Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: vacuum (user goal)
rejecting: vacuum-2.2.0.0, vacuum-2.1.0.1, vacuum-2.1.0.0, vacuum-2.0.0.0,
vacuum-1.0.0.2, vacuum-1.0.0.1, vacuum-1.0.0, vacuum-0.0.95, vacuum-0.0.94,
vacuum-0.0.93, vacuum-0.0.92, vacuum-0.0.91, vacuum-0.0.9, vacuum-0.0.8,
vacuum-0.0.7, vacuum-0.0.6, vacuum-0.0.5.1, vacuum-0.0.5, vacuum-0.0.4,
vacuum-0.0.3, vacuum-0.0.2 (constraint from user target requires ==0.0.1)
trying: vacuum-0.0.1
next goal: ghc (dependency of vacuum-0.0.1)
rejecting: ghc-8.0.1.20161018/installed-8.0... (conflict: vacuum =>
ghc==6.10.1)
Dependency tree exhaustively searched.