2012/1/8 Ingo Wechsung <ingo.wechsung@googlemail.com>:

>
>
> 2012/1/8 Gábor Lehel <illissius@gmail.com>
>
>>
>> The second is that only the author of the datatype could put functions
>> into its namespace; the 'data.foo' notation would only be available
>> for functions written by the datatype's author, while for every other
>> function you would have to use 'foo data'. I dislike this special
>> treatment in OO languages and I dislike it here.
>
>
> Please allow me to clarify as far as Frege is concerned.
> In Frege, this is not so, because implementations of class functions in an
> instance will be linked back to the  instantiated types name space. Hence
> one could do the following:
>
> module RExtension where
>
> import original.M(R)    -- access the R record defined in module original.M
>
> class Rextension1 r where
>       firstNewFunction :: .....
>       secondNewFunction :: .....
>
> instance Rextension1 R where
>      -- implementation for new functions
>
> And now, in another module one could
>
> import RExtension()      -- equivalent to qualified import in Haskell
>
> and, voilá, the new functions are accessible (only) through R

Ah, I see. And that answers my other question as well about why you
would special case class methods like this. Thanks. I think I prefer
Disciple's approach of introducing a new keyword alongside 'class' to
distinguish 'virtual record fields' (which get put in the namespace)
from any old class methods (which don't). Otherwise the two ideas seem
very similar. (While at the same time I still dislike the
wrong-direction aspect of both.)