fun appendAll []      = []
  | appendAll (x::xs) = x @ (appendAll xs);

fun funPairs default []           _ = default
  | funPairs default ((u,v)::uvs) x =
    if u = x then
        v
    else
        funPairs default uvs x;

fun sumList []      = 0
  | sumList (x::xs) = x + (sumList xs);

fun gradeStatus gradePairs name =
  let
      val score = funPairs 0 gradePairs name; (* look up the grade *)
      val (names, grades) = ListPair.unzip gradePairs;
      val ave = (sumList grades) div (length grades);
  in
      if score > ave then "Above average" else "Below average"
  end;