Zipper fundamentals • Purely functional data structure • Think of it as a breacrumb or a zipper, that remember every direction you took from the root but starting from where you are, like an inverted glove
loc, node and root A loc (location) point to the current node along with the context (up, left and right) think: « like a pointer » to a particular node in the tree (node loc) returns the node at the loc (root loc) returns the root node (and not the loc!)