adam authored Apr 25, 2017 and Ben Gamari committed Apr 25, 2017

Namely `Num`, `Functor`, `Applicative`, `Monad`, `Semigroup` and
`Monoid` for `Data.Ord.Down` (#13097).

Reviewers: austin, hvr, bgamari, RyanGlScott

Reviewed By: bgamari, RyanGlScott

Subscribers: RyanGlScott, rwbarton, thomie

GHC Trac Issues: #13097

Differential Revision: https://phabricator.haskell.org/D3500