aboutsummaryrefslogtreecommitdiff
path: root/haddock-api/src/Haddock/Convert.hs
blob: 2bd111d625d5589e1860ef576bc95b8db5c8d35f (plain) (blame)
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
{-# LANGUAGE CPP, PatternGuards #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Haddock.Convert
-- Copyright   :  (c) Isaac Dupree 2009,
-- License     :  BSD-like
--
-- Maintainer  :  haddock@projects.haskell.org
-- Stability   :  experimental
-- Portability :  portable
--
-- Conversion between TyThing and HsDecl. This functionality may be moved into
-- GHC at some point.
-----------------------------------------------------------------------------
module Haddock.Convert where
-- Some other functions turned out to be useful for converting
-- instance heads, which aren't TyThings, so just export everything.

import Bag ( emptyBag )
import BasicTypes ( TupleSort(..) )
import Class
import CoAxiom
import ConLike
import Data.Either (lefts, rights)
import Data.List( partition )
import DataCon
import FamInstEnv
import HsSyn
import Kind ( splitKindFunTys, synTyConResKind, isKind )
import Name
import PatSyn
import PrelNames (ipClassName)
import SrcLoc ( Located, noLoc, unLoc, noSrcSpan )
import TcType ( tcSplitSigmaTy )
import TyCon
import Type (isStrLitTy, mkFunTys)
import TypeRep
import TysPrim ( alphaTyVars )
import TysWiredIn ( listTyConName, eqTyCon )
import Unique ( getUnique )
import Var

import Haddock.Types
import Haddock.Interface.Specialize



-- the main function here! yay!
tyThingToLHsDecl :: TyThing -> Either ErrMsg ([ErrMsg], (HsDecl Name))
tyThingToLHsDecl t = case t of
  -- ids (functions and zero-argument a.k.a. CAFs) get a type signature.
  -- Including built-in functions like seq.
  -- foreign-imported functions could be represented with ForD
  -- instead of SigD if we wanted...
  --
  -- in a future code version we could turn idVarDetails = foreign-call
  -- into a ForD instead of a SigD if we wanted.  Haddock doesn't
  -- need to care.
  AnId i -> allOK $ SigD (synifyIdSig ImplicitizeForAll i)

  -- type-constructors (e.g. Maybe) are complicated, put the definition
  -- later in the file (also it's used for class associated-types too.)
  ATyCon tc
    | Just cl <- tyConClass_maybe tc -- classes are just a little tedious
    -> let extractFamilyDecl :: TyClDecl a -> Either ErrMsg (LFamilyDecl a)
           extractFamilyDecl (FamDecl d) = return $ noLoc d
           extractFamilyDecl _           =
             Left "tyThingToLHsDecl: impossible associated tycon"

           atTyClDecls = [synifyTyCon Nothing at_tc | ATI at_tc _ <- classATItems cl]
           atFamDecls  = map extractFamilyDecl (rights atTyClDecls)
           tyClErrors = lefts atTyClDecls
           famDeclErrors = lefts atFamDecls
       in withErrs (tyClErrors ++ famDeclErrors) . TyClD $ ClassDecl
         { tcdCtxt = synifyCtx (classSCTheta cl)
         , tcdLName = synifyName cl
         , tcdTyVars = synifyTyVars (classTyVars cl)
         , tcdFDs = map (\ (l,r) -> noLoc
                        (map (noLoc . getName) l, map (noLoc . getName) r) ) $
                         snd $ classTvsFds cl
         , tcdSigs = noLoc (MinimalSig mempty . fmap noLoc $ classMinimalDef cl) :
                      map (noLoc . synifyIdSig DeleteTopLevelQuantification)
                        (classMethods cl)
         , tcdMeths = emptyBag --ignore default method definitions, they don't affect signature
         -- class associated-types are a subset of TyCon:
         , tcdATs = rights atFamDecls
         , tcdATDefs = [] --ignore associated type defaults
         , tcdDocs = [] --we don't have any docs at this point
         , tcdFVs = placeHolderNamesTc }
    | otherwise
    -> synifyTyCon Nothing tc >>= allOK . TyClD

  -- type-constructors (e.g. Maybe) are complicated, put the definition
  -- later in the file (also it's used for class associated-types too.)
  ACoAxiom ax -> synifyAxiom ax >>= allOK

  -- a data-constructor alone just gets rendered as a function:
  AConLike (RealDataCon dc) -> allOK $ SigD (TypeSig [synifyName dc]
    (synifyType ImplicitizeForAll (dataConUserType dc)) [])

  AConLike (PatSynCon ps) ->
      let (univ_tvs, ex_tvs, req_theta, prov_theta, arg_tys, res_ty) = patSynSig ps
          qtvs = univ_tvs ++ ex_tvs
          ty = mkFunTys arg_tys res_ty
      in allOK . SigD $ PatSynSig (synifyName ps)
                          (Implicit, synifyTyVars qtvs)
                          (synifyCtx req_theta)
                          (synifyCtx prov_theta)
                          (synifyType WithinType ty)
  where
    withErrs e x = return (e, x)
    allOK x = return (mempty, x)

synifyAxBranch :: TyCon -> CoAxBranch -> TyFamInstEqn Name
synifyAxBranch tc (CoAxBranch { cab_tvs = tkvs, cab_lhs = args, cab_rhs = rhs })
  = let name       = synifyName tc
        typats     = map (synifyType WithinType) args
        hs_rhs     = synifyType WithinType rhs
        (kvs, tvs) = partition isKindVar tkvs
    in TyFamEqn { tfe_tycon = name
                , tfe_pats  = HsWB { hswb_cts = typats
                                    , hswb_kvs = map tyVarName kvs
                                    , hswb_tvs = map tyVarName tvs
                                    , hswb_wcs = [] }
                , tfe_rhs   = hs_rhs }

synifyAxiom :: CoAxiom br -> Either ErrMsg (HsDecl Name)
synifyAxiom ax@(CoAxiom { co_ax_tc = tc })
  | isOpenTypeFamilyTyCon tc
  , Just branch <- coAxiomSingleBranch_maybe ax
  = return $ InstD (TyFamInstD
                    (TyFamInstDecl { tfid_eqn = noLoc $ synifyAxBranch tc branch
                                   , tfid_fvs = placeHolderNamesTc }))

  | Just ax' <- isClosedSynFamilyTyCon_maybe tc
  , getUnique ax' == getUnique ax   -- without the getUniques, type error
  = synifyTyCon (Just ax) tc >>= return . TyClD

  | otherwise
  = Left "synifyAxiom: closed/open family confusion"

-- | Turn type constructors into type class declarations
synifyTyCon :: Maybe (CoAxiom br) -> TyCon -> Either ErrMsg (TyClDecl Name)
synifyTyCon coax tc
  | isFunTyCon tc || isPrimTyCon tc
  = return $
    DataDecl { tcdLName = synifyName tc
             , tcdTyVars =       -- tyConTyVars doesn't work on fun/prim, but we can make them up:
                         let mk_hs_tv realKind fakeTyVar
                                = noLoc $ KindedTyVar (noLoc (getName fakeTyVar))
                                                      (synifyKindSig realKind)
                         in HsQTvs { hsq_kvs = []   -- No kind polymorphism
                                   , hsq_tvs = zipWith mk_hs_tv (fst (splitKindFunTys (tyConKind tc)))
                                                                alphaTyVars --a, b, c... which are unfortunately all kind *
                                   }

           , tcdDataDefn = HsDataDefn { dd_ND = DataType  -- arbitrary lie, they are neither
                                                    -- algebraic data nor newtype:
                                      , dd_ctxt = noLoc []
                                      , dd_cType = Nothing
                                      , dd_kindSig = Just (synifyKindSig (tyConKind tc))
                                               -- we have their kind accurately:
                                      , dd_cons = []  -- No constructors
                                      , dd_derivs = Nothing }
           , tcdFVs = placeHolderNamesTc }

  | isTypeFamilyTyCon tc
  = case famTyConFlav_maybe tc of
      Just rhs ->
        let info = case rhs of
              OpenSynFamilyTyCon -> return OpenTypeFamily
              ClosedSynFamilyTyCon (CoAxiom { co_ax_branches = branches }) ->
                return $ ClosedTypeFamily
                  (brListMap (noLoc . synifyAxBranch tc) branches)
              BuiltInSynFamTyCon {} -> return $ ClosedTypeFamily []
              AbstractClosedSynFamilyTyCon {} -> return $ ClosedTypeFamily []
        in info >>= \i ->
           return (FamDecl
                   (FamilyDecl { fdInfo = i
                               , fdLName = synifyName tc
                               , fdTyVars = synifyTyVars (tyConTyVars tc)
                               , fdKindSig =
                                 Just (synifyKindSig (synTyConResKind tc))
                               }))
      Nothing -> Left "synifyTyCon: impossible open type synonym?"

  | isDataFamilyTyCon tc
  = --(why no "isOpenAlgTyCon"?)
    case algTyConRhs tc of
        DataFamilyTyCon -> return $
          FamDecl (FamilyDecl DataFamily (synifyName tc) (synifyTyVars (tyConTyVars tc))
                              Nothing) --always kind '*'
        _ -> Left "synifyTyCon: impossible open data type?"
  | Just ty <- synTyConRhs_maybe tc
  = return $ SynDecl { tcdLName = synifyName tc
                     , tcdTyVars = synifyTyVars (tyConTyVars tc)
                     , tcdRhs = synifyType WithinType ty
                     , tcdFVs = placeHolderNamesTc }
  | otherwise =
  -- (closed) newtype and data
  let
  alg_nd = if isNewTyCon tc then NewType else DataType
  alg_ctx = synifyCtx (tyConStupidTheta tc)
  name = case coax of
    Just a -> synifyName a -- Data families are named according to their
                           -- CoAxioms, not their TyCons
    _ -> synifyName tc
  tyvars = synifyTyVars (tyConTyVars tc)
  kindSig = Just (tyConKind tc)
  -- The data constructors.
  --
  -- Any data-constructors not exported from the module that *defines* the
  -- type will not (cannot) be included.
  --
  -- Very simple constructors, Haskell98 with no existentials or anything,
  -- probably look nicer in non-GADT syntax.  In source code, all constructors
  -- must be declared with the same (GADT vs. not) syntax, and it probably
  -- is less confusing to follow that principle for the documentation as well.
  --
  -- There is no sensible infix-representation for GADT-syntax constructor
  -- declarations.  They cannot be made in source code, but we could end up
  -- with some here in the case where some constructors use existentials.
  -- That seems like an acceptable compromise (they'll just be documented
  -- in prefix position), since, otherwise, the logic (at best) gets much more
  -- complicated. (would use dataConIsInfix.)
  use_gadt_syntax = any (not . isVanillaDataCon) (tyConDataCons tc)
  consRaw = map (synifyDataCon use_gadt_syntax) (tyConDataCons tc)
  cons = rights consRaw
  -- "deriving" doesn't affect the signature, no need to specify any.
  alg_deriv = Nothing
  defn = HsDataDefn { dd_ND      = alg_nd
                    , dd_ctxt    = alg_ctx
                    , dd_cType   = Nothing
                    , dd_kindSig = fmap synifyKindSig kindSig
                    , dd_cons    = cons
                    , dd_derivs  = alg_deriv }
 in case lefts consRaw of
  [] -> return $
        DataDecl { tcdLName = name, tcdTyVars = tyvars, tcdDataDefn = defn
                 , tcdFVs = placeHolderNamesTc }
  dataConErrs -> Left $ unlines dataConErrs

-- User beware: it is your responsibility to pass True (use_gadt_syntax)
-- for any constructor that would be misrepresented by omitting its
-- result-type.
-- But you might want pass False in simple enough cases,
-- if you think it looks better.
synifyDataCon :: Bool -> DataCon -> Either ErrMsg (LConDecl Name)
synifyDataCon use_gadt_syntax dc =
 let
  -- dataConIsInfix allegedly tells us whether it was declared with
  -- infix *syntax*.
  use_infix_syntax = dataConIsInfix dc
  use_named_field_syntax = not (null field_tys)
  name = synifyName dc
  -- con_qvars means a different thing depending on gadt-syntax
  (univ_tvs, ex_tvs, _eq_spec, theta, arg_tys, res_ty) = dataConFullSig dc

  qvars = if use_gadt_syntax
          then synifyTyVars (univ_tvs ++ ex_tvs)
          else synifyTyVars ex_tvs

  -- skip any EqTheta, use 'orig'inal syntax
  ctx = synifyCtx theta

  linear_tys = zipWith (\ty bang ->
            let tySyn = synifyType WithinType ty
                src_bang = case bang of
                             HsUnpack {} -> HsSrcBang Nothing (Just True) True
                             HsStrict    -> HsSrcBang Nothing (Just False) True
                             _           -> bang
            in case src_bang of
                 HsNoBang -> tySyn
                 _        -> noLoc $ HsBangTy bang tySyn
            -- HsNoBang never appears, it's implied instead.
          )
          arg_tys (dataConSrcBangs dc)
  field_tys = zipWith (\field synTy -> noLoc $ ConDeclField
                                               [synifyName field] synTy Nothing)
                (dataConFieldLabels dc) linear_tys
  hs_arg_tys = case (use_named_field_syntax, use_infix_syntax) of
          (True,True) -> Left "synifyDataCon: contradiction!"
          (True,False) -> return $ RecCon (noLoc field_tys)
          (False,False) -> return $ PrefixCon linear_tys
          (False,True) -> case linear_tys of
                           [a,b] -> return $ InfixCon a b
                           _ -> Left "synifyDataCon: infix with non-2 args?"
  hs_res_ty = if use_gadt_syntax
              then ResTyGADT noSrcSpan (synifyType WithinType res_ty)
              else ResTyH98
 -- finally we get synifyDataCon's result!
 in hs_arg_tys >>=
      \hat -> return . noLoc $ ConDecl [name] Implicit -- we don't know nor care
                qvars ctx hat hs_res_ty Nothing
                -- we don't want any "deprecated GADT syntax" warnings!
                False

synifyName :: NamedThing n => n -> Located Name
synifyName = noLoc . getName


synifyIdSig :: SynifyTypeState -> Id -> Sig Name
synifyIdSig s i = TypeSig [synifyName i] (synifyType s (varType i)) []


synifyCtx :: [PredType] -> LHsContext Name
synifyCtx = noLoc . map (synifyType WithinType)


synifyTyVars :: [TyVar] -> LHsTyVarBndrs Name
synifyTyVars ktvs = HsQTvs { hsq_kvs = map tyVarName kvs
                           , hsq_tvs = map synifyTyVar tvs }
  where
    (kvs, tvs) = partition isKindVar ktvs
    synifyTyVar tv
      | isLiftedTypeKind kind = noLoc (UserTyVar name)
      | otherwise             = noLoc (KindedTyVar (noLoc name) (synifyKindSig kind))
      where
        kind = tyVarKind tv
        name = getName tv

--states of what to do with foralls:
data SynifyTypeState
  = WithinType
  -- ^ normal situation.  This is the safe one to use if you don't
  -- quite understand what's going on.
  | ImplicitizeForAll
  -- ^ beginning of a function definition, in which, to make it look
  --   less ugly, those rank-1 foralls are made implicit.
  | DeleteTopLevelQuantification
  -- ^ because in class methods the context is added to the type
  --   (e.g. adding @forall a. Num a =>@ to @(+) :: a -> a -> a@)
  --   which is rather sensible,
  --   but we want to restore things to the source-syntax situation where
  --   the defining class gets to quantify all its functions for free!


synifyType :: SynifyTypeState -> Type -> LHsType Name
synifyType _ (TyVarTy tv) = noLoc $ HsTyVar (getName tv)
synifyType _ (TyConApp tc tys)
  -- Use non-prefix tuple syntax where possible, because it looks nicer.
  | Just sort <- tyConTuple_maybe tc
  , tyConArity tc == length tys
  = noLoc $ HsTupleTy (case sort of
                          BoxedTuple      -> HsBoxedTuple
                          ConstraintTuple -> HsConstraintTuple
                          UnboxedTuple    -> HsUnboxedTuple)
                       (map (synifyType WithinType) tys)
  -- ditto for lists
  | getName tc == listTyConName, [ty] <- tys =
     noLoc $ HsListTy (synifyType WithinType ty)
  -- ditto for implicit parameter tycons
  | tyConName tc == ipClassName
  , [name, ty] <- tys
  , Just x <- isStrLitTy name
  = noLoc $ HsIParamTy (HsIPName x) (synifyType WithinType ty)
  -- and equalities
  | tc == eqTyCon
  , [ty1, ty2] <- tys
  = noLoc $ HsEqTy (synifyType WithinType ty1) (synifyType WithinType ty2)
  -- Most TyCons:
  | otherwise =
    foldl (\t1 t2 -> noLoc (HsAppTy t1 t2))
      (noLoc $ HsTyVar (getName tc))
      (map (synifyType WithinType) tys)
synifyType _ (AppTy t1 t2) = let
  s1 = synifyType WithinType t1
  s2 = synifyType WithinType t2
  in noLoc $ HsAppTy s1 s2
synifyType _ (FunTy t1 t2) = let
  s1 = synifyType WithinType t1
  s2 = synifyType WithinType t2
  in noLoc $ HsFunTy s1 s2
synifyType s forallty@(ForAllTy _tv _ty) =
  let (tvs, ctx, tau) = tcSplitSigmaTy forallty
      sTvs = synifyTyVars tvs
      sCtx = synifyCtx ctx
      sTau = synifyType WithinType tau
      mkHsForAllTy forallPlicitness =
        noLoc $ HsForAllTy forallPlicitness Nothing sTvs sCtx sTau
  in case s of
    DeleteTopLevelQuantification -> synifyType ImplicitizeForAll tau
    WithinType -> mkHsForAllTy Explicit
    ImplicitizeForAll -> mkHsForAllTy Implicit

synifyType _ (LitTy t) = noLoc $ HsTyLit $ synifyTyLit t

synifyTyLit :: TyLit -> HsTyLit
synifyTyLit (NumTyLit n) = HsNumTy mempty n
synifyTyLit (StrTyLit s) = HsStrTy mempty s

synifyKindSig :: Kind -> LHsKind Name
synifyKindSig k = synifyType WithinType k

synifyInstHead :: ([TyVar], [PredType], Class, [Type]) -> InstHead Name
synifyInstHead (_, preds, cls, types) = specializeInstHead $ InstHead
    { ihdClsName = getName cls
    , ihdKinds = map (unLoc . synifyType WithinType) ks
    , ihdTypes = map (unLoc . synifyType WithinType) ts
    , ihdInstType = ClassInst
        { clsiCtx = map (unLoc . synifyType WithinType) preds
        , clsiTyVars = synifyTyVars $ classTyVars cls
        , clsiSigs = map synifyClsIdSig $ classMethods cls
        , clsiAssocTys = do
            (Right (FamDecl fam)) <- map (synifyTyCon Nothing) $ classATs cls
            pure $ mkPseudoFamilyDecl fam
        }
    }
  where
    (ks,ts) = break (not . isKind) types
    synifyClsIdSig = synifyIdSig DeleteTopLevelQuantification

-- Convert a family instance, this could be a type family or data family
synifyFamInst :: FamInst -> Bool -> Either ErrMsg (InstHead Name)
synifyFamInst fi opaque = do
    ityp' <- ityp $ fi_flavor fi
    return InstHead
        { ihdClsName = fi_fam fi
        , ihdKinds = synifyTypes ks
        , ihdTypes = synifyTypes ts
        , ihdInstType = ityp'
        }
  where
    ityp SynFamilyInst | opaque = return $ TypeInst Nothing
    ityp SynFamilyInst =
        return . TypeInst . Just . unLoc . synifyType WithinType $ fi_rhs fi
    ityp (DataFamilyInst c) =
        DataInst <$> synifyTyCon (Just $ famInstAxiom fi) c
    (ks,ts) = break (not . isKind) $ fi_tys fi
    synifyTypes = map (unLoc. synifyType WithinType)