Haskell-Source with Extensions (HSE, haskell-src-exts) is an extension
of the standard haskell-src package, and handles most common syntactic
extensions to Haskell, including:

    * Multi-parameter type classes with functional dependencies
    * Indexed type families (including associated types)
    * Empty data declarations
    * GADTs
    * Implicit parameters
    * Template Haskell

and a few more. Apart from these standard extensions, it also handles
regular patterns as per the HaRP extension as well as HSX-style
embedded XML syntax.