How to use Export inside a Callback

[louispan]

Should Export constructor be exported?
How do I convert a JSVal into an Export?

I'm trying to export a haskell value so that it can be called from javascript (in a callback). Therefore the callback should have the signature Callback (Export a -> IO JSVal).
The closest match is callback1 :: Callback (JSVal -> IO JSVal)which means I need a way to convert JSVal to Export.

Unless there is an alternative way to do this?