As of May, 25th 2022, this project is officially unmaintained. If you would like to take over, drop a message to @lierdakil.
If you're looking for a decent editor support for Haskell, consider using VSCode with Haskell extensions.
Refer to Atom Flight Manual section on packages for more detailed information
You can find a complete list of Atom-Haskell packages on atom.io package registry
There are binary dependencies which are not touched upon in this section. Refer to the requirements list for more information.
You can pick and choose what packages you want and do not want to install. However, bear in mind that language-haskell is absolutely mandatory, and ide-haskell is most likely required too.
Most people would want at least core Atom-Haskell packages, which can be installed with a simple apm (Atom Package Manager) command. From terminal, run:
apm install language-haskell ide-haskell ide-haskell-cabal
You can install other packages on case-by-case basis.