As usual the FFI "looks through" newtypes. But now that we have FunPtr, the following typing makes much more sense:

'foreign' 'export' [callconv] 'dynamic' varid :: prim_type -> IO (FunPtr prim_type)

where both prim_types have to be the *same*. We should probably allow the old Addr-typing as well for some time to facilitate the transition, but not the Ptr-typing (bleeding edge people will know what to do :-). The corresponding changes to GHC look easy, so I'd like to commit this if there are no objections.

Sounds reasonable to me. Simon