj), access| ["#{access} #{level} methods", obj.send("#{access}_instance_methods", false)] }
  ] # Argh, when will Matz accept Enumerable#associate?
end

dict = Hash[
          ObjectSpace.each_object(Module)
          .select(&:name) # reject anonymous classes, not sure why there is one in 2.0.0     
          .map{|k| [k.name, class_signature(k)]}
        ] # I really hate Hash[]

class Hash
  def -(other) # dirty hack to recursively diff hashes, with arrays leaves
    Hash[
      map do |key, val|
        [key, other.has_key?(key) ? val - other[key] : 'all']
      end
    ] # Did I say how much we need a way to convert Enumerables to Hash?
    .reject{|_key, val| val.empty?}
  end
end

require 'yaml'
require 'pp'
if $stdin.tty?
  YAML.dump dict, $stdout
else
  other_dict = YAML.load($stdin)
  pp added:   dict - other_dict,
     removed: other_dict - dict
end