Resolving dependencies... Error: cabal: Could not resolve dependencies: [__0] trying: keelung-0.9.0.0 (user goal) [__1] trying: galois-field-1.0.2 (dependency of keelung) [__2] next goal: protolude (dependency of galois-field) [__2] rejecting: protolude-0.3.3 (conflict: galois-field => protolude>=0.2 && <0.3) [__2] skipping: protolude-0.3.2, protolude-0.3.1, protolude-0.3.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=0.2 && <0.3' from 'galois-field') [__2] trying: protolude-0.2.4 [__3] next goal: base (dependency of keelung) [__3] rejecting: base-4.16.3.0/installed-4.16.3.0 (conflict: protolude => base>=4.6 && <4.16) [__3] skipping: base-4.17.0.0, base-4.16.4.0, base-4.16.3.0, base-4.16.2.0, base-4.16.1.0, base-4.16.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=4.6 && <4.16' from 'protolude') [__3] rejecting: base-4.15.1.0, base-4.15.0.0, base-4.14.3.0, base-4.14.2.0, base-4.14.1.0, base-4.14.0.0, base-4.13.0.0, base-4.12.0.0, 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) [__3] fail (backjumping, conflict set: base, keelung, protolude) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: base, protolude, galois-field, keelung Try running with --minimize-conflict-set to improve the error message.