Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: alex (user goal)
rejecting: alex-3.1.4, 3.1.3, 3.1.2, 3.1.1, 3.1.0, 3.0.5, 3.0.4, 3.0.3, 3.0.2,
3.0.1, 3.0, 2.3.5, 2.3.4, 2.3.3, 2.3.2, 2.3.1, 2.3, 2.2 (global constraint
requires ==2.1.0)
trying: alex-2.1.0
next goal: base (dependency of alex-2.1.0)
rejecting: base-4.7.0.1/installed-e4b... (conflict: alex => base>=1.0 && <4.3)
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.