[Haskell-cafe] Re: [Haskell] Top Level <-

[Ashley Yakeley]

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