Naturally

This is just an experiment to generate and deploy the monocle Lenses associated to a case class as implicit values, using shapeless instead of macros.

Consider the following hierarchy of nested case classes as an example:

case class City(population: Int, name: String, university: University)
case class University(name: String, math: Department)
case class Department(budget: Int)

We could use Shapelens to generate monocle's Lenses for each field. For instance, we could generate the lens that points at the name field of a City as follows:

import monocle.Lens
val nameLn: Lens[City, String] = Shapelens[City, 'name :: HNil]

(*) The current encodings use Witness.`'name`.T instead of 'name, so we need to provide ad hoc aliases to make the invocation readable.

As you can see, beyond the involved case class, we need to provide the context where we expect to find the field. Thereby, if we were interested in pointing at a nested field we'd need to reflect it in the path:

val univBudgetLn = Shapelens[University, 'math :: 'budget :: HNil]

We find the context useful to disambiguate lenses that share the same type. For instance, there are two possible lenses with type Lens[City, String]: the one that points at the city name and the one that points at the university name of a city. We use the context path (instead of using the field type) to be precise about which field we are interested in:

val cityNameLn = Shapelens[City, 'name :: HNil]
val univNameLn = Shapelens[City, 'university :: 'name :: HNil]

You can find the whole example here.

Finally, we must say that we are exploiting this idea to provide automatic instances of state-based algebraic theories in the upcoming new version of Stateless. However, we find this technique general enough to publish it on its own. Having said so, we hope you find a crazy scenario where you can apply it!

(*) As @julien-truffaut pointed out, you can use GenLens[City](_.university.name) to get the same behaviour in Monocle. Anyway, the Shapelens type class is still useful when you require implicit lens evidences in scope.