+1 Seems obvious. People shouldn't have to define orphan instances for these. Any instance (of a class in base) that makes sense should be included whenever possible. -- Dan Burton On Thu, Dec 11, 2014 at 7:30 AM, Sean Leather wrote:

As of base 4.7.0.1, none of the newtype wrappers in Data.Monoid have instances for:

- Typeable - Data - Functor

It looks like the base library repository has AutoDeriveTypeable, so I presume that takes care of the Typeable instances. It also looks like First and Last now have Functor instances, amongst others.

In particular, I would like to add Functor instances for all parameterized types, where applicable (i.e. Dual, Sum, Product).

In general, I think we should add whatever other instances make sense. Data came to mind. Others?

Discussion period: 2 weeks (or perhaps until after the beginning of the new year)

Regards, Sean

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

Sean Leather wrote:

newtype wrappers in Data.Monoid... I would like to add Functor instances for all parameterized types, where applicable (i.e. Dual, Sum, Product). In general, I think we should add whatever other instances make sense. Data came to mind.

+1

Others?

NFData. But that's not in base, so those instances need to be added in the deepseq library. -Yitz

I'm a very strong +1 on this. We've already sat down to add some of these, and there was a general resolution by the core libraries committee in response to a similar raised issue for the types in GHC.Generics that missing instances like this that have obvious canonical implementations should be added wherever possible. -Edward On Fri, Dec 12, 2014 at 2:30 AM, Sean Leather wrote:

As of base 4.7.0.1, none of the newtype wrappers in Data.Monoid have instances for:

- Typeable - Data - Functor

It looks like the base library repository has AutoDeriveTypeable, so I presume that takes care of the Typeable instances. It also looks like First and Last now have Functor instances, amongst others.

In particular, I would like to add Functor instances for all parameterized types, where applicable (i.e. Dual, Sum, Product).

In general, I think we should add whatever other instances make sense. Data came to mind. Others?

Discussion period: 2 weeks (or perhaps until after the beginning of the new year)

Regards, Sean

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

Hello Sean, On 2014-12-11 at 16:30:53 +0100, Sean Leather wrote:

As of base 4.7.0.1, none of the newtype wrappers in Data.Monoid have instances for:

- Typeable - Data - Functor

It looks like the base library repository has AutoDeriveTypeable, so I presume that takes care of the Typeable instances.

As a side-note: base-4.7 had AutoDeriveTypeable enabled as well for that module, however, AutoDeriveTypeable is broken in GHC 7.8 (fails to derive instances in most cases), only starting with GHC 7.10 it is working properly.

It also looks like First and Last now have Functor instances, amongst others.

Jfyi, here's a current documentation snapshot for the upcoming base-4.8: https://hackage.haskell.org/package/base-4.8.0.0/candidate/docs/Data-Monoid....

In particular, I would like to add Functor instances for all parameterized types, where applicable (i.e. Dual, Sum, Product).

In general, I think we should add whatever other instances make sense. Data came to mind. Others?

Do you mind making a concrete list of which instances missing for each newtype wrapper asap? That way we can already add them (assuming they are all nobrainers) optimistically before GHC 7.10.1RC1 ships (and should anything turn out to be problematic (which doesn't seem likely given the current discussion progress) we can kill them again by RC2) Cheers, hvr