Resolving dependencies... cabal: Could not resolve dependencies: [__0] next goal: numhask-range (user goal) [__0] rejecting: numhask-range-0.2.3.1, numhask-range-0.2.2.1, numhask-range-0.2.2.0, numhask-range-0.2.1.0 (constraint from user target requires ==0.2.0.0) [__0] trying: numhask-range-0.2.0.0 [__1] next goal: base (dependency of numhask-range) [__1] rejecting: base-4.14.1.0/installed-4.14.1.0 (conflict: numhask-range => base>=4.7 && <4.12) [__1] skipping: base-4.15.0.0, base-4.14.1.0, base-4.14.0.0, base-4.13.0.0, base-4.12.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=4.7 && <4.12' from 'numhask-range') [__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) [__1] fail (backjumping, conflict set: base, numhask-range) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: base, numhask-range