simplified view on the haskell-src-exts AST; documentation

 This package provides a shim for haskell-src-exts (HSE), exposing the
 same AST but without annotations, using ghc's pattern synonyms.
 .
 This package is useful for synthesizing and manipulating HSE ASTs that
 don't carry source location information. It may also aid in porting
 packages from haskell-src-exts 1.17 to 1.18, but it is not a drop-in
 replacement for the old annotation-free AST.
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.