[Haskell] reasons for non-portability

[Simon Marlow]

> Thanks for the info.
> 
> Well, according to that explanation, all modules would be 
> non-portable since 
> the Prelude is normally implemented using non-standard 
> features.  I think, 
> this is solved by declaring all modules described in the 
> Haskell 98 Report 
> portable.
> 
> One question: Every module which imports a non-standard 
> module has to list all 
> of this other module's non-portability reasons in its own 
> reasons section again, rigtht?

You're right - the definition is incomplete.  Additionally, we "declare"
some modules to be portable.  These modules must be available under all
implementations:

 - The Haskell 98 standard libraries (including Prelude)
 - Modules listed under "Approved extensions" in that document

Cheers,
	Simon