PROPOSAL: Add instances to Data.Monoid newtype wrappers

Sean Leather sean.leather at
Thu Dec 11 15:30:53 UTC 2014

As of base, 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

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