Resolving dependencies... cabal: Could not resolve dependencies: next goal: epanet-haskell (user goal) rejecting: epanet-haskell-2.0.12.4, 2.0.12.3, 2.0.12.2 (global constraint requires ==2.0.12.1) trying: epanet-haskell-2.0.12.1 next goal: base (dependency of epanet-haskell-2.0.12.1) rejecting: base-4.8.1.0/installed-4f7... (conflict: epanet-haskell => base==4.6.*) rejecting: base-4.8.1.0, 4.8.0.0, 4.7.0.2, 4.7.0.1, 4.7.0.0, 4.6.0.1, 4.6.0.0, 4.5.1.0, 4.5.0.0, 4.4.1.0, 4.4.0.0, 4.3.1.0, 4.3.0.0, 4.2.0.2, 4.2.0.1, 4.2.0.0, 4.1.0.0, 4.0.0.0, 3.0.3.2, 3.0.3.1 (global constraint requires installed instance) Dependency tree exhaustively searched.