object ListUtil
{
  def dedupe(elements:List[String]):List[String] = {
    if (elements.isEmpty)
      elements
    else
      elements.head :: dedupe(for (x <- elements.tail if x != elements.head) yield x)
  }
}

// example usage:
ListUtil.dedupe(List("one", "two", "one")).foreach(println)

http://abel-perez.com

Recursively remove duplicate elements from a List

Scala - Remove duplicates from List

Scala