StreamingT use-case

[ceedubs]

This is mostly a question for @non. But I think that the answer could be beneficial to others and that it would be nice if it were turned into some documentation, so a GitHub issue might be a good place.

I hadn't looked very closely at StreamingT until today. I'm now seeing that other than the first element, every single element is wrapped in an F[StreamingT[F, A]]. That is, for a stream of N elements, there are at least (N - 1) F instances. This seems like it could potentially be a performance concern. For example, I'm picturing a situation where I have batches of Future[List[A]] and I want to turn those into a single StreamingT[Future, A]. If I understand correctly, I would have to wrap each individual A element in its own Future, even though I can fetch a whole batch at a time.

However, I also think there is a pretty real possibility that I'm not picturing the same sort of use-cases as you are. In my example above, I think I'm kind of using StreamingT as a more constrained form of an FS2 stream/process. I was wondering what sort of use-cases you had in mind for StreamingT.

Thanks!

[ceedubs]

Obsolete because of #910.