trait Cache[F[_], K, V] {

  def get(key: K): F[Option[V]]

  /**
    * Does not run `value` concurrently for the same key
    */
  def getOrUpdate(key: K)(value: => F[V]): F[V]

  /**
    * @return previous value if any, possibly not yet loaded
    */
  def put(key: K, value: V): F[Option[F[V]]]


  def keys: F[Set[K]]

  /**
    * Might be an expensive call
    */
  def values: F[Map[K, F[V]]]

  /**
    * @return previous value if any, possibly not yet loaded
    */
  def remove(key: K): F[Option[F[V]]]


  /**
    * Removes loading values from the cache, however does not cancel them
    */
  def clear: F[Unit]
}

resolvers += Resolver.bintrayRepo("evolutiongaming", "maven")

libraryDependencies += "com.evolutiongaming" %% "scache" % "0.0.1"