An indexed sequence of elements of the same type.

This is a primitive interface that any finite integer-indexable sequence can implement. It is intended for data structures where access by index is the most efficient way to access the data.

abstract class Sequence<T> {
  /**
   * The limit of valid indices of the sequence.
   *
   * The length getter should be efficient.
   */
  int get length;

  /**
   * Returns the value at the given [index].
   *
   * Valid indices must be in the range [:0..length - 1:].
   * The lookup operator should be efficient.
   */
  T operator[](int index);
}