HsDecls.hs 86.5 KB
Newer Older
Austin Seipp's avatar
Austin Seipp committed
1 2 3 4
{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-}
5

6 7
{-# LANGUAGE DeriveDataTypeable, DeriveFunctor, DeriveFoldable,
             DeriveTraversable #-}
8 9 10 11 12
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE UndecidableInstances #-} -- Note [Pass sensitive types]
                                      -- in module PlaceHolder
{-# LANGUAGE ConstraintKinds #-}
13
{-# LANGUAGE TypeFamilies #-}
14

15 16
-- | Abstract syntax of global declarations.
--
17
-- Definitions for: @SynDecl@ and @ConDecl@, @ClassDecl@,
18
-- @InstDecl@, @DefaultDecl@ and @ForeignDecl@.
19
module HsDecls (
20
  -- * Toplevel declarations
21
  HsDecl(..), LHsDecl, HsDataDefn(..), HsDeriving,
22
  HsDerivingClause(..), LHsDerivingClause, NewOrData(..), newOrDataToFlavour,
23

24
  -- ** Class or type declarations
25
  TyClDecl(..), LTyClDecl,
26 27
  TyClGroup(..), mkTyClGroup, emptyTyClGroup,
  tyClGroupTyClDecls, tyClGroupInstDecls, tyClGroupRoleDecls,
28 29
  isClassDecl, isDataDecl, isSynDecl, tcdName,
  isFamilyDecl, isTypeFamilyDecl, isDataFamilyDecl,
30
  isOpenTypeFamilyInfo, isClosedTypeFamilyInfo,
31 32 33
  tyFamInstDeclName, tyFamInstDeclLName,
  countTyClDecls, pprTyClDeclFlavour,
  tyClDeclLName, tyClDeclTyVars,
34
  hsDeclHasCusk, famDeclHasCusk,
35
  FamilyDecl(..), LFamilyDecl,
36

37
  -- ** Instance declarations
38
  InstDecl(..), LInstDecl, FamilyInfo(..),
39
  TyFamInstDecl(..), LTyFamInstDecl, instDeclDataFamInsts,
40
  DataFamInstDecl(..), LDataFamInstDecl, pprDataFamInstFlavour, pprFamInstLHS,
41 42
  FamInstEqn, LFamInstEqn, FamEqn(..),
  TyFamInstEqn, LTyFamInstEqn, TyFamDefltEqn, LTyFamDefltEqn,
Alan Zimmerman's avatar
Alan Zimmerman committed
43
  HsTyPats,
44
  LClsInstDecl, ClsInstDecl(..),
45

46 47 48
  -- ** Standalone deriving declarations
  DerivDecl(..), LDerivDecl,
  -- ** @RULE@ declarations
Alan Zimmerman's avatar
Alan Zimmerman committed
49
  LRuleDecls,RuleDecls(..),RuleDecl(..), LRuleDecl, RuleBndr(..),LRuleBndr,
50
  collectRuleBndrSigTys,
51
  flattenRuleDecls, pprFullRuleName,
52 53
  -- ** @VECTORISE@ declarations
  VectDecl(..), LVectDecl,
54
  lvectDeclName, lvectInstDecl,
55 56
  -- ** @default@ declarations
  DefaultDecl(..), LDefaultDecl,
57
  -- ** Template haskell declaration splice
58
  SpliceExplicitFlag(..),
59
  SpliceDecl(..), LSpliceDecl,
60 61
  -- ** Foreign function interface declarations
  ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
62
  noForeignImportCoercionYet, noForeignExportCoercionYet,
63
  CImportSpec(..),
64
  -- ** Data-constructor declarations
Alan Zimmerman's avatar
Alan Zimmerman committed
65
  ConDecl(..), LConDecl,
66 67
  HsConDeclDetails, hsConDeclArgTys, hsConDeclTheta,
  getConNames, getConArgs,
68 69 70 71
  -- ** Document comments
  DocDecl(..), LDocDecl, docDeclDoc,
  -- ** Deprecations
  WarnDecl(..),  LWarnDecl,
Alan Zimmerman's avatar
Alan Zimmerman committed
72
  WarnDecls(..), LWarnDecls,
73
  -- ** Annotations
74
  AnnDecl(..), LAnnDecl,
75
  AnnProvenance(..), annProvenanceName_maybe,
76 77
  -- ** Role annotations
  RoleAnnotDecl(..), LRoleAnnotDecl, roleAnnotDeclName,
Jan Stolarek's avatar
Jan Stolarek committed
78 79 80
  -- ** Injective type families
  FamilyResultSig(..), LFamilyResultSig, InjectivityAnn(..), LInjectivityAnn,
  resultVariableName,
81 82

  -- * Grouping
83
  HsGroup(..),  emptyRdrGroup, emptyRnGroup, appendGroups, hsGroupInstDecls
84

85
    ) where
86 87

-- friends:
88 89
import GhcPrelude

Alan Zimmerman's avatar
Alan Zimmerman committed
90 91
import {-# SOURCE #-}   HsExpr( LHsExpr, HsExpr, HsSplice, pprExpr,
                                pprSpliceDecl )
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
92
        -- Because Expr imports Decls via HsBracket
93

94
import HsBinds
95
import HsTypes
96
import HsDoc
97
import TyCon
98
import Name
99
import BasicTypes
100
import Coercion
101
import ForeignCall
Ben Gamari's avatar
Ben Gamari committed
102
import PlaceHolder ( PlaceHolder(..) )
103
import HsExtension
104
import NameSet
105 106

-- others:
107
import InstEnv
108
import Class
109
import Outputable
110 111 112
import Util
import SrcLoc

113
import Bag
eir@cis.upenn.edu's avatar
eir@cis.upenn.edu committed
114
import Maybes
115
import Data.Data        hiding (TyCon,Fixity, Infix)
116

Austin Seipp's avatar
Austin Seipp committed
117 118 119
{-
************************************************************************
*                                                                      *
120
\subsection[HsDecl]{Declarations}
Austin Seipp's avatar
Austin Seipp committed
121 122 123
*                                                                      *
************************************************************************
-}
124

125
type LHsDecl id = Located (HsDecl id)
Alan Zimmerman's avatar
Alan Zimmerman committed
126 127 128 129
        -- ^ When in a list this may have
        --
        --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnSemi'
        --
130

131 132
-- For details on above see note [Api annotations] in ApiAnnotation

133
-- | A Haskell Declaration
134
data HsDecl id
135 136 137 138 139 140 141 142 143 144 145 146 147 148 149
  = TyClD       (TyClDecl id)      -- ^ Type or Class Declaration
  | InstD       (InstDecl  id)     -- ^ Instance declaration
  | DerivD      (DerivDecl id)     -- ^ Deriving declaration
  | ValD        (HsBind id)        -- ^ Value declaration
  | SigD        (Sig id)           -- ^ Signature declaration
  | DefD        (DefaultDecl id)   -- ^ 'default' declaration
  | ForD        (ForeignDecl id)   -- ^ Foreign declaration
  | WarningD    (WarnDecls id)     -- ^ Warning declaration
  | AnnD        (AnnDecl id)       -- ^ Annotation declaration
  | RuleD       (RuleDecls id)     -- ^ Rule declaration
  | VectD       (VectDecl id)      -- ^ Vectorise declaration
  | SpliceD     (SpliceDecl id)    -- ^ Splice declaration
                                   -- (Includes quasi-quotes)
  | DocD        (DocDecl)          -- ^ Documentation comment declaration
  | RoleAnnotD  (RoleAnnotDecl id) -- ^ Role annotation declaration
Ben Gamari's avatar
Ben Gamari committed
150
deriving instance (DataId id) => Data (HsDecl id)
151

152 153

-- NB: all top-level fixity decls are contained EITHER
154
-- EITHER SigDs
155 156 157
-- OR     in the ClassDecls in TyClDs
--
-- The former covers
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
158 159 160 161 162
--      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
163 164
--
-- The latter is for class methods only
165

166 167 168
-- | Haskell Group
--
-- A 'HsDecl' is categorised into a 'HsGroup' before being
169 170 171
-- fed to the renamer.
data HsGroup id
  = HsGroup {
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
172
        hs_valds  :: HsValBinds id,
173
        hs_splcds :: [LSpliceDecl id],
174

175
        hs_tyclds :: [TyClGroup id],
176 177
                -- A list of mutually-recursive groups;
                -- This includes `InstDecl`s as well;
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
178 179
                -- Parser generates a singleton list;
                -- renamer does dependency analysis
180

181
        hs_derivds :: [LDerivDecl id],
182

chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
183 184 185
        hs_fixds  :: [LFixitySig id],
                -- Snaffled out of both top-level fixity signatures,
                -- and those in class declarations
186

187 188
        hs_defds  :: [LDefaultDecl id],
        hs_fords  :: [LForeignDecl id],
Alan Zimmerman's avatar
Alan Zimmerman committed
189
        hs_warnds :: [LWarnDecls id],
190
        hs_annds  :: [LAnnDecl id],
Alan Zimmerman's avatar
Alan Zimmerman committed
191
        hs_ruleds :: [LRuleDecls id],
192
        hs_vects  :: [LVectDecl id],
193

194
        hs_docs   :: [LDocDecl]
195
  }
Ben Gamari's avatar
Ben Gamari committed
196
deriving instance (DataId id) => Data (HsGroup id)
197

Ben Gamari's avatar
Ben Gamari committed
198
emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup a
199 200 201
emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
emptyRnGroup  = emptyGroup { hs_valds = emptyValBindsOut }

202 203 204 205
hsGroupInstDecls :: HsGroup id -> [LInstDecl id]
hsGroupInstDecls = (=<<) group_instds . hs_tyclds

emptyGroup = HsGroup { hs_tyclds = [],
206
                       hs_derivds = [],
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
207 208 209
                       hs_fixds = [], hs_defds = [], hs_annds = [],
                       hs_fords = [], hs_warnds = [], hs_ruleds = [], hs_vects = [],
                       hs_valds = error "emptyGroup hs_valds: Can't happen",
210
                       hs_splcds = [],
211
                       hs_docs = [] }
212

Ben Gamari's avatar
Ben Gamari committed
213
appendGroups :: HsGroup a -> HsGroup a -> HsGroup a
214 215
appendGroups
    HsGroup {
216
        hs_valds  = val_groups1,
217
        hs_splcds = spliceds1,
218
        hs_tyclds = tyclds1,
219
        hs_derivds = derivds1,
220
        hs_fixds  = fixds1,
221 222
        hs_defds  = defds1,
        hs_annds  = annds1,
223
        hs_fords  = fords1,
224 225 226
        hs_warnds = warnds1,
        hs_ruleds = rulds1,
        hs_vects = vects1,
227
  hs_docs   = docs1 }
228
    HsGroup {
229
        hs_valds  = val_groups2,
230
        hs_splcds = spliceds2,
231
        hs_tyclds = tyclds2,
232
        hs_derivds = derivds2,
233
        hs_fixds  = fixds2,
234 235
        hs_defds  = defds2,
        hs_annds  = annds2,
236
        hs_fords  = fords2,
237 238 239 240
        hs_warnds = warnds2,
        hs_ruleds = rulds2,
        hs_vects  = vects2,
        hs_docs   = docs2 }
241 242
  =
    HsGroup {
243
        hs_valds  = val_groups1 `plusHsValBinds` val_groups2,
244 245
        hs_splcds = spliceds1 ++ spliceds2,
        hs_tyclds = tyclds1 ++ tyclds2,
246
        hs_derivds = derivds1 ++ derivds2,
247 248 249
        hs_fixds  = fixds1 ++ fixds2,
        hs_annds  = annds1 ++ annds2,
        hs_defds  = defds1 ++ defds2,
250
        hs_fords  = fords1 ++ fords2,
251 252 253 254
        hs_warnds = warnds1 ++ warnds2,
        hs_ruleds = rulds1 ++ rulds2,
        hs_vects  = vects1 ++ vects2,
        hs_docs   = docs1  ++ docs2 }
255

256
instance (p ~ GhcPass pass, OutputableBndrId p) => Outputable (HsDecl p) where
257 258 259 260 261 262 263 264
    ppr (TyClD dcl)             = ppr dcl
    ppr (ValD binds)            = ppr binds
    ppr (DefD def)              = ppr def
    ppr (InstD inst)            = ppr inst
    ppr (DerivD deriv)          = ppr deriv
    ppr (ForD fd)               = ppr fd
    ppr (SigD sd)               = ppr sd
    ppr (RuleD rd)              = ppr rd
265
    ppr (VectD vect)            = ppr vect
Ian Lynagh's avatar
Ian Lynagh committed
266
    ppr (WarningD wd)           = ppr wd
267
    ppr (AnnD ad)               = ppr ad
268 269
    ppr (SpliceD dd)            = ppr dd
    ppr (DocD doc)              = ppr doc
270
    ppr (RoleAnnotD ra)         = ppr ra
271

272
instance (p ~ GhcPass pass, OutputableBndrId p) => Outputable (HsGroup p) where
273
    ppr (HsGroup { hs_valds  = val_decls,
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
274
                   hs_tyclds = tycl_decls,
275
                   hs_derivds = deriv_decls,
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
276 277 278 279 280 281 282
                   hs_fixds  = fix_decls,
                   hs_warnds = deprec_decls,
                   hs_annds  = ann_decls,
                   hs_fords  = foreign_decls,
                   hs_defds  = default_decls,
                   hs_ruleds = rule_decls,
                   hs_vects  = vect_decls })
283 284
        = vcat_mb empty
            [ppr_ds fix_decls, ppr_ds default_decls,
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
285 286 287
             ppr_ds deprec_decls, ppr_ds ann_decls,
             ppr_ds rule_decls,
             ppr_ds vect_decls,
288 289
             if isEmptyValBinds val_decls
                then Nothing
290
                else Just (ppr val_decls),
291 292
             ppr_ds (tyClGroupTyClDecls tycl_decls),
             ppr_ds (tyClGroupInstDecls tycl_decls),
293
             ppr_ds deriv_decls,
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
294 295
             ppr_ds foreign_decls]
        where
296
          ppr_ds :: Outputable a => [a] -> Maybe SDoc
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
297 298
          ppr_ds [] = Nothing
          ppr_ds ds = Just (vcat (map ppr ds))
299 300

          vcat_mb :: SDoc -> [Maybe SDoc] -> SDoc
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
301
          -- Concatenate vertically with white-space between non-blanks
302 303 304
          vcat_mb _    []             = empty
          vcat_mb gap (Nothing : ds) = vcat_mb gap ds
          vcat_mb gap (Just d  : ds) = gap $$ d $$ vcat_mb blankLine ds
305

306
-- | Located Splice Declaration
307
type LSpliceDecl pass = Located (SpliceDecl pass)
308 309

-- | Splice Declaration
310
data SpliceDecl id
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
311
  = SpliceDecl                  -- Top level splice
312
        (Located (HsSplice id))
313
        SpliceExplicitFlag
Ben Gamari's avatar
Ben Gamari committed
314
deriving instance (DataId id) => Data (SpliceDecl id)
315

316 317
instance (p ~ GhcPass pass, OutputableBndrId p)
       => Outputable (SpliceDecl p) where
Alan Zimmerman's avatar
Alan Zimmerman committed
318
   ppr (SpliceDecl (L _ e) f) = pprSpliceDecl e f
319

Austin Seipp's avatar
Austin Seipp committed
320 321 322
{-
************************************************************************
*                                                                      *
323
            Type and class declarations
Austin Seipp's avatar
Austin Seipp committed
324 325
*                                                                      *
************************************************************************
326

327 328
Note [The Naming story]
~~~~~~~~~~~~~~~~~~~~~~~
329 330
Here is the story about the implicit names that go with type, class,
and instance decls.  It's a bit tricky, so pay attention!
331 332 333

"Implicit" (or "system") binders
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
334
  Each data type decl defines
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
335 336
        a worker name for each constructor
        to-T and from-T convertors
337
  Each class decl defines
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
338 339 340 341
        a tycon for the class
        a data constructor for that tycon
        the worker for that constructor
        a selector for each superclass
342

343 344
All have occurrence names that are derived uniquely from their parent
declaration.
345 346 347 348 349 350 351

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:
352
 - Ensure they "point to" the parent data/class decl
353
   when loading that decl from an interface file
354 355 356 357 358
   (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
359

360 361
These are the two places that we have to conjure up the magic derived
names.  (The actual magic is in OccName.mkWorkerOcc, etc.)
362

363 364 365 366 367 368
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
369 370
   the ClassOpSig (in HsBinds), in the DefMethInfo field.
   (DefMethInfo is defined in Class.hs)
371 372 373 374 375 376 377

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:
378

379 380 381 382 383
 - When parsing, every ClassOpSig gets a DefMeth with a suitable RdrName
   This is done by RdrHsSyn.mkClassOpSigDM

 - The renamer renames it to a Name

384
 - During typechecking, we generate a binding for each $dm for
385
   which there's a programmer-supplied default method:
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
386 387 388 389
        class Foo a where
          op1 :: <type>
          op2 :: <type>
          op1 = ...
390
   We generate a binding for $dmop1 but not for $dmop2.
391 392
   The Class for Foo has a Nothing for op2 and
                         a Just ($dm_op1, VanillaDM) for op1.
393 394 395 396 397
   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:
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
398 399 400
        class Foo a where
          op1 = :: <type>       -- NB the '='
          op2   :: <type>
401 402 403 404 405
    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
406
    the binding for $dmop1 will be sucked in.  (See RnHsSyn.tyClDeclFVs)
407 408 409 410 411 412 413 414 415 416 417 418 419 420
    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:
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
421 422
        instance {Eq Int} = dEqInt
        dEqInt :: {Eq Int} <pragma info>
423 424 425 426 427 428 429 430 431 432 433

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').

434
  - The occurrence name it chooses is derived from the instance decl (just for
435 436
    documentation really) --- e.g. dNumInt.  Two dict funs may share a common
    occurrence name, but will have different uniques.  E.g.
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
437 438
        instance Foo [Int]  where ...
        instance Foo [Bool] where ...
439 440
    These might both be dFooList

441
  - The CoreTidy phase externalises the name, and ensures the occurrence name is
442 443
    unique (this isn't special to dict funs).  So we'd get dFooList and dFooList1.

444
  - We can take this relaxed approach (changing the occurrence name later)
445 446 447 448 449 450 451 452 453
    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.
454

455 456
  - RnHsSyn.instDeclFVs treats the dict fun name as free in the decl, so that we
    suck in the dfun binding
Austin Seipp's avatar
Austin Seipp committed
457
-}
458

459
-- | Located Declaration of a Type or Class
460
type LTyClDecl pass = Located (TyClDecl pass)
461

462
-- | A type or class declaration.
463
data TyClDecl pass
Yuras's avatar
Yuras committed
464
  = -- | @type/data family T :: *->*@
Alan Zimmerman's avatar
Alan Zimmerman committed
465 466 467
    --
    --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
    --             'ApiAnnotation.AnnData',
468
    --             'ApiAnnotation.AnnFamily','ApiAnnotation.AnnDcolon',
Jan Stolarek's avatar
Jan Stolarek committed
469 470 471 472
    --             'ApiAnnotation.AnnWhere','ApiAnnotation.AnnOpenP',
    --             'ApiAnnotation.AnnDcolon','ApiAnnotation.AnnCloseP',
    --             'ApiAnnotation.AnnEqual','ApiAnnotation.AnnRarrow',
    --             'ApiAnnotation.AnnVbar'
Alan Zimmerman's avatar
Alan Zimmerman committed
473

474
    -- For details on above see note [Api annotations] in ApiAnnotation
475
    FamDecl { tcdFam :: FamilyDecl pass }
476

477
  | -- | @type@ declaration
Alan Zimmerman's avatar
Alan Zimmerman committed
478 479 480
    --
    --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
    --             'ApiAnnotation.AnnEqual',
481 482

    -- For details on above see note [Api annotations] in ApiAnnotation
483 484 485 486
    SynDecl { tcdLName  :: Located (IdP pass)     -- ^ Type constructor
            , tcdTyVars :: LHsQTyVars pass        -- ^ Type variables; for an
                                                  -- associated type these
                                                  -- include outer binders
487
            , tcdFixity :: LexicalFixity    -- ^ Fixity used in the declaration
488 489
            , tcdRhs    :: LHsType pass           -- ^ RHS of type declaration
            , tcdFVs    :: PostRn pass NameSet }
490 491

  | -- | @data@ declaration
Alan Zimmerman's avatar
Alan Zimmerman committed
492 493 494 495
    --
    --  - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnData',
    --              'ApiAnnotation.AnnFamily',
    --              'ApiAnnotation.AnnNewType',
496 497
    --              'ApiAnnotation.AnnNewType','ApiAnnotation.AnnDcolon'
    --              'ApiAnnotation.AnnWhere',
498 499

    -- For details on above see note [Api annotations] in ApiAnnotation
500 501 502 503 504 505 506 507 508
    DataDecl { tcdLName    :: Located (IdP pass) -- ^ Type constructor
             , tcdTyVars   :: LHsQTyVars pass  -- ^ Type variables; for an
                                               -- associated type
                                               --   these include outer binders
                                               -- Eg  class T a where
                                               --       type F a :: *
                                               --       type F a = a -> a
                                               -- Here the type decl for 'f'
                                               -- includes 'a' in its tcdTyVars
509
             , tcdFixity  :: LexicalFixity -- ^ Fixity used in the declaration
510 511 512
             , tcdDataDefn :: HsDataDefn pass
             , tcdDataCusk :: PostRn pass Bool    -- ^ does this have a CUSK?
             , tcdFVs      :: PostRn pass NameSet }
513

514 515 516
  | ClassDecl { tcdCtxt    :: LHsContext pass,         -- ^ Context...
                tcdLName   :: Located (IdP pass),      -- ^ Name of the class
                tcdTyVars  :: LHsQTyVars pass,         -- ^ Class type variables
517
                tcdFixity  :: LexicalFixity, -- ^ Fixity used in the declaration
518
                tcdFDs     :: [Located (FunDep (Located (IdP pass)))],
Alan Zimmerman's avatar
Alan Zimmerman committed
519
                                                        -- ^ Functional deps
520 521 522 523 524
                tcdSigs    :: [LSig pass],              -- ^ Methods' signatures
                tcdMeths   :: LHsBinds pass,            -- ^ Default methods
                tcdATs     :: [LFamilyDecl pass],       -- ^ Associated types;
                tcdATDefs  :: [LTyFamDefltEqn pass],
                                                   -- ^ Associated type defaults
525
                tcdDocs    :: [LDocDecl],               -- ^ Haddock docs
526
                tcdFVs     :: PostRn pass NameSet
527
    }
Alan Zimmerman's avatar
Alan Zimmerman committed
528 529 530 531 532 533
        -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnClass',
        --           'ApiAnnotation.AnnWhere','ApiAnnotation.AnnOpen',
        --           'ApiAnnotation.AnnClose'
        --   - The tcdFDs will have 'ApiAnnotation.AnnVbar',
        --                          'ApiAnnotation.AnnComma'
        --                          'ApiAnnotation.AnnRarrow'
534

535 536
        -- For details on above see note [Api annotations] in ApiAnnotation

Ben Gamari's avatar
Ben Gamari committed
537
deriving instance (DataId id) => Data (TyClDecl id)
538

539

Jan Stolarek's avatar
Jan Stolarek committed
540 541
-- Simple classifiers for TyClDecl
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
542

543
-- | @True@ <=> argument is a @data@\/@newtype@
544
-- declaration.
545
isDataDecl :: TyClDecl pass -> Bool
546 547
isDataDecl (DataDecl {}) = True
isDataDecl _other        = False
548

549
-- | type or type instance declaration
550
isSynDecl :: TyClDecl pass -> Bool
551 552
isSynDecl (SynDecl {})   = True
isSynDecl _other        = False
553

554
-- | type class
555
isClassDecl :: TyClDecl pass -> Bool
556
isClassDecl (ClassDecl {}) = True
557
isClassDecl _              = False
558

559
-- | type/data family declaration
560
isFamilyDecl :: TyClDecl pass -> Bool
561
isFamilyDecl (FamDecl {})  = True
562
isFamilyDecl _other        = False
563 564

-- | type family declaration
565
isTypeFamilyDecl :: TyClDecl pass -> Bool
566 567 568 569 570
isTypeFamilyDecl (FamDecl (FamilyDecl { fdInfo = info })) = case info of
  OpenTypeFamily      -> True
  ClosedTypeFamily {} -> True
  _                   -> False
isTypeFamilyDecl _ = False
571

572
-- | open type family info
573
isOpenTypeFamilyInfo :: FamilyInfo pass -> Bool
574 575 576 577
isOpenTypeFamilyInfo OpenTypeFamily = True
isOpenTypeFamilyInfo _              = False

-- | closed type family info
578
isClosedTypeFamilyInfo :: FamilyInfo pass -> Bool
579 580 581
isClosedTypeFamilyInfo (ClosedTypeFamily {}) = True
isClosedTypeFamilyInfo _                     = False

582
-- | data family declaration
583
isDataFamilyDecl :: TyClDecl pass -> Bool
584
isDataFamilyDecl (FamDecl (FamilyDecl { fdInfo = DataFamily })) = True
585
isDataFamilyDecl _other      = False
586

Austin Seipp's avatar
Austin Seipp committed
587
-- Dealing with names
588

589
tyFamInstDeclName :: TyFamInstDecl pass -> (IdP pass)
590 591
tyFamInstDeclName = unLoc . tyFamInstDeclLName

592
tyFamInstDeclLName :: TyFamInstDecl pass -> Located (IdP pass)
593
tyFamInstDeclLName (TyFamInstDecl { tfid_eqn =
594
                     (HsIB { hsib_body = FamEqn { feqn_tycon = ln }}) })
595 596
  = ln

597
tyClDeclLName :: TyClDecl pass -> Located (IdP pass)
598 599
tyClDeclLName (FamDecl { tcdFam = FamilyDecl { fdLName = ln } }) = ln
tyClDeclLName decl = tcdLName decl
600

601
tcdName :: TyClDecl pass -> (IdP pass)
602 603
tcdName = unLoc . tyClDeclLName

604
tyClDeclTyVars :: TyClDecl pass -> LHsQTyVars pass
605 606
tyClDeclTyVars (FamDecl { tcdFam = FamilyDecl { fdTyVars = tvs } }) = tvs
tyClDeclTyVars d = tcdTyVars d
607

608
countTyClDecls :: [TyClDecl pass] -> (Int, Int, Int, Int, Int)
609
        -- class, synonym decls, data, newtype, family decls
610
countTyClDecls decls
611 612 613 614
 = (count isClassDecl    decls,
    count isSynDecl      decls,  -- excluding...
    count isDataTy       decls,  -- ...family...
    count isNewTy        decls,  -- ...instances
615
    count isFamilyDecl   decls)
sof's avatar
sof committed
616
 where
617 618
   isDataTy DataDecl{ tcdDataDefn = HsDataDefn { dd_ND = DataType } } = True
   isDataTy _                                                       = False
619

620 621
   isNewTy DataDecl{ tcdDataDefn = HsDataDefn { dd_ND = NewType } } = True
   isNewTy _                                                      = False
622 623 624

-- | Does this declaration have a complete, user-supplied kind signature?
-- See Note [Complete user-supplied kind signatures]
625
hsDeclHasCusk :: TyClDecl GhcRn -> Bool
eir@cis.upenn.edu's avatar
eir@cis.upenn.edu committed
626
hsDeclHasCusk (FamDecl { tcdFam = fam_decl }) = famDeclHasCusk Nothing fam_decl
627
hsDeclHasCusk (SynDecl { tcdTyVars = tyvars, tcdRhs = rhs })
628
  -- NB: Keep this synchronized with 'getInitialKind'
629 630 631
  = hsTvbAllKinded tyvars && rhs_annotated rhs
  where
    rhs_annotated (L _ ty) = case ty of
Ben Gamari's avatar
Ben Gamari committed
632 633 634
      HsParTy lty  -> rhs_annotated lty
      HsKindSig {} -> True
      _            -> False
eir@cis.upenn.edu's avatar
eir@cis.upenn.edu committed
635
hsDeclHasCusk (DataDecl { tcdDataCusk = cusk }) = cusk
636 637
hsDeclHasCusk (ClassDecl { tcdTyVars = tyvars }) = hsTvbAllKinded tyvars

Jan Stolarek's avatar
Jan Stolarek committed
638 639
-- Pretty-printing TyClDecl
-- ~~~~~~~~~~~~~~~~~~~~~~~~
640

641
instance (p ~ GhcPass pass, OutputableBndrId p) => Outputable (TyClDecl p) where
642

643
    ppr (FamDecl { tcdFam = decl }) = ppr decl
644 645
    ppr (SynDecl { tcdLName = ltycon, tcdTyVars = tyvars, tcdFixity = fixity
                 , tcdRhs = rhs })
646
      = hang (text "type" <+>
647
              pp_vanilla_decl_head ltycon tyvars fixity [] <+> equals)
648
          4 (ppr rhs)
649

650 651 652
    ppr (DataDecl { tcdLName = ltycon, tcdTyVars = tyvars, tcdFixity = fixity
                  , tcdDataDefn = defn })
      = pp_data_defn (pp_vanilla_decl_head ltycon tyvars fixity) defn
653

654
    ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars,
655
                    tcdFixity = fixity,
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
656
                    tcdFDs  = fds,
657 658 659
                    tcdSigs = sigs, tcdMeths = methods,
                    tcdATs = ats, tcdATDefs = at_defs})
      | null sigs && isEmptyBag methods && null ats && null at_defs -- No "where" part
660 661
      = top_matter

chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
662
      | otherwise       -- Laid out
663
      = vcat [ top_matter <+> text "where"
664
             , nest 2 $ pprDeclList (map (pprFamilyDecl NotTopLevel . unLoc) ats ++
665
                                     map ppr_fam_deflt_eqn at_defs ++
chak@cse.unsw.edu.au.'s avatar
chak@cse.unsw.edu.au. committed
666
                                     pprLHsBindsForUser methods sigs) ]
667
      where
668
        top_matter = text "class"
669 670
                    <+> pp_vanilla_decl_head lclas tyvars fixity (unLoc context)
                    <+> pprFundeps (map unLoc fds)
671

672 673
instance (p ~ GhcPass pass, OutputableBndrId p)
       => Outputable (TyClGroup p) where
674 675 676 677 678
  ppr (TyClGroup { group_tyclds = tyclds
                 , group_roles = roles
                 , group_instds = instds
                 }
      )
679
    = ppr tyclds $$
680 681
      ppr roles $$
      ppr instds
682

683 684 685
pp_vanilla_decl_head :: (OutputableBndrId (GhcPass p))
   => Located (IdP (GhcPass p))
   -> LHsQTyVars (GhcPass p)
686
   -> LexicalFixity
687
   -> HsContext (GhcPass p)
Jan Stolarek's avatar
Jan Stolarek committed
688
   -> SDoc
689
pp_vanilla_decl_head thing (HsQTvs { hsq_explicit = tyvars }) fixity context
Alan Zimmerman's avatar
Alan Zimmerman committed
690 691 692
 = hsep [pprHsContext context, pp_tyvars tyvars]
  where
    pp_tyvars (varl:varsr)
693 694 695 696
      | fixity == Infix && length varsr > 1
         = hsep [char '(',ppr (unLoc varl), pprInfixOcc (unLoc thing)
                , (ppr.unLoc) (head varsr), char ')'
                , hsep (map (ppr.unLoc) (tail varsr))]
697
      | fixity == Infix
Alan Zimmerman's avatar
Alan Zimmerman committed
698 699 700 701 702
         = hsep [ppr (unLoc varl), pprInfixOcc (unLoc thing)
         , hsep (map (ppr.unLoc) varsr)]
      | otherwise = hsep [ pprPrefixOcc (unLoc thing)
                  , hsep (map (ppr.unLoc) (varl:varsr))]
    pp_tyvars [] = ppr thing
Jan Stolarek's avatar
Jan Stolarek committed
703 704

pprTyClDeclFlavour :: TyClDecl a -> SDoc
705 706
pprTyClDeclFlavour (ClassDecl {})   = text "class"
pprTyClDeclFlavour (SynDecl {})     = text "type"
Jan Stolarek's avatar
Jan Stolarek committed
707
pprTyClDeclFlavour (FamDecl { tcdFam = FamilyDecl { fdInfo = info }})
708
  = pprFlavour info <+> text "family"
Jan Stolarek's avatar
Jan Stolarek committed
709 710 711 712
pprTyClDeclFlavour (DataDecl { tcdDataDefn = HsDataDefn { dd_ND = nd } })
  = ppr nd


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
{- Note [Complete user-supplied kind signatures]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We kind-check declarations differently if they have a complete, user-supplied
kind signature (CUSK). This is because we can safely generalise a CUSKed
declaration before checking all of the others, supporting polymorphic recursion.
See ghc.haskell.org/trac/ghc/wiki/GhcKinds/KindInference#Proposednewstrategy
and #9200 for lots of discussion of how we got here.

A declaration has a CUSK if we can know its complete kind without doing any
inference, at all. Here are the rules:

 - A class or datatype is said to have a CUSK if and only if all of its type
variables are annotated. Its result kind is, by construction, Constraint or *
respectively.

 - A type synonym has a CUSK if and only if all of its type variables and its
RHS are annotated with kinds.

 - A closed type family is said to have a CUSK if and only if all of its type
variables and its return type are annotated.

 - An open type family always has a CUSK -- unannotated type variables (and
return type) default to *.

 - Additionally, if -XTypeInType is on, then a data definition with a top-level
   :: must explicitly bind all kind variables to the right of the ::.
   See test dependent/should_compile/KindLevels, which requires this case.
   (Naturally, any kind variable mentioned before the :: should not be bound
   after it.)
-}


{- *********************************************************************
*                                                                      *
                         TyClGroup
        Strongly connected components of
      type, class, instance, and role declarations
*                                                                      *
********************************************************************* -}

{- Note [TyClGroups and dependency analysis]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A TyClGroup represents a strongly connected components of type/class/instance
decls, together with the role annotations for the type/class declarations.

The hs_tyclds :: [TyClGroup] field of a HsGroup is a dependency-order
sequence of strongly-connected components.

Invariants
 * The type and class declarations, group_tyclds, may depend on each
   other, or earlier TyClGroups, but not on later ones

 * The role annotations, group_roles, are role-annotations for some or
   all of the types and classes in group_tyclds (only).

 * The instance declarations, group_instds, may (and usually will)
   depend on group_tyclds, or on earlier TyClGroups, but not on later
   ones.

See Note [Dependency analsis of type, class, and instance decls]
in RnSource for more info.
-}

776
-- | Type or Class Group
777 778 779 780
data TyClGroup pass  -- See Note [TyClGroups and dependency analysis]
  = TyClGroup { group_tyclds :: [LTyClDecl pass]
              , group_roles  :: [LRoleAnnotDecl pass]
              , group_instds :: [LInstDecl pass] }
Ben Gamari's avatar
Ben Gamari committed
781
deriving instance (DataId id) => Data (TyClGroup id)
782

783
emptyTyClGroup :: TyClGroup pass
784 785
emptyTyClGroup = TyClGroup [] [] []

786
tyClGroupTyClDecls :: [TyClGroup pass] -> [LTyClDecl pass]
787 788
tyClGroupTyClDecls = concatMap group_tyclds

789
tyClGroupInstDecls :: [TyClGroup pass] -> [LInstDecl pass]
790 791
tyClGroupInstDecls = concatMap group_instds

792
tyClGroupRoleDecls :: [TyClGroup pass] -> [LRoleAnnotDecl pass]
793 794
tyClGroupRoleDecls = concatMap group_roles

795
mkTyClGroup :: [LTyClDecl pass] -> [LInstDecl pass] -> TyClGroup pass
796 797 798 799 800 801 802 803
mkTyClGroup decls instds = TyClGroup
  { group_tyclds = decls
  , group_roles = []
  , group_instds = instds
  }



Jan Stolarek's avatar
Jan Stolarek committed
804 805 806 807 808 809
{- *********************************************************************
*                                                                      *
               Data and type family declarations
*                                                                      *
********************************************************************* -}

810 811
{- Note [FamilyResultSig]
~~~~~~~~~~~~~~~~~~~~~~~~~
Jan Stolarek's avatar
Jan Stolarek committed
812

813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871
This data type represents the return signature of a type family.  Possible
values are:

 * NoSig - the user supplied no return signature:
      type family Id a where ...

 * KindSig - the user supplied the return kind:
      type family Id a :: * where ...

 * TyVarSig - user named the result with a type variable and possibly
   provided a kind signature for that variable:
      type family Id a = r where ...
      type family Id a = (r :: *) where ...

   Naming result of a type family is required if we want to provide
   injectivity annotation for a type family:
      type family Id a = r | r -> a where ...

See also: Note [Injectivity annotation]

Note [Injectivity annotation]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A user can declare a type family to be injective:

   type family Id a = r | r -> a where ...

 * The part after the "|" is called "injectivity annotation".
 * "r -> a" part is called "injectivity condition"; at the moment terms
   "injectivity annotation" and "injectivity condition" are synonymous
   because we only allow a single injectivity condition.
 * "r" is the "LHS of injectivity condition". LHS can only contain the
   variable naming the result of a type family.

 * "a" is the "RHS of injectivity condition". RHS contains space-separated
   type and kind variables representing the arguments of a type
   family. Variables can be omitted if a type family is not injective in
   these arguments. Example:
         type family Foo a b c = d | d -> a c where ...

Note that:
 (a) naming of type family result is required to provide injectivity
     annotation
 (b) for associated types if the result was named then injectivity annotation
     is mandatory. Otherwise result type variable is indistinguishable from
     associated type default.

It is possible that in the future this syntax will be extended to support
more complicated injectivity annotations. For example we could declare that
if we know the result of Plus and one of its arguments we can determine the
other argument:

   type family Plus a b = (r :: Nat) | r a -> b, r b -> a where ...

Here injectivity annotation would consist of two comma-separated injectivity
conditions.

See also Note [Injective type families] in TyCon
-}
Jan Stolarek's avatar
Jan Stolarek committed
872

873
-- | Located type Family Result Signature
874
type LFamilyResultSig pass = Located (FamilyResultSig pass)
875 876

-- | type Family Result Signature
877
data FamilyResultSig pass = -- see Note [FamilyResultSig]
Jan Stolarek's avatar
Jan Stolarek committed
878 879 880 881 882
    NoSig
  -- ^ - 'ApiAnnotation.AnnKeywordId' :

  -- For details on above see note [Api annotations] in ApiAnnotation

883
  | KindSig  (LHsKind pass)
Jan Stolarek's avatar
Jan Stolarek committed
884 885 886 887 888 889
  -- ^ - 'ApiAnnotation.AnnKeywordId' :
  --             'ApiAnnotation.AnnOpenP','ApiAnnotation.AnnDcolon',
  --             'ApiAnnotation.AnnCloseP'

  -- For details on above see note [Api annotations] in ApiAnnotation

890
  | TyVarSig (LHsTyVarBndr pass)
Jan Stolarek's avatar
Jan Stolarek committed
891 892 893 894 895 896
  -- ^ - 'ApiAnnotation.AnnKeywordId' :
  --             'ApiAnnotation.AnnOpenP','ApiAnnotation.AnnDcolon',
  --             'ApiAnnotation.AnnCloseP', 'ApiAnnotation.AnnEqual'

  -- For details on above see note [Api annotations] in ApiAnnotation

Ben Gamari's avatar
Ben Gamari committed
897
deriving instance (DataId pass) => Data (FamilyResultSig pass)
Jan Stolarek's avatar
Jan Stolarek committed
898

899
-- | Located type Family Declaration
900
type LFamilyDecl pass = Located (FamilyDecl pass)
901 902

-- | type Family Declaration
903 904 905 906
data FamilyDecl pass = FamilyDecl
  { fdInfo           :: FamilyInfo pass              -- type/data, closed/open
  , fdLName          :: Located (IdP pass)           -- type constructor
  , fdTyVars         :: LHsQTyVars pass              -- type variables