Functional Programming Principles in Scala. Week 04. Huffman Coding

Лаконичный подсчет частоты символов в scala 2.8
def freq(chars: List[Char]): List[(Char, Int)] = chars.groupBy(x => x).mapValues(_.length).toList
http://nikolajlindberg.blogspot.com/2010/02/counting-strings-and-things-in-scala-28.html