summaryrefslogtreecommitdiff
path: root/compiler/hsSyn/HsDecls.lhs
blob: 8ff39857c610ab4d4af4e3ef09c914af3818651a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[HsDecls]{Abstract syntax: global declarations}

Definitions for: @TyDecl@ and @oCnDecl@, @ClassDecl@,
@InstDecl@, @DefaultDecl@ and @ForeignDecl@.

\begin{code}
module HsDecls (
	HsDecl(..), LHsDecl, TyClDecl(..), LTyClDecl, 
	InstDecl(..), LInstDecl, NewOrData(..),
	RuleDecl(..), LRuleDecl, RuleBndr(..),
	DefaultDecl(..), LDefaultDecl, SpliceDecl(..),
	ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
	CImportSpec(..), FoType(..),
	ConDecl(..), ResType(..), LConDecl,	
	DeprecDecl(..),  LDeprecDecl,
	HsGroup(..),  emptyRdrGroup, emptyRnGroup, appendGroups,
	tcdName, tyClDeclNames, tyClDeclTyVars,
	isClassDecl, isSynDecl, isDataDecl, 
	countTyClDecls,
	conDetailsTys,
	collectRuleBndrSigTys, 
    ) where

#include "HsVersions.h"

-- friends:
import {-# SOURCE #-}	HsExpr( HsExpr, pprExpr )
	-- Because Expr imports Decls via HsBracket

import HsBinds		( HsValBinds(..), HsBind, LHsBinds, plusHsValBinds,
			  Sig(..), LSig, LFixitySig, pprLHsBinds,
			  emptyValBindsIn, emptyValBindsOut )
import HsPat		( HsConDetails(..), hsConArgs )
import HsImpExp		( pprHsVar )
import HsTypes
import NameSet          ( NameSet )
import HscTypes		( DeprecTxt )
import CoreSyn		( RuleName )
import Kind		( Kind, pprKind )
import BasicTypes	( Activation(..) )
import ForeignCall	( CCallTarget(..), DNCallSpec, CCallConv, Safety,
			  CExportSpec(..), CLabelString ) 

-- others:
import FunDeps		( pprFundeps )
import Class		( FunDep )
import Outputable	
import Util		( count )
import SrcLoc		( Located(..), unLoc, noLoc )
import FastString
\end{code}


%************************************************************************
%*									*
\subsection[HsDecl]{Declarations}
%*									*
%************************************************************************

\begin{code}
type LHsDecl id = Located (HsDecl id)

data HsDecl id
  = TyClD	(TyClDecl id)
  | InstD	(InstDecl  id)
  | ValD	(HsBind id)
  | SigD	(Sig id)
  | DefD	(DefaultDecl id)
  | ForD        (ForeignDecl id)
  | DeprecD	(DeprecDecl id)
  | RuleD	(RuleDecl id)
  | SpliceD	(SpliceDecl id)

-- NB: all top-level fixity decls are contained EITHER
-- EITHER SigDs
-- OR     in the ClassDecls in TyClDs
--
-- The former covers
-- 	a) data constructors
-- 	b) class methods (but they can be also done in the
-- 		signatures of class decls)
--	c) imported functions (that have an IfacSig)
--	d) top level decls
--
-- The latter is for class methods only

-- A [HsDecl] is categorised into a HsGroup before being 
-- fed to the renamer.
data HsGroup id
  = HsGroup {
	hs_valds  :: HsValBinds id,
	hs_tyclds :: [LTyClDecl id],
	hs_instds :: [LInstDecl id],

	hs_fixds  :: [LFixitySig id],
		-- Snaffled out of both top-level fixity signatures,
		-- and those in class declarations

	hs_defds  :: [LDefaultDecl id],
	hs_fords  :: [LForeignDecl id],
	hs_depds  :: [LDeprecDecl id],
	hs_ruleds :: [LRuleDecl id]
  }

emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup a
emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
emptyRnGroup  = emptyGroup { hs_valds = emptyValBindsOut }

emptyGroup = HsGroup { hs_tyclds = [], hs_instds = [],
		       hs_fixds = [], hs_defds = [], hs_fords = [], 
		       hs_depds = [], hs_ruleds = [],
		       hs_valds = error "emptyGroup hs_valds: Can't happen" }

appendGroups :: HsGroup a -> HsGroup a -> HsGroup a
appendGroups 
    HsGroup { 
	hs_valds  = val_groups1,
	hs_tyclds = tyclds1, 
	hs_instds = instds1,
	hs_fixds  = fixds1, 
	hs_defds  = defds1,
	hs_fords  = fords1, 
	hs_depds  = depds1,
	hs_ruleds = rulds1 }
    HsGroup { 
	hs_valds  = val_groups2,
	hs_tyclds = tyclds2, 
	hs_instds = instds2,
	hs_fixds  = fixds2, 
	hs_defds  = defds2,
	hs_fords  = fords2, 
	hs_depds  = depds2,
	hs_ruleds = rulds2 }
  = 
    HsGroup { 
	hs_valds  = val_groups1 `plusHsValBinds` val_groups2,
	hs_tyclds = tyclds1 ++ tyclds2, 
	hs_instds = instds1 ++ instds2,
	hs_fixds  = fixds1 ++ fixds2, 
	hs_defds  = defds1 ++ defds2,
	hs_fords  = fords1 ++ fords2, 
	hs_depds  = depds1 ++ depds2,
	hs_ruleds = rulds1 ++ rulds2 }
\end{code}

\begin{code}
instance OutputableBndr name => Outputable (HsDecl name) where
    ppr (TyClD dcl)  = ppr dcl
    ppr (ValD binds) = ppr binds
    ppr (DefD def)   = ppr def
    ppr (InstD inst) = ppr inst
    ppr (ForD fd)    = ppr fd
    ppr (SigD sd)    = ppr sd
    ppr (RuleD rd)   = ppr rd
    ppr (DeprecD dd) = ppr dd
    ppr (SpliceD dd) = ppr dd

instance OutputableBndr name => Outputable (HsGroup name) where
    ppr (HsGroup { hs_valds  = val_decls,
		   hs_tyclds = tycl_decls,
		   hs_instds = inst_decls,
		   hs_fixds  = fix_decls,
		   hs_depds  = deprec_decls,
		   hs_fords  = foreign_decls,
		   hs_defds  = default_decls,
		   hs_ruleds = rule_decls })
	= vcat [ppr_ds fix_decls, ppr_ds default_decls, 
		ppr_ds deprec_decls, ppr_ds rule_decls,
		ppr val_decls,
		ppr_ds tycl_decls, ppr_ds inst_decls,
		ppr_ds foreign_decls]
	where
	  ppr_ds [] = empty
	  ppr_ds ds = text "" $$ vcat (map ppr ds)

data SpliceDecl id = SpliceDecl (Located (HsExpr id))	-- Top level splice

instance OutputableBndr name => Outputable (SpliceDecl name) where
   ppr (SpliceDecl e) = ptext SLIT("$") <> parens (pprExpr (unLoc e))
\end{code}


%************************************************************************
%*									*
\subsection[TyDecl]{@data@, @newtype@ or @type@ (synonym) type declaration}
%*									*
%************************************************************************

		--------------------------------
			THE NAMING STORY
		--------------------------------

Here is the story about the implicit names that go with type, class,
and instance decls.  It's a bit tricky, so pay attention!

"Implicit" (or "system") binders
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Each data type decl defines 
	a worker name for each constructor
	to-T and from-T convertors
  Each class decl defines
	a tycon for the class
	a data constructor for that tycon
	the worker for that constructor
	a selector for each superclass

All have occurrence names that are derived uniquely from their parent
declaration.

None of these get separate definitions in an interface file; they are
fully defined by the data or class decl.  But they may *occur* in
interface files, of course.  Any such occurrence must haul in the
relevant type or class decl.

Plan of attack:
 - Ensure they "point to" the parent data/class decl 
   when loading that decl from an interface file
   (See RnHiFiles.getSysBinders)

 - When typechecking the decl, we build the implicit TyCons and Ids.
   When doing so we look them up in the name cache (RnEnv.lookupSysName),
   to ensure correct module and provenance is set

These are the two places that we have to conjure up the magic derived
names.  (The actual magic is in OccName.mkWorkerOcc, etc.)

Default methods
~~~~~~~~~~~~~~~
 - Occurrence name is derived uniquely from the method name
   E.g. $dmmax

 - If there is a default method name at all, it's recorded in
   the ClassOpSig (in HsBinds), in the DefMeth field.
   (DefMeth is defined in Class.lhs)

Source-code class decls and interface-code class decls are treated subtly
differently, which has given me a great deal of confusion over the years.
Here's the deal.  (We distinguish the two cases because source-code decls
have (Just binds) in the tcdMeths field, whereas interface decls have Nothing.

In *source-code* class declarations:

 - When parsing, every ClassOpSig gets a DefMeth with a suitable RdrName
   This is done by RdrHsSyn.mkClassOpSigDM

 - The renamer renames it to a Name

 - During typechecking, we generate a binding for each $dm for 
   which there's a programmer-supplied default method:
	class Foo a where
	  op1 :: <type>
	  op2 :: <type>
	  op1 = ...
   We generate a binding for $dmop1 but not for $dmop2.
   The Class for Foo has a NoDefMeth for op2 and a DefMeth for op1.
   The Name for $dmop2 is simply discarded.

In *interface-file* class declarations:
  - When parsing, we see if there's an explicit programmer-supplied default method
    because there's an '=' sign to indicate it:
	class Foo a where
	  op1 = :: <type>	-- NB the '='
  	  op2   :: <type>
    We use this info to generate a DefMeth with a suitable RdrName for op1,
    and a NoDefMeth for op2
  - The interface file has a separate definition for $dmop1, with unfolding etc.
  - The renamer renames it to a Name.
  - The renamer treats $dmop1 as a free variable of the declaration, so that
    the binding for $dmop1 will be sucked in.  (See RnHsSyn.tyClDeclFVs)  
    This doesn't happen for source code class decls, because they *bind* the default method.

Dictionary functions
~~~~~~~~~~~~~~~~~~~~
Each instance declaration gives rise to one dictionary function binding.

The type checker makes up new source-code instance declarations
(e.g. from 'deriving' or generic default methods --- see
TcInstDcls.tcInstDecls1).  So we can't generate the names for
dictionary functions in advance (we don't know how many we need).

On the other hand for interface-file instance declarations, the decl
specifies the name of the dictionary function, and it has a binding elsewhere
in the interface file:
	instance {Eq Int} = dEqInt
	dEqInt :: {Eq Int} <pragma info>

So again we treat source code and interface file code slightly differently.

Source code:
  - Source code instance decls have a Nothing in the (Maybe name) field
    (see data InstDecl below)

  - The typechecker makes up a Local name for the dict fun for any source-code
    instance decl, whether it comes from a source-code instance decl, or whether
    the instance decl is derived from some other construct (e.g. 'deriving').

  - The occurrence name it chooses is derived from the instance decl (just for 
    documentation really) --- e.g. dNumInt.  Two dict funs may share a common
    occurrence name, but will have different uniques.  E.g.
	instance Foo [Int]  where ...
	instance Foo [Bool] where ...
    These might both be dFooList

  - The CoreTidy phase externalises the name, and ensures the occurrence name is
    unique (this isn't special to dict funs).  So we'd get dFooList and dFooList1.

  - We can take this relaxed approach (changing the occurrence name later) 
    because dict fun Ids are not captured in a TyCon or Class (unlike default
    methods, say).  Instead, they are kept separately in the InstEnv.  This
    makes it easy to adjust them after compiling a module.  (Once we've finished
    compiling that module, they don't change any more.)


Interface file code:
  - The instance decl gives the dict fun name, so the InstDecl has a (Just name)
    in the (Maybe name) field.

  - RnHsSyn.instDeclFVs treats the dict fun name as free in the decl, so that we
    suck in the dfun binding


\begin{code}
-- TyClDecls are precisely the kind of declarations that can 
-- appear in interface files; or (internally) in GHC's interface
-- for a module.  That's why (despite the misnomer) IfaceSig and ForeignType
-- are both in TyClDecl

type LTyClDecl name = Located (TyClDecl name)

data TyClDecl name
  = ForeignType { 
		tcdLName    :: Located name,
		tcdExtName  :: Maybe FastString,
		tcdFoType   :: FoType
  }

  | TyData {	tcdND     :: NewOrData,
		tcdCtxt   :: LHsContext name,	 	-- Context
		tcdLName  :: Located name,	 	-- Type constructor
		tcdTyVars :: [LHsTyVarBndr name], 	-- Type variables
		tcdKindSig :: Maybe Kind,		-- Optional kind sig; 
							-- (only for the 'where' form)

		tcdCons	  :: [LConDecl name],	 	-- Data constructors
			-- For data T a = T1 | T2 a          the LConDecls all have ResTyH98
			-- For data T a where { T1 :: T a }  the LConDecls all have ResTyGADT

		tcdDerivs :: Maybe [LHsType name]
			-- Derivings; Nothing => not specified
			-- 	      Just [] => derive exactly what is asked
			-- These "types" must be of form
			--	forall ab. C ty1 ty2
			-- Typically the foralls and ty args are empty, but they
			-- are non-empty for the newtype-deriving case
    }

  | TySynonym {	tcdLName  :: Located name,	        -- type constructor
		tcdTyVars :: [LHsTyVarBndr name],	-- type variables
		tcdSynRhs :: LHsType name	        -- synonym expansion
    }

  | ClassDecl {	tcdCtxt    :: LHsContext name, 	 	-- Context...
		tcdLName   :: Located name,	    	-- Name of the class
		tcdTyVars  :: [LHsTyVarBndr name],	-- Class type variables
		tcdFDs     :: [Located (FunDep name)],	-- Functional deps
		tcdSigs    :: [LSig name],		-- Methods' signatures
		tcdMeths   :: LHsBinds name		-- Default methods
    }

data NewOrData
  = NewType  	-- "newtype Blah ..."
  | DataType 	-- "data Blah ..."
  deriving( Eq )	-- Needed because Demand derives Eq
\end{code}

Simple classifiers

\begin{code}
isDataDecl, isSynDecl, isClassDecl :: TyClDecl name -> Bool

isSynDecl (TySynonym {}) = True
isSynDecl other		 = False

isDataDecl (TyData {}) = True
isDataDecl other       = False

isClassDecl (ClassDecl {}) = True
isClassDecl other	   = False
\end{code}

Dealing with names

\begin{code}
tcdName :: TyClDecl name -> name
tcdName decl = unLoc (tcdLName decl)

tyClDeclNames :: Eq name => TyClDecl name -> [Located name]
-- Returns all the *binding* names of the decl, along with their SrcLocs
-- The first one is guaranteed to be the name of the decl
-- For record fields, the first one counts as the SrcLoc
-- We use the equality to filter out duplicate field names

tyClDeclNames (TySynonym   {tcdLName = name})  = [name]
tyClDeclNames (ForeignType {tcdLName = name})  = [name]

tyClDeclNames (ClassDecl {tcdLName = cls_name, tcdSigs = sigs})
  = cls_name : [n | L _ (TypeSig n _) <- sigs]

tyClDeclNames (TyData {tcdLName = tc_name, tcdCons = cons})
  = tc_name : conDeclsNames (map unLoc cons)

tyClDeclTyVars (TySynonym {tcdTyVars = tvs}) = tvs
tyClDeclTyVars (TyData    {tcdTyVars = tvs}) = tvs
tyClDeclTyVars (ClassDecl {tcdTyVars = tvs}) = tvs
tyClDeclTyVars (ForeignType {})		     = []
\end{code}

\begin{code}
countTyClDecls :: [TyClDecl name] -> (Int, Int, Int, Int)
	-- class, data, newtype, synonym decls
countTyClDecls decls 
 = (count isClassDecl     decls,
    count isSynDecl       decls,
    count isDataTy        decls,
    count isNewTy         decls) 
 where
   isDataTy TyData{tcdND=DataType} = True
   isDataTy _                      = False
   
   isNewTy TyData{tcdND=NewType} = True
   isNewTy _                     = False
\end{code}

\begin{code}
instance OutputableBndr name
	      => Outputable (TyClDecl name) where

    ppr (ForeignType {tcdLName = ltycon})
	= hsep [ptext SLIT("foreign import type dotnet"), ppr ltycon]

    ppr (TySynonym {tcdLName = ltycon, tcdTyVars = tyvars, tcdSynRhs = mono_ty})
      = hang (ptext SLIT("type") <+> pp_decl_head [] ltycon tyvars <+> equals)
	     4 (ppr mono_ty)

    ppr (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = ltycon,
		 tcdTyVars = tyvars, tcdKindSig = mb_sig, tcdCons = condecls, 
		 tcdDerivs = derivings})
      = pp_tydecl (ppr new_or_data <+> pp_decl_head (unLoc context) ltycon tyvars <+> ppr_sig mb_sig)
		  (pp_condecls condecls)
		  derivings
      where
	ppr_sig Nothing = empty
	ppr_sig (Just kind) = dcolon <+> pprKind kind

    ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars, tcdFDs = fds,
		    tcdSigs = sigs, tcdMeths = methods})
      | null sigs	-- No "where" part
      = top_matter

      | otherwise	-- Laid out
      = sep [hsep [top_matter, ptext SLIT("where {")],
	     nest 4 (sep [sep (map ppr_sig sigs), ppr methods, char '}'])]
      where
        top_matter  = ptext SLIT("class") <+> pp_decl_head (unLoc context) lclas tyvars <+> pprFundeps (map unLoc fds)
	ppr_sig sig = ppr sig <> semi

pp_decl_head :: OutputableBndr name
   => HsContext name
   -> Located name
   -> [LHsTyVarBndr name]
   -> SDoc
pp_decl_head context thing tyvars
  = hsep [pprHsContext context, ppr thing, interppSP tyvars]
pp_condecls cs@(L _ ConDecl{ con_res = ResTyGADT _ } : _) -- In GADT syntax
  = hang (ptext SLIT("where")) 2 (vcat (map ppr cs))
pp_condecls cs 			  -- In H98 syntax
  = equals <+> sep (punctuate (ptext SLIT(" |")) (map ppr cs))

pp_tydecl pp_head pp_decl_rhs derivings
  = hang pp_head 4 (sep [
	pp_decl_rhs,
	case derivings of
	  Nothing 	   -> empty
	  Just ds	   -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
    ])

instance Outputable NewOrData where
  ppr NewType  = ptext SLIT("newtype")
  ppr DataType = ptext SLIT("data")
\end{code}


%************************************************************************
%*									*
\subsection[ConDecl]{A data-constructor declaration}
%*									*
%************************************************************************

\begin{code}
type LConDecl name = Located (ConDecl name)

-- data T b = forall a. Eq a => MkT a b
--   MkT :: forall b a. Eq a => MkT a b

-- data T b where
--	MkT1 :: Int -> T Int

-- data T = Int `MkT` Int
--	  | MkT2

-- data T a where
--	Int `MkT` Int :: T Int

data ConDecl name
  = ConDecl
    { con_name      :: Located name	    -- Constructor name; this is used for the
                                            -- DataCon itself, and for the user-callable wrapper Id

    , con_explicit  :: HsExplicitForAll     -- Is there an user-written forall? (cf. HStypes.HsForAllTy)

    , con_qvars     :: [LHsTyVarBndr name]  -- ResTyH98: the constructor's existential type variables
					    -- ResTyGADT:    all the constructor's quantified type variables

    , con_cxt       :: LHsContext name      -- The context.  This *does not* include the
					    -- "stupid theta" which lives only in the TyData decl

    , con_details   :: HsConDetails name (LBangType name)	-- The main payload

    , con_res       :: ResType name         -- Result type of the constructor
    }

data ResType name
   = ResTyH98		-- Constructor was declared using Haskell 98 syntax
   | ResTyGADT (LHsType name)	-- Constructor was declared using GADT-style syntax,
				--	and here is its result type
\end{code}

\begin{code}
conDeclsNames :: Eq name => [ConDecl name] -> [Located name]
  -- See tyClDeclNames for what this does
  -- The function is boringly complicated because of the records
  -- And since we only have equality, we have to be a little careful
conDeclsNames cons
  = snd (foldl do_one ([], []) cons)
  where
    do_one (flds_seen, acc) (ConDecl { con_name = lname, con_details = RecCon flds })
	= (map unLoc new_flds ++ flds_seen, lname : [f | f <- new_flds] ++ acc)
	where
	  new_flds = [ f | (f,_) <- flds, not (unLoc f `elem` flds_seen) ]

    do_one (flds_seen, acc) c
	= (flds_seen, (con_name c):acc)

conDetailsTys details = map getBangType (hsConArgs details)
\end{code}
  

\begin{code}
instance (OutputableBndr name) => Outputable (ConDecl name) where
    ppr = pprConDecl

pprConDecl (ConDecl con expl tvs cxt details ResTyH98)
  = sep [pprHsForAll expl tvs cxt, ppr_details con details]
  where
    ppr_details con (InfixCon t1 t2) = hsep [ppr t1, pprHsVar con, ppr t2]
    ppr_details con (PrefixCon tys)  = hsep (pprHsVar con : map ppr tys)
    ppr_details con (RecCon fields)  = ppr con <+> ppr_fields fields

pprConDecl (ConDecl con expl tvs cxt details (ResTyGADT res_ty))
  = sep [pprHsForAll expl tvs cxt, ppr con <+> ppr_details details]
  where
    ppr_details (PrefixCon arg_tys) = dcolon <+> ppr (foldr mk_fun_ty res_ty arg_tys)
    ppr_details (RecCon fields)     = ppr fields <+> dcolon <+> ppr res_ty

    mk_fun_ty a b = noLoc (HsFunTy a b)

ppr_fields fields = braces (sep (punctuate comma (map ppr_field fields)))
ppr_field (n, ty) = ppr n <+> dcolon <+> ppr ty
\end{code}

%************************************************************************
%*									*
\subsection[InstDecl]{An instance declaration
%*									*
%************************************************************************

\begin{code}
type LInstDecl name = Located (InstDecl name)

data InstDecl name
  = InstDecl	(LHsType name)	-- Context => Class Instance-type
				-- Using a polytype means that the renamer conveniently
				-- figures out the quantified type variables for us.
		(LHsBinds name)
		[LSig name]		-- User-supplied pragmatic info

instance (OutputableBndr name) => Outputable (InstDecl name) where

    ppr (InstDecl inst_ty binds uprags)
      = vcat [hsep [ptext SLIT("instance"), ppr inst_ty, ptext SLIT("where")],
	      nest 4 (ppr uprags),
	      nest 4 (pprLHsBinds binds) ]
\end{code}

%************************************************************************
%*									*
\subsection[DefaultDecl]{A @default@ declaration}
%*									*
%************************************************************************

There can only be one default declaration per module, but it is hard
for the parser to check that; we pass them all through in the abstract
syntax, and that restriction must be checked in the front end.

\begin{code}
type LDefaultDecl name = Located (DefaultDecl name)

data DefaultDecl name
  = DefaultDecl	[LHsType name]

instance (OutputableBndr name)
	      => Outputable (DefaultDecl name) where

    ppr (DefaultDecl tys)
      = ptext SLIT("default") <+> parens (interpp'SP tys)
\end{code}

%************************************************************************
%*									*
\subsection{Foreign function interface declaration}
%*									*
%************************************************************************

\begin{code}

-- foreign declarations are distinguished as to whether they define or use a
-- Haskell name
--
--  * the Boolean value indicates whether the pre-standard deprecated syntax
--   has been used
--
type LForeignDecl name = Located (ForeignDecl name)

data ForeignDecl name
  = ForeignImport (Located name) (LHsType name) ForeignImport Bool  -- defines name
  | ForeignExport (Located name) (LHsType name) ForeignExport Bool  -- uses name

-- specification of an imported external entity in dependence on the calling
-- convention 
--
data ForeignImport = -- import of a C entity
		     --
                     --  * the two strings specifying a header file or library
                     --   may be empty, which indicates the absence of a
                     --   header or object specification (both are not used
                     --   in the case of `CWrapper' and when `CFunction'
                     --   has a dynamic target)
		     --
		     --  * the calling convention is irrelevant for code
		     --   generation in the case of `CLabel', but is needed
		     --   for pretty printing 
		     --
		     --  * `Safety' is irrelevant for `CLabel' and `CWrapper'
		     --
		     CImport  CCallConv	      -- ccall or stdcall
			      Safety	      -- safe or unsafe
			      FastString      -- name of C header
			      FastString      -- name of library object
			      CImportSpec     -- details of the C entity

                     -- import of a .NET function
		     --
		   | DNImport DNCallSpec

-- details of an external C entity
--
data CImportSpec = CLabel    CLabelString     -- import address of a C label
		 | CFunction CCallTarget      -- static or dynamic function
		 | CWrapper		      -- wrapper to expose closures
					      -- (former f.e.d.)

-- specification of an externally exported entity in dependence on the calling
-- convention
--
data ForeignExport = CExport  CExportSpec    -- contains the calling convention
		   | DNExport		     -- presently unused

-- abstract type imported from .NET
--
data FoType = DNType 		-- In due course we'll add subtype stuff
	    deriving (Eq)	-- Used for equality instance for TyClDecl


-- pretty printing of foreign declarations
--

instance OutputableBndr name => Outputable (ForeignDecl name) where
  ppr (ForeignImport n ty fimport _) =
    ptext SLIT("foreign import") <+> ppr fimport <+> 
    ppr n <+> dcolon <+> ppr ty
  ppr (ForeignExport n ty fexport _) =
    ptext SLIT("foreign export") <+> ppr fexport <+> 
    ppr n <+> dcolon <+> ppr ty

instance Outputable ForeignImport where
  ppr (DNImport			        spec) = 
    ptext SLIT("dotnet") <+> ppr spec
  ppr (CImport  cconv safety header lib spec) =
    ppr cconv <+> ppr safety <+> 
    char '"' <> pprCEntity header lib spec <> char '"'
    where
      pprCEntity header lib (CLabel lbl) = 
        ptext SLIT("static") <+> ftext header <+> char '&' <>
	pprLib lib <> ppr lbl
      pprCEntity header lib (CFunction (StaticTarget lbl)) = 
        ptext SLIT("static") <+> ftext header <+> char '&' <>
	pprLib lib <> ppr lbl
      pprCEntity header lib (CFunction (DynamicTarget)) = 
        ptext SLIT("dynamic")
      pprCEntity _      _   (CWrapper) = ptext SLIT("wrapper")
      --
      pprLib lib | nullFS lib = empty
		 | otherwise  = char '[' <> ppr lib <> char ']'

instance Outputable ForeignExport where
  ppr (CExport  (CExportStatic lbl cconv)) = 
    ppr cconv <+> char '"' <> ppr lbl <> char '"'
  ppr (DNExport                          ) = 
    ptext SLIT("dotnet") <+> ptext SLIT("\"<unused>\"")

instance Outputable FoType where
  ppr DNType = ptext SLIT("type dotnet")
\end{code}


%************************************************************************
%*									*
\subsection{Transformation rules}
%*									*
%************************************************************************

\begin{code}
type LRuleDecl name = Located (RuleDecl name)

data RuleDecl name
  = HsRule			-- Source rule
	RuleName		-- Rule name
	Activation
	[RuleBndr name]		-- Forall'd vars; after typechecking this includes tyvars
	(Located (HsExpr name))	-- LHS
        NameSet                 -- Free-vars from the LHS
	(Located (HsExpr name))	-- RHS
        NameSet                 -- Free-vars from the RHS

data RuleBndr name
  = RuleBndr (Located name)
  | RuleBndrSig (Located name) (LHsType name)

collectRuleBndrSigTys :: [RuleBndr name] -> [LHsType name]
collectRuleBndrSigTys bndrs = [ty | RuleBndrSig _ ty <- bndrs]

instance OutputableBndr name => Outputable (RuleDecl name) where
  ppr (HsRule name act ns lhs fv_lhs rhs fv_rhs)
	= sep [text "{-# RULES" <+> doubleQuotes (ftext name) <+> ppr act,
	       nest 4 (pp_forall <+> pprExpr (unLoc lhs)), 
	       nest 4 (equals <+> pprExpr (unLoc rhs) <+> text "#-}") ]
	where
	  pp_forall | null ns   = empty
		    | otherwise	= text "forall" <+> fsep (map ppr ns) <> dot

instance OutputableBndr name => Outputable (RuleBndr name) where
   ppr (RuleBndr name) = ppr name
   ppr (RuleBndrSig name ty) = ppr name <> dcolon <> ppr ty
\end{code}


%************************************************************************
%*									*
\subsection[DeprecDecl]{Deprecations}
%*									*
%************************************************************************

We use exported entities for things to deprecate.

\begin{code}
type LDeprecDecl name = Located (DeprecDecl name)

data DeprecDecl name = Deprecation name DeprecTxt

instance OutputableBndr name => Outputable (DeprecDecl name) where
    ppr (Deprecation thing txt)
      = hsep [text "{-# DEPRECATED", ppr thing, doubleQuotes (ppr txt), text "#-}"]
\end{code}