baffling manual sections

[Alexander Dunlap]

On Tue, May 19, 2009 at 6:22 PM, Denis Bueno <dbueno at gmail.com> wrote:
> On Tue, May 19, 2009 at 16:07, Jason Dusek <jason.dusek at gmail.com> wrote:
>>  The former page also has a curious discussion of standalone
>>  deriving with a `for` keyword:
>>
>>    http://www.haskell.org/ghc/dist/current/docs/users_guide/type-extensions.html#stand-alone-deriving
>
> Without this extension, adding an Eq implementation to a data type for
> which you do not have source requires an explicit class declaration,
> even if there is no reason the original data type author couldn't have
> written "deriving Eq".  Standalone deriving allows you to get the
> convenience of deriving classes everywhere, not just on datatypes for
> which you can obtain, and use, the source.
>
>                              Denis
> _______________________________________________

I think what he's referring to is that StandaloneDeriving actually has
the syntax

deriving instance Eq Foo

not

deriving Eq for foo

Alex