I read that article a few weeks ago in order to get a basic personal site server running on Heroku. I used a standard cabal setup and updated a few things.
end result here, which I think should serve as a good starter point for developing with Scotty:
for a true beginner, it starts with an outdated cabal definition for virthualenv/hsenv that has specific old versions. nobody will be able to just copy and paste trhu the tutorial.
but it seems well written if you can get past that point. Most beginners won't though.
Although it uses virthualenv instead of a cabal sandbox.