Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: yi (user goal)
rejecting: yi-0.13.5, yi-0.13.4, yi-0.13.3, yi-0.13.2, yi-0.13.1, yi-0.13.0.2,
yi-0.13.0.1, yi-0.13, yi-0.12.6, yi-0.12.5, yi-0.12.4, yi-0.12.3, yi-0.12.2,
yi-0.12.1, yi-0.12.0, yi-0.11.2, yi-0.11.1, yi-0.11.0, yi-0.10.1, yi-0.10.0,
yi-0.8.2, yi-0.8.1 (constraint from user target requires ==0.8.0)
trying: yi-0.8.0
next goal: ghc (dependency of yi-0.8.0)
rejecting: ghc-8.0.1.20161018/installed-8.0... (conflict: ghc =>
filepath==1.4.1.0/installed-1.4..., yi => filepath>=1.1 && <1.4)
Dependency tree exhaustively searched.