Hello, I am interested in the argument to Done, namely, leftover data. More specifically, when implementing a conduit/sink, what should the conduit specify for the (Maybe i) argument to Done in the following scenarios (Please note that these scenarios only make sense if the type of 'i' is something in Monoid): 1) The conduit outputted the last thing that it felt like outputting, and exited willfully. There seem to be two options here - a) the conduit/sink should greedily gather up all the remaining input in the stream and mconcat them, or b) Return the part of the last thing that never got represented in any part of anything outputted. Option b seems to make the most sense here. 2) Something upstream produced Done, so the second argument to NeedInput gets run. This is guaranteed to be run at the boundary of an item, so should it always return Nothing? Instead, should it remember all the input it has consumed for the current (yet-to-be-outputted) element, so it can let Data.Conduit know that, even though the conduit appeared to consume the past few items, it actually didn't (because it needs more input items to make an output)? Remembering this sequence could potentially have disastrous memory usage. On the other hand, It could also greedily gather everything remaining in the stream. 3) The conduit/sink encountered an error mid-item. In general, is there a commonly-accepted way to deal with this? If a conduit fails in the middle of an item, it might not be clear where it should pick up processing, so the conduit probably shouldn't even attempt to continue. It would probably be good to return some notion of where it was in the input when it failed. It could return (Done (???) (Left errcode)) but this requires that everything downstream in the pipeline be aware of Errcode, which is not ideal.I could use MonadError along with PipeM, but this approach completely abandons the part of the stream that has been processed successfully. I'd like to avoid using Exceptions if at all possible. It doesn't seem that a user application even has any way to access leftover data anyway, so perhaps this discussion will only be relevant in a future version of Conduit. At any rate, any feedback you could give me on this issue would be greatly appreciated. Thanks, Myles