The feedback on a code bug at /goldilocks/GoldilocksSecondarySort.scala

[SnailDove]

where does the val list head :: rest appear from in the following function ?

def groupSorted[K,S,V]( it : Iterator[((K, S), V)] ) : Iterator[(K, List[(S, V)])] = {
        val res = List[ (K, ArrayBuffer[(S, V)]) ]()
        it.foldLeft(res)(
            (list, next) => list match {
                case Nil => val ((firstKey, secondKey), value) = next
                            List((firstKey, ArrayBuffer((secondKey, value))))
                case head :: rest => 
                       val (curKey, valueBuf) = head
                       val ((firstKey, secondKey), value) = next
                       if (!firstKey.equals(curKey) ) {
                            (firstKey, ArrayBuffer((secondKey, value))) :: list
          	        } else {
                            valueBuf.append((secondKey, value))
                            list
                        }
      	    }
        ).map { case (key, buf) => (key, buf.toList) }.iterator
  }