Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: QuickCheck (user goal)
rejecting: QuickCheck-2.9.2, QuickCheck-2.9.1, QuickCheck-2.9,
QuickCheck-2.8.2, QuickCheck-2.8.1, QuickCheck-2.8, QuickCheck-2.7.6,
QuickCheck-2.7.5, QuickCheck-2.7.4, QuickCheck-2.7.3, QuickCheck-2.7.2,
QuickCheck-2.7.1, QuickCheck-2.7, QuickCheck-2.6, QuickCheck-2.5.1.1,
QuickCheck-2.5.1, QuickCheck-2.5, QuickCheck-2.4.2, QuickCheck-2.4.1.1,
QuickCheck-2.4.1, QuickCheck-2.4.0.1, QuickCheck-2.4, QuickCheck-2.3.0.2,
QuickCheck-2.3.0.1, QuickCheck-2.3, QuickCheck-2.2, QuickCheck-2.1.2,
QuickCheck-2.1.1.1, QuickCheck-2.1.1, QuickCheck-2.1.0.3, QuickCheck-2.1.0.2,
QuickCheck-2.1.0.1 (constraint from user target requires ==2.1)
trying: QuickCheck-2.1
next goal: base (dependency of QuickCheck-2.1)
rejecting: base-4.9.0.0/installed-4.9... (conflict: QuickCheck => base>=3 &&
<4 || <3)
rejecting: 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)
Dependency tree exhaustively searched.