Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: Cabal (user goal)
rejecting: Cabal-1.22.7.0, 1.22.6.0, 1.22.5.0, 1.22.4.0, 1.22.3.0, 1.22.2.0,
1.22.1.1, 1.22.1.0, 1.22.0.0 (global constraint requires ==1.20.0.4)
trying: Cabal-1.20.0.4
trying: base-4.8.1.0/installed-4f7... (dependency of Cabal-1.20.0.4)
trying: array-0.5.1.0/installed-d42... (dependency of Cabal-1.20.0.4)
next goal: deepseq (dependency of Cabal-1.20.0.4)
rejecting: deepseq-1.4.1.1/installed-8fb..., 1.4.1.2, 1.4.1.1, 1.4.1.0,
1.4.0.0 (conflict: Cabal => deepseq>=1.3 && <1.4)
rejecting: deepseq-1.3.0.2 (conflict: base==4.8.1.0/installed-4f7..., deepseq
=> base>=4.3 && <4.8)
rejecting: deepseq-1.3.0.1, 1.3.0.0 (conflict:
array==0.5.1.0/installed-d42..., deepseq => array>=0.1 && <0.5)
rejecting: deepseq-1.2.0.1, 1.2.0.0, 1.1.0.2, 1.1.0.1, 1.1.0.0, 1.0.0.0
(conflict: Cabal => deepseq>=1.3 && <1.4)
Dependency tree exhaustively searched.

Note: when using a sandbox, all packages are required to have consistent
dependencies. Try reinstalling/unregistering the offending packages or
recreating the sandbox.