build.sc

import mill._, scalalib._

object example extends ScalaModule {
  def scalaVersion = "2.13.1"
  def ivyDeps = Agg[Dep](
    ivy"org.wvlet.airframe::airframe:20.2.0"
  )
}

error.log

❯ ./mill example.run
[27/37] example.compile
[info] Compiling 1 Scala source to /home/okuno/study/scala/airframe/out/example/compile/dest/classes ...
[error] /home/okuno/study/scala/airframe/example/src/Service.scala:6:17: illegal inheritance from sealed trait Adt
[error]   val adt = bind[Adt]
[error]                 ^
[error] one error found
1 targets failed
example.compile Compilation failed

Main.scala

package example

import wvlet.airframe._

sealed trait Adt
object Adt {
  object Foo extends Adt
  object Bar extends Adt
}

object Main extends App {
  val design = Design.newDesign.bind[Adt].toInstance(Adt.Foo)
  design.build[Adt](adt => println(adt))
}

Service.scala

package example

import wvlet.airframe._

// Does not compile
// trait Service {
//  val adt = bind[Adt]
//}

// ok
class Service (adt: Adt)