Use annotated Haskell modules as notebook format

[amigalemming]

Currently hyper-haskell uses a custom JSON format for its notebooks.
What about to also support loading Haskell modules, i.e. parsing LANGUAGE pragmas, import statements and top-level definitions? It would simplify to switch between hyper-haskell and GHCi.
A problem would be that the user might expect that all module information and even formatting is maintained when hyper-haskell writes back an edited module. Also there must be a way to store cell inputs like this one:

test <- return “Test”
test

[HeinrichApfelmus]

Since there a notebook is not a bona fide Haskell module, I do not think that it makes sense to use plain .hs file as a notebook format. However, it might be sensible to use literal Haskell files as notebook format.

This would be very similar to, e.g. R Markdown.