PathDependentSchoko.scala

trait Sys {
  type Global
}

object Settings {
  def apply(sys: Sys)(glob: sys.Global): Settings { type S = sys.type } =
    new Settings {
      type S                 = sys.type
      val system: S          = sys
      val global: sys.Global = glob
    }
}
trait Settings {
  type S <: Sys
  val system: S
  def global: system.Global
}

trait Foo[S <: Sys] { foo =>
  val system: S

  protected var global: system.Global
  
  def read(value: Settings { type S = foo.system.type }): Unit =
    global = value.global
}

trait Bar[S <: Sys] extends Foo[S] {
  val test = Settings(system)(???)
  read(test)
}