Naive implementation of Hamming distance for exercism.io

Hamming_naive.rb

class Hamming
  def self.compute(s1,s2)
    if s1.length != s2.length
      raise ArgumentError
    else
      index = 0
      count = 0
      while index < (s1.length)
        if s1[index] != s2[index]
          count += 1
        end
        index += 1
      end
      return count
    end
  end
end