Example3.scala

trait Dao[F[_]] {
  def currentPoints(userId: UUID): F[Int]
  def updatePoints(userId: UUID, value: Int): F[Unit]
}

import doobie._
import doobie.implicits._
import doobie.postgres.implicits._

object DefaultDao extends Dao[ConnectionIO] {
  override def currentPoints(userId: UUID): doobie.ConnectionIO[Int] =
    sql"SELECT points FROM user_points WHERE user_id = $userId"
      .query[Int].unique

  override def updatePoints(userId: UUID, value: Int): doobie.ConnectionIO[Unit] =
    sql"UPDATE user_points SET points = $value WHERE user_id = $userId"
      .update.run.map(_ => ())
}