vector

type Iterator interface {
	// Elem returns the element at the current position.
	Elem() interface{}
	// HasElem returns whether the iterator is pointing to an element.
	HasElem() bool
	// Next moves the iterator to the next position.
	Next()
}

type Vector interface {
	// Len returns the length of the vector.
	Len() int
	// Index returns the i-th element of the vector, if it exists. The second
	// return value indicates whether the element exists.
	Index(i int) (interface{}, bool)
	// Assoc returns an almost identical Vector, with the i-th element
	// replaced. If the index is smaller than 0 or greater than the length of
	// the vector, it returns nil. If the index is equal to the size of the
	// vector, it is equivalent to Cons.
	Assoc(i int, val interface{}) Vector
	// Cons returns an almost identical Vector, with an additional element
	// appended to the end.
	Cons(val interface{}) Vector
	// Pop returns an almost identical Vector, with the last element removed. It
	// returns nil if the vector is already empty.
	Pop() Vector
	// SubVector returns a subvector containing the elements from i up to but
	// not including j.
	SubVector(i, j int) Vector
	// Iterator returns an iterator over the vector.
	Iterator() Iterator
}