ghetto_edit_distance.rb

# TODO: Fix this to work with addition and deletion distances
def edit_distance(word_1, word_2)
  # transforms 'str' to ['s', 't', 'r']
  to_array = -> (word) { word.each_char.map{|c| c} }

  # xor(['s', 't', 'r'], ['s', 't', 'r']) = 0
  # xor(['s', 't', 'r'], ['a', 't', 'r']) = 1
  # xor(['s', 't', 'r'], ['a', 'b', 'c']) = 3
  substitution_distance = -> (top, bottom) { top.zip(bottom).map{|top_node, bottom_node| top_node == bottom_node ? 0 : 1 }.inject(:+) }

  word_1_array = to_array[word_1]
  word_2_array = to_array[word_2]

  substitution_distance[word_1_array, word_2_array]
end