- A commonly used built-in class is a
**vector**of items. - A
**vector**is an array that can dynamically expand or contract. - Items can be inserted within the vector.
- Vector elements can be indexed, using the square bracket notation in the prior section.
- A vector class instance is prepared by normal class construction and initialization.
- The following is an example:
`v = ^^ vector( 'a', 'b', 'c' )`

- The above method of constructing a vector is somewhat ungainly for such a common programming task.
- Consequently, roo!™ supports a shorter alternative that uses curly braces:
v = { 'a', 'b', 'c' }

- Methods can be applied after the right curly brace:
say { 'a', 'b', 'c' } ~ toString

- Vectors can be arbitrarily nested:
vectorOfvectors = { 'a', 'b', { 'x', 'y', 'z' } }

- A vector of vectors can be composed:
vectorOfvectors = { { 'a', 'b', 'c' }, { 'x', 'y', 'z' } }

- An empty vector can be prepared:
e = { }