Running Lenght Encoding problem: Given a string with repeated characters, return a string with the repeating characters and their frequency: e.g. aaabbc = a3b2c1

RunningLengthEncoding.scala

object RunningLengthEncoding {
  def encode(s:String):String = {
    def encSeq(s:String):String = s.head.toString+s.length
    if (s.isEmpty()) "" else {
	val (same,rest) = s.span(_==s(0));
	encSeq(same) ++ encode(rest)
    }
  }   
}