Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: arbtt (user goal)
rejecting: arbtt-0.9.0.11, arbtt-0.9.0.10, arbtt-0.9.0.9, arbtt-0.9.0.8,
arbtt-0.9.0.7, arbtt-0.9.0.6, arbtt-0.9.0.5, arbtt-0.9.0.4, arbtt-0.9.0.3,
arbtt-0.9.0.2 (constraint from user target requires ==0.9.0.1)
trying: arbtt-0.9.0.1
next goal: base (dependency of arbtt-0.9.0.1)
rejecting: base-4.9.0.0/installed-4.9... (conflict: arbtt => base==4.5.* ||
==4.6.* || ==4.7.* || ==4.8.*)
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.