Resolving dependencies... cabal: Could not resolve dependencies: [__0] next goal: composition-prelude (user goal) [__0] rejecting: composition-prelude-1.5.0.3 (constraint from user target requires ==1.5.0.2) [__0] trying: composition-prelude-1.5.0.2 [__1] next goal: base (dependency of composition-prelude) [__1] rejecting: base-4.10.1.0/installed-4.1... (conflict: composition-prelude => base>=5 && <5) [__1] rejecting: base-4.11.1.0, base-4.11.0.0, base-4.10.1.0, base-4.10.0.0, base-4.9.1.0, 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) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: composition-prelude, base