SlickRepository.scala

trait EntityBase {
  def id: String
}

trait Repository {
  type Entity <: EntityBase

  def get(id: String): Option[Entity]
}

trait SlickRepository extends Repository {
  val profile: scala.slick.driver.JdbcProfile
  def database: profile.simple.Database

  import profile.simple._

  abstract class BaseTable(tag: Tag, tableName: String) extends Table[Entity](tag, tableName) {
    def id: Column[String]
  }

  val table: TableQuery[BaseTable]  // needs to be covariant

  override def get(id: String): Option[Entity] = database.withSession { implicit session =>
    table.filter(_.id === id).list.headOption
  }

}

case class User(id: String, name: String, email: String) extends EntityBase

abstract class UserRepository extends SlickRepository {

  type Entity = User

  import profile.simple._

  class UserTable(tag: Tag) extends BaseTable(tag, "user") {
    def id = column[String]("userid", O.PrimaryKey, O.AutoInc)
    def name = column[String]("name")
    def email = column[String]("email")

    def * = (id, name, email) <> (User.tupled, User.unapply)
  }

  val table:TableQuery[BaseTable] = TableQuery[UserTable]
}

  import scalaz.syntax.traverse._
  import scalaz.std.AllInstances._ // IDEA says it's not used, but it's a lie

  val rs: List[List[Throwable \/ Report]] = ls map { _.sequence } // IDEA says it's an error, it's not!
  val rs2 : List[Throwable \/ List[Report]] =  rs.transpose map { _.sequenceU }

Have you found a way to get around this? I'm struggling with a way to come up with a base repository like this, running into those same "value table has incompatible type" errors.