Reply to https://groups.google.com/d/msg/scalaquery/IWkeKPBdYV4/k3T78L5bHZYJ

Inherited type mapper

import scala.slick.driver.JdbcProfile
import scala.slick.ast.BaseTypedType
trait Profile {
  val profile: JdbcProfile
}
trait TableComponent extends Profile {
  import profile.simple._
  trait TypedId{ def id:Long }
  trait Entity[ID]{
    def id : Option[ID]
  }
  case class AccountId( id:Long ) extends TypedId
  case class Account( emal:String, id:Option[AccountId] ) extends Entity[AccountId]
  abstract class PowerTable[ID <: TypedId, E <: Entity[ID]](tag:Tag, tableName: String)
    extends Table[E](tag, tableName) with HasId[ID] {
 
  }
  trait HasId[ID <: TypedId] {
    self: Table[_] =>
    protected val idColumnName = "id"
    implicit val idMapper: BaseTypedType[ID] // changed the type here
    def id = column[ID](idColumnName, O.AutoInc, O.NotNull)
  }
}
trait AccountTable {
  self: TableComponent =>
  import profile.simple._
  val accountQuery = TableQuery[Accounts]
  class Accounts(tag:Tag) extends PowerTable[AccountId, Account](tag, "accounts")
    with HasId[AccountId] {
    implicit lazy val idMapper : BaseTypedType[AccountId] = MappedColumnType.base[AccountId, Long](
      i => i.id,
      l => AccountId(l)
    )
    def create = Account.apply _
    def extrator = Account.unapply _
    
    def email = column[String]("email", O.NotNull)
    def * = (email, id.?) <> ( create.tupled, extrator)
  }
}

In slick 3.x (dunno about 2.x) it's possible to make AccountId successor of MappedTo

 import slick.lifted.MappedTo
 case class AccountId( value:Long ) extends MappedTo[Long]

and in AccountTable write

def baseTypedType: BaseTypedType[AccountId] = implicitly[BaseTypedType[Id]]