Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: checkers (user goal)
rejecting: checkers-0.4.6, checkers-0.4.5, checkers-0.4.4, checkers-0.4.3,
checkers-0.4.2, checkers-0.4.1, checkers-0.4.0, checkers-0.3.2,
checkers-0.3.1, checkers-0.3.0, checkers-0.2.9, checkers-0.2.8,
checkers-0.2.7, checkers-0.2.6, checkers-0.2.5, checkers-0.2.4, checkers-0.2.3
(constraint from user target requires ==0.2.2)
trying: checkers-0.2.2
next goal: base (dependency of checkers-0.2.2)
rejecting: base-4.9.0.0/installed-4.9... (conflict: checkers => base<=4)
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.