Resolving dependencies... cabal: Could not resolve dependencies: next goal: tickle (user goal) rejecting: tickle-0.0.9 (constraint from user target requires ==0.0.8) trying: tickle-0.0.8 trying: base-4.10.1.0/installed-4.1... (dependency of tickle-0.0.8) trying: lens-4.15.4 (dependency of papa-lens-implement-0.3.1) trying: profunctors-5.2.1 (dependency of lens-4.15.4) next goal: bifunctors (dependency of tickle-0.0.8) rejecting: bifunctors-5.5, bifunctors-5.4.2, bifunctors-5.4.1 (conflict: tickle => bifunctors>=3.0 && <5.4) rejecting: bifunctors-5.3, bifunctors-5.2.1, bifunctors-5.2 (conflict: base==4.10.1.0/installed-4.1..., bifunctors => base>=4 && <4.10) rejecting: bifunctors-5.1 (conflict: profunctors => bifunctors>=5.2 && <6) rejecting: bifunctors-5, bifunctors-4.2.1, bifunctors-4.2, bifunctors-4.1.1.1, bifunctors-4.1.1, bifunctors-4.1.0.1, bifunctors-4.1, bifunctors-4.0, bifunctors-3.2.0.1, bifunctors-3.2, bifunctors-3.1, bifunctors-3.0.4, bifunctors-3.0.3, bifunctors-3.0.2, bifunctors-3.0.1, bifunctors-3.0 (conflict: lens => bifunctors>=5.1 && <6) rejecting: bifunctors-0.1.3.3, bifunctors-0.1.3.1, bifunctors-0.1.3, bifunctors-0.1.2, bifunctors-0.1.1.3, bifunctors-0.1.1.2, bifunctors-0.1.1.1, bifunctors-0.1.1, bifunctors-0.1, bifunctors-5.4 (conflict: tickle => bifunctors>=3.0 && <5.4) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: bifunctors, tickle, base