all permutations of a list in ruby

node_permutations_ruby.rb

def permutations(list)
  return [list] if list.size == 1

  result = []
  list.each do |locked|
    list_copy = list.dup
    list_copy.delete locked
    permutations(list_copy).each do |permutation|
      result << permutation.insert(0, locked)
    end
  end
  result # this implicitly returns result.  Initially I forgot to add it in and got weird results until I realized this was missing
end

if __FILE__ == $0
  p permutations %w[a b c] # %w is ruby shorthand for an array of strings, this example creates the array: ['a', 'b', 'c']
  p permutations %w[d e f g]
end