haskell-src-exts (HSX, haskell-source with extensions) 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 (ghc and hugs style)
  * Template Haskell
 .
 This package provides a library for the Haskell programming language.
 See http://www.haskell.org/ for more information on Haskell.