Example3.scala

import java.util.UUID

import cats._
import cats.implicits._

class Points[F[_]: Monad](dao: Dao[F]) {
  def increase(userId: UUID): F[Unit] =
    for {
      current <- dao.currentPoints(userId)
      updated = calculatePointsIncrease(current)
      _ <- dao.updatePoints(userId, updated)
    } yield ()

  private def calculatePointsIncrease(points: Int): Int = {
    if (points % 2 == 0) points + 3 else points + 1
  }
}