Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: fei-modelzoo-1.0.0 (user goal)
[__1] trying: fei-base-1.0.0 (dependency of fei-modelzoo)
[__2] next goal: optparse-applicative (dependency of fei-base)
[__2] rejecting: optparse-applicative-0.16.1.0 (conflict: fei-base =>
optparse-applicative>=0.14 && <0.15)
[__2] skipping: optparse-applicative-0.16.0.0, optparse-applicative-0.15.1.0,
optparse-applicative-0.15.0.0 (has the same characteristics that caused the
previous version to fail: excluded by constraint '>=0.14 && <0.15' from
'fei-base')
[__2] trying: optparse-applicative-0.14.3.0
[__3] next goal: base (dependency of fei-modelzoo)
[__3] rejecting: base-4.14.1.0/installed-4.14.1.0 (conflict:
optparse-applicative => base>=4 && <4.13)
[__3] skipping: 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 && <4.13' from 'optparse-applicative')
[__3] 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)
[__3] fail (backjumping, conflict set: base, fei-modelzoo,
optparse-applicative)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: optparse-applicative, fei-base, base,
fei-modelzoo
Try running with --minimize-conflict-set to improve the error message.