Indentation support for bird-style Literate Haskell

Currently, using bird-style Literate Haskell means that Visual Studio Code believes no line is indented, which means folding doesn't work.
In addition, hitting Enter will always place one at the beginning of the line, no matter the indentation level behind the 'bird marker' - instead a marker should be automatically inserted and the indentation level continued as if no marker existed.

I would probably try implementing this if I could figure out what the right APIs are.