I was wondering that myself. Maybe they will release code examples on how that works. I'm only slightly familiar with the Haskell ecosystem but I have also wondered if it has a plugin like system (e.g. OSGI for Java).
I've had some mild success with https://hackage.haskell.org/package/dynamic-loader (which is basically just a Haskell wrapper around the C-functions in the RTS), but compared to writing normal Haskell, this is playing with fire as you loose all type-checking guarantees.
