Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: servant-benchmark-0.2.0.0 (user goal) [__1] trying: servant-0.18.3 (dependency of servant-benchmark) [__2] next goal: aeson (dependency of servant-benchmark) [__2] rejecting: aeson-2.0.1.0 (conflict: servant => aeson>=1.4.1.0 && <1.6) [__2] skipping: aeson-2.0.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=1.4.1.0 && <1.6' from 'servant') [__2] rejecting: aeson-1.5.6.0 (conflict: servant-benchmark => aeson>=2.0.1.0 && <2.1) [__2] skipping: aeson-1.5.5.1, aeson-1.5.5.0, aeson-1.5.4.1, aeson-1.5.4.0, aeson-1.5.3.0, aeson-1.5.2.0, aeson-1.5.1.0, aeson-1.5.0.0, aeson-1.4.7.1, aeson-1.4.7.0, aeson-1.4.6.0, aeson-1.4.5.0, aeson-1.4.4.0, aeson-1.4.3.0, aeson-1.4.2.0, aeson-1.4.1.0, aeson-1.4.0.0, aeson-1.3.1.1, aeson-1.3.1.0, aeson-1.3.0.0, aeson-1.2.4.0, aeson-1.2.3.0, aeson-1.2.2.0, aeson-1.2.1.0, aeson-1.2.0.0, aeson-1.1.2.0, aeson-1.1.1.0, aeson-1.1.0.0, aeson-1.0.2.1, aeson-1.0.2.0, aeson-1.0.1.0, aeson-1.0.0.0, aeson-0.11.3.0, aeson-0.11.2.1, aeson-0.11.2.0, aeson-0.11.1.4, aeson-0.11.1.3, aeson-0.11.1.2, aeson-0.11.1.1, aeson-0.11.1.0, aeson-0.11.0.0, aeson-0.9.0.1, aeson-0.9.0.0, aeson-0.8.1.1, aeson-0.8.1.0, aeson-0.8.0.2, aeson-0.7.0.6, aeson-0.7.0.4, aeson-0.6.2.1, aeson-0.6.2.0, aeson-0.6.1.0, aeson-0.6.0.2, aeson-0.6.0.1, aeson-0.6.0.0, aeson-0.5.0.0, aeson-0.4.0.1, aeson-0.4.0.0, aeson-0.3.2.14, aeson-0.3.2.13, aeson-0.3.2.12, aeson-0.3.2.11, aeson-0.3.2.10, aeson-0.3.2.9, aeson-0.3.2.8, aeson-0.3.2.7, aeson-0.3.2.6, aeson-0.3.2.5, aeson-0.3.2.4, aeson-0.3.2.3, aeson-0.3.2.2, aeson-0.3.2.1, aeson-0.3.2.0, aeson-0.3.1.1, aeson-0.3.1.0, aeson-0.3.0.0, aeson-0.2.0.0, aeson-0.1.0.0, aeson-0.10.0.0, aeson-0.8.0.1, aeson-0.8.0.0, aeson-0.7.0.5, aeson-0.7.0.3, aeson-0.7.0.2, aeson-0.7.0.1, aeson-0.7.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=2.0.1.0 && <2.1' from 'servant-benchmark') [__2] fail (backjumping, conflict set: aeson, servant, servant-benchmark) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: servant-benchmark, aeson, servant