I can confirm that cabal install core/ lib/ contrib/ svg/ -j --constraint=semigroups==0.12 dual-tree/ monoid-extras/ active/ works, after bumping the semigroups constraints on all 6 packages. (svg doesn't actually have a semigroups dependency.)

It looks as though semigroups-0.12 is all additions, no API changes.

@byorgey Is it OK if I just push these to the respective master branches?

Yes, it looks like semigroups-0.12 adds a class instance for Const, which according to the PVP requires a major version bump (because it breaks any code which had declared an orphan instance). But it shouldn't affect us since we don't have an orphan instance for Const. Go ahead and push, and I'll put out some minor releases (I have a script for doing the process quickly).

Done. Thanks for the explanation about the orphan instance issue; I did not understand that before.

Released monoid-extras-0.3.2.4, dual-tree-0.2.0.1, active-0.1.0.10, diagrams-core-1.0.0.1, diagrams-lib-1.0.0.1, and diagrams-contrib-1.0.0.1.