Addressing questions one to three: one of the main applications for HLists is abstracting over arity. Arity is typically statically known at any given use site of an abstraction, but varies from site to site. Take this, from shapeless’s examples, def flatten[T <: Product, L <: HList](t : T) (implicit hl : HListerAux[T, L], flatten … Read more
This is my working solution using old-style macro annotations. import scala.language.experimental.macros import scala.reflect.macros.blackbox.Context import scala.annotation.StaticAnnotation class fieldable extends StaticAnnotation { def macroTransform(annottees: Any*): Any = macro fieldableMacro.impl } object fieldableMacro { def impl(c: Context)(annottees: c.Expr[Any]*): c.Tree = { import c.universe._ annottees.map(_.tree) match { case (param @ q”case class $className(..$fields)”) :: Nil => { val implicits … Read more