Michał,

Dataflow module could indeed use cleanup. I have made two attempts at this in the past but I don't
think any of them was merged - see [1] and [2]. [2] was mostly type-directed simplifications. It
would be nice to have this included in one form or another. It sounds like you also have a more
in-depth refactoring in mind. Personally as long as it is semantically correct I think it will be
a good thing. I would especially support removing dead code that we don't really use.

[1] https://github.com/jstolarek/ghc/commits/js-hoopl-cleanup-v2
[2] https://github.com/jstolarek/ghc/commits/js-hoopl-cleanup-v2

> Second question: how could we merge this? (...)
I'm not sure if I understand. The end result after merging will be exactly the same, right? Are
you asking for advice what is the best way of doing this from a technical point if view? I would
simply edit the existing module. Introducing a temporary second module seems like unnecessary
extra work and perhaps complicating the patch review.

> I’m happy to export the code to Phab if you prefer - I wasn’t sure what’s
> the recommended workflow for code that’s not ready for review…
This is OK but please remember to set status of revision to "Planned changes" after uploading it
to Phab so it doesn't sit in reviewing queue.