Transformer variant

Have you considered having a transformer variant of `Managed` so that extra effects could be layered on top of IO?

Or at that point is it just as easy to use `ContT ()`?

Start by reading the proposal in this issue and comparing the requested transformer variant of Managed with ContT (). Determine whether layering extra effects on IO requires a distinct abstraction or is already covered by ContT (). Done means reaching a clear design decision about whether and how the variant should exist.

Written by the indexing model from the issue text.