Building ghc-mod

This is a post about building ghc-mod for Haskell IDEs.

To build ghc-mod with
 - ghc-8.2.2

needs some manual editing on stack.yaml in your project generated by stack.
Here is my edit for a successful build of ghc-mod 5.9.0.0.

extra-deps: 

- https://hackage.haskell.org/package/ghc-mod-5.9.0.0/candidate/ghc-mod-5.9.0.0.tar.gz

- cabal-helper-0.8.0.0

- monad-journal-0.7.2

- optparse-applicative-0.13.2.0

- either-4.4.1.1

- extra-1.6.6

- free-4.12.4

- haskell-src-exts-1.20.1

The operating system is Mac OS High Sierra (10.13.4), but the dependencies listed above seem to be universal over other operating systems.