Add module for streaming with iteratees [WIP]

[travisbrown]

This is just a sketch (from experiments at the Typelevel summit last week) but I wanted to go ahead and open a PR to track it. Needs tests and examples, and it should be a little cleaner and more efficient to bypass AsyncStream and use Reader / Writer directly.

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[vkostyukov]

Given that we now have Encode.ApplicationJson can we write that in a generic way and convert Enumerator[Future, A: Encode.ApplcationJson] into streamed JSON array? I mean we can have both Buf and A: Encode.ApplicationJson defined here.

[vkostyukov]

Going back to this.

I think it would be totally awesome if we could include this into finch-circe (like Circe support in Finch comes with built-in iteratee-powered streaming). I think we have all the required machinery now (including Decode and Encode type-classes parametrized with content-types) to make this happen.

What do you think @travisbrown?

[travisbrown]

@vkostyukov Sounds good to me, if you don't mind the extra iteratee.io dependency for finch-circe. I might not get a chance to get things updated until after Scala by the Bay, though.

[vkostyukov]

I'm closing this as @imliar took good care about iteratee in #812.

Thanks @travisbrown for the inspiration and sharing your ahead-of-time perspective!

[travisbrown]

Yes, thanks @imliar—it's great to see this get merged!