This tarversal focuses on a field which may not be present. So the to-list function on an ix tarversal produces a vector with at most one element.

Constructs a traversal from a traverse function. A traverse function expects an applicative and a function which takes a value and produces another value in the given applicative. The result returned by the traverse function again should be in the applicative.

Standard tree tarversal. The function disassemble should turn the tree into a list of nodes and subrees and reassemble should be able to put it back preserving the shape of th tree without touching the contents of the tree

This is the standard traversal structure on vectors.