Current status and future plans for msgpack serialization
Official documentation states that:

> Warning This is a very new feature of pandas. We intend to provide certain optimizations in the io of the msgpack data. Since this is marked as an EXPERIMENTAL LIBRARY, the storage format may not be stable until a future release.

Since msgpack is around for a while now and new formats appeared in the mean time (that don't have EXPERIMENTAL tag) I would like to ask what are the team's plans related to msgpack.

A bit of context here: we have inhomogeneous tool stack (part in Python part in Haskell) and we need some format to transfer data from one world to the other. Currently we are using arff, because it has type information and is easy to parse. However, on python side there is no library that properly saves arff's (we have quoting problems with liac-arff); we ended up with our own solution that is painfully slow.

Msgpack would be a good replacement: writing parser for Haskell should be quite easy. But we are concerned that the format will be changing rapidly on the pandas side and thus require a lot of maintenance on Haskell side.

I am aware of issue #15841, but it has not been update for a year.