pipeline interface

[c-cube]

queue operations paired with a future (reply Lwt.u or reply -> unit possibly, depending on backend); send the whole batch in one go. Possibly with the following API:

Redis.pipelined client
  (fun () ->
     R.set c "a" 1;
     R.set c "b" 2)

where normal operations could take an optional reply IO.future that they fullfill once the pipeline is processed.