Resolving dependencies... cabal: Could not resolve dependencies: next goal: treeviz (user goal) rejecting: treeviz-2.0.3, treeviz-2.0.2, treeviz-1.0.0, treeviz-0.0.8, treeviz-0.0.7, treeviz-0.0.6, treeviz-0.0.5, treeviz-0.0.4, treeviz-0.0.3 (constraint from user target requires ==0.0.2) trying: treeviz-0.0.2 next goal: base (dependency of treeviz-0.0.2) rejecting: base-4.9.0.0/installed-4.9... (conflict: treeviz => base>=2 && <4) rejecting: base-4.9.0.0, base-4.8.2.0, base-4.8.1.0, base-4.8.0.0, base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1, base-4.6.0.0, base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0, base-4.3.1.0, base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0, base-4.1.0.0, base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from non-upgradeable package requires installed instance) Dependency tree exhaustively searched.