Tested with GHC 7.10, 8.0, 8.2, 8.4, 8.4, 8.6, 8.8, 8.10, 9.0.
Build with either cabal or stack.
In order to generate tags for all Haskell files under current directory, issue
fast-tags -R .
You can also generate tags that span accross directories or projects:
fast-tags -R . path/to/other/project
See the tools directory for editor and source control integration.