Scala challenge #1

compression.scala

// Solution to Pere's first Scala challenge 
// by Dejan
object Compression {
  
  // Drops element ++el++ and all its consecutive appearances in head of the list ++li++
  def chop(li: List[Any], el: Any) = {
    li dropWhile (_ == el) 
  }

  // Eliminates consecutive duplicates of list elements 
  // If a list contains repeated elements they should be replaced with a single copy of the element. 
  // The order of the elements should not be changed.
  def compress(li: List[Any]): List[Any] = li match { 
    case Nil => li
    case _   => List(li.head) ++ compress(chop(li, li.head)) 
  }

  def main(args: Array[String]) {
    val li = List('a', 'a', 'a', 'a', 'b', 'c', 'c', 'a', 'a', 'd', 'e', 'e', 'e', 'e')
    println(compress(li)) // List(a, b, c, a, d, e) 
  }

}