"Functions of pointers" do seem an in-place equivalent for simple lenses. Pointers themselves less so - you can't compose pointers, and they take zero (when getting) or one (when setting) argument whereas a lens takes one or two.
Much like traditional getters and setters, lenses can offer more functionality though - for instance, an angle can be got and set in radians or degrees.
Yeah, that's interesting. I chose pointers because I was looking for a simple metaphor that imperative programmers would understand easily. If you ask random C programmer how to pass a single thing to a function such that you can both get and set it, pointers are the first thing that most of them will think of.
Much like traditional getters and setters, lenses can offer more functionality though - for instance, an angle can be got and set in radians or degrees.