1{-# LANGUAGE Safe #-}
2-- | contains a prettyprinter for the
3-- Template Haskell datatypes
4
5module Language.Haskell.TH.Ppr where
6    -- All of the exports from this module should
7    -- be "public" functions.  The main module TH
8    -- re-exports them all.
9
10import Text.PrettyPrint (render)
11import Language.Haskell.TH.PprLib
12import Language.Haskell.TH.Syntax
13import Data.Word ( Word8 )
14import Data.Char ( toLower, chr)
15import GHC.Show  ( showMultiLineString )
16import GHC.Lexeme( startsVarSym )
17import Data.Ratio ( numerator, denominator )
18import Prelude hiding ((<>))
19
20nestDepth :: Int
21nestDepth = 4
22
23type Precedence = Int
24appPrec, opPrec, unopPrec, sigPrec, noPrec :: Precedence
25appPrec  = 4    -- Argument of a function application
26opPrec   = 3    -- Argument of an infix operator
27unopPrec = 2    -- Argument of an unresolved infix operator
28sigPrec  = 1    -- Argument of an explicit type signature
29noPrec   = 0    -- Others
30
31parensIf :: Bool -> Doc -> Doc
32parensIf True d = parens d
33parensIf False d = d
34
35------------------------------
36
37pprint :: Ppr a => a -> String
38pprint x = render $ to_HPJ_Doc $ ppr x
39
40class Ppr a where
41    ppr :: a -> Doc
42    ppr_list :: [a] -> Doc
43    ppr_list = vcat . map ppr
44
45instance Ppr a => Ppr [a] where
46    ppr x = ppr_list x
47
48------------------------------
49instance Ppr Name where
50    ppr v = pprName v
51
52------------------------------
53instance Ppr Info where
54    ppr (TyConI d)     = ppr d
55    ppr (ClassI d is)  = ppr d $$ vcat (map ppr is)
56    ppr (FamilyI d is) = ppr d $$ vcat (map ppr is)
57    ppr (PrimTyConI name arity is_unlifted)
58      = text "Primitive"
59        <+> (if is_unlifted then text "unlifted" else empty)
60        <+> text "type constructor" <+> quotes (ppr name)
61        <+> parens (text "arity" <+> int arity)
62    ppr (ClassOpI v ty cls)
63      = text "Class op from" <+> ppr cls <> colon <+> ppr_sig v ty
64    ppr (DataConI v ty tc)
65      = text "Constructor from" <+> ppr tc <> colon <+> ppr_sig v ty
66    ppr (PatSynI nm ty) = pprPatSynSig nm ty
67    ppr (TyVarI v ty)
68      = text "Type variable" <+> ppr v <+> equals <+> ppr ty
69    ppr (VarI v ty mb_d)
70      = vcat [ppr_sig v ty,
71              case mb_d of { Nothing -> empty; Just d -> ppr d }]
72
73ppr_sig :: Name -> Type -> Doc
74ppr_sig v ty = pprName' Applied v <+> dcolon <+> ppr ty
75
76pprFixity :: Name -> Fixity -> Doc
77pprFixity _ f | f == defaultFixity = empty
78pprFixity v (Fixity i d) = ppr_fix d <+> int i <+> ppr v
79    where ppr_fix InfixR = text "infixr"
80          ppr_fix InfixL = text "infixl"
81          ppr_fix InfixN = text "infix"
82
83-- | Pretty prints a pattern synonym type signature
84pprPatSynSig :: Name -> PatSynType -> Doc
85pprPatSynSig nm ty
86  = text "pattern" <+> pprPrefixOcc nm <+> dcolon <+> pprPatSynType ty
87
88-- | Pretty prints a pattern synonym's type; follows the usual
89-- conventions to print a pattern synonym type compactly, yet
90-- unambiguously. See the note on 'PatSynType' and the section on
91-- pattern synonyms in the GHC user's guide for more information.
92pprPatSynType :: PatSynType -> Doc
93pprPatSynType ty@(ForallT uniTys reqs ty'@(ForallT exTys provs ty''))
94  | null exTys,  null provs = ppr (ForallT uniTys reqs ty'')
95  | null uniTys, null reqs  = noreqs <+> ppr ty'
96  | null reqs               = forall uniTys <+> noreqs <+> ppr ty'
97  | otherwise               = ppr ty
98  where noreqs     = text "() =>"
99        forall tvs = text "forall" <+> (hsep (map ppr tvs)) <+> text "."
100pprPatSynType ty            = ppr ty
101
102------------------------------
103instance Ppr Module where
104  ppr (Module pkg m) = text (pkgString pkg) <+> text (modString m)
105
106instance Ppr ModuleInfo where
107  ppr (ModuleInfo imps) = text "Module" <+> vcat (map ppr imps)
108
109------------------------------
110instance Ppr Exp where
111    ppr = pprExp noPrec
112
113pprPrefixOcc :: Name -> Doc
114-- Print operators with parens around them
115pprPrefixOcc n = parensIf (isSymOcc n) (ppr n)
116
117isSymOcc :: Name -> Bool
118isSymOcc n
119  = case nameBase n of
120      []    -> True  -- Empty name; weird
121      (c:_) -> startsVarSym c
122                   -- c.f. OccName.startsVarSym in GHC itself
123
124pprInfixExp :: Exp -> Doc
125pprInfixExp (VarE v) = pprName' Infix v
126pprInfixExp (ConE v) = pprName' Infix v
127pprInfixExp (UnboundVarE v) = pprName' Infix v
128-- This case will only ever be reached in exceptional circumstances.
129-- For example, when printing an error message in case of a malformed expression.
130pprInfixExp e = text "`" <> ppr e <> text "`"
131
132pprExp :: Precedence -> Exp -> Doc
133pprExp _ (VarE v)     = pprName' Applied v
134pprExp _ (ConE c)     = pprName' Applied c
135pprExp i (LitE l)     = pprLit i l
136pprExp i (AppE e1 e2) = parensIf (i >= appPrec) $ pprExp opPrec e1
137                                              <+> pprExp appPrec e2
138pprExp i (AppTypeE e t)
139 = parensIf (i >= appPrec) $ pprExp opPrec e <+> char '@' <> pprParendType t
140pprExp _ (ParensE e)  = parens (pprExp noPrec e)
141pprExp i (UInfixE e1 op e2)
142 = parensIf (i > unopPrec) $ pprExp unopPrec e1
143                         <+> pprInfixExp op
144                         <+> pprExp unopPrec e2
145pprExp i (InfixE (Just e1) op (Just e2))
146 = parensIf (i >= opPrec) $ pprExp opPrec e1
147                        <+> pprInfixExp op
148                        <+> pprExp opPrec e2
149pprExp _ (InfixE me1 op me2) = parens $ pprMaybeExp noPrec me1
150                                    <+> pprInfixExp op
151                                    <+> pprMaybeExp noPrec me2
152pprExp i (LamE [] e) = pprExp i e -- #13856
153pprExp i (LamE ps e) = parensIf (i > noPrec) $ char '\\' <> hsep (map (pprPat appPrec) ps)
154                                           <+> text "->" <+> ppr e
155pprExp i (LamCaseE ms) = parensIf (i > noPrec)
156                       $ text "\\case" $$ nest nestDepth (ppr ms)
157pprExp i (TupE es)
158  | [Just e] <- es
159  = pprExp i (ConE (tupleDataName 1) `AppE` e)
160  | otherwise
161  = parens (commaSepWith (pprMaybeExp noPrec) es)
162pprExp _ (UnboxedTupE es) = hashParens (commaSepWith (pprMaybeExp noPrec) es)
163pprExp _ (UnboxedSumE e alt arity) = unboxedSumBars (ppr e) alt arity
164-- Nesting in Cond is to avoid potential problems in do statements
165pprExp i (CondE guard true false)
166 = parensIf (i > noPrec) $ sep [text "if"   <+> ppr guard,
167                       nest 1 $ text "then" <+> ppr true,
168                       nest 1 $ text "else" <+> ppr false]
169pprExp i (MultiIfE alts)
170  = parensIf (i > noPrec) $ vcat $
171      case alts of
172        []            -> [text "if {}"]
173        (alt : alts') -> text "if" <+> pprGuarded arrow alt
174                         : map (nest 3 . pprGuarded arrow) alts'
175pprExp i (LetE ds_ e) = parensIf (i > noPrec) $ text "let" <+> pprDecs ds_
176                                             $$ text " in" <+> ppr e
177  where
178    pprDecs []  = empty
179    pprDecs [d] = ppr d
180    pprDecs ds  = braces (semiSep ds)
181
182pprExp i (CaseE e ms)
183 = parensIf (i > noPrec) $ text "case" <+> ppr e <+> text "of"
184                        $$ nest nestDepth (ppr ms)
185pprExp i (DoE ss_) = parensIf (i > noPrec) $ text "do" <+> pprStms ss_
186  where
187    pprStms []  = empty
188    pprStms [s] = ppr s
189    pprStms ss  = braces (semiSep ss)
190pprExp i (MDoE ss_) = parensIf (i > noPrec) $ text "mdo" <+> pprStms ss_
191  where
192    pprStms []  = empty
193    pprStms [s] = ppr s
194    pprStms ss  = braces (semiSep ss)
195
196pprExp _ (CompE []) = text "<<Empty CompExp>>"
197-- This will probably break with fixity declarations - would need a ';'
198pprExp _ (CompE ss) =
199    if null ss'
200       -- If there are no statements in a list comprehension besides the last
201       -- one, we simply treat it like a normal list.
202       then text "[" <> ppr s <> text "]"
203       else text "[" <> ppr s
204        <+> bar
205        <+> commaSep ss'
206         <> text "]"
207  where s = last ss
208        ss' = init ss
209pprExp _ (ArithSeqE d) = ppr d
210pprExp _ (ListE es) = brackets (commaSep es)
211pprExp i (SigE e t) = parensIf (i > noPrec) $ pprExp sigPrec e
212                                          <+> dcolon <+> ppr t
213pprExp _ (RecConE nm fs) = ppr nm <> braces (pprFields fs)
214pprExp _ (RecUpdE e fs) = pprExp appPrec e <> braces (pprFields fs)
215pprExp i (StaticE e) = parensIf (i >= appPrec) $
216                         text "static"<+> pprExp appPrec e
217pprExp _ (UnboundVarE v) = pprName' Applied v
218pprExp _ (LabelE s) = text "#" <> text s
219pprExp _ (ImplicitParamVarE n) = text ('?' : n)
220
221pprFields :: [(Name,Exp)] -> Doc
222pprFields = sep . punctuate comma . map (\(s,e) -> ppr s <+> equals <+> ppr e)
223
224pprMaybeExp :: Precedence -> Maybe Exp -> Doc
225pprMaybeExp _ Nothing = empty
226pprMaybeExp i (Just e) = pprExp i e
227
228------------------------------
229instance Ppr Stmt where
230    ppr (BindS p e) = ppr p <+> text "<-" <+> ppr e
231    ppr (LetS ds) = text "let" <+> (braces (semiSep ds))
232    ppr (NoBindS e) = ppr e
233    ppr (ParS sss) = sep $ punctuate bar
234                         $ map commaSep sss
235    ppr (RecS ss) = text "rec" <+> (braces (semiSep ss))
236
237------------------------------
238instance Ppr Match where
239    ppr (Match p rhs ds) = pprMatchPat p <+> pprBody False rhs
240                        $$ where_clause ds
241
242pprMatchPat :: Pat -> Doc
243-- Everything except pattern signatures bind more tightly than (->)
244pprMatchPat p@(SigP {}) = parens (ppr p)
245pprMatchPat p           = ppr p
246
247------------------------------
248pprGuarded :: Doc -> (Guard, Exp) -> Doc
249pprGuarded eqDoc (guard, expr) = case guard of
250  NormalG guardExpr -> bar <+> ppr guardExpr <+> eqDoc <+> ppr expr
251  PatG    stmts     -> bar <+> vcat (punctuate comma $ map ppr stmts) $$
252                         nest nestDepth (eqDoc <+> ppr expr)
253
254------------------------------
255pprBody :: Bool -> Body -> Doc
256pprBody eq body = case body of
257    GuardedB xs -> nest nestDepth $ vcat $ map (pprGuarded eqDoc) xs
258    NormalB  e  -> eqDoc <+> ppr e
259  where eqDoc | eq        = equals
260              | otherwise = arrow
261
262------------------------------
263instance Ppr Lit where
264  ppr = pprLit noPrec
265
266pprLit :: Precedence -> Lit -> Doc
267pprLit i (IntPrimL x)    = parensIf (i > noPrec && x < 0)
268                                    (integer x <> char '#')
269pprLit _ (WordPrimL x)    = integer x <> text "##"
270pprLit i (FloatPrimL x)  = parensIf (i > noPrec && x < 0)
271                                    (float (fromRational x) <> char '#')
272pprLit i (DoublePrimL x) = parensIf (i > noPrec && x < 0)
273                                    (double (fromRational x) <> text "##")
274pprLit i (IntegerL x)    = parensIf (i > noPrec && x < 0) (integer x)
275pprLit _ (CharL c)       = text (show c)
276pprLit _ (CharPrimL c)   = text (show c) <> char '#'
277pprLit _ (StringL s)     = pprString s
278pprLit _ (StringPrimL s) = pprString (bytesToString s) <> char '#'
279pprLit _ (BytesPrimL {}) = pprString "<binary data>"
280pprLit i (RationalL rat) = parensIf (i > noPrec) $
281                           integer (numerator rat) <+> char '/'
282                              <+> integer (denominator rat)
283
284bytesToString :: [Word8] -> String
285bytesToString = map (chr . fromIntegral)
286
287pprString :: String -> Doc
288-- Print newlines as newlines with Haskell string escape notation,
289-- not as '\n'.  For other non-printables use regular escape notation.
290pprString s = vcat (map text (showMultiLineString s))
291
292------------------------------
293instance Ppr Pat where
294    ppr = pprPat noPrec
295
296pprPat :: Precedence -> Pat -> Doc
297pprPat i (LitP l)     = pprLit i l
298pprPat _ (VarP v)     = pprName' Applied v
299pprPat i (TupP ps)
300  | [_] <- ps
301  = pprPat i (ConP (tupleDataName 1) ps)
302  | otherwise
303  = parens (commaSep ps)
304pprPat _ (UnboxedTupP ps) = hashParens (commaSep ps)
305pprPat _ (UnboxedSumP p alt arity) = unboxedSumBars (ppr p) alt arity
306pprPat i (ConP s ps)  = parensIf (i >= appPrec) $ pprName' Applied s
307                                              <+> sep (map (pprPat appPrec) ps)
308pprPat _ (ParensP p)  = parens $ pprPat noPrec p
309pprPat i (UInfixP p1 n p2)
310                      = parensIf (i > unopPrec) (pprPat unopPrec p1 <+>
311                                                 pprName' Infix n   <+>
312                                                 pprPat unopPrec p2)
313pprPat i (InfixP p1 n p2)
314                      = parensIf (i >= opPrec) (pprPat opPrec p1 <+>
315                                                pprName' Infix n <+>
316                                                pprPat opPrec p2)
317pprPat i (TildeP p)   = parensIf (i > noPrec) $ char '~' <> pprPat appPrec p
318pprPat i (BangP p)    = parensIf (i > noPrec) $ char '!' <> pprPat appPrec p
319pprPat i (AsP v p)    = parensIf (i > noPrec) $ ppr v <> text "@"
320                                                      <> pprPat appPrec p
321pprPat _ WildP        = text "_"
322pprPat _ (RecP nm fs)
323 = parens $     ppr nm
324            <+> braces (sep $ punctuate comma $
325                        map (\(s,p) -> ppr s <+> equals <+> ppr p) fs)
326pprPat _ (ListP ps) = brackets (commaSep ps)
327pprPat i (SigP p t) = parensIf (i > noPrec) $ ppr p <+> dcolon <+> ppr t
328pprPat _ (ViewP e p) = parens $ pprExp noPrec e <+> text "->" <+> pprPat noPrec p
329
330------------------------------
331instance Ppr Dec where
332    ppr = ppr_dec True
333
334ppr_dec :: Bool     -- declaration on the toplevel?
335        -> Dec
336        -> Doc
337ppr_dec _ (FunD f cs)   = vcat $ map (\c -> pprPrefixOcc f <+> ppr c) cs
338ppr_dec _ (ValD p r ds) = ppr p <+> pprBody True r
339                          $$ where_clause ds
340ppr_dec _ (TySynD t xs rhs)
341  = ppr_tySyn empty (Just t) (hsep (map ppr xs)) rhs
342ppr_dec _ (DataD ctxt t xs ksig cs decs)
343  = ppr_data empty ctxt (Just t) (hsep (map ppr xs)) ksig cs decs
344ppr_dec _ (NewtypeD ctxt t xs ksig c decs)
345  = ppr_newtype empty ctxt (Just t) (sep (map ppr xs)) ksig c decs
346ppr_dec _  (ClassD ctxt c xs fds ds)
347  = text "class" <+> pprCxt ctxt <+> ppr c <+> hsep (map ppr xs) <+> ppr fds
348    $$ where_clause ds
349ppr_dec _ (InstanceD o ctxt i ds) =
350        text "instance" <+> maybe empty ppr_overlap o <+> pprCxt ctxt <+> ppr i
351                                  $$ where_clause ds
352ppr_dec _ (SigD f t)    = pprPrefixOcc f <+> dcolon <+> ppr t
353ppr_dec _ (KiSigD f k)  = text "type" <+> pprPrefixOcc f <+> dcolon <+> ppr k
354ppr_dec _ (ForeignD f)  = ppr f
355ppr_dec _ (InfixD fx n) = pprFixity n fx
356ppr_dec _ (PragmaD p)   = ppr p
357ppr_dec isTop (DataFamilyD tc tvs kind)
358  = text "data" <+> maybeFamily <+> ppr tc <+> hsep (map ppr tvs) <+> maybeKind
359  where
360    maybeFamily | isTop     = text "family"
361                | otherwise = empty
362    maybeKind | (Just k') <- kind = dcolon <+> ppr k'
363              | otherwise = empty
364ppr_dec isTop (DataInstD ctxt bndrs ty ksig cs decs)
365  = ppr_data (maybeInst <+> ppr_bndrs bndrs)
366             ctxt Nothing (ppr ty) ksig cs decs
367  where
368    maybeInst | isTop     = text "instance"
369              | otherwise = empty
370ppr_dec isTop (NewtypeInstD ctxt bndrs ty ksig c decs)
371  = ppr_newtype (maybeInst <+> ppr_bndrs bndrs)
372                ctxt Nothing (ppr ty) ksig c decs
373  where
374    maybeInst | isTop     = text "instance"
375              | otherwise = empty
376ppr_dec isTop (TySynInstD (TySynEqn mb_bndrs ty rhs))
377  = ppr_tySyn (maybeInst <+> ppr_bndrs mb_bndrs)
378              Nothing (ppr ty) rhs
379  where
380    maybeInst | isTop     = text "instance"
381              | otherwise = empty
382ppr_dec isTop (OpenTypeFamilyD tfhead)
383  = text "type" <+> maybeFamily <+> ppr_tf_head tfhead
384  where
385    maybeFamily | isTop     = text "family"
386                | otherwise = empty
387ppr_dec _ (ClosedTypeFamilyD tfhead eqns)
388  = hang (text "type family" <+> ppr_tf_head tfhead <+> text "where")
389      nestDepth (vcat (map ppr_eqn eqns))
390  where
391    ppr_eqn (TySynEqn mb_bndrs lhs rhs)
392      = ppr_bndrs mb_bndrs <+> ppr lhs <+> text "=" <+> ppr rhs
393ppr_dec _ (RoleAnnotD name roles)
394  = hsep [ text "type role", ppr name ] <+> hsep (map ppr roles)
395ppr_dec _ (StandaloneDerivD ds cxt ty)
396  = hsep [ text "deriving"
397         , maybe empty ppr_deriv_strategy ds
398         , text "instance"
399         , pprCxt cxt
400         , ppr ty ]
401ppr_dec _ (DefaultSigD n ty)
402  = hsep [ text "default", pprPrefixOcc n, dcolon, ppr ty ]
403ppr_dec _ (PatSynD name args dir pat)
404  = text "pattern" <+> pprNameArgs <+> ppr dir <+> pprPatRHS
405  where
406    pprNameArgs | InfixPatSyn a1 a2 <- args = ppr a1 <+> ppr name <+> ppr a2
407                | otherwise                 = ppr name <+> ppr args
408    pprPatRHS   | ExplBidir cls <- dir = hang (ppr pat <+> text "where")
409                                           nestDepth (ppr name <+> ppr cls)
410                | otherwise            = ppr pat
411ppr_dec _ (PatSynSigD name ty)
412  = pprPatSynSig name ty
413ppr_dec _ (ImplicitParamBindD n e)
414  = hsep [text ('?' : n), text "=", ppr e]
415
416ppr_deriv_strategy :: DerivStrategy -> Doc
417ppr_deriv_strategy ds =
418  case ds of
419    StockStrategy    -> text "stock"
420    AnyclassStrategy -> text "anyclass"
421    NewtypeStrategy  -> text "newtype"
422    ViaStrategy ty   -> text "via" <+> pprParendType ty
423
424ppr_overlap :: Overlap -> Doc
425ppr_overlap o = text $
426  case o of
427    Overlaps      -> "{-# OVERLAPS #-}"
428    Overlappable  -> "{-# OVERLAPPABLE #-}"
429    Overlapping   -> "{-# OVERLAPPING #-}"
430    Incoherent    -> "{-# INCOHERENT #-}"
431
432ppr_data :: Doc -> Cxt -> Maybe Name -> Doc -> Maybe Kind -> [Con] -> [DerivClause]
433         -> Doc
434ppr_data maybeInst ctxt t argsDoc ksig cs decs
435  = sep [text "data" <+> maybeInst
436            <+> pprCxt ctxt
437            <+> case t of
438                 Just n -> pprName' Applied n <+> argsDoc
439                 Nothing -> argsDoc
440            <+> ksigDoc <+> maybeWhere,
441         nest nestDepth (sep (pref $ map ppr cs)),
442         if null decs
443           then empty
444           else nest nestDepth
445              $ vcat $ map ppr_deriv_clause decs]
446  where
447    pref :: [Doc] -> [Doc]
448    pref xs | isGadtDecl = xs
449    pref []              = []      -- No constructors; can't happen in H98
450    pref (d:ds)          = (char '=' <+> d):map (bar <+>) ds
451
452    maybeWhere :: Doc
453    maybeWhere | isGadtDecl = text "where"
454               | otherwise  = empty
455
456    isGadtDecl :: Bool
457    isGadtDecl = not (null cs) && all isGadtCon cs
458        where isGadtCon (GadtC _ _ _   ) = True
459              isGadtCon (RecGadtC _ _ _) = True
460              isGadtCon (ForallC _ _ x ) = isGadtCon x
461              isGadtCon  _               = False
462
463    ksigDoc = case ksig of
464                Nothing -> empty
465                Just k  -> dcolon <+> ppr k
466
467ppr_newtype :: Doc -> Cxt -> Maybe Name -> Doc -> Maybe Kind -> Con -> [DerivClause]
468            -> Doc
469ppr_newtype maybeInst ctxt t argsDoc ksig c decs
470  = sep [text "newtype" <+> maybeInst
471            <+> pprCxt ctxt
472            <+> case t of
473                 Just n -> ppr n <+> argsDoc
474                 Nothing -> argsDoc
475            <+> ksigDoc,
476         nest 2 (char '=' <+> ppr c),
477         if null decs
478           then empty
479           else nest nestDepth
480                $ vcat $ map ppr_deriv_clause decs]
481  where
482    ksigDoc = case ksig of
483                Nothing -> empty
484                Just k  -> dcolon <+> ppr k
485
486ppr_deriv_clause :: DerivClause -> Doc
487ppr_deriv_clause (DerivClause ds ctxt)
488  = text "deriving" <+> pp_strat_before
489                    <+> ppr_cxt_preds ctxt
490                    <+> pp_strat_after
491  where
492    -- @via@ is unique in that in comes /after/ the class being derived,
493    -- so we must special-case it.
494    (pp_strat_before, pp_strat_after) =
495      case ds of
496        Just (via@ViaStrategy{}) -> (empty, ppr_deriv_strategy via)
497        _                        -> (maybe empty ppr_deriv_strategy ds, empty)
498
499ppr_tySyn :: Doc -> Maybe Name -> Doc -> Type -> Doc
500ppr_tySyn maybeInst t argsDoc rhs
501  = text "type" <+> maybeInst
502    <+> case t of
503         Just n -> ppr n <+> argsDoc
504         Nothing -> argsDoc
505    <+> text "=" <+> ppr rhs
506
507ppr_tf_head :: TypeFamilyHead -> Doc
508ppr_tf_head (TypeFamilyHead tc tvs res inj)
509  = ppr tc <+> hsep (map ppr tvs) <+> ppr res <+> maybeInj
510  where
511    maybeInj | (Just inj') <- inj = ppr inj'
512             | otherwise          = empty
513
514ppr_bndrs :: Maybe [TyVarBndr] -> Doc
515ppr_bndrs (Just bndrs) = text "forall" <+> sep (map ppr bndrs) <> text "."
516ppr_bndrs Nothing = empty
517
518------------------------------
519instance Ppr FunDep where
520    ppr (FunDep xs ys) = hsep (map ppr xs) <+> text "->" <+> hsep (map ppr ys)
521    ppr_list [] = empty
522    ppr_list xs = bar <+> commaSep xs
523
524------------------------------
525instance Ppr FamilyResultSig where
526    ppr NoSig           = empty
527    ppr (KindSig k)     = dcolon <+> ppr k
528    ppr (TyVarSig bndr) = text "=" <+> ppr bndr
529
530------------------------------
531instance Ppr InjectivityAnn where
532    ppr (InjectivityAnn lhs rhs) =
533        bar <+> ppr lhs <+> text "->" <+> hsep (map ppr rhs)
534
535------------------------------
536instance Ppr Foreign where
537    ppr (ImportF callconv safety impent as typ)
538       = text "foreign import"
539     <+> showtextl callconv
540     <+> showtextl safety
541     <+> text (show impent)
542     <+> ppr as
543     <+> dcolon <+> ppr typ
544    ppr (ExportF callconv expent as typ)
545        = text "foreign export"
546      <+> showtextl callconv
547      <+> text (show expent)
548      <+> ppr as
549      <+> dcolon <+> ppr typ
550
551------------------------------
552instance Ppr Pragma where
553    ppr (InlineP n inline rm phases)
554       = text "{-#"
555     <+> ppr inline
556     <+> ppr rm
557     <+> ppr phases
558     <+> ppr n
559     <+> text "#-}"
560    ppr (SpecialiseP n ty inline phases)
561       =   text "{-# SPECIALISE"
562       <+> maybe empty ppr inline
563       <+> ppr phases
564       <+> sep [ ppr n <+> dcolon
565               , nest 2 $ ppr ty ]
566       <+> text "#-}"
567    ppr (SpecialiseInstP inst)
568       = text "{-# SPECIALISE instance" <+> ppr inst <+> text "#-}"
569    ppr (RuleP n ty_bndrs tm_bndrs lhs rhs phases)
570       = sep [ text "{-# RULES" <+> pprString n <+> ppr phases
571             , nest 4 $ ppr_ty_forall ty_bndrs <+> ppr_tm_forall ty_bndrs
572                                               <+> ppr lhs
573             , nest 4 $ char '=' <+> ppr rhs <+> text "#-}" ]
574      where ppr_ty_forall Nothing      = empty
575            ppr_ty_forall (Just bndrs) = text "forall"
576                                         <+> fsep (map ppr bndrs)
577                                         <+> char '.'
578            ppr_tm_forall Nothing | null tm_bndrs = empty
579            ppr_tm_forall _ = text "forall"
580                              <+> fsep (map ppr tm_bndrs)
581                              <+> char '.'
582    ppr (AnnP tgt expr)
583       = text "{-# ANN" <+> target1 tgt <+> ppr expr <+> text "#-}"
584      where target1 ModuleAnnotation    = text "module"
585            target1 (TypeAnnotation t)  = text "type" <+> ppr t
586            target1 (ValueAnnotation v) = ppr v
587    ppr (LineP line file)
588       = text "{-# LINE" <+> int line <+> text (show file) <+> text "#-}"
589    ppr (CompleteP cls mty)
590       = text "{-# COMPLETE" <+> (fsep $ punctuate comma $ map ppr cls)
591                <+> maybe empty (\ty -> dcolon <+> ppr ty) mty
592
593------------------------------
594instance Ppr Inline where
595    ppr NoInline  = text "NOINLINE"
596    ppr Inline    = text "INLINE"
597    ppr Inlinable = text "INLINABLE"
598
599------------------------------
600instance Ppr RuleMatch where
601    ppr ConLike = text "CONLIKE"
602    ppr FunLike = empty
603
604------------------------------
605instance Ppr Phases where
606    ppr AllPhases       = empty
607    ppr (FromPhase i)   = brackets $ int i
608    ppr (BeforePhase i) = brackets $ char '~' <> int i
609
610------------------------------
611instance Ppr RuleBndr where
612    ppr (RuleVar n)         = ppr n
613    ppr (TypedRuleVar n ty) = parens $ ppr n <+> dcolon <+> ppr ty
614
615------------------------------
616instance Ppr Clause where
617    ppr (Clause ps rhs ds) = hsep (map (pprPat appPrec) ps) <+> pprBody True rhs
618                             $$ where_clause ds
619
620------------------------------
621instance Ppr Con where
622    ppr (NormalC c sts) = ppr c <+> sep (map pprBangType sts)
623
624    ppr (RecC c vsts)
625        = ppr c <+> braces (sep (punctuate comma $ map pprVarBangType vsts))
626
627    ppr (InfixC st1 c st2) = pprBangType st1
628                         <+> pprName' Infix c
629                         <+> pprBangType st2
630
631    ppr (ForallC ns ctxt (GadtC c sts ty))
632        = commaSepApplied c <+> dcolon <+> pprForall ns ctxt
633      <+> pprGadtRHS sts ty
634
635    ppr (ForallC ns ctxt (RecGadtC c vsts ty))
636        = commaSepApplied c <+> dcolon <+> pprForall ns ctxt
637      <+> pprRecFields vsts ty
638
639    ppr (ForallC ns ctxt con)
640        = pprForall ns ctxt <+> ppr con
641
642    ppr (GadtC c sts ty)
643        = commaSepApplied c <+> dcolon <+> pprGadtRHS sts ty
644
645    ppr (RecGadtC c vsts ty)
646        = commaSepApplied c <+> dcolon <+> pprRecFields vsts ty
647
648instance Ppr PatSynDir where
649  ppr Unidir        = text "<-"
650  ppr ImplBidir     = text "="
651  ppr (ExplBidir _) = text "<-"
652    -- the ExplBidir's clauses are pretty printed together with the
653    -- entire pattern synonym; so only print the direction here.
654
655instance Ppr PatSynArgs where
656  ppr (PrefixPatSyn args) = sep $ map ppr args
657  ppr (InfixPatSyn a1 a2) = ppr a1 <+> ppr a2
658  ppr (RecordPatSyn sels) = braces $ sep (punctuate comma (map ppr sels))
659
660commaSepApplied :: [Name] -> Doc
661commaSepApplied = commaSepWith (pprName' Applied)
662
663pprForall :: [TyVarBndr] -> Cxt -> Doc
664pprForall = pprForall' ForallInvis
665
666pprForallVis :: [TyVarBndr] -> Cxt -> Doc
667pprForallVis = pprForall' ForallVis
668
669pprForall' :: ForallVisFlag -> [TyVarBndr] -> Cxt -> Doc
670pprForall' fvf tvs cxt
671  -- even in the case without any tvs, there could be a non-empty
672  -- context cxt (e.g., in the case of pattern synonyms, where there
673  -- are multiple forall binders and contexts).
674  | [] <- tvs = pprCxt cxt
675  | otherwise = text "forall" <+> hsep (map ppr tvs)
676                              <+> separator <+> pprCxt cxt
677  where
678    separator = case fvf of
679                  ForallVis   -> text "->"
680                  ForallInvis -> char '.'
681
682pprRecFields :: [(Name, Strict, Type)] -> Type -> Doc
683pprRecFields vsts ty
684    = braces (sep (punctuate comma $ map pprVarBangType vsts))
685  <+> arrow <+> ppr ty
686
687pprGadtRHS :: [(Strict, Type)] -> Type -> Doc
688pprGadtRHS [] ty
689    = ppr ty
690pprGadtRHS sts ty
691    = sep (punctuate (space <> arrow) (map pprBangType sts))
692  <+> arrow <+> ppr ty
693
694------------------------------
695pprVarBangType :: VarBangType -> Doc
696-- Slight infelicity: with print non-atomic type with parens
697pprVarBangType (v, bang, t) = ppr v <+> dcolon <+> pprBangType (bang, t)
698
699------------------------------
700pprBangType :: BangType -> Doc
701-- Make sure we print
702--
703-- Con {-# UNPACK #-} a
704--
705-- rather than
706--
707-- Con {-# UNPACK #-}a
708--
709-- when there's no strictness annotation. If there is a strictness annotation,
710-- it's okay to not put a space between it and the type.
711pprBangType (bt@(Bang _ NoSourceStrictness), t) = ppr bt <+> pprParendType t
712pprBangType (bt, t) = ppr bt <> pprParendType t
713
714------------------------------
715instance Ppr Bang where
716    ppr (Bang su ss) = ppr su <+> ppr ss
717
718------------------------------
719instance Ppr SourceUnpackedness where
720    ppr NoSourceUnpackedness = empty
721    ppr SourceNoUnpack       = text "{-# NOUNPACK #-}"
722    ppr SourceUnpack         = text "{-# UNPACK #-}"
723
724------------------------------
725instance Ppr SourceStrictness where
726    ppr NoSourceStrictness = empty
727    ppr SourceLazy         = char '~'
728    ppr SourceStrict       = char '!'
729
730------------------------------
731instance Ppr DecidedStrictness where
732    ppr DecidedLazy   = empty
733    ppr DecidedStrict = char '!'
734    ppr DecidedUnpack = text "{-# UNPACK #-} !"
735
736------------------------------
737{-# DEPRECATED pprVarStrictType
738               "As of @template-haskell-2.11.0.0@, 'VarStrictType' has been replaced by 'VarBangType'. Please use 'pprVarBangType' instead." #-}
739pprVarStrictType :: (Name, Strict, Type) -> Doc
740pprVarStrictType = pprVarBangType
741
742------------------------------
743{-# DEPRECATED pprStrictType
744               "As of @template-haskell-2.11.0.0@, 'StrictType' has been replaced by 'BangType'. Please use 'pprBangType' instead." #-}
745pprStrictType :: (Strict, Type) -> Doc
746pprStrictType = pprBangType
747
748------------------------------
749pprParendType :: Type -> Doc
750pprParendType (VarT v)            = pprName' Applied v
751-- `Applied` is used here instead of `ppr` because of infix names (#13887)
752pprParendType (ConT c)            = pprName' Applied c
753pprParendType (TupleT 0)          = text "()"
754pprParendType (TupleT 1)          = pprParendType (ConT (tupleTypeName 1))
755pprParendType (TupleT n)          = parens (hcat (replicate (n-1) comma))
756pprParendType (UnboxedTupleT n)   = hashParens $ hcat $ replicate (n-1) comma
757pprParendType (UnboxedSumT arity) = hashParens $ hcat $ replicate (arity-1) bar
758pprParendType ArrowT              = parens (text "->")
759pprParendType ListT               = text "[]"
760pprParendType (LitT l)            = pprTyLit l
761pprParendType (PromotedT c)       = text "'" <> pprName' Applied c
762pprParendType (PromotedTupleT 0)  = text "'()"
763pprParendType (PromotedTupleT 1)  = pprParendType (PromotedT (tupleDataName 1))
764pprParendType (PromotedTupleT n)  = quoteParens (hcat (replicate (n-1) comma))
765pprParendType PromotedNilT        = text "'[]"
766pprParendType PromotedConsT       = text "'(:)"
767pprParendType StarT               = char '*'
768pprParendType ConstraintT         = text "Constraint"
769pprParendType (SigT ty k)         = parens (ppr ty <+> text "::" <+> ppr k)
770pprParendType WildCardT           = char '_'
771pprParendType (InfixT x n y)      = parens (ppr x <+> pprName' Infix n <+> ppr y)
772pprParendType t@(UInfixT {})      = parens (pprUInfixT t)
773pprParendType (ParensT t)         = ppr t
774pprParendType tuple | (TupleT n, args) <- split tuple
775                    , length args == n
776                    = parens (commaSep args)
777pprParendType (ImplicitParamT n t)= text ('?':n) <+> text "::" <+> ppr t
778pprParendType EqualityT           = text "(~)"
779pprParendType t@(ForallT {})      = parens (ppr t)
780pprParendType t@(ForallVisT {})   = parens (ppr t)
781pprParendType t@(AppT {})         = parens (ppr t)
782pprParendType t@(AppKindT {})     = parens (ppr t)
783
784pprUInfixT :: Type -> Doc
785pprUInfixT (UInfixT x n y) = pprUInfixT x <+> pprName' Infix n <+> pprUInfixT y
786pprUInfixT t               = ppr t
787
788instance Ppr Type where
789    ppr (ForallT tvars ctxt ty) = sep [pprForall tvars ctxt, ppr ty]
790    ppr (ForallVisT tvars ty)   = sep [pprForallVis tvars [], ppr ty]
791    ppr ty = pprTyApp (split ty)
792       -- Works, in a degnerate way, for SigT, and puts parens round (ty :: kind)
793       -- See Note [Pretty-printing kind signatures]
794instance Ppr TypeArg where
795    ppr (TANormal ty) = ppr ty
796    ppr (TyArg ki) = char '@' <> ppr ki
797
798pprParendTypeArg :: TypeArg -> Doc
799pprParendTypeArg (TANormal ty) = pprParendType ty
800pprParendTypeArg (TyArg ki) = char '@' <> pprParendType ki
801{- Note [Pretty-printing kind signatures]
802~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
803GHC's parser only recognises a kind signature in a type when there are
804parens around it.  E.g. the parens are required here:
805   f :: (Int :: *)
806   type instance F Int = (Bool :: *)
807So we always print a SigT with parens (see #10050). -}
808
809pprTyApp :: (Type, [TypeArg]) -> Doc
810pprTyApp (ArrowT, [TANormal arg1, TANormal arg2]) = sep [pprFunArgType arg1 <+> text "->", ppr arg2]
811pprTyApp (EqualityT, [TANormal arg1, TANormal arg2]) =
812    sep [pprFunArgType arg1 <+> text "~", ppr arg2]
813pprTyApp (ListT, [TANormal arg]) = brackets (ppr arg)
814pprTyApp (TupleT n, args)
815 | length args == n
816 = if n == 1
817   then pprTyApp (ConT (tupleTypeName 1), args)
818   else parens (commaSep args)
819pprTyApp (PromotedTupleT n, args)
820 | length args == n
821 = if n == 1
822   then pprTyApp (PromotedT (tupleDataName 1), args)
823   else quoteParens (commaSep args)
824pprTyApp (fun, args) = pprParendType fun <+> sep (map pprParendTypeArg args)
825
826pprFunArgType :: Type -> Doc    -- Should really use a precedence argument
827-- Everything except forall and (->) binds more tightly than (->)
828pprFunArgType ty@(ForallT {})                 = parens (ppr ty)
829pprFunArgType ty@(ForallVisT {})              = parens (ppr ty)
830pprFunArgType ty@((ArrowT `AppT` _) `AppT` _) = parens (ppr ty)
831pprFunArgType ty@(SigT _ _)                   = parens (ppr ty)
832pprFunArgType ty                              = ppr ty
833
834data ForallVisFlag = ForallVis   -- forall a -> {...}
835                   | ForallInvis -- forall a.   {...}
836  deriving Show
837
838data TypeArg = TANormal Type
839             | TyArg Kind
840
841split :: Type -> (Type, [TypeArg])    -- Split into function and args
842split t = go t []
843    where go (AppT t1 t2) args = go t1 (TANormal t2:args)
844          go (AppKindT ty ki) args = go ty (TyArg ki:args)
845          go ty           args = (ty, args)
846
847pprTyLit :: TyLit -> Doc
848pprTyLit (NumTyLit n) = integer n
849pprTyLit (StrTyLit s) = text (show s)
850
851instance Ppr TyLit where
852  ppr = pprTyLit
853
854------------------------------
855instance Ppr TyVarBndr where
856    ppr (PlainTV nm)    = ppr nm
857    ppr (KindedTV nm k) = parens (ppr nm <+> dcolon <+> ppr k)
858
859instance Ppr Role where
860    ppr NominalR          = text "nominal"
861    ppr RepresentationalR = text "representational"
862    ppr PhantomR          = text "phantom"
863    ppr InferR            = text "_"
864
865------------------------------
866pprCxt :: Cxt -> Doc
867pprCxt [] = empty
868pprCxt ts = ppr_cxt_preds ts <+> text "=>"
869
870ppr_cxt_preds :: Cxt -> Doc
871ppr_cxt_preds [] = empty
872ppr_cxt_preds [t@ImplicitParamT{}] = parens (ppr t)
873ppr_cxt_preds [t@ForallT{}] = parens (ppr t)
874ppr_cxt_preds [t] = ppr t
875ppr_cxt_preds ts = parens (commaSep ts)
876
877------------------------------
878instance Ppr Range where
879    ppr = brackets . pprRange
880        where pprRange :: Range -> Doc
881              pprRange (FromR e) = ppr e <> text ".."
882              pprRange (FromThenR e1 e2) = ppr e1 <> text ","
883                                        <> ppr e2 <> text ".."
884              pprRange (FromToR e1 e2) = ppr e1 <> text ".." <> ppr e2
885              pprRange (FromThenToR e1 e2 e3) = ppr e1 <> text ","
886                                             <> ppr e2 <> text ".."
887                                             <> ppr e3
888
889------------------------------
890where_clause :: [Dec] -> Doc
891where_clause [] = empty
892where_clause ds = nest nestDepth $ text "where" <+> vcat (map (ppr_dec False) ds)
893
894showtextl :: Show a => a -> Doc
895showtextl = text . map toLower . show
896
897hashParens :: Doc -> Doc
898hashParens d = text "(# " <> d <> text " #)"
899
900quoteParens :: Doc -> Doc
901quoteParens d = text "'(" <> d <> text ")"
902
903-----------------------------
904instance Ppr Loc where
905  ppr (Loc { loc_module = md
906           , loc_package = pkg
907           , loc_start = (start_ln, start_col)
908           , loc_end = (end_ln, end_col) })
909    = hcat [ text pkg, colon, text md, colon
910           , parens $ int start_ln <> comma <> int start_col
911           , text "-"
912           , parens $ int end_ln <> comma <> int end_col ]
913
914-- Takes a list of printable things and prints them separated by commas followed
915-- by space.
916commaSep :: Ppr a => [a] -> Doc
917commaSep = commaSepWith ppr
918
919-- Takes a list of things and prints them with the given pretty-printing
920-- function, separated by commas followed by space.
921commaSepWith :: (a -> Doc) -> [a] -> Doc
922commaSepWith pprFun = sep . punctuate comma . map pprFun
923
924-- Takes a list of printable things and prints them separated by semicolons
925-- followed by space.
926semiSep :: Ppr a => [a] -> Doc
927semiSep = sep . punctuate semi . map ppr
928
929-- Prints out the series of vertical bars that wraps an expression or pattern
930-- used in an unboxed sum.
931unboxedSumBars :: Doc -> SumAlt -> SumArity -> Doc
932unboxedSumBars d alt arity = hashParens $
933    bars (alt-1) <> d <> bars (arity - alt)
934  where
935    bars i = hsep (replicate i bar)
936
937-- Text containing the vertical bar character.
938bar :: Doc
939bar = char '|'
940