Haskell-Source with Extensions (HSE, haskell-src-exts) is an extension of the standard haskell-src package, and handles most registered 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. All extensions implemented in GHC are supported. Apart from these standard extensions, it also handles regular patterns as per the HaRP extension as well as HSX-style embedded XML syntax.