Definitely more lens than zipper. If you think of a lens, in simple form, as a path into a structure then a zipper is a structure plus a path into itself. This

Definitely more lens than zipper. If you think of a lens, in simple form, as a path into a structure then a zipper is a structure plus a path into itself. This constrains the form that a zipper can take. If you examine these paths on their own then you get into general "optics" which is where the lens type lives and where specter lives (it seems). In particular, we start talking about generalized folds and traversals.