Idea: Managed resource map

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

  def +=(pair: (K, Resource[F, V])): F[Unit]

  def -=(key: K): F[Unit]

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

  def join(key: K): F[V]
}

object Manager {
  def apply[F[_]: Sync, K, V]: Resource[F, Manager[F, K, V]] = ???
}

The idea here is that it's often useful to have a concurrent map-like data structure which manages Resource lifecycles for you, indexed by some key (so you can retrieve the results). These resources can be submitted (via +=) and will be evaluated in background, with their value stored in the map once complete. Removing the key from the map would close the resource scope. Similarly, closing the resource scope on the Manager would close all constituent Resources and cancel any outstanding computations.

Start with the proposed Manager trait and Manager.apply signature in this issue, then trace the Resource and Sync abstractions used by cats-effect. Done means defining and implementing the requested submission, lookup, join, removal, and manager-shutdown lifecycle semantics, including pending computations.