recursive subsets

gistfile1.rb

def recursive_subsets(array)
  return [] if array.empty?

  inner_array = array.first

  if array.length == 1
    return inner_array.map { |item| [item] }
  end

  results = []
  rest_subsets = recursive_subsets(array[1..-1])
  inner_array.each do |item|
    rest_subsets.each do |subset|
      results << [item] + subset
    end
  end

  results
end