It seems that the Hackage version is somewhat behind. The HEAD builds fine on GHC 8, but not the Hackage version 0.17.1.
src/Yi/Interact.hs:225:10-39: error:
• No instance for (Semigroup (InteractState event w))
arising from the superclasses of an instance declaration
• In the instance declaration for ‘Monoid (InteractState event w)’
It seems that the Hackage version is somewhat behind. The HEAD builds fine on GHC 8, but not the Hackage version 0.17.1.