scala-inmemory-repository-with-cats-ref-example2.scala

import cats.Applicative
import cats.effect.concurrent.Ref
import cats.implicits._
import cats.effect._

class InMemorySimpleCrud[F[_]: Applicative](ref: Ref[F, Map[String, Human]])
  extends SimpleCrud.Service[F] {
    override def add(human: Human): F[Unit] = 
      ref.update(_.updated(human.name, human))
    override def find(name: String): F[Option[Human]] = 
      ref.get.map_.get(name)
}
object InMemorySimpleCrud {
  def apply[F[_]: Applicative](implicit FF: Sync[F]): InMemorySimpleCrud[F] =
    new InMemorySimpleCrud[F](Ref.unsafe[F, Map[String, Human]](Map[String, OrderHistory]().empty))
}