content: -- | contains a prettyprinter for the
  -- Template Haskell datatypes
  {-# LANGUAGE CPP #-}
  module Language.Eta.Meta.Ppr where
      -- All of the exports from this module should
      -- be "public" functions.  The main module TH
      -- re-exports them all.
  
  import Eta.Location
  import Text.PrettyPrint (render)
  import Language.Eta.Meta.PprLib
  import Language.Eta.Meta.Syntax
  import Data.Word ( Word8 )
  import Data.Char ( toLower, chr, ord, isSymbol )
  import GHC.Show  ( showMultiLineString )
  import Data.Ratio ( numerator, denominator )
  
  #if MIN_VERSION_base(4,11,0)
  import Prelude hiding ((<>))
  #endif
  
  nestDepth :: Int
  nestDepth = 4
  
  type Precedence = Int
  appPrec, unopPrec, opPrec, noPrec :: Precedence
  appPrec = 3    -- Argument of a function application
  opPrec  = 2    -- Argument of an infix operator
  unopPrec = 1   -- Argument of an unresolved infix operator
  noPrec  = 0    -- Others
  
  parensIf :: Bool -> Doc -> Doc
  parensIf True d = parens d
  parensIf False d = d
  
  ------------------------------
  
  pprint :: Ppr a => a -> String
  pprint x = render $ to_HPJ_Doc $ ppr x
  
  class Ppr a where
      ppr :: a -> Doc
      ppr_list :: [a] -> Doc
      ppr_list = vcat . map ppr
  
  instance Ppr a => Ppr [a] where
      ppr x = ppr_list x
  
  ------------------------------
  instance Ppr Name where
      ppr v = pprName v
  
  ------------------------------
  instance Ppr Info where
      ppr (TyConI d)     = ppr d
      ppr (ClassI d is)  = ppr d $$ vcat (map ppr is)
      ppr (FamilyI d is) = ppr d $$ vcat (map ppr is)
      ppr (PrimTyConI name arity is_unlifted)
        = text "Primitive"
          <+> (if is_unlifted then text "unlifted" else empty)
          <+> text "type constructor" <+> quotes (ppr name)
          <+> parens (text "arity" <+> int arity)
      ppr (ClassOpI v ty cls)
        = text "Class op from" <+> ppr cls <> colon <+> ppr_sig v ty
      ppr (DataConI v ty tc)
        = text "Constructor from" <+> ppr tc <> colon <+> ppr_sig v ty
      ppr (TyVarI v ty)
        = text "Type variable" <+> ppr v <+> equals <+> ppr ty
      ppr (VarI v ty mb_d)
        = vcat [ppr_sig v ty,
                case mb_d of { Nothing -> empty; Just d -> ppr d }]
  
  ppr_sig :: Name -> Type -> Doc
  ppr_sig v ty = pprName' Applied v <+> dcolon <+> ppr ty
  
  pprFixity :: Name -> Fixity -> Doc
  pprFixity _ f | f == defaultFixity = empty
  pprFixity v (Fixity i d) = ppr_fix d <+> int i <+> ppr v
      where ppr_fix InfixR = text "infixr"
            ppr_fix InfixL = text "infixl"
            ppr_fix InfixN = text "infix"
  
  
  ------------------------------
  instance Ppr Module where
    ppr (Module pkg m) = text (pkgString pkg) <+> text (modString m)
  
  instance Ppr ModuleInfo where
    ppr (ModuleInfo imps) = text "Module" <+> vcat (map ppr imps)
  
  ------------------------------
  instance Ppr Exp where
      ppr = pprExp noPrec
  
  pprPrefixOcc :: Name -> Doc
  -- Print operators with parens around them
  pprPrefixOcc n = parensIf (isSymOcc n) (ppr n)
  
  isSymOcc :: Name -> Bool
  isSymOcc n
    = case nameBase n of
        []    -> True  -- Empty name; weird
        (c:_) -> isSymbolASCII c || (ord c > 0x7f && isSymbol c)
                     -- c.f. OccName.startsVarSym in GHC itself
  
  isSymbolASCII :: Char -> Bool
  isSymbolASCII c = c `elem` "!#$%&*+./<=>?@\\^|~-"
  
  pprInfixExp :: Exp -> Doc
  pprInfixExp (VarE v) = pprName' Infix v
  pprInfixExp (ConE v) = pprName' Infix v
  pprInfixExp _        = text "<<Non-variable/constructor in infix context>>"
  
  pprExp :: Precedence -> Exp -> Doc
  pprExp _ (VarE v)     = pprName' Applied v
  pprExp _ (ConE c)     = pprName' Applied c
  pprExp i (LitE l)     = pprLit i l
  pprExp i (AppE e1 e2) = parensIf (i >= appPrec) $ pprExp opPrec e1
                                                <+> pprExp appPrec e2
  pprExp _ (ParensE e)  = parens (pprExp noPrec e)
  pprExp i (UInfixE e1 op e2)
   = parensIf (i > unopPrec) $ pprExp unopPrec e1
                           <+> pprInfixExp op
                           <+> pprExp unopPrec e2
  pprExp i (InfixE (Just e1) op (Just e2))
   = parensIf (i >= opPrec) $ pprExp opPrec e1
                          <+> pprInfixExp op
                          <+> pprExp opPrec e2
  pprExp _ (InfixE me1 op me2) = parens $ pprMaybeExp noPrec me1
                                      <+> pprInfixExp op
                                      <+> pprMaybeExp noPrec me2
  pprExp i (LamE ps e) = parensIf (i > noPrec) $ char '\\' <> hsep (map (pprPat appPrec) ps)
                                             <+> text "->" <+> ppr e
  pprExp i (LamCaseE ms) = parensIf (i > noPrec)
                         $ text "\\case" $$ nest nestDepth (ppr ms)
  pprExp _ (TupE es) = parens (commaSep es)
  pprExp _ (UnboxedTupE es) = hashParens (commaSep es)
  -- Nesting in Cond is to avoid potential problems in do statments
  pprExp i (CondE guard true false)
   = parensIf (i > noPrec) $ sep [text "if"   <+> ppr guard,
                         nest 1 $ text "then" <+> ppr true,
                         nest 1 $ text "else" <+> ppr false]
  pprExp i (MultiIfE alts)
    = parensIf (i > noPrec) $ vcat $
        case alts of
          []            -> [text "if {}"]
          (alt : alts') -> text "if" <+> pprGuarded arrow alt
                           : map (nest 3 . pprGuarded arrow) alts'
  pprExp i (LetE ds_ e) = parensIf (i > noPrec) $ text "let" <+> pprDecs ds_
                                               $$ text " in" <+> ppr e
    where
      pprDecs []  = empty
      pprDecs [d] = ppr d
      pprDecs ds  = braces (semiSep ds)
  
  pprExp i (CaseE e ms)
   = parensIf (i > noPrec) $ text "case" <+> ppr e <+> text "of"
                          $$ nest nestDepth (ppr ms)
  pprExp i (DoE ss_) = parensIf (i > noPrec) $ text "do" <+> pprStms ss_
    where
      pprStms []  = empty
      pprStms [s] = ppr s
      pprStms ss  = braces (semiSep ss)
  
  pprExp _ (CompE []) = text "<<Empty CompExp>>"
  -- This will probably break with fixity declarations - would need a ';'
  pprExp _ (CompE ss) =
      if null ss'
         -- If there are no statements in a list comprehension besides the last
         -- one, we simply treat it like a normal list.
         then text "[" <> ppr s <> text "]"
         else text "[" <> ppr s
          <+> text "|"
          <+> commaSep ss'
           <> text "]"
    where s = last ss
          ss' = init ss
  pprExp _ (ArithSeqE d) = ppr d
  pprExp _ (ListE es) = brackets (commaSep es)
  pprExp i (SigE e t) = parensIf (i > noPrec) $ ppr e <+> dcolon <+> ppr t
  pprExp _ (RecConE nm fs) = ppr nm <> braces (pprFields fs)
  pprExp _ (RecUpdE e fs) = pprExp appPrec e <> braces (pprFields fs)
  pprExp i (StaticE e) = parensIf (i >= appPrec) $
                           text "static"<+> pprExp appPrec e
  pprExp _ (UnboundVarE v) = pprName' Applied v
  
  pprFields :: [(Name,Exp)] -> Doc
  pprFields = sep . punctuate comma . map (\(s,e) -> ppr s <+> equals <+> ppr e)
  
  pprMaybeExp :: Precedence -> Maybe Exp -> Doc
  pprMaybeExp _ Nothing = empty
  pprMaybeExp i (Just e) = pprExp i e
  
  ------------------------------
  instance Ppr Stmt where
      ppr (BindS p e) = ppr p <+> text "<-" <+> ppr e
      ppr (LetS ds) = text "let" <+> (braces (semiSep ds))
      ppr (NoBindS e) = ppr e
      ppr (ParS sss) = sep $ punctuate (text "|")
                           $ map commaSep sss
  
  ------------------------------
  instance Ppr Match where
      ppr (Match p rhs ds) = ppr p <+> pprBody False rhs
                          $$ where_clause ds
  
  ------------------------------
  pprGuarded :: Doc -> (Guard, Exp) -> Doc
  pprGuarded eqDoc (guard, expr) = case guard of
    NormalG guardExpr -> char '|' <+> ppr guardExpr <+> eqDoc <+> ppr expr
    PatG    stmts     -> char '|' <+> vcat (punctuate comma $ map ppr stmts) $$
                           nest nestDepth (eqDoc <+> ppr expr)
  
  ------------------------------
  pprBody :: Bool -> Body -> Doc
  pprBody eq body = case body of
      GuardedB xs -> nest nestDepth $ vcat $ map (pprGuarded eqDoc) xs
      NormalB  e  -> eqDoc <+> ppr e
    where eqDoc | eq        = equals
                | otherwise = arrow
  
  ------------------------------
  instance Ppr Lit where
    ppr = pprLit noPrec
  
  pprLit :: Precedence -> Lit -> Doc
  pprLit i (IntPrimL x)    = parensIf (i > noPrec && x < 0)
                                      (integer x <> char '#')
  pprLit _ (WordPrimL x)    = integer x <> text "##"
  pprLit i (FloatPrimL x)  = parensIf (i > noPrec && x < 0)
                                      (float (fromRational x) <> char '#')
  pprLit i (DoublePrimL x) = parensIf (i > noPrec && x < 0)
                                      (double (fromRational x) <> text "##")
  pprLit i (IntegerL x)    = parensIf (i > noPrec && x < 0) (integer x)
  pprLit _ (CharL c)       = text (show c)
  pprLit _ (CharPrimL c)   = text (show c) <> char '#'
  pprLit _ (StringL s)     = pprString s
  pprLit _ (StringPrimL s) = pprString (bytesToString s) <> char '#'
  pprLit i (RationalL rat) = parensIf (i > noPrec) $
                             integer (numerator rat) <+> char '/'
                                <+> integer (denominator rat)
  
  bytesToString :: [Word8] -> String
  bytesToString = map (chr . fromIntegral)
  
  pprString :: String -> Doc
  -- Print newlines as newlines with Haskell string escape notation,
  -- not as '\n'.  For other non-printables use regular escape notation.
  pprString s = vcat (map text (showMultiLineString s))
  
  ------------------------------
  instance Ppr Pat where
      ppr = pprPat noPrec
  
  pprPat :: Precedence -> Pat -> Doc
  pprPat i (LitP l)     = pprLit i l
  pprPat _ (VarP v)     = pprName' Applied v
  pprPat _ (TupP ps)    = parens (commaSep ps)
  pprPat _ (UnboxedTupP ps) = hashParens (commaSep ps)
  pprPat i (ConP s ps)  = parensIf (i >= appPrec) $ pprName' Applied s
                                                <+> sep (map (pprPat appPrec) ps)
  pprPat _ (ParensP p)  = parens $ pprPat noPrec p
  pprPat i (UInfixP p1 n p2)
                        = parensIf (i > unopPrec) (pprPat unopPrec p1 <+>
                                                   pprName' Infix n   <+>
                                                   pprPat unopPrec p2)
  pprPat i (InfixP p1 n p2)
                        = parensIf (i >= opPrec) (pprPat opPrec p1 <+>
                                                  pprName' Infix n <+>
                                                  pprPat opPrec p2)
  pprPat i (TildeP p)   = parensIf (i > noPrec) $ char '~' <> pprPat appPrec p
  pprPat i (BangP p)    = parensIf (i > noPrec) $ char '!' <> pprPat appPrec p
  pprPat i (AsP v p)    = parensIf (i > noPrec) $ ppr v <> text "@"
                                                        <> pprPat appPrec p
  pprPat _ WildP        = text "_"
  pprPat _ (RecP nm fs)
   = parens $     ppr nm
              <+> braces (sep $ punctuate comma $
                          map (\(s,p) -> ppr s <+> equals <+> ppr p) fs)
  pprPat _ (ListP ps) = brackets (commaSep ps)
  pprPat i (SigP p t) = parensIf (i > noPrec) $ ppr p <+> dcolon <+> ppr t
  pprPat _ (ViewP e p) = parens $ pprExp noPrec e <+> text "->" <+> pprPat noPrec p
  
  ------------------------------
  instance Ppr Dec where
      ppr = ppr_dec True
  
  ppr_dec :: Bool     -- declaration on the toplevel?
          -> Dec
          -> Doc
  ppr_dec _ (FunD f cs)   = vcat $ map (\c -> pprPrefixOcc f <+> ppr c) cs
  ppr_dec _ (ValD p r ds) = ppr p <+> pprBody True r
                            $$ where_clause ds
  ppr_dec _ (TySynD t xs rhs)
    = ppr_tySyn empty t (hsep (map ppr xs)) rhs
  ppr_dec _ (DataD ctxt t xs ksig cs decs)
    = ppr_data empty ctxt t (hsep (map ppr xs)) ksig cs decs
  ppr_dec _ (NewtypeD ctxt t xs ksig c decs)
    = ppr_newtype empty ctxt t (sep (map ppr xs)) ksig c decs
  ppr_dec _  (ClassD ctxt c xs fds ds)
    = text "class" <+> pprCxt ctxt <+> ppr c <+> hsep (map ppr xs) <+> ppr fds
      $$ where_clause ds
  ppr_dec _ (InstanceD o ctxt i ds) =
          text "instance" <+> maybe empty ppr_overlap o <+> pprCxt ctxt <+> ppr i
                                    $$ where_clause ds
  ppr_dec _ (SigD f t)    = pprPrefixOcc f <+> dcolon <+> ppr t
  ppr_dec _ (ForeignD f)  = ppr f
  ppr_dec _ (InfixD fx n) = pprFixity n fx
  ppr_dec _ (PragmaD p)   = ppr p
  ppr_dec isTop (DataFamilyD tc tvs kind)
    = text "data" <+> maybeFamily <+> ppr tc <+> hsep (map ppr tvs) <+> maybeKind
    where
      maybeFamily | isTop     = text "family"
                  | otherwise = empty
      maybeKind | (Just k') <- kind = dcolon <+> ppr k'
                | otherwise = empty
  ppr_dec isTop (DataInstD ctxt tc tys ksig cs decs)
    = ppr_data maybeInst ctxt tc (sep (map pprParendType tys)) ksig cs decs
    where
      maybeInst | isTop     = text "instance"
                | otherwise = empty
  ppr_dec isTop (NewtypeInstD ctxt tc tys ksig c decs)
    = ppr_newtype maybeInst ctxt tc (sep (map pprParendType tys)) ksig c decs
    where
      maybeInst | isTop     = text "instance"
                | otherwise = empty
  ppr_dec isTop (TySynInstD tc (TySynEqn tys rhs))
    = ppr_tySyn maybeInst tc (sep (map pprParendType tys)) rhs
    where
      maybeInst | isTop     = text "instance"
                | otherwise = empty
  ppr_dec isTop (OpenTypeFamilyD tfhead)
    = text "type" <+> maybeFamily <+> ppr_tf_head tfhead
    where
      maybeFamily | isTop     = text "family"
                  | otherwise = empty
  ppr_dec _ (ClosedTypeFamilyD tfhead@(TypeFamilyHead tc _ _ _) eqns)
    = hang (text "type family" <+> ppr_tf_head tfhead <+> text "where")
        nestDepth (vcat (map ppr_eqn eqns))
    where
      ppr_eqn (TySynEqn lhs rhs)
        = ppr tc <+> sep (map pprParendType lhs) <+> text "=" <+> ppr rhs
  
  ppr_dec _ (RoleAnnotD name roles)
    = hsep [ text "type role", ppr name ] <+> hsep (map ppr roles)
  
  ppr_dec _ (StandaloneDerivD cxt ty)
    = hsep [ text "deriving instance", pprCxt cxt, ppr ty ]
  
  ppr_dec _ (DefaultSigD n ty)
    = hsep [ text "default", pprPrefixOcc n, dcolon, ppr ty ]
  
  
  ppr_overlap :: Overlap -> Doc
  ppr_overlap o = text $
    case o of
      Overlaps      -> "{-# OVERLAPS #-}"
      Overlappable  -> "{-# OVERLAPPABLE #-}"
      Overlapping   -> "{-# OVERLAPPING #-}"
      Incoherent    -> "{-# INCOHERENT #-}"
  
  ppr_data :: Doc -> Cxt -> Name -> Doc -> Maybe Kind -> [Con] -> Cxt -> Doc
  ppr_data maybeInst ctxt t argsDoc ksig cs decs
    = sep [text "data" <+> maybeInst
              <+> pprCxt ctxt
              <+> ppr t <+> argsDoc <+> ksigDoc <+> maybeWhere,
           nest nestDepth (sep (pref $ map ppr cs)),
           if null decs
             then empty
             else nest nestDepth
                $ text "deriving" <+> ppr_cxt_preds decs]
    where
      pref :: [Doc] -> [Doc]
      pref xs | isGadtDecl = xs
      pref []              = []      -- No constructors; can't happen in H98
      pref (d:ds)          = (char '=' <+> d):map (char '|' <+>) ds
  
      maybeWhere :: Doc
      maybeWhere | isGadtDecl = text "where"
                 | otherwise  = empty
  
      isGadtDecl :: Bool
      isGadtDecl = not (null cs) && all isGadtCon cs
          where isGadtCon (GadtC _ _ _   ) = True
                isGadtCon (RecGadtC _ _ _) = True
                isGadtCon (ForallC _ _ x ) = isGadtCon x
                isGadtCon  _               = False
  
      ksigDoc = case ksig of
                  Nothing -> empty
                  Just k  -> dcolon <+> ppr k
  
  ppr_newtype :: Doc -> Cxt -> Name -> Doc -> Maybe Kind -> Con -> Cxt -> Doc
  ppr_newtype maybeInst ctxt t argsDoc ksig c decs
    = sep [text "newtype" <+> maybeInst
              <+> pprCxt ctxt
              <+> ppr t <+> argsDoc <+> ksigDoc,
           nest 2 (char '=' <+> ppr c),
           if null decs
             then empty
             else nest nestDepth
                  $ text "deriving" <+> ppr_cxt_preds decs]
    where
      ksigDoc = case ksig of
                  Nothing -> empty
                  Just k  -> dcolon <+> ppr k
  
  ppr_tySyn :: Doc -> Name -> Doc -> Type -> Doc
  ppr_tySyn maybeInst t argsDoc rhs
    = text "type" <+> maybeInst <+> ppr t <+> argsDoc <+> text "=" <+> ppr rhs
  
  ppr_tf_head :: TypeFamilyHead -> Doc
  ppr_tf_head (TypeFamilyHead tc tvs res inj)
    = ppr tc <+> hsep (map ppr tvs) <+> ppr res <+> maybeInj
    where
      maybeInj | (Just inj') <- inj = ppr inj'
               | otherwise          = empty
  
  ------------------------------
  instance Ppr FunDep where
      ppr (FunDep xs ys) = hsep (map ppr xs) <+> text "->" <+> hsep (map ppr ys)
      ppr_list [] = empty
      ppr_list xs = char '|' <+> commaSep xs
  
  ------------------------------
  instance Ppr FamFlavour where
      ppr DataFam = text "data"
      ppr TypeFam = text "type"
  
  ------------------------------
  instance Ppr FamilyResultSig where
      ppr NoSig           = empty
      ppr (KindSig k)     = dcolon <+> ppr k
      ppr (TyVarSig bndr) = text "=" <+> ppr bndr
  
  ------------------------------
  instance Ppr InjectivityAnn where
      ppr (InjectivityAnn lhs rhs) =
          char '|' <+> ppr lhs <+> text "->" <+> hsep (map ppr rhs)
  
  ------------------------------
  instance Ppr Foreign where
      ppr (ImportF callconv safety impent as typ)
         = text "foreign import"
       <+> showtextl callconv
       <+> showtextl safety
       <+> text (show impent)
       <+> ppr as
       <+> dcolon <+> ppr typ
      ppr (ExportF callconv expent as typ)
          = text "foreign export"
        <+> showtextl callconv
        <+> text (show expent)
        <+> ppr as
        <+> dcolon <+> ppr typ
  
  ------------------------------
  instance Ppr Pragma where
      ppr (InlineP n inline rm phases)
         = text "{-#"
       <+> ppr inline
       <+> ppr rm
       <+> ppr phases
       <+> ppr n
       <+> text "#-}"
      ppr (SpecialiseP n ty inline phases)
         =   text "{-# SPECIALISE"
         <+> maybe empty ppr inline
         <+> ppr phases
         <+> sep [ ppr n <+> dcolon
                 , nest 2 $ ppr ty ]
         <+> text "#-}"
      ppr (SpecialiseInstP inst)
         = text "{-# SPECIALISE instance" <+> ppr inst <+> text "#-}"
      ppr (RuleP n bndrs lhs rhs phases)
         = sep [ text "{-# RULES" <+> pprString n <+> ppr phases
               , nest 4 $ ppr_forall <+> ppr lhs
               , nest 4 $ char '=' <+> ppr rhs <+> text "#-}" ]
        where ppr_forall | null bndrs =   empty
                         | otherwise  =   text "forall"
                                      <+> fsep (map ppr bndrs)
                                      <+> char '.'
      ppr (AnnP tgt expr)
         = text "{-# ANN" <+> target1 tgt <+> ppr expr <+> text "#-}"
        where target1 ModuleAnnotation    = text "module"
              target1 (TypeAnnotation t)  = text "type" <+> ppr t
              target1 (ValueAnnotation v) = ppr v
      ppr (LineP line file)
         = text "{-# LINE" <+> int line <+> text (show file) <+> text "#-}"
  
  ------------------------------
  instance Ppr Inline where
      ppr NoInline  = text "NOINLINE"
      ppr Inline    = text "INLINE"
      ppr Inlinable = text "INLINABLE"
  
  ------------------------------
  instance Ppr RuleMatch where
      ppr ConLike = text "CONLIKE"
      ppr FunLike = empty
  
  ------------------------------
  instance Ppr Phases where
      ppr AllPhases       = empty
      ppr (FromPhase i)   = brackets $ int i
      ppr (BeforePhase i) = brackets $ char '~' <> int i
  
  ------------------------------
  instance Ppr RuleBndr where
      ppr (RuleVar n)         = ppr n
      ppr (TypedRuleVar n ty) = parens $ ppr n <+> dcolon <+> ppr ty
  
  ------------------------------
  instance Ppr Clause where
      ppr (Clause ps rhs ds) = hsep (map (pprPat appPrec) ps) <+> pprBody True rhs
                               $$ where_clause ds
  
  ------------------------------
  instance Ppr Con where
      ppr (NormalC c sts) = ppr c <+> sep (map pprBangType sts)
  
      ppr (RecC c vsts)
          = ppr c <+> braces (sep (punctuate comma $ map pprVarBangType vsts))
  
      ppr (InfixC st1 c st2) = pprBangType st1
                           <+> pprName' Infix c
                           <+> pprBangType st2
  
      ppr (ForallC ns ctxt (GadtC c sts ty))
          = commaSepApplied c <+> dcolon <+> pprForall ns ctxt
        <+> pprGadtRHS sts ty
  
      ppr (ForallC ns ctxt (RecGadtC c vsts ty))
          = commaSepApplied c <+> dcolon <+> pprForall ns ctxt
        <+> pprRecFields vsts ty
  
      ppr (ForallC ns ctxt con)
          = pprForall ns ctxt <+> ppr con
  
      ppr (GadtC c sts ty)
          = commaSepApplied c <+> dcolon <+> pprGadtRHS sts ty
  
      ppr (RecGadtC c vsts ty)
          = commaSepApplied c <+> dcolon <+> pprRecFields vsts ty
  
  commaSepApplied :: [Name] -> Doc
  commaSepApplied = commaSepWith (pprName' Applied)
  
  pprForall :: [TyVarBndr] -> Cxt -> Doc
  pprForall ns ctxt
      = text "forall" <+> hsep (map ppr ns)
    <+> char '.' <+> pprCxt ctxt
  
  pprRecFields :: [(Name, Strict, Type)] -> Type -> Doc
  pprRecFields vsts ty
      = braces (sep (punctuate comma $ map pprVarBangType vsts))
    <+> arrow <+> ppr ty
  
  pprGadtRHS :: [(Strict, Type)] -> Type -> Doc
  pprGadtRHS [] ty
      = ppr ty
  pprGadtRHS sts ty
      = sep (punctuate (space <> arrow) (map pprBangType sts))
    <+> arrow <+> ppr ty
  
  ------------------------------
  pprVarBangType :: VarBangType -> Doc
  -- Slight infelicity: with print non-atomic type with parens
  pprVarBangType (v, bang, t) = ppr v <+> dcolon <+> pprBangType (bang, t)
  
  ------------------------------
  pprBangType :: BangType -> Doc
  -- Make sure we print
  --
  -- Con {-# UNPACK #-} a
  --
  -- rather than
  --
  -- Con {-# UNPACK #-}a
  --
  -- when there's no strictness annotation. If there is a strictness annotation,
  -- it's okay to not put a space between it and the type.
  pprBangType (bt@(Bang _ NoSourceStrictness), t) = ppr bt <+> pprParendType t
  pprBangType (bt, t) = ppr bt <> pprParendType t
  
  ------------------------------
  instance Ppr Bang where
      ppr (Bang su ss) = ppr su <+> ppr ss
  
  ------------------------------
  instance Ppr SourceUnpackedness where
      ppr NoSourceUnpackedness = empty
      ppr SourceNoUnpack       = text "{-# NOUNPACK #-}"
      ppr SourceUnpack         = text "{-# UNPACK #-}"
  
  ------------------------------
  instance Ppr SourceStrictness where
      ppr NoSourceStrictness = empty
      ppr SourceLazy         = char '~'
      ppr SourceStrict       = char '!'
  
  ------------------------------
  instance Ppr DecidedStrictness where
      ppr DecidedLazy   = empty
      ppr DecidedStrict = char '!'
      ppr DecidedUnpack = text "{-# UNPACK #-} !"
  
  ------------------------------
  {-# DEPRECATED pprVarStrictType
                 "As of @template-haskell-2.11.0.0@, 'VarStrictType' has been replaced by 'VarBangType'. Please use 'pprVarBangType' instead." #-}
  pprVarStrictType :: (Name, Strict, Type) -> Doc
  pprVarStrictType = pprVarBangType
  
  ------------------------------
  {-# DEPRECATED pprStrictType
                 "As of @template-haskell-2.11.0.0@, 'StrictType' has been replaced by 'BangType'. Please use 'pprBangType' instead." #-}
  pprStrictType :: (Strict, Type) -> Doc
  pprStrictType = pprBangType
  
  ------------------------------
  pprParendType :: Type -> Doc
  pprParendType (VarT v)            = ppr v
  pprParendType (ConT c)            = ppr c
  pprParendType (TupleT 0)          = text "()"
  pprParendType (TupleT n)          = parens (hcat (replicate (n-1) comma))
  pprParendType (UnboxedTupleT n)   = hashParens $ hcat $ replicate (n-1) comma
  pprParendType ArrowT              = parens (text "->")
  pprParendType ListT               = text "[]"
  pprParendType (LitT l)            = pprTyLit l
  pprParendType (PromotedT c)       = text "'" <> ppr c
  pprParendType (PromotedTupleT 0)  = text "'()"
  pprParendType (PromotedTupleT n)  = quoteParens (hcat (replicate (n-1) comma))
  pprParendType PromotedNilT        = text "'[]"
  pprParendType PromotedConsT       = text "(':)"
  pprParendType StarT               = char '*'
  pprParendType ConstraintT         = text "Constraint"
  pprParendType (SigT ty k)         = parens (ppr ty <+> text "::" <+> ppr k)
  pprParendType WildCardT           = char '_'
  pprParendType (InfixT x n y)      = parens (ppr x <+> pprName' Infix n <+> ppr y)
  pprParendType t@(UInfixT {})      = parens (pprUInfixT t)
  pprParendType (ParensT t)         = ppr t
  pprParendType tuple | (TupleT n, args) <- split tuple
                      , length args == n
                      = parens (commaSep args)
  pprParendType other               = parens (ppr other)
  
  pprUInfixT :: Type -> Doc
  pprUInfixT (UInfixT x n y) = pprUInfixT x <+> pprName' Infix n <+> pprUInfixT y
  pprUInfixT t               = ppr t
  
  instance Ppr Type where
      ppr (ForallT tvars ctxt ty)
        = text "forall" <+> hsep (map ppr tvars) <+> text "."
                        <+> sep [pprCxt ctxt, ppr ty]
      ppr ty = pprTyApp (split ty)
         -- Works, in a degnerate way, for SigT, and puts parens round (ty :: kind)
         -- See Note [Pretty-printing kind signatures]
  
  {- Note [Pretty-printing kind signatures]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  GHC's parser only recognises a kind signature in a type when there are
  parens around it.  E.g. the parens are required here:
     f :: (Int :: *)
     type instance F Int = (Bool :: *)
  So we always print a SigT with parens (see Trac #10050). -}
  
  pprTyApp :: (Type, [Type]) -> Doc
  pprTyApp (ArrowT, [arg1,arg2]) = sep [pprFunArgType arg1 <+> text "->", ppr arg2]
  pprTyApp (EqualityT, [arg1, arg2]) =
      sep [pprFunArgType arg1 <+> text "~", ppr arg2]
  pprTyApp (ListT, [arg]) = brackets (ppr arg)
  pprTyApp (TupleT n, args)
   | length args == n = parens (commaSep args)
  pprTyApp (PromotedTupleT n, args)
   | length args == n = quoteParens (commaSep args)
  pprTyApp (fun, args) = pprParendType fun <+> sep (map pprParendType args)
  
  pprFunArgType :: Type -> Doc    -- Should really use a precedence argument
  -- Everything except forall and (->) binds more tightly than (->)
  pprFunArgType ty@(ForallT {})                 = parens (ppr ty)
  pprFunArgType ty@((ArrowT `AppT` _) `AppT` _) = parens (ppr ty)
  pprFunArgType ty@(SigT _ _)                   = parens (ppr ty)
  pprFunArgType ty                              = ppr ty
  
  split :: Type -> (Type, [Type])    -- Split into function and args
  split t = go t []
      where go (AppT t1 t2) args = go t1 (t2:args)
            go ty           args = (ty, args)
  
  pprTyLit :: TyLit -> Doc
  pprTyLit (NumTyLit n) = integer n
  pprTyLit (StrTyLit s) = text (show s)
  
  instance Ppr TyLit where
    ppr = pprTyLit
  
  ------------------------------
  instance Ppr TyVarBndr where
      ppr (PlainTV nm)    = ppr nm
      ppr (KindedTV nm k) = parens (ppr nm <+> dcolon <+> ppr k)
  
  instance Ppr Role where
      ppr NominalR          = text "nominal"
      ppr RepresentationalR = text "representational"
      ppr PhantomR          = text "phantom"
      ppr InferR            = text "_"
  
  ------------------------------
  pprCxt :: Cxt -> Doc
  pprCxt [] = empty
  pprCxt ts = ppr_cxt_preds ts <+> text "=>"
  
  ppr_cxt_preds :: Cxt -> Doc
  ppr_cxt_preds [] = empty
  ppr_cxt_preds [t] = ppr t
  ppr_cxt_preds ts = parens (commaSep ts)
  
  ------------------------------
  instance Ppr Range where
      ppr = brackets . pprRange
          where pprRange :: Range -> Doc
                pprRange (FromR e) = ppr e <> text ".."
                pprRange (FromThenR e1 e2) = ppr e1 <> text ","
                                          <> ppr e2 <> text ".."
                pprRange (FromToR e1 e2) = ppr e1 <> text ".." <> ppr e2
                pprRange (FromThenToR e1 e2 e3) = ppr e1 <> text ","
                                               <> ppr e2 <> text ".."
                                               <> ppr e3
  
  ------------------------------
  where_clause :: [Dec] -> Doc
  where_clause [] = empty
  where_clause ds = nest nestDepth $ text "where" <+> vcat (map (ppr_dec False) ds)
  
  showtextl :: Show a => a -> Doc
  showtextl = text . map toLower . show
  
  hashParens :: Doc -> Doc
  hashParens d = text "(# " <> d <> text " #)"
  
  quoteParens :: Doc -> Doc
  quoteParens d = text "'(" <> d <> text ")"
  
  -----------------------------
  instance Ppr Loc where
    ppr (Loc { loc_module = md
             , loc_package = pkg
             , loc_start = (start_ln, start_col)
             , loc_end = (end_ln, end_col) })
      = hcat [ text pkg, colon, text md, colon
             , parens $ int start_ln <> comma <> int start_col
             , text "-"
             , parens $ int end_ln <> comma <> int end_col ]
  
  -- Takes a list of printable things and prints them separated by commas followed
  -- by space.
  commaSep :: Ppr a => [a] -> Doc
  commaSep = commaSepWith ppr
  
  -- Takes a list of things and prints them with the given pretty-printing
  -- function, separated by commas followed by space.
  commaSepWith :: (a -> Doc) -> [a] -> Doc
  commaSepWith pprFun = sep . punctuate comma . map pprFun
  
  -- Takes a list of printable things and prints them separated by semicolons
  -- followed by space.
  semiSep :: Ppr a => [a] -> Doc
  semiSep = sep . punctuate semi . map ppr
  