Resolving dependencies...
cabal: Could not resolve dependencies:
trying: haskell-tools-demo-0.6.0.0 (user goal)
next goal: ghc (dependency of haskell-tools-demo-0.6.0.0)
rejecting: ghc-8.0.1.20161018/installed-8.0... (conflict: haskell-tools-demo
=> ghc>=8.0.2 && <8.1)
Dependency tree exhaustively searched.