Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: arbtt (user goal)
rejecting: arbtt-0.9.0.2, 0.9.0.1, 0.9, 0.8.1.4, 0.8.1.3, 0.8.1.2, 0.8.1.1,
0.8.1, 0.8, 0.7 (global constraint requires ==0.6.4.1)
trying: arbtt-0.6.4.1
next goal: base (dependency of arbtt-0.6.4.1)
rejecting: base-4.7.0.1/installed-e4b... (conflict: arbtt => base==4.5.*)
rejecting: base-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.