Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: ivory-avr-atmega328p-registers-0.1.0.0 (user goal) [__1] next goal: monadLib (dependency of ivory-avr-atmega328p-registers) [__1] rejecting: monadLib-3.10 (conflict: ivory-avr-atmega328p-registers => monadLib>=3.7.3 && <3.8) [__1] skipping: monadLib-3.9, monadLib-3.8 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=3.7.3 && <3.8' from 'ivory-avr-atmega328p-registers') [__1] trying: monadLib-3.7.3 [__2] next goal: base (dependency of ivory-avr-atmega328p-registers) [__2] rejecting: base-4.14.1.0/installed-4.14.1.0 (conflict: monadLib +/-base3 => base<4 || >=4.4 && <4.13) [__2] rejecting: 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) [__2] fail (backjumping, conflict set: base, ivory-avr-atmega328p-registers, monadLib) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: base, ivory-avr-atmega328p-registers, monadLib