Starting a new thread to continuing discussing this (I should have done so in the first place).

Here's the problem: a class like Default is most useful if everyone's using the same class. The reason is that multiple libraries are all free to reexport the `def` symbol, and they'll all refer to the same identifier. If multiple `def`s exist, then this doesn't work, you need to be careful about *which* `def` you're using, and you may as well just export a default value under its own unique name.

I think data-default-generics is overall an improvement on data-default, but the very nature of a fork here makes both packages less useful. I'd much rather that data-default simply merged in data-default-generics.

On Wed, May 21, 2014 at 6:12 PM, João Cristóvão <jmacristovao@gmail.com> wrote:

Sorry for continuing the off-topic, and for promoting a package of mine:

If you only need the class definition, http://hackage.haskell.org/package/data-default-class is a better choice, with no dependencies.

If you prefer a single package with all the dependencies (and with additional generics support), my own fork might be useful:
http://hackage.haskell.org/package/data-default-generics

Although I mirrored the original package dependencies, many of which might actually be unnecessary... (given the generics implementation).

Cheers

2014-05-21 15:59 GMT+01:00 Michael Snoyman <michael@snoyman.com>:

At the risk of veering terribly off-topic... the splitting of data-default into all of those packages caused me a bunch of dependency headaches, most of which I still don't fully comprehend. I miss the good ol' days of a single package.

On Wed, May 21, 2014 at 5:53 PM, Edward Kmett <ekmett@gmail.com> wrote:

I find myself rather hesitant to recommend that instantiation of the idea ever since it exploded into a half-dozen packages full of orphan instances, but yes.

-Edward

On Wed, May 21, 2014 at 6:38 AM, Herbert Valerio Riedel <hvr@gnu.org> wrote:

On 2014-05-21 at 00:23:44 +0200, Andreas Abel wrote:
>>> _Lots_ of users initialize empty maps with mempty
>
> Well, this is another issue, empty should be overloaded via
>
> class Empty a where
>   empty :: a

Btw, isn't this what

  http://hackage.haskell.org/package/data-default

provides?

_______________________________________________
Libraries mailing list
Libraries@haskell.org
http://www.haskell.org/mailman/listinfo/libraries

_______________________________________________
Libraries mailing list
Libraries@haskell.org
http://www.haskell.org/mailman/listinfo/libraries

_______________________________________________
Libraries mailing list
Libraries@haskell.org
http://www.haskell.org/mailman/listinfo/libraries