The very rough idea is that vlists are lists of arrays whose size decreases exponentially towards the tail of the list. So "hello, world" could be stored as

The very rough idea is that vlists are lists of arrays whose size decreases exponentially towards the tail of the list. So "hello, world" could be stored as "hello" -> ", wo" -> "rl" -> "d" with space for 3 more characters to be consed in front of "hello".