Language/Haskell/TH/Ppr.hs

{-# LANGUAGE Safe #-}
-- | contains a prettyprinter for the
-- Template Haskell datatypes

module Language.Haskell.TH.Ppr where
 -- All of the exports from this module should
 -- be "public" functions. The main module TH
 -- re-exports them all.

import Text.PrettyPrint (render)
import Language.Haskell.TH.PprLib
import Language.Haskell.TH.Syntax
import Data.Word ( Word8 )
import Data.Char ( toLower, chr)
import GHC.Show ( showMultiLineString )
import GHC.Lexeme( startsVarSym )
import Data.Ratio ( numerator, denominator )
import Prelude hiding ((<>))

nestDepth :: Int
nestDepth = 4

type Precedence = Int
appPrec, opPrec, unopPrec, sigPrec, noPrec :: Precedence
appPrec = 4 -- Argument of a function application
opPrec = 3 -- Argument of an infix operator
unopPrec = 2 -- Argument of an unresolved infix operator
sigPrec = 1 -- Argument of an explicit type signature
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 (PatSynI nm ty) = pprPatSynSig nm 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"

-- | Pretty prints a pattern synonym type signature
pprPatSynSig :: Name -> PatSynType -> Doc
pprPatSynSig nm ty
 = text "pattern" <+> pprPrefixOcc nm <+> dcolon <+> pprPatSynType ty

-- | Pretty prints a pattern synonym's type; follows the usual
-- conventions to print a pattern synonym type compactly, yet
-- unambiguously. See the note on 'PatSynType' and the section on
-- pattern synonyms in the GHC user's guide for more information.
pprPatSynType :: PatSynType -> Doc
pprPatSynType ty@(ForallT uniTys reqs ty'@(ForallT exTys provs ty''))
 | null exTys, null provs = ppr (ForallT uniTys reqs ty'')
 | null uniTys, null reqs = noreqs <+> ppr ty'
 | null reqs = forall uniTys <+> noreqs <+> ppr ty'
 | otherwise = ppr ty
 where noreqs = text "() =>"
 forall tvs = text "forall" <+> (hsep (map ppr tvs)) <+> text "."
pprPatSynType ty = ppr ty

------------------------------
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:_) -> startsVarSym c
 -- c.f. OccName.startsVarSym in GHC itself

pprInfixExp :: Exp -> Doc
pprInfixExp (VarE v) = pprName' Infix v
pprInfixExp (ConE v) = pprName' Infix v
pprInfixExp (UnboundVarE v) = pprName' Infix v
-- This case will only ever be reached in exceptional circumstances.
-- For example, when printing an error message in case of a malformed expression.
pprInfixExp e = text "`" <> ppr e <> text "`"

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 i (AppTypeE e t)
 = parensIf (i >= appPrec) $ pprExp opPrec e <+> char '@' <> pprParendType t
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 [] e) = pprExp i e -- #13856
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" $$ nest nestDepth (ppr ms)
pprExp i (TupE es)
 | [Just e] <- es
 = pprExp i (ConE (tupleDataName 1) `AppE` e)
 | otherwise
 = parens (commaSepWith (pprMaybeExp noPrec) es)
pprExp _ (UnboxedTupE es) = hashParens (commaSepWith (pprMaybeExp noPrec) es)
pprExp _ (UnboxedSumE e alt arity) = unboxedSumBars (ppr e) alt arity
-- Nesting in Cond is to avoid potential problems in do statements
pprExp i (CondE guard true false)
 = parensIf (i > noPrec) $ sep [text "if" <+> ppr guard,
 nest 1 $ text "then" <+> ppr true,
 nest 1 $ text "else" <+> ppr false]
pprExp i (MultiIfE alts)
 = parensIf (i > noPrec) $ vcat $
 case alts of
 [] -> [text "if {}"]
 (alt : alts') -> text "if" <+> pprGuarded arrow alt
 : map (nest 3 . pprGuarded arrow) alts'
pprExp i (LetE ds_ e) = parensIf (i > noPrec) $ text "let" <+> pprDecs ds_
 $$ 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 m ss_) = parensIf (i > noPrec) $
 pprQualifier m <> text "do" <+> pprStms ss_
 where
 pprQualifier Nothing = empty
 pprQualifier (Just modName) = text (modString modName) <> char '.'
 pprStms [] = empty
 pprStms [s] = ppr s
 pprStms ss = braces (semiSep ss)
pprExp i (MDoE m ss_) = parensIf (i > noPrec) $
 pprQualifier m <> text "mdo" <+> pprStms ss_
 where
 pprQualifier Nothing = empty
 pprQualifier (Just modName) = text (modString modName) <> char '.'
 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
 <+> bar
 <+> 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) $ pprExp sigPrec 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
pprExp _ (LabelE s) = text "#" <> text s
pprExp _ (ImplicitParamVarE n) = text ('?' : n)

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 bar
 $ map commaSep sss
 ppr (RecS ss) = text "rec" <+> (braces (semiSep ss))

------------------------------
instance Ppr Match where
 ppr (Match p rhs ds) = pprMatchPat p <+> pprBody False rhs
 $$ where_clause ds

pprMatchPat :: Pat -> Doc
-- Everything except pattern signatures bind more tightly than (->)
pprMatchPat p@(SigP {}) = parens (ppr p)
pprMatchPat p = ppr p

------------------------------
pprGuarded :: Doc -> (Guard, Exp) -> Doc
pprGuarded eqDoc (guard, expr) = case guard of
 NormalG guardExpr -> bar <+> ppr guardExpr <+> eqDoc <+> ppr expr
 PatG stmts -> bar <+> 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 _ (BytesPrimL {}) = pprString "<binary data>"
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 i (TupP ps)
 | [_] <- ps
 = pprPat i (ConP (tupleDataName 1) ps)
 | otherwise
 = parens (commaSep ps)
pprPat _ (UnboxedTupP ps) = hashParens (commaSep ps)
pprPat _ (UnboxedSumP p alt arity) = unboxedSumBars (ppr p) alt arity
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
 $$ where_clause ds
ppr_dec _ (TySynD t xs rhs)
 = ppr_tySyn empty (Just t) (hsep (map ppr xs)) rhs
ppr_dec _ (DataD ctxt t xs ksig cs decs)
 = ppr_data empty ctxt (Just t) (hsep (map ppr xs)) ksig cs decs
ppr_dec _ (NewtypeD ctxt t xs ksig c decs)
 = ppr_newtype empty ctxt (Just t) (sep (map ppr xs)) ksig c decs
ppr_dec _ (ClassD ctxt c xs fds ds)
 = text "class" <+> pprCxt ctxt <+> ppr c <+> hsep (map ppr xs) <+> ppr fds
 $$ 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 _ (KiSigD f k) = text "type" <+> pprPrefixOcc f <+> dcolon <+> ppr k
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 bndrs ty ksig cs decs)
 = ppr_data (maybeInst <+> ppr_bndrs bndrs)
 ctxt Nothing (ppr ty) ksig cs decs
 where
 maybeInst | isTop = text "instance"
 | otherwise = empty
ppr_dec isTop (NewtypeInstD ctxt bndrs ty ksig c decs)
 = ppr_newtype (maybeInst <+> ppr_bndrs bndrs)
 ctxt Nothing (ppr ty) ksig c decs
 where
 maybeInst | isTop = text "instance"
 | otherwise = empty
ppr_dec isTop (TySynInstD (TySynEqn mb_bndrs ty rhs))
 = ppr_tySyn (maybeInst <+> ppr_bndrs mb_bndrs)
 Nothing (ppr ty) 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 eqns)
 = hang (text "type family" <+> ppr_tf_head tfhead <+> text "where")
 nestDepth (vcat (map ppr_eqn eqns))
 where
 ppr_eqn (TySynEqn mb_bndrs lhs rhs)
 = ppr_bndrs mb_bndrs <+> ppr lhs <+> text "=" <+> ppr rhs
ppr_dec _ (RoleAnnotD name roles)
 = hsep [ text "type role", ppr name ] <+> hsep (map ppr roles)
ppr_dec _ (StandaloneDerivD ds cxt ty)
 = hsep [ text "deriving"
 , maybe empty ppr_deriv_strategy ds
 , text "instance"
 , pprCxt cxt
 , ppr ty ]
ppr_dec _ (DefaultSigD n ty)
 = hsep [ text "default", pprPrefixOcc n, dcolon, ppr ty ]
ppr_dec _ (PatSynD name args dir pat)
 = text "pattern" <+> pprNameArgs <+> ppr dir <+> pprPatRHS
 where
 pprNameArgs | InfixPatSyn a1 a2 <- args = ppr a1 <+> ppr name <+> ppr a2
 | otherwise = ppr name <+> ppr args
 pprPatRHS | ExplBidir cls <- dir = hang (ppr pat <+> text "where")
 nestDepth (ppr name <+> ppr cls)
 | otherwise = ppr pat
ppr_dec _ (PatSynSigD name ty)
 = pprPatSynSig name ty
ppr_dec _ (ImplicitParamBindD n e)
 = hsep [text ('?' : n), text "=", ppr e]

ppr_deriv_strategy :: DerivStrategy -> Doc
ppr_deriv_strategy ds =
 case ds of
 StockStrategy -> text "stock"
 AnyclassStrategy -> text "anyclass"
 NewtypeStrategy -> text "newtype"
 ViaStrategy ty -> text "via" <+> pprParendType ty

ppr_overlap :: Overlap -> Doc
ppr_overlap o = text $
 case o of
 Overlaps -> "{-# OVERLAPS #-}"
 Overlappable -> "{-# OVERLAPPABLE #-}"
 Overlapping -> "{-# OVERLAPPING #-}"
 Incoherent -> "{-# INCOHERENT #-}"

ppr_data :: Doc -> Cxt -> Maybe Name -> Doc -> Maybe Kind -> [Con] -> [DerivClause]
 -> Doc
ppr_data maybeInst ctxt t argsDoc ksig cs decs
 = sep [text "data" <+> maybeInst
 <+> pprCxt ctxt
 <+> case t of
 Just n -> pprName' Applied n <+> argsDoc
 Nothing -> argsDoc
 <+> ksigDoc <+> maybeWhere,
 nest nestDepth (sep (pref $ map ppr cs)),
 if null decs
 then empty
 else nest nestDepth
 $ vcat $ map ppr_deriv_clause decs]
 where
 pref :: [Doc] -> [Doc]
 pref xs | isGadtDecl = xs
 pref [] = [] -- No constructors; can't happen in H98
 pref (d:ds) = (char '=' <+> d):map (bar <+>) 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 -> Maybe Name -> Doc -> Maybe Kind -> Con -> [DerivClause]
 -> Doc
ppr_newtype maybeInst ctxt t argsDoc ksig c decs
 = sep [text "newtype" <+> maybeInst
 <+> pprCxt ctxt
 <+> case t of
 Just n -> ppr n <+> argsDoc
 Nothing -> argsDoc
 <+> ksigDoc,
 nest 2 (char '=' <+> ppr c),
 if null decs
 then empty
 else nest nestDepth
 $ vcat $ map ppr_deriv_clause decs]
 where
 ksigDoc = case ksig of
 Nothing -> empty
 Just k -> dcolon <+> ppr k

ppr_deriv_clause :: DerivClause -> Doc
ppr_deriv_clause (DerivClause ds ctxt)
 = text "deriving" <+> pp_strat_before
 <+> ppr_cxt_preds ctxt
 <+> pp_strat_after
 where
 -- @via@ is unique in that in comes /after/ the class being derived,
 -- so we must special-case it.
 (pp_strat_before, pp_strat_after) =
 case ds of
 Just (via@ViaStrategy{}) -> (empty, ppr_deriv_strategy via)
 _ -> (maybe empty ppr_deriv_strategy ds, empty)

ppr_tySyn :: Doc -> Maybe Name -> Doc -> Type -> Doc
ppr_tySyn maybeInst t argsDoc rhs
 = text "type" <+> maybeInst
 <+> case t of
 Just n -> ppr n <+> argsDoc
 Nothing -> 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

ppr_bndrs :: PprFlag flag => Maybe [TyVarBndr flag] -> Doc
ppr_bndrs (Just bndrs) = text "forall" <+> sep (map ppr bndrs) <> text "."
ppr_bndrs Nothing = empty

------------------------------
instance Ppr FunDep where
 ppr (FunDep xs ys) = hsep (map ppr xs) <+> text "->" <+> hsep (map ppr ys)
 ppr_list [] = empty
 ppr_list xs = bar <+> commaSep xs

------------------------------
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) =
 bar <+> 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 ty_bndrs tm_bndrs lhs rhs phases)
 = sep [ text "{-# RULES" <+> pprString n <+> ppr phases
 , nest 4 $ ppr_ty_forall ty_bndrs <+> ppr_tm_forall ty_bndrs
 <+> ppr lhs
 , nest 4 $ char '=' <+> ppr rhs <+> text "#-}" ]
 where ppr_ty_forall Nothing = empty
 ppr_ty_forall (Just bndrs) = text "forall"
 <+> fsep (map ppr bndrs)
 <+> char '.'
 ppr_tm_forall Nothing | null tm_bndrs = empty
 ppr_tm_forall _ = text "forall"
 <+> fsep (map ppr tm_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 "#-}"
 ppr (CompleteP cls mty)
 = text "{-# COMPLETE" <+> (fsep $ punctuate comma $ map ppr cls)
 <+> maybe empty (\ty -> dcolon <+> ppr ty) mty

------------------------------
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

instance Ppr PatSynDir where
 ppr Unidir = text "<-"
 ppr ImplBidir = text "="
 ppr (ExplBidir _) = text "<-"
 -- the ExplBidir's clauses are pretty printed together with the
 -- entire pattern synonym; so only print the direction here.

instance Ppr PatSynArgs where
 ppr (PrefixPatSyn args) = sep $ map ppr args
 ppr (InfixPatSyn a1 a2) = ppr a1 <+> ppr a2
 ppr (RecordPatSyn sels) = braces $ sep (punctuate comma (map ppr sels))

commaSepApplied :: [Name] -> Doc
commaSepApplied = commaSepWith (pprName' Applied)

pprForall :: [TyVarBndr Specificity] -> Cxt -> Doc
pprForall = pprForall' ForallInvis

pprForallVis :: [TyVarBndr ()] -> Cxt -> Doc
pprForallVis = pprForall' ForallVis

pprForall' :: PprFlag flag => ForallVisFlag -> [TyVarBndr flag] -> Cxt -> Doc
pprForall' fvf tvs cxt
 -- even in the case without any tvs, there could be a non-empty
 -- context cxt (e.g., in the case of pattern synonyms, where there
 -- are multiple forall binders and contexts).
 | [] <- tvs = pprCxt cxt
 | otherwise = text "forall" <+> hsep (map ppr tvs)
 <+> separator <+> pprCxt cxt
 where
 separator = case fvf of
 ForallVis -> text "->"
 ForallInvis -> char '.'

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) = pprName' Applied v
-- `Applied` is used here instead of `ppr` because of infix names (#13887)
pprParendType (ConT c) = pprName' Applied c
pprParendType (TupleT 0) = text "()"
pprParendType (TupleT 1) = pprParendType (ConT (tupleTypeName 1))
pprParendType (TupleT n) = parens (hcat (replicate (n-1) comma))
pprParendType (UnboxedTupleT n) = hashParens $ hcat $ replicate (n-1) comma
pprParendType (UnboxedSumT arity) = hashParens $ hcat $ replicate (arity-1) bar
pprParendType ArrowT = parens (text "->")
pprParendType MulArrowT = text "FUN"
pprParendType ListT = text "[]"
pprParendType (LitT l) = pprTyLit l
pprParendType (PromotedT c) = text "'" <> pprName' Applied c
pprParendType (PromotedTupleT 0) = text "'()"
pprParendType (PromotedTupleT 1) = pprParendType (PromotedT (tupleDataName 1))
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 (ImplicitParamT n t)= text ('?':n) <+> text "::" <+> ppr t
pprParendType EqualityT = text "(~)"
pprParendType t@(ForallT {}) = parens (ppr t)
pprParendType t@(ForallVisT {}) = parens (ppr t)
pprParendType t@(AppT {}) = parens (ppr t)
pprParendType t@(AppKindT {}) = parens (ppr t)

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) = sep [pprForall tvars ctxt, ppr ty]
 ppr (ForallVisT tvars ty) = sep [pprForallVis tvars [], ppr ty]
 ppr ty = pprTyApp (split ty)
 -- Works, in a degenerate way, for SigT, and puts parens round (ty :: kind)
 -- See Note [Pretty-printing kind signatures]
instance Ppr TypeArg where
 ppr (TANormal ty) = parensIf (isStarT ty) (ppr ty)
 ppr (TyArg ki) = char '@' <> parensIf (isStarT ki) (ppr ki)

pprParendTypeArg :: TypeArg -> Doc
pprParendTypeArg (TANormal ty) = parensIf (isStarT ty) (pprParendType ty)
pprParendTypeArg (TyArg ki) = char '@' <> parensIf (isStarT ki) (pprParendType ki)

isStarT :: Type -> Bool
isStarT StarT = True
isStarT _ = False

{- 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 #10050). -}

pprTyApp :: (Type, [TypeArg]) -> Doc
pprTyApp (MulArrowT, [TANormal (PromotedT c), TANormal arg1, TANormal arg2])
 | c == oneName = sep [pprFunArgType arg1 <+> text "%1 ->", ppr arg2]
 | c == manyName = sep [pprFunArgType arg1 <+> text "->", ppr arg2]
pprTyApp (MulArrowT, [TANormal argm, TANormal arg1, TANormal arg2]) =
 sep [pprFunArgType arg1 <+> text "%" <> ppr argm <+> text "->", ppr arg2]
pprTyApp (ArrowT, [TANormal arg1, TANormal arg2]) = sep [pprFunArgType arg1 <+> text "->", ppr arg2]
pprTyApp (EqualityT, [TANormal arg1, TANormal arg2]) =
 sep [pprFunArgType arg1 <+> text "~", ppr arg2]
pprTyApp (ListT, [TANormal arg]) = brackets (ppr arg)
pprTyApp (TupleT 1, args) = pprTyApp (ConT (tupleTypeName 1), args)
pprTyApp (PromotedTupleT 1, args) = pprTyApp (PromotedT (tupleDataName 1), args)
pprTyApp (TupleT n, args)
 | length args == n, Just args' <- traverse fromTANormal args
 = parens (commaSep args')
pprTyApp (PromotedTupleT n, args)
 | length args == n, Just args' <- traverse fromTANormal args
 = quoteParens (commaSep args')
pprTyApp (fun, args) = pprParendType fun <+> sep (map pprParendTypeArg args)

fromTANormal :: TypeArg -> Maybe Type
fromTANormal (TANormal arg) = Just arg
fromTANormal (TyArg _) = Nothing

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@(ForallVisT {}) = parens (ppr ty)
pprFunArgType ty@(((MulArrowT `AppT` _) `AppT` _) `AppT` _) = parens (ppr ty)
pprFunArgType ty@((ArrowT `AppT` _) `AppT` _) = parens (ppr ty)
pprFunArgType ty@(SigT _ _) = parens (ppr ty)
pprFunArgType ty = ppr ty

data ForallVisFlag = ForallVis -- forall a -> {...}
 | ForallInvis -- forall a. {...}
 deriving Show

data TypeArg = TANormal Type
 | TyArg Kind

split :: Type -> (Type, [TypeArg]) -- Split into function and args
split t = go t []
 where go (AppT t1 t2) args = go t1 (TANormal t2:args)
 go (AppKindT ty ki) args = go ty (TyArg ki: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

------------------------------
class PprFlag flag where
 pprTyVarBndr :: (TyVarBndr flag) -> Doc

instance PprFlag () where
 pprTyVarBndr (PlainTV nm ()) = ppr nm
 pprTyVarBndr (KindedTV nm () k) = parens (ppr nm <+> dcolon <+> ppr k)

instance PprFlag Specificity where
 pprTyVarBndr (PlainTV nm SpecifiedSpec) = ppr nm
 pprTyVarBndr (PlainTV nm InferredSpec) = braces (ppr nm)
 pprTyVarBndr (KindedTV nm SpecifiedSpec k) = parens (ppr nm <+> dcolon <+> ppr k)
 pprTyVarBndr (KindedTV nm InferredSpec k) = braces (ppr nm <+> dcolon <+> ppr k)

instance PprFlag flag => Ppr (TyVarBndr flag) where
 ppr bndr = pprTyVarBndr bndr

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@ImplicitParamT{}] = parens (ppr t)
ppr_cxt_preds [t@ForallT{}] = parens (ppr t)
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

-- Prints out the series of vertical bars that wraps an expression or pattern
-- used in an unboxed sum.
unboxedSumBars :: Doc -> SumAlt -> SumArity -> Doc
unboxedSumBars d alt arity = hashParens $
 bars (alt-1) <> d <> bars (arity - alt)
 where
 bars i = hsep (replicate i bar)

-- Text containing the vertical bar character.
bar :: Doc
bar = char '|'