Sittampalam, Ganesh wrote:
I think it treats them as compatible, using the fact that Data.Typeable returns the same type reps (which was why I initially mentioned Data.Typeable in this thread). This is fine for "normal" modules. There's a bit of description in the "Dynamic Typing" section of http://www.cse.unsw.edu.au/~dons/hs-plugins/hs-plugins-Z-H-5.html#node_s ec_9
It's clearly the wrong thing to do for Data.Unique and any anything else that might use <-; but if there are no such types in the interface of the plugin, then it won't matter. I can't see how to make it safe to pass Data.Unique etc across a plugin interface without severely restricting the possible implementation strategies for a plugin library and its host.
I think it's bad design for a dynamic loader to load a module more than once anyway. It's a waste of memory, for a start. We already know that hs-plugins won't for modules it already loaded itself (apparently it crashes the RTS), and I suspect it doesn't at all. -- Ashley Yakeley