gistfile1.scala

def times(chars: List[Char]): List[(Char, Int)] = {
  def incr(pairs: List[(Char, Int)], C: Char): List[(Char, Int)] =
    pairs match {
      case Nil => List((C, 1))
      case (C, n) :: ps => (C, n+1) :: ps
      case p :: ps => p :: incr(ps, C)
    }
  (chars foldLeft List[(Char, Int)]())(incr)
}