Generalise constraint on `instance Monoid (Maybe a)` to Semigroup
authorHerbert Valerio Riedel <hvr@gnu.org>
Tue, 19 Sep 2017 05:54:40 +0000 (07:54 +0200)
committerHerbert Valerio Riedel <hvr@gnu.org>
Tue, 19 Sep 2017 05:56:52 +0000 (07:56 +0200)
commit10ca8018900364579123bf3912202176d338d3c6
treee04509b6684a150c91e35e64c9d8ebbd658ad21b
parent120c568a0b400fecde1cd60f665df104785e6d49
Generalise constraint on `instance Monoid (Maybe a)` to Semigroup

This now becomes possible due to the introduction of the
Semigroup=>Monoid superclass relation (see #14191).

Reviewers: ekmett, RyanGlScott, austin, bgamari

Reviewed By: ekmett, RyanGlScott, bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3972
libraries/base/GHC/Base.hs
libraries/base/changelog.md
testsuite/tests/ghci/scripts/T4175.stdout