Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: formatting (user goal)
rejecting: formatting-6.2.4, formatting-6.2.3, formatting-6.2.2,
formatting-6.2.1, formatting-6.2.0, formatting-6.1.2, formatting-6.1.1,
formatting-6.1.0, formatting-6.0.0, formatting-5.4, formatting-5.3,
formatting-5.2, formatting-5.1, formatting-5.0, formatting-4.1,
formatting-4.0, formatting-3.1.4, formatting-3.1.3, formatting-3.1.2
(constraint from user target requires ==3.1.1)
trying: formatting-3.1.1
next goal: base (dependency of formatting-3.1.1)
rejecting: base-4.9.0.0/installed-4.9... (conflict: formatting => base<0)
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.