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