Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: lens (user goal)
rejecting: lens-4.13, 4.12.3, 4.12.2, 4.12.1, 4.12, 4.11.1, 4.11, 4.10, 4.9.1,
4.9, 4.8, 4.7.0.1, 4.7, 4.6.0.1, 4.6, 4.5, 4.4.0.2, 4.4.0.1, 4.4, 4.3.3,
4.3.2, 4.3.1, 4.3, 4.2, 4.1.2.1, 4.1.2, 4.1.1, 4.1, 4.0.7, 4.0.6, 4.0.5,
4.0.4, 4.0.3, 4.0.2, 4.0.1, 4.0, 3.10.3, 3.10.2, 3.10.1, 3.10.0.1, 3.10,
3.9.2, 3.9.1, 3.9.0.3, 3.9.0.2, 3.9.0.1, 3.9, 3.8.7.3, 3.8.7.2, 3.8.7.1,
3.8.7, 3.8.6, 3.8.5, 3.8.4, 3.8.3, 3.8.2, 3.8.1, 3.8.0.2, 3.8.0.1, 3.8, 3.7.6,
3.7.5, 3.7.4, 3.7.3, 3.7.2, 3.7.1.2, 3.7.1.1, 3.7.1, 3.7.0.2, 3.7.0.1, 3.7,
3.6.0.4, 3.6.0.3, 3.6.0.2, 3.6.0.1, 3.6, 3.5.1, 3.5, 3.4, 3.3, 3.2, 3.1,
3.0.6, 3.0.5, 3.0.4, 3.0.3, 3.0.2, 3.0.1, 3.0, 2.9, 2.8, 2.7.0.1 (global
constraint requires ==2.7)
trying: lens-2.7
next goal: base (dependency of lens-2.7)
rejecting: base-4.8.1.0/installed-4f7... (conflict: lens => base<0)
rejecting: base-4.8.1.0, 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.