Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: hills (user goal)
rejecting: hills-0.1.2, 0.1.1.0 (global constraint requires ==0.1.0.1)
trying: hills-0.1.0.1
trying: base-4.8.1.0/installed-4f7... (dependency of hills-0.1.0.1)
next goal: optparse-applicative (dependency of hills-0.1.0.1)
rejecting: optparse-applicative-0.12.0.0, 0.11.0.2, 0.11.0.1, 0.11.0
(conflict: hills => optparse-applicative>=0.10 && <0.11)
rejecting: optparse-applicative-0.10.0 (conflict:
base==4.8.1.0/installed-4f7..., optparse-applicative => base>=4 && <4.8)
rejecting: optparse-applicative-0.9.1.1, 0.9.1, 0.9.0, 0.8.1, 0.8.0.1, 0.8.0,
0.7.0.2, 0.7.0.1, 0.7.0, 0.6.0, 0.5.2.1, 0.5.2, 0.5.1, 0.5.0, 0.4.3, 0.4.2,
0.4.1, 0.4.0, 0.3.2, 0.3.1, 0.3.0, 0.2.0, 0.1.1, 0.1.0, 0.0.1 (conflict: hills
=> optparse-applicative>=0.10 && <0.11)
Dependency tree exhaustively searched.