haskell-src-exts-qq: quasiquote Haskell

Write programs that generate Haskell programs much more concisely and legibly. This package supports:

• Antiquotations, denoted by stealing the splice syntax of Template Haskell, for example:

  [hs| $x ++ $(Hs.strE "bar") |]

Splices may not nested.

• Antiquoting pattern variables in patterns, using double parentheses. For instance:

  let x = Hs.name "n"
  in [hs| \ ((x)) -> $(Hs.Var (Hs.UnQual x)) + 1 |]

• Antiquoting bound names. Names that are antiquoted appear surrounded by double underscores. For instance:

  let f = "incr"
      fE = Hs.Var $ Hs.UnQual $ Hs.name f
  in [hs| let __f__ x = x + 1 in $fE 10 |]

We need three different syntaxes for antiquotations, because we do not extend the haskell-src-exts parser in any way and the Template Haskell splicing syntax is only available in expression contexts.