Resolving dependencies... cabal: Could not resolve dependencies: next goal: sieve (user goal) rejecting: sieve-0.1.0.1 (global constraint requires ==0.1.0.0) trying: sieve-0.1.0.0 next goal: base (dependency of sieve-0.1.0.0) rejecting: base-4.8.1.0/installed-4f7... (conflict: sieve => base==4.5.*) 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.