Docstrings aren't highlighted

[tankorsmash]

This is the code from the docstring docs

{-| Convert a list of characters into a String. Can be useful if you
want to create a string primarly by consing, perhaps for decoding
something.

    fromList ['e','l','m'] == "elm"
-}
fromList : List Char -> String
fromList = ...

and this is how it appears in my vim

I'd expect the docstring comment starting on line 1 to be grey.

[tankorsmash]

Hmm, I just disabled all my plugins except this one, and it appears to be working, so this seems to be on my end

[tankorsmash]

Well score one for rubber ducking, it's an issue with https://github.com/luochen1990/rainbow thanks for reading.