gistfile1.scala

trait ConfigComponent {
  type Config
  def config: Config
}

trait MySQLStorageComponent extends StorageComponent with ConfigComponent {
  type Config <: MySQLConfig

  override def storeUser(user: User) { ... }
  override def retrieveUser(id: Int): Option[User] = ...

  case class User(id: Int, hash:Vector[Byte]) extends UserLike

  trait MySQLConfig {
    def mysqlHost: String
    def mysqlPort: Int
  }
}

trait GravatarComponent extends StorageComponent {
  type Config <: GravatarConfig

  def avatarURL(user: User): String = { ... }

  trait GravatarConfig {
    def token: String
  }
}

class RESTService extends MySQLStorageComponent with GravatarComponent with ... {
  type Config = config.type

  override object config extends MySQLConfig with GravatarConfig {
    val mysqlHost = "localhost
    val mysqlPort = 3336

    val token = "1234cafebabe"
  }

  ...
}