Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] next goal: madlang (user goal)
[__0] rejecting: madlang-4.0.2.16, madlang-4.0.2.15, madlang-4.0.2.14,
madlang-4.0.2.13, madlang-4.0.2.12, madlang-4.0.2.11, madlang-4.0.2.9,
madlang-4.0.2.8, madlang-4.0.2.7, madlang-4.0.2.6, madlang-4.0.2.5 (constraint
from user target requires ==4.0.2.2)
[__0] trying: madlang-4.0.2.2
[__1] next goal: megaparsec (dependency of madlang)
[__1] rejecting: megaparsec-9.0.1 (conflict: madlang => megaparsec>=6.0 &&
<7.0)
[__1] skipping: megaparsec-9.0.0, megaparsec-8.0.0, megaparsec-7.0.5,
megaparsec-7.0.4, megaparsec-7.0.3, megaparsec-7.0.2, megaparsec-7.0.1,
megaparsec-7.0.0 (has the same characteristics that caused the previous
version to fail: excluded by constraint '>=6.0 && <7.0' from 'madlang')
[__1] trying: megaparsec-6.5.0
[__2] next goal: base (dependency of madlang)
[__2] rejecting: base-4.14.1.0/installed-4.14.1.0 (conflict: megaparsec =>
base>=4.7 && <4.13)
[__2] skipping: base-4.15.0.0, base-4.14.1.0, base-4.14.0.0, base-4.13.0.0
(has the same characteristics that caused the previous version to fail:
excluded by constraint '>=4.7 && <4.13' from 'megaparsec')
[__2] rejecting: base-4.12.0.0, base-4.11.1.0, base-4.11.0.0, base-4.10.1.0,
base-4.10.0.0, base-4.9.1.0, 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)
[__2] fail (backjumping, conflict set: base, madlang, megaparsec)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: madlang, base, megaparsec