Ch3, Ex5

declare SumList
fun {SumList L}
   fun {IterSumList X Y}
      case X of nil then Y
      [] Xs|L2 then {IterSumList L2 Y+Xs}
      end
   end
in
   {IterSumList L 0}
end
{Browse {SumList [2 3 4 5]}}