Proxy and new-typeable

Edward Kmett ekmett at
Wed Mar 20 09:48:49 CET 2013

If you insist on adding Proxy to Data.Typeable, I'd like to strongly
suggest that we might want to look at promoting Data.Proxy from the tagged
package to base.

It offers a lot of instances that I currently rely upon in production code
and is already in use in a large portion of the ~42 reverse dependencies of
that package:

Of course we could invert the dependencies from packages outside of base at
that time.

Exporting a crippled Proxy from Data.Typeable *without* those instances
will basically just ensure that I need to somehow support both, fight
needlessly with orphans and/or deal with qualified imports everywhere, and
it will break about 3 dozen modules of mine, and impact others.

All in all this makes me personally rather strongly opposed to the idea of
just randomly throwing a Proxy type in the module without ensuring we don't
lose existing functionality along the way.


On Wed, Mar 20, 2013 at 4:04 AM, José Pedro Magalhães <jpm at> wrote:

> Data.Typeable no longer uses Proxy, yet I think it is convenient to have a
> Proxy datatype
> defined somewhere in base, and re-export it from Data.Typeable, as you
> might often often
> want to use it.
> Cheers,
> Pedro
> On Wed, Mar 20, 2013 at 12:35 AM, Edward Kmett <ekmett at> wrote:
>> +1 for finding a resolution. The idea of another Proxy floating around
>> fills me with unease.
>> -Edward
>> On Tue, Mar 19, 2013 at 7:48 PM, Ben Gamari <bgamari.foss at>wrote:
>>> José Pedro Magalhães <jpm at> writes:
>>> > Yes, it's entirely unproblematic, and a good suggestion.
>>> >
>>> What happened to this proposal? As far as I can tell the new-typeable
>>> work is in (or rather, the branch has been deleted) yet Data.Typeable
>>> still seems to have its own Proxy. Given that there has been talk of a
>>> 7.8 release, this should probably be resolved quickly (although it's not
>>> clear to me from the massive thread where that discussion concluded).
>>> Cheers,
>>> - Ben
>>> _______________________________________________
>>> Libraries mailing list
>>> Libraries at
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the Libraries mailing list