Lists

• Type: List[T]

• Construction:

  val fruit = List("apple", "banana", "orange")
  val nums = 1 :: 2 :: Nil
  

• Decomposition

  val apple = fruit.head
  

  • The most useful functions: nums.head, nums.tail, nums.isEmpty
  • nums.length
  • nums.last, nums.init: the opposite of nums.head, nums.tail
  • nums.take(n): get first n nodes
  • nums.drop(n): get the rest after drop the first n nodes.
  • nums(i): get the i^th node. It equals to nums.apply(i)

• Creating a new list

  • xs ::: ys or xs ++ ys: concat 2 lists, and return a new one
  • xs.reverse: return a reversed xs
  • xs.update(i, x): update the i^th node by x, and return a new one

• Finding a node

  • xs.indexOf(x): return the index of x in xs. -1 if not found.
  • xs.contains(x): Same as xs.indexOf(x) >= 0