Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: gruff (user goal)
rejecting: gruff-0.4, gruff-0.3.4, gruff-0.3.3 (constraint from user target
requires ==0.3.1)
trying: gruff-0.3.1
trying: bytestring-0.10.8.1/installed-0.1... (dependency of gruff-0.3.1)
next goal: parallel (dependency of gruff-0.3.1)
rejecting: parallel-3.2.1.0, parallel-3.2.0.6, parallel-3.2.0.5,
parallel-3.2.0.4, parallel-3.2.0.3, parallel-3.2.0.2, parallel-3.2.0.0
(conflict: gruff => parallel>=3.1 && <3.2)
rejecting: parallel-3.1.0.1, parallel-3.1.0.0 (conflict: bytestring =>
deepseq==1.4.2.0/installed-1.4..., parallel => deepseq>=1.1 && <1.2)
rejecting: parallel-3.0.0.0, parallel-2.2.0.1, parallel-2.2.0.0,
parallel-2.1.0.0, parallel-2.0.0.0, parallel-1.1.0.1, parallel-1.1.0.0,
parallel-1.0.0.1, parallel-1.0.0.0 (conflict: gruff => parallel>=3.1 && <3.2)
Dependency tree exhaustively searched.