The underlying type of the tree. and update of immutable trees.
Tree node that is the current focus.
All children of the parent that are to the left of the focus node.
Everything required to rebuild all levels of the tree above this one. At the root level of a tree this array will be empty, when focused on any of the children of the root node it will hold a single level, and so on. The number of levels found is the depth of the zipper.
Parent node value of the focus node at the level we are encoding. All nodes have a parent except the root node.
All children of the parent that are to the right of the focus node.
A zipper encodes a location with a tree, allowing for efficient navigation