gistfile1.txt

//this should be builtin in 2.8
def groupBy[T](list: List[T], eq: (T,T) => Boolean ): List[List[T]] = list match {
  case Nil   => Nil
  case x::xs => {
    val (ys:List[T],zs:List[T]) = xs.span(eq(_,x));
    (x::ys)::groupBy(zs, eq) 
    }
}

def compress3[T](list: List[T]): List[T] =
  groupBy(list,_==_).map(_.head)
println(compress3(List('a','a','a','a','b','c','c','a','a','d','e','e','e','e')))