Make the InMemoryBackend more flexible about fun-cqrs HOT 3 OPEN

Hi Francis,

Thanks for the suggestion and feedback.
Have you done some experiments with it? If so, can you push it on fork branch?

from fun-cqrs.

One second thought...

The InMemoryBackend works with the IdentityInterpreter which interpret everything to Identity[_].

We could have a AbstractInMemoryBackend[F[_]] and some implementations that that defines the type of F[_].

So, the AbstractInMemoryBackend[F[_]] together with IdentityInterpreter gives you the current InMemortyBackend.

The AbstractInMemoryBackend[F[_]] together with AsyncInterpreter gives you a AsyncInMemortyBackend. That you can use wherever you use a AsyncBackend, for instance the AkkaBackend

from fun-cqrs.

My use case was testing play controllers with an in memory backend by making my controller have a constructor withbillingBackend: BillingBackend where BillingBackend looks like

trait BillingBackend extends Backend[Future] {
  def accountRef(number: AccountNumber): AggregateRef[Account, Future]
}

But I got stuck when defining the InMemoryBillingBackend because it can't extend the current InMemoryBackend

class InMemoryBillingBackend extends InMemoryBackend with BillingBackend{
// this conflicts because InMemoryBackend is a Backend[Identity] and BillingBackend is a Backend[Future]
}

So I then wanted to wrap the InMemoryBillingBackend but there I again got problems so I gave up and created a ticket 🤔

Your solution sounds like it would allow my use case.

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