Resolving dependencies...
Error: cabal: Could not resolve dependencies:
[__0] next goal: open-witness (user goal)
[__0] rejecting: open-witness-0.7 (conflict: requires unknown extension
TypeAbstractions; did you mean TypeApplications?)
[__0] rejecting: open-witness-0.6, open-witness-0.5, open-witness-0.4.0.1,
open-witness-0.4, open-witness-0.3.1, open-witness-0.1.1, open-witness-0.1
(constraint from user target requires ==0.7)
[__0] fail (backjumping, conflict set: open-witness)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: open-witness