Shapeless - get a field's name in a type-safe way

shapeless-fieldname.scala

import shapeless._
import shapeless.ops.record.Keys
import shapeless.ops.hlist.Selector
import shapeless.tag._

/**
  * Gets the name of a case class's field, in a type-safe way.
  * If the class does not have a field with the given name, the program won't compile.
  *
  * Kinda similar to C#'s `nameof` operator, but not bolted onto the language
  * https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/nameof
  *
  * @example
  *
  * {{{
  *   > import shapeless.Witness
  *
  *   > case class C(a: Int)
  *
  *   > getFieldName[C, Witness.`"a"`.T].get
  *   res0: String = "a"
  *
  *   > getFieldName[C, Witness.`"b"`.T].get
  *   error: could not find implicit (...)
  * }}}
  *
  * Using Typelevel's scala compiler (https://typelevel.org/scala/)
  *
  * {{{
  *   > getFieldName[C, "a"].get
  *   res0: String = "a"
  * }}}
  */
  def getFieldName[A, F]: GetFieldName[A, F] = new GetFieldName

  class GetFieldName[A, F] {
    def get[L <: HList, KeyList <: HList](implicit
                                          // we need to be able to convert our case class `A` to a labelled hlist `L`
                                          ev: LabelledGeneric.Aux[A, L],
                                          // we grab the keys of the labelled `L`, into an hlist `KeyList`
                                          ev2: Keys.Aux[L, KeyList],
                                          // from the key list, we select the first field with a name matching `F`
                                          ev3: Selector[KeyList, Symbol with Tagged[F]]
                                         ): String = {
      val keys: KeyList = Keys[ev.Repr].apply()

      keys.select[Symbol with Tagged[F]].name
    }
  }