Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: plugins (user goal)
rejecting: plugins-1.5.5.0, plugins-1.5.4.0, plugins-1.5.3.0, plugins-1.5.2.3,
plugins-1.5.2.2, plugins-1.5.2.1, plugins-1.5.1.4, plugins-1.5.1.3,
plugins-1.5.1.2, plugins-1.5.1.1 (constraint from user target requires
==1.5.1)
trying: plugins-1.5.1
next goal: ghc (dependency of plugins-1.5.1)
rejecting: ghc-8.0.1.20161018/installed-8.0... (conflict: plugins => ghc>=6.10
&& <7.2)
Dependency tree exhaustively searched.