Hash#map_values.rb

class Hash
  def map_values
    h = {}; self.each_pair { |k,v| h[k] = yield(v) }; h
  end
end

[ 'asdf', 'qwer' ].map{ |val| val * 2 }
  # => [ 'asdfasdf', 'qwerqwer' ]

{ :one => 'asdf', :two => 'qwer' }.map{ |val| val * 2 }
  # => [ [:one, 'asdfasdf'], [:two, 'qwerqwer'] ]

{ :one => 'asdf', :two => 'qwer' }.map_values{ |val| val * 2 }
  # => { :one => 'asdfasdf', :two => 'qwerqwer' }