title: What are the similarities and differences among Haskell indentation modes for Emacs?
body: <p>By scrutinizing <a href="https://github.com/haskell/haskell-mode" rel="noreferrer">the documentation</a>, I have learned that Emacs <code>haskell-mode</code> ships with three different, mutually exclusive methods of automated indentation.  They are called <code>haskell-indentation</code>, <code>haskell-indent</code>, and <code>haskell-simple-indent</code>.  Can anyone explain how these methods are similar and how they are different?  I am interested not only in individual features but also if one is a <em>de facto</em> standard or if one or two are no longer maintained.</p>