2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
6 HsDecls: Abstract syntax: global declarations
8 Definitions for: @TyDecl@ and @oCnDecl@, @ClassDecl@,
9 @InstDecl@, @DefaultDecl@ and @ForeignDecl@.
13 HsDecl(..), LHsDecl, TyClDecl(..), LTyClDecl,
14 InstDecl(..), LInstDecl, DerivDecl(..), LDerivDecl, NewOrData(..),
15 RuleDecl(..), LRuleDecl, RuleBndr(..),
16 DefaultDecl(..), LDefaultDecl, SpliceDecl(..),
17 ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
18 CImportSpec(..), FoType(..),
19 ConDecl(..), ResType(..), LConDecl,
20 DocDecl(..), LDocDecl, docDeclDoc, DocEntity(..),
21 DeprecDecl(..), LDeprecDecl,
22 HsGroup(..), emptyRdrGroup, emptyRnGroup, appendGroups,
23 tcdName, tyClDeclNames, tyClDeclTyVars,
24 isClassDecl, isTFunDecl, isSynDecl, isDataDecl, isKindSigDecl,
29 collectRuleBndrSigTys,
32 #include "HsVersions.h"
35 import {-# SOURCE #-} HsExpr( HsExpr, pprExpr )
36 -- Because Expr imports Decls via HsBracket
45 import {- Kind parts of -} Type
56 import Data.Maybe ( isJust )
59 %************************************************************************
61 \subsection[HsDecl]{Declarations}
63 %************************************************************************
66 type LHsDecl id = Located (HsDecl id)
71 | DerivD (DerivDecl id)
74 | DefD (DefaultDecl id)
75 | ForD (ForeignDecl id)
76 | DeprecD (DeprecDecl id)
78 | SpliceD (SpliceDecl id)
82 -- NB: all top-level fixity decls are contained EITHER
84 -- OR in the ClassDecls in TyClDs
87 -- a) data constructors
88 -- b) class methods (but they can be also done in the
89 -- signatures of class decls)
90 -- c) imported functions (that have an IfacSig)
93 -- The latter is for class methods only
95 -- A [HsDecl] is categorised into a HsGroup before being
96 -- fed to the renamer.
99 hs_valds :: HsValBinds id,
100 hs_tyclds :: [LTyClDecl id],
101 hs_instds :: [LInstDecl id],
102 hs_derivds :: [LDerivDecl id],
104 hs_fixds :: [LFixitySig id],
105 -- Snaffled out of both top-level fixity signatures,
106 -- and those in class declarations
108 hs_defds :: [LDefaultDecl id],
109 hs_fords :: [LForeignDecl id],
110 hs_depds :: [LDeprecDecl id],
111 hs_ruleds :: [LRuleDecl id],
113 hs_docs :: [DocEntity id]
114 -- Used to remember the module structure,
115 -- which is needed to produce Haddock documentation
118 emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup a
119 emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
120 emptyRnGroup = emptyGroup { hs_valds = emptyValBindsOut }
122 emptyGroup = HsGroup { hs_tyclds = [], hs_instds = [], hs_derivds = [],
123 hs_fixds = [], hs_defds = [], hs_fords = [],
124 hs_depds = [], hs_ruleds = [],
125 hs_valds = error "emptyGroup hs_valds: Can't happen",
128 appendGroups :: HsGroup a -> HsGroup a -> HsGroup a
131 hs_valds = val_groups1,
134 hs_derivds = derivds1,
142 hs_valds = val_groups2,
145 hs_derivds = derivds2,
154 hs_valds = val_groups1 `plusHsValBinds` val_groups2,
155 hs_tyclds = tyclds1 ++ tyclds2,
156 hs_instds = instds1 ++ instds2,
157 hs_derivds = derivds1 ++ derivds2,
158 hs_fixds = fixds1 ++ fixds2,
159 hs_defds = defds1 ++ defds2,
160 hs_fords = fords1 ++ fords2,
161 hs_depds = depds1 ++ depds2,
162 hs_ruleds = rulds1 ++ rulds2,
163 hs_docs = docs1 ++ docs2 }
167 instance OutputableBndr name => Outputable (HsDecl name) where
168 ppr (TyClD dcl) = ppr dcl
169 ppr (ValD binds) = ppr binds
170 ppr (DefD def) = ppr def
171 ppr (InstD inst) = ppr inst
172 ppr (DerivD deriv) = ppr deriv
173 ppr (ForD fd) = ppr fd
174 ppr (SigD sd) = ppr sd
175 ppr (RuleD rd) = ppr rd
176 ppr (DeprecD dd) = ppr dd
177 ppr (SpliceD dd) = ppr dd
178 ppr (DocD doc) = ppr doc
180 instance OutputableBndr name => Outputable (HsGroup name) where
181 ppr (HsGroup { hs_valds = val_decls,
182 hs_tyclds = tycl_decls,
183 hs_instds = inst_decls,
184 hs_derivds = deriv_decls,
185 hs_fixds = fix_decls,
186 hs_depds = deprec_decls,
187 hs_fords = foreign_decls,
188 hs_defds = default_decls,
189 hs_ruleds = rule_decls })
190 = vcat [ppr_ds fix_decls, ppr_ds default_decls,
191 ppr_ds deprec_decls, ppr_ds rule_decls,
193 ppr_ds tycl_decls, ppr_ds inst_decls,
195 ppr_ds foreign_decls]
198 ppr_ds ds = text "" $$ vcat (map ppr ds)
200 data SpliceDecl id = SpliceDecl (Located (HsExpr id)) -- Top level splice
202 instance OutputableBndr name => Outputable (SpliceDecl name) where
203 ppr (SpliceDecl e) = ptext SLIT("$") <> parens (pprExpr (unLoc e))
207 %************************************************************************
209 \subsection[TyDecl]{@data@, @newtype@ or @type@ (synonym) type declaration}
211 %************************************************************************
213 --------------------------------
215 --------------------------------
217 Here is the story about the implicit names that go with type, class,
218 and instance decls. It's a bit tricky, so pay attention!
220 "Implicit" (or "system") binders
221 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
222 Each data type decl defines
223 a worker name for each constructor
224 to-T and from-T convertors
225 Each class decl defines
226 a tycon for the class
227 a data constructor for that tycon
228 the worker for that constructor
229 a selector for each superclass
231 All have occurrence names that are derived uniquely from their parent
234 None of these get separate definitions in an interface file; they are
235 fully defined by the data or class decl. But they may *occur* in
236 interface files, of course. Any such occurrence must haul in the
237 relevant type or class decl.
240 - Ensure they "point to" the parent data/class decl
241 when loading that decl from an interface file
242 (See RnHiFiles.getSysBinders)
244 - When typechecking the decl, we build the implicit TyCons and Ids.
245 When doing so we look them up in the name cache (RnEnv.lookupSysName),
246 to ensure correct module and provenance is set
248 These are the two places that we have to conjure up the magic derived
249 names. (The actual magic is in OccName.mkWorkerOcc, etc.)
253 - Occurrence name is derived uniquely from the method name
256 - If there is a default method name at all, it's recorded in
257 the ClassOpSig (in HsBinds), in the DefMeth field.
258 (DefMeth is defined in Class.lhs)
260 Source-code class decls and interface-code class decls are treated subtly
261 differently, which has given me a great deal of confusion over the years.
262 Here's the deal. (We distinguish the two cases because source-code decls
263 have (Just binds) in the tcdMeths field, whereas interface decls have Nothing.
265 In *source-code* class declarations:
267 - When parsing, every ClassOpSig gets a DefMeth with a suitable RdrName
268 This is done by RdrHsSyn.mkClassOpSigDM
270 - The renamer renames it to a Name
272 - During typechecking, we generate a binding for each $dm for
273 which there's a programmer-supplied default method:
278 We generate a binding for $dmop1 but not for $dmop2.
279 The Class for Foo has a NoDefMeth for op2 and a DefMeth for op1.
280 The Name for $dmop2 is simply discarded.
282 In *interface-file* class declarations:
283 - When parsing, we see if there's an explicit programmer-supplied default method
284 because there's an '=' sign to indicate it:
286 op1 = :: <type> -- NB the '='
288 We use this info to generate a DefMeth with a suitable RdrName for op1,
289 and a NoDefMeth for op2
290 - The interface file has a separate definition for $dmop1, with unfolding etc.
291 - The renamer renames it to a Name.
292 - The renamer treats $dmop1 as a free variable of the declaration, so that
293 the binding for $dmop1 will be sucked in. (See RnHsSyn.tyClDeclFVs)
294 This doesn't happen for source code class decls, because they *bind* the default method.
298 Each instance declaration gives rise to one dictionary function binding.
300 The type checker makes up new source-code instance declarations
301 (e.g. from 'deriving' or generic default methods --- see
302 TcInstDcls.tcInstDecls1). So we can't generate the names for
303 dictionary functions in advance (we don't know how many we need).
305 On the other hand for interface-file instance declarations, the decl
306 specifies the name of the dictionary function, and it has a binding elsewhere
307 in the interface file:
308 instance {Eq Int} = dEqInt
309 dEqInt :: {Eq Int} <pragma info>
311 So again we treat source code and interface file code slightly differently.
314 - Source code instance decls have a Nothing in the (Maybe name) field
315 (see data InstDecl below)
317 - The typechecker makes up a Local name for the dict fun for any source-code
318 instance decl, whether it comes from a source-code instance decl, or whether
319 the instance decl is derived from some other construct (e.g. 'deriving').
321 - The occurrence name it chooses is derived from the instance decl (just for
322 documentation really) --- e.g. dNumInt. Two dict funs may share a common
323 occurrence name, but will have different uniques. E.g.
324 instance Foo [Int] where ...
325 instance Foo [Bool] where ...
326 These might both be dFooList
328 - The CoreTidy phase externalises the name, and ensures the occurrence name is
329 unique (this isn't special to dict funs). So we'd get dFooList and dFooList1.
331 - We can take this relaxed approach (changing the occurrence name later)
332 because dict fun Ids are not captured in a TyCon or Class (unlike default
333 methods, say). Instead, they are kept separately in the InstEnv. This
334 makes it easy to adjust them after compiling a module. (Once we've finished
335 compiling that module, they don't change any more.)
339 - The instance decl gives the dict fun name, so the InstDecl has a (Just name)
340 in the (Maybe name) field.
342 - RnHsSyn.instDeclFVs treats the dict fun name as free in the decl, so that we
343 suck in the dfun binding
347 -- Representation of indexed types
348 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
349 -- Kind signatures of indexed types come in two flavours:
351 -- * kind signatures for type functions: variant `TyFunction' and
353 -- * kind signatures for indexed data types and newtypes : variant `TyData'
354 -- iff a kind is present in `tcdKindSig' and there are no constructors in
357 -- Indexed types are represented by 'TyData' and 'TySynonym' using the field
358 -- 'tcdTyPats::Maybe [LHsType name]', with the following meaning:
360 -- * If it is 'Nothing', we have a *vanilla* data type declaration or type
361 -- synonym declaration and 'tcdVars' contains the type parameters of the
364 -- * If it is 'Just pats', we have the definition of an indexed type Then,
365 -- 'pats' are type patterns for the type-indexes of the type constructor
366 -- and 'tcdVars' are the variables in those patterns. Hence, the arity of
367 -- the indexed type (ie, the number of indexes) is 'length tcdTyPats' and
368 -- *not* 'length tcdVars'.
370 -- In both cases, 'tcdVars' collects all variables we need to quantify over.
372 type LTyClDecl name = Located (TyClDecl name)
376 tcdLName :: Located name,
377 tcdExtName :: Maybe FastString,
381 | TyData { tcdND :: NewOrData,
382 tcdCtxt :: LHsContext name, -- Context
383 tcdLName :: Located name, -- Type constructor
385 tcdTyVars :: [LHsTyVarBndr name], -- Type variables
387 tcdTyPats :: Maybe [LHsType name], -- Type patterns
388 -- Just [t1..tn] for data instance T t1..tn = ...
389 -- in this case tcdTyVars = fv( tcdTyPats )
390 -- Nothing for everything else
392 tcdKindSig:: Maybe Kind, -- Optional kind sig
394 -- (a) GADT-style data type decls with user kind sig
395 -- (b) 'data instance' decls with user kind sig
396 -- (c) 'data family' decls, whether or not there is a kind sig
397 -- (this is how we distinguish a data family decl)
399 tcdCons :: [LConDecl name], -- Data constructors
400 -- For data T a = T1 | T2 a the LConDecls all have ResTyH98
401 -- For data T a where { T1 :: T a } the LConDecls all have ResTyGADT
403 tcdDerivs :: Maybe [LHsType name]
404 -- Derivings; Nothing => not specified
405 -- Just [] => derive exactly what is asked
406 -- These "types" must be of form
407 -- forall ab. C ty1 ty2
408 -- Typically the foralls and ty args are empty, but they
409 -- are non-empty for the newtype-deriving case
411 -- data family: tcdPats = Nothing, tcdCons = [], tcdKindSig = Just k
412 -- data instance: tcdPats = Just tys
413 -- data: tcdPats = Nothing, tcdCons is non-empty
415 | TyFunction {tcdLName :: Located name, -- type constructor
416 tcdTyVars :: [LHsTyVarBndr name], -- type variables
417 tcdIso :: Bool, -- injective type?
418 tcdKind :: Kind -- result kind
421 | TySynonym { tcdLName :: Located name, -- type constructor
422 tcdTyVars :: [LHsTyVarBndr name], -- type variables
423 tcdTyPats :: Maybe [LHsType name], -- Type patterns
424 -- See comments for tcdTyPats in TyData
425 -- 'Nothing' => vanilla type synonym
427 tcdSynRhs :: LHsType name -- synonym expansion
430 | ClassDecl { tcdCtxt :: LHsContext name, -- Context...
431 tcdLName :: Located name, -- Name of the class
432 tcdTyVars :: [LHsTyVarBndr name], -- Class type variables
433 tcdFDs :: [Located (FunDep name)], -- Functional deps
434 tcdSigs :: [LSig name], -- Methods' signatures
435 tcdMeths :: LHsBinds name, -- Default methods
436 tcdATs :: [LTyClDecl name], -- Associated types; ie
440 tcdDocs :: [DocEntity name] -- Haddock docs
444 = NewType -- "newtype Blah ..."
445 | DataType -- "data Blah ..."
446 deriving( Eq ) -- Needed because Demand derives Eq
452 isTFunDecl, isDataDecl, isSynDecl, isClassDecl, isKindSigDecl, isIdxTyDecl ::
453 TyClDecl name -> Bool
455 -- type function kind signature
456 isTFunDecl (TyFunction {}) = True
457 isTFunDecl other = False
459 -- vanilla Haskell type synonym
460 isSynDecl (TySynonym {tcdTyPats = Nothing}) = True
461 isSynDecl other = False
463 -- type equation (of a type function)
464 isTEqnDecl (TySynonym {tcdTyPats = Just _}) = True
465 isTEqnDecl other = False
467 isDataDecl (TyData {}) = True
468 isDataDecl other = False
470 isClassDecl (ClassDecl {}) = True
471 isClassDecl other = False
473 -- kind signature (for an indexed type)
474 isKindSigDecl (TyFunction {} ) = True
475 isKindSigDecl (TyData {tcdKindSig = Just _,
476 tcdCons = [] }) = True
477 isKindSigDecl other = False
479 -- definition of an instance of an indexed type
481 | isTEqnDecl tydecl = True
482 | isDataDecl tydecl = isJust (tcdTyPats tydecl)
489 tcdName :: TyClDecl name -> name
490 tcdName decl = unLoc (tcdLName decl)
492 tyClDeclNames :: Eq name => TyClDecl name -> [Located name]
493 -- Returns all the *binding* names of the decl, along with their SrcLocs
494 -- The first one is guaranteed to be the name of the decl
495 -- For record fields, the first one counts as the SrcLoc
496 -- We use the equality to filter out duplicate field names
498 tyClDeclNames (TyFunction {tcdLName = name}) = [name]
499 tyClDeclNames (TySynonym {tcdLName = name}) = [name]
500 tyClDeclNames (ForeignType {tcdLName = name}) = [name]
502 tyClDeclNames (ClassDecl {tcdLName = cls_name, tcdSigs = sigs, tcdATs = ats})
504 concatMap (tyClDeclNames . unLoc) ats ++ [n | L _ (TypeSig n _) <- sigs]
506 tyClDeclNames (TyData {tcdLName = tc_name, tcdCons = cons})
507 = tc_name : conDeclsNames (map unLoc cons)
509 tyClDeclTyVars (TyFunction {tcdTyVars = tvs}) = tvs
510 tyClDeclTyVars (TySynonym {tcdTyVars = tvs}) = tvs
511 tyClDeclTyVars (TyData {tcdTyVars = tvs}) = tvs
512 tyClDeclTyVars (ClassDecl {tcdTyVars = tvs}) = tvs
513 tyClDeclTyVars (ForeignType {}) = []
517 countTyClDecls :: [TyClDecl name] -> (Int, Int, Int, Int, Int, Int)
518 -- class, synonym decls, type function signatures,
519 -- type function equations, data, newtype
521 = (count isClassDecl decls,
522 count isSynDecl decls,
523 count isTFunDecl decls,
524 count isTEqnDecl decls,
525 count isDataTy decls,
528 isDataTy TyData{tcdND=DataType} = True
531 isNewTy TyData{tcdND=NewType} = True
536 instance OutputableBndr name
537 => Outputable (TyClDecl name) where
539 ppr (ForeignType {tcdLName = ltycon})
540 = hsep [ptext SLIT("foreign import type dotnet"), ppr ltycon]
542 ppr (TyFunction {tcdLName = ltycon, tcdTyVars = tyvars, tcdIso = iso,
544 = typeMaybeIso <+> pp_decl_head [] ltycon tyvars Nothing <+>
545 dcolon <+> pprKind kind
547 typeMaybeIso = if iso
548 then ptext SLIT("type family iso")
549 else ptext SLIT("type family")
551 ppr (TySynonym {tcdLName = ltycon, tcdTyVars = tyvars, tcdTyPats = typats,
552 tcdSynRhs = mono_ty})
553 = hang (ptext SLIT("type") <+>
554 (if isJust typats then ptext SLIT("instance") else empty) <+>
555 pp_decl_head [] ltycon tyvars typats <+>
559 ppr (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = ltycon,
560 tcdTyVars = tyvars, tcdTyPats = typats, tcdKindSig = mb_sig,
561 tcdCons = condecls, tcdDerivs = derivings})
562 = pp_tydecl (null condecls && isJust mb_sig)
564 (if isJust typats then ptext SLIT("instance") else empty) <+>
565 pp_decl_head (unLoc context) ltycon tyvars typats <+>
567 (pp_condecls condecls)
570 ppr_sig Nothing = empty
571 ppr_sig (Just kind) = dcolon <+> pprKind kind
573 ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars,
575 tcdSigs = sigs, tcdMeths = methods, tcdATs = ats})
576 | null sigs && null ats -- No "where" part
579 | otherwise -- Laid out
580 = sep [hsep [top_matter, ptext SLIT("where {")],
581 nest 4 (sep [ sep (map ppr_semi ats)
582 , sep (map ppr_semi sigs)
583 , pprLHsBinds methods
586 top_matter = ptext SLIT("class")
587 <+> pp_decl_head (unLoc context) lclas tyvars Nothing
588 <+> pprFundeps (map unLoc fds)
589 ppr_semi decl = ppr decl <> semi
591 pp_decl_head :: OutputableBndr name
594 -> [LHsTyVarBndr name]
595 -> Maybe [LHsType name]
597 pp_decl_head context thing tyvars Nothing -- no explicit type patterns
598 = hsep [pprHsContext context, ppr thing, interppSP tyvars]
599 pp_decl_head context thing _ (Just typats) -- explicit type patterns
600 = hsep [ pprHsContext context, ppr thing
601 , hsep (map (pprParendHsType.unLoc) typats)]
603 pp_condecls cs@(L _ ConDecl{ con_res = ResTyGADT _ } : _) -- In GADT syntax
604 = hang (ptext SLIT("where")) 2 (vcat (map ppr cs))
605 pp_condecls cs -- In H98 syntax
606 = equals <+> sep (punctuate (ptext SLIT(" |")) (map ppr cs))
608 pp_tydecl True pp_head pp_decl_rhs derivings
610 pp_tydecl False pp_head pp_decl_rhs derivings
611 = hang pp_head 4 (sep [
615 Just ds -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
618 instance Outputable NewOrData where
619 ppr NewType = ptext SLIT("newtype")
620 ppr DataType = ptext SLIT("data")
624 %************************************************************************
626 \subsection[ConDecl]{A data-constructor declaration}
628 %************************************************************************
631 type LConDecl name = Located (ConDecl name)
633 -- data T b = forall a. Eq a => MkT a b
634 -- MkT :: forall b a. Eq a => MkT a b
637 -- MkT1 :: Int -> T Int
639 -- data T = Int `MkT` Int
643 -- Int `MkT` Int :: T Int
647 { con_name :: Located name -- Constructor name; this is used for the
648 -- DataCon itself, and for the user-callable wrapper Id
650 , con_explicit :: HsExplicitForAll -- Is there an user-written forall? (cf. HStypes.HsForAllTy)
652 , con_qvars :: [LHsTyVarBndr name] -- ResTyH98: the constructor's existential type variables
653 -- ResTyGADT: all the constructor's quantified type variables
655 , con_cxt :: LHsContext name -- The context. This *does not* include the
656 -- "stupid theta" which lives only in the TyData decl
658 , con_details :: HsConDetails name (LBangType name) -- The main payload
660 , con_res :: ResType name -- Result type of the constructor
662 , con_doc :: Maybe (LHsDoc name) -- A possible Haddock comment
666 = ResTyH98 -- Constructor was declared using Haskell 98 syntax
667 | ResTyGADT (LHsType name) -- Constructor was declared using GADT-style syntax,
668 -- and here is its result type
672 conDeclsNames :: Eq name => [ConDecl name] -> [Located name]
673 -- See tyClDeclNames for what this does
674 -- The function is boringly complicated because of the records
675 -- And since we only have equality, we have to be a little careful
677 = snd (foldl do_one ([], []) cons)
679 do_one (flds_seen, acc) (ConDecl { con_name = lname, con_details = RecCon flds })
680 = (map unLoc new_flds ++ flds_seen, lname : [f | f <- new_flds] ++ acc)
682 new_flds = [ f | (HsRecField f _ _) <- flds, not (unLoc f `elem` flds_seen) ]
684 do_one (flds_seen, acc) c
685 = (flds_seen, (con_name c):acc)
687 conDetailsTys details = map getBangType (hsConArgs details)
692 instance (OutputableBndr name) => Outputable (ConDecl name) where
695 pprConDecl (ConDecl con expl tvs cxt details ResTyH98 doc)
696 = sep [ppr_mbDoc doc, pprHsForAll expl tvs cxt, ppr_details con details]
698 ppr_details con (InfixCon t1 t2) = hsep [ppr t1, pprHsVar con, ppr t2]
699 ppr_details con (PrefixCon tys) = hsep (pprHsVar con : map ppr tys)
700 ppr_details con (RecCon fields) = ppr con <+> ppr_fields fields
702 pprConDecl (ConDecl con expl tvs cxt (PrefixCon arg_tys) (ResTyGADT res_ty) _)
703 = ppr con <+> dcolon <+>
704 sep [pprHsForAll expl tvs cxt, ppr (foldr mk_fun_ty res_ty arg_tys)]
706 mk_fun_ty a b = noLoc (HsFunTy a b)
708 pprConDecl (ConDecl con expl tvs cxt (RecCon fields) (ResTyGADT res_ty) _)
709 = sep [pprHsForAll expl tvs cxt, ppr con <+> ppr_fields fields <+> dcolon <+> ppr res_ty]
711 ppr_fields fields = braces (sep (punctuate comma (map ppr fields)))
714 %************************************************************************
716 \subsection[InstDecl]{An instance declaration
718 %************************************************************************
721 type LInstDecl name = Located (InstDecl name)
724 = InstDecl (LHsType name) -- Context => Class Instance-type
725 -- Using a polytype means that the renamer conveniently
726 -- figures out the quantified type variables for us.
728 [LSig name] -- User-supplied pragmatic info
729 [LTyClDecl name]-- Associated types (ie, 'TyData' and
732 instance (OutputableBndr name) => Outputable (InstDecl name) where
734 ppr (InstDecl inst_ty binds uprags ats)
735 = vcat [hsep [ptext SLIT("instance"), ppr inst_ty, ptext SLIT("where")],
738 nest 4 (pprLHsBinds binds) ]
740 -- Extract the declarations of associated types from an instance
742 instDeclATs :: InstDecl name -> [LTyClDecl name]
743 instDeclATs (InstDecl _ _ _ ats) = ats
746 %************************************************************************
748 \subsection[DerivDecl]{A stand-alone instance deriving declaration
750 %************************************************************************
753 type LDerivDecl name = Located (DerivDecl name)
755 data DerivDecl name = DerivDecl (LHsType name)
757 instance (OutputableBndr name) => Outputable (DerivDecl name) where
759 = hsep [ptext SLIT("derived instance"), ppr ty]
762 %************************************************************************
764 \subsection[DefaultDecl]{A @default@ declaration}
766 %************************************************************************
768 There can only be one default declaration per module, but it is hard
769 for the parser to check that; we pass them all through in the abstract
770 syntax, and that restriction must be checked in the front end.
773 type LDefaultDecl name = Located (DefaultDecl name)
775 data DefaultDecl name
776 = DefaultDecl [LHsType name]
778 instance (OutputableBndr name)
779 => Outputable (DefaultDecl name) where
781 ppr (DefaultDecl tys)
782 = ptext SLIT("default") <+> parens (interpp'SP tys)
785 %************************************************************************
787 \subsection{Foreign function interface declaration}
789 %************************************************************************
793 -- foreign declarations are distinguished as to whether they define or use a
796 -- * the Boolean value indicates whether the pre-standard deprecated syntax
799 type LForeignDecl name = Located (ForeignDecl name)
801 data ForeignDecl name
802 = ForeignImport (Located name) (LHsType name) ForeignImport -- defines name
803 | ForeignExport (Located name) (LHsType name) ForeignExport -- uses name
805 -- Specification Of an imported external entity in dependence on the calling
808 data ForeignImport = -- import of a C entity
810 -- * the two strings specifying a header file or library
811 -- may be empty, which indicates the absence of a
812 -- header or object specification (both are not used
813 -- in the case of `CWrapper' and when `CFunction'
814 -- has a dynamic target)
816 -- * the calling convention is irrelevant for code
817 -- generation in the case of `CLabel', but is needed
818 -- for pretty printing
820 -- * `Safety' is irrelevant for `CLabel' and `CWrapper'
822 CImport CCallConv -- ccall or stdcall
823 Safety -- safe or unsafe
824 FastString -- name of C header
825 FastString -- name of library object
826 CImportSpec -- details of the C entity
828 -- import of a .NET function
830 | DNImport DNCallSpec
832 -- details of an external C entity
834 data CImportSpec = CLabel CLabelString -- import address of a C label
835 | CFunction CCallTarget -- static or dynamic function
836 | CWrapper -- wrapper to expose closures
839 -- specification of an externally exported entity in dependence on the calling
842 data ForeignExport = CExport CExportSpec -- contains the calling convention
843 | DNExport -- presently unused
845 -- abstract type imported from .NET
847 data FoType = DNType -- In due course we'll add subtype stuff
848 deriving (Eq) -- Used for equality instance for TyClDecl
851 -- pretty printing of foreign declarations
854 instance OutputableBndr name => Outputable (ForeignDecl name) where
855 ppr (ForeignImport n ty fimport) =
856 ptext SLIT("foreign import") <+> ppr fimport <+>
857 ppr n <+> dcolon <+> ppr ty
858 ppr (ForeignExport n ty fexport) =
859 ptext SLIT("foreign export") <+> ppr fexport <+>
860 ppr n <+> dcolon <+> ppr ty
862 instance Outputable ForeignImport where
863 ppr (DNImport spec) =
864 ptext SLIT("dotnet") <+> ppr spec
865 ppr (CImport cconv safety header lib spec) =
866 ppr cconv <+> ppr safety <+>
867 char '"' <> pprCEntity header lib spec <> char '"'
869 pprCEntity header lib (CLabel lbl) =
870 ptext SLIT("static") <+> ftext header <+> char '&' <>
871 pprLib lib <> ppr lbl
872 pprCEntity header lib (CFunction (StaticTarget lbl)) =
873 ptext SLIT("static") <+> ftext header <+> char '&' <>
874 pprLib lib <> ppr lbl
875 pprCEntity header lib (CFunction (DynamicTarget)) =
876 ptext SLIT("dynamic")
877 pprCEntity _ _ (CWrapper) = ptext SLIT("wrapper")
879 pprLib lib | nullFS lib = empty
880 | otherwise = char '[' <> ppr lib <> char ']'
882 instance Outputable ForeignExport where
883 ppr (CExport (CExportStatic lbl cconv)) =
884 ppr cconv <+> char '"' <> ppr lbl <> char '"'
886 ptext SLIT("dotnet") <+> ptext SLIT("\"<unused>\"")
888 instance Outputable FoType where
889 ppr DNType = ptext SLIT("type dotnet")
893 %************************************************************************
895 \subsection{Transformation rules}
897 %************************************************************************
900 type LRuleDecl name = Located (RuleDecl name)
903 = HsRule -- Source rule
904 RuleName -- Rule name
906 [RuleBndr name] -- Forall'd vars; after typechecking this includes tyvars
907 (Located (HsExpr name)) -- LHS
908 NameSet -- Free-vars from the LHS
909 (Located (HsExpr name)) -- RHS
910 NameSet -- Free-vars from the RHS
913 = RuleBndr (Located name)
914 | RuleBndrSig (Located name) (LHsType name)
916 collectRuleBndrSigTys :: [RuleBndr name] -> [LHsType name]
917 collectRuleBndrSigTys bndrs = [ty | RuleBndrSig _ ty <- bndrs]
919 instance OutputableBndr name => Outputable (RuleDecl name) where
920 ppr (HsRule name act ns lhs fv_lhs rhs fv_rhs)
921 = sep [text "{-# RULES" <+> doubleQuotes (ftext name) <+> ppr act,
922 nest 4 (pp_forall <+> pprExpr (unLoc lhs)),
923 nest 4 (equals <+> pprExpr (unLoc rhs) <+> text "#-}") ]
925 pp_forall | null ns = empty
926 | otherwise = text "forall" <+> fsep (map ppr ns) <> dot
928 instance OutputableBndr name => Outputable (RuleBndr name) where
929 ppr (RuleBndr name) = ppr name
930 ppr (RuleBndrSig name ty) = ppr name <> dcolon <> ppr ty
933 %************************************************************************
935 \subsection[DocDecl]{Document comments}
937 %************************************************************************
941 -- source code entities, for representing the module structure
944 | DocEntity (DocDecl name)
946 type LDocDecl name = Located (DocDecl name)
949 = DocCommentNext (HsDoc name)
950 | DocCommentPrev (HsDoc name)
951 | DocCommentNamed String (HsDoc name)
952 | DocGroup Int (HsDoc name)
954 -- Okay, I need to reconstruct the document comments, but for now:
955 instance Outputable (DocDecl name) where
956 ppr _ = text "<document comment>"
958 docDeclDoc (DocCommentNext d) = d
959 docDeclDoc (DocCommentPrev d) = d
960 docDeclDoc (DocCommentNamed _ d) = d
961 docDeclDoc (DocGroup _ d) = d
965 %************************************************************************
967 \subsection[DeprecDecl]{Deprecations}
969 %************************************************************************
971 We use exported entities for things to deprecate.
974 type LDeprecDecl name = Located (DeprecDecl name)
976 data DeprecDecl name = Deprecation name DeprecTxt
978 instance OutputableBndr name => Outputable (DeprecDecl name) where
979 ppr (Deprecation thing txt)
980 = hsep [text "{-# DEPRECATED", ppr thing, doubleQuotes (ppr txt), text "#-}"]