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
384 tcdTyVars :: [LHsTyVarBndr name], -- Type variables
385 tcdTyPats :: Maybe [LHsType name], -- Type patterns
386 tcdKindSig:: Maybe Kind, -- Optional kind sig;
389 -- indexed type sigs)
391 tcdCons :: [LConDecl name], -- Data constructors
392 -- For data T a = T1 | T2 a the LConDecls all have ResTyH98
393 -- For data T a where { T1 :: T a } the LConDecls all have ResTyGADT
395 tcdDerivs :: Maybe [LHsType name]
396 -- Derivings; Nothing => not specified
397 -- Just [] => derive exactly what is asked
398 -- These "types" must be of form
399 -- forall ab. C ty1 ty2
400 -- Typically the foralls and ty args are empty, but they
401 -- are non-empty for the newtype-deriving case
404 | TyFunction {tcdLName :: Located name, -- type constructor
405 tcdTyVars :: [LHsTyVarBndr name], -- type variables
406 tcdIso :: Bool, -- injective type?
407 tcdKind :: Kind -- result kind
410 | TySynonym { tcdLName :: Located name, -- type constructor
411 tcdTyVars :: [LHsTyVarBndr name], -- type variables
412 tcdTyPats :: Maybe [LHsType name], -- Type patterns
413 -- 'Nothing' => vanilla
415 tcdSynRhs :: LHsType name -- synonym expansion
418 | ClassDecl { tcdCtxt :: LHsContext name, -- Context...
419 tcdLName :: Located name, -- Name of the class
420 tcdTyVars :: [LHsTyVarBndr name], -- Class type variables
421 tcdFDs :: [Located (FunDep name)], -- Functional deps
422 tcdSigs :: [LSig name], -- Methods' signatures
423 tcdMeths :: LHsBinds name, -- Default methods
424 tcdATs :: [LTyClDecl name], -- Associated types; ie
428 tcdDocs :: [DocEntity name] -- Haddock docs
432 = NewType -- "newtype Blah ..."
433 | DataType -- "data Blah ..."
434 deriving( Eq ) -- Needed because Demand derives Eq
440 isTFunDecl, isDataDecl, isSynDecl, isClassDecl, isKindSigDecl, isIdxTyDecl ::
441 TyClDecl name -> Bool
443 -- type function kind signature
444 isTFunDecl (TyFunction {}) = True
445 isTFunDecl other = False
447 -- vanilla Haskell type synonym
448 isSynDecl (TySynonym {tcdTyPats = Nothing}) = True
449 isSynDecl other = False
451 -- type equation (of a type function)
452 isTEqnDecl (TySynonym {tcdTyPats = Just _}) = True
453 isTEqnDecl other = False
455 isDataDecl (TyData {}) = True
456 isDataDecl other = False
458 isClassDecl (ClassDecl {}) = True
459 isClassDecl other = False
461 -- kind signature (for an indexed type)
462 isKindSigDecl (TyFunction {} ) = True
463 isKindSigDecl (TyData {tcdKindSig = Just _,
464 tcdCons = [] }) = True
465 isKindSigDecl other = False
467 -- definition of an instance of an indexed type
469 | isTEqnDecl tydecl = True
470 | isDataDecl tydecl = isJust (tcdTyPats tydecl)
477 tcdName :: TyClDecl name -> name
478 tcdName decl = unLoc (tcdLName decl)
480 tyClDeclNames :: Eq name => TyClDecl name -> [Located name]
481 -- Returns all the *binding* names of the decl, along with their SrcLocs
482 -- The first one is guaranteed to be the name of the decl
483 -- For record fields, the first one counts as the SrcLoc
484 -- We use the equality to filter out duplicate field names
486 tyClDeclNames (TyFunction {tcdLName = name}) = [name]
487 tyClDeclNames (TySynonym {tcdLName = name}) = [name]
488 tyClDeclNames (ForeignType {tcdLName = name}) = [name]
490 tyClDeclNames (ClassDecl {tcdLName = cls_name, tcdSigs = sigs, tcdATs = ats})
492 concatMap (tyClDeclNames . unLoc) ats ++ [n | L _ (TypeSig n _) <- sigs]
494 tyClDeclNames (TyData {tcdLName = tc_name, tcdCons = cons})
495 = tc_name : conDeclsNames (map unLoc cons)
497 tyClDeclTyVars (TyFunction {tcdTyVars = tvs}) = tvs
498 tyClDeclTyVars (TySynonym {tcdTyVars = tvs}) = tvs
499 tyClDeclTyVars (TyData {tcdTyVars = tvs}) = tvs
500 tyClDeclTyVars (ClassDecl {tcdTyVars = tvs}) = tvs
501 tyClDeclTyVars (ForeignType {}) = []
505 countTyClDecls :: [TyClDecl name] -> (Int, Int, Int, Int, Int, Int)
506 -- class, synonym decls, type function signatures,
507 -- type function equations, data, newtype
509 = (count isClassDecl decls,
510 count isSynDecl decls,
511 count isTFunDecl decls,
512 count isTEqnDecl decls,
513 count isDataTy decls,
516 isDataTy TyData{tcdND=DataType} = True
519 isNewTy TyData{tcdND=NewType} = True
524 instance OutputableBndr name
525 => Outputable (TyClDecl name) where
527 ppr (ForeignType {tcdLName = ltycon})
528 = hsep [ptext SLIT("foreign import type dotnet"), ppr ltycon]
530 ppr (TyFunction {tcdLName = ltycon, tcdTyVars = tyvars, tcdIso = iso,
532 = typeMaybeIso <+> pp_decl_head [] ltycon tyvars Nothing <+>
533 dcolon <+> pprKind kind
535 typeMaybeIso = if iso
536 then ptext SLIT("type family iso")
537 else ptext SLIT("type family")
539 ppr (TySynonym {tcdLName = ltycon, tcdTyVars = tyvars, tcdTyPats = typats,
540 tcdSynRhs = mono_ty})
541 = hang (ptext SLIT("type") <+>
542 (if isJust typats then ptext SLIT("instance") else empty) <+>
543 pp_decl_head [] ltycon tyvars typats <+>
547 ppr (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = ltycon,
548 tcdTyVars = tyvars, tcdTyPats = typats, tcdKindSig = mb_sig,
549 tcdCons = condecls, tcdDerivs = derivings})
550 = pp_tydecl (null condecls && isJust mb_sig)
552 (if isJust typats then ptext SLIT("instance") else empty) <+>
553 pp_decl_head (unLoc context) ltycon tyvars typats <+>
555 (pp_condecls condecls)
558 ppr_sig Nothing = empty
559 ppr_sig (Just kind) = dcolon <+> pprKind kind
561 ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars,
563 tcdSigs = sigs, tcdMeths = methods, tcdATs = ats})
564 | null sigs && null ats -- No "where" part
567 | otherwise -- Laid out
568 = sep [hsep [top_matter, ptext SLIT("where {")],
569 nest 4 (sep [ sep (map ppr_semi ats)
570 , sep (map ppr_semi sigs)
571 , pprLHsBinds methods
574 top_matter = ptext SLIT("class")
575 <+> pp_decl_head (unLoc context) lclas tyvars Nothing
576 <+> pprFundeps (map unLoc fds)
577 ppr_semi decl = ppr decl <> semi
579 pp_decl_head :: OutputableBndr name
582 -> [LHsTyVarBndr name]
583 -> Maybe [LHsType name]
585 pp_decl_head context thing tyvars Nothing -- no explicit type patterns
586 = hsep [pprHsContext context, ppr thing, interppSP tyvars]
587 pp_decl_head context thing _ (Just typats) -- explicit type patterns
588 = hsep [ pprHsContext context, ppr thing
589 , hsep (map (pprParendHsType.unLoc) typats)]
591 pp_condecls cs@(L _ ConDecl{ con_res = ResTyGADT _ } : _) -- In GADT syntax
592 = hang (ptext SLIT("where")) 2 (vcat (map ppr cs))
593 pp_condecls cs -- In H98 syntax
594 = equals <+> sep (punctuate (ptext SLIT(" |")) (map ppr cs))
596 pp_tydecl True pp_head pp_decl_rhs derivings
598 pp_tydecl False pp_head pp_decl_rhs derivings
599 = hang pp_head 4 (sep [
603 Just ds -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
606 instance Outputable NewOrData where
607 ppr NewType = ptext SLIT("newtype")
608 ppr DataType = ptext SLIT("data")
612 %************************************************************************
614 \subsection[ConDecl]{A data-constructor declaration}
616 %************************************************************************
619 type LConDecl name = Located (ConDecl name)
621 -- data T b = forall a. Eq a => MkT a b
622 -- MkT :: forall b a. Eq a => MkT a b
625 -- MkT1 :: Int -> T Int
627 -- data T = Int `MkT` Int
631 -- Int `MkT` Int :: T Int
635 { con_name :: Located name -- Constructor name; this is used for the
636 -- DataCon itself, and for the user-callable wrapper Id
638 , con_explicit :: HsExplicitForAll -- Is there an user-written forall? (cf. HStypes.HsForAllTy)
640 , con_qvars :: [LHsTyVarBndr name] -- ResTyH98: the constructor's existential type variables
641 -- ResTyGADT: all the constructor's quantified type variables
643 , con_cxt :: LHsContext name -- The context. This *does not* include the
644 -- "stupid theta" which lives only in the TyData decl
646 , con_details :: HsConDetails name (LBangType name) -- The main payload
648 , con_res :: ResType name -- Result type of the constructor
650 , con_doc :: Maybe (LHsDoc name) -- A possible Haddock comment
654 = ResTyH98 -- Constructor was declared using Haskell 98 syntax
655 | ResTyGADT (LHsType name) -- Constructor was declared using GADT-style syntax,
656 -- and here is its result type
660 conDeclsNames :: Eq name => [ConDecl name] -> [Located name]
661 -- See tyClDeclNames for what this does
662 -- The function is boringly complicated because of the records
663 -- And since we only have equality, we have to be a little careful
665 = snd (foldl do_one ([], []) cons)
667 do_one (flds_seen, acc) (ConDecl { con_name = lname, con_details = RecCon flds })
668 = (map unLoc new_flds ++ flds_seen, lname : [f | f <- new_flds] ++ acc)
670 new_flds = [ f | (HsRecField f _ _) <- flds, not (unLoc f `elem` flds_seen) ]
672 do_one (flds_seen, acc) c
673 = (flds_seen, (con_name c):acc)
675 conDetailsTys details = map getBangType (hsConArgs details)
680 instance (OutputableBndr name) => Outputable (ConDecl name) where
683 pprConDecl (ConDecl con expl tvs cxt details ResTyH98 doc)
684 = sep [ppr_mbDoc doc, pprHsForAll expl tvs cxt, ppr_details con details]
686 ppr_details con (InfixCon t1 t2) = hsep [ppr t1, pprHsVar con, ppr t2]
687 ppr_details con (PrefixCon tys) = hsep (pprHsVar con : map ppr tys)
688 ppr_details con (RecCon fields) = ppr con <+> ppr_fields fields
690 pprConDecl (ConDecl con expl tvs cxt (PrefixCon arg_tys) (ResTyGADT res_ty) _)
691 = ppr con <+> dcolon <+>
692 sep [pprHsForAll expl tvs cxt, ppr (foldr mk_fun_ty res_ty arg_tys)]
694 mk_fun_ty a b = noLoc (HsFunTy a b)
696 pprConDecl (ConDecl con expl tvs cxt (RecCon fields) (ResTyGADT res_ty) _)
697 = sep [pprHsForAll expl tvs cxt, ppr con <+> ppr_fields fields <+> dcolon <+> ppr res_ty]
699 ppr_fields fields = braces (sep (punctuate comma (map ppr fields)))
702 %************************************************************************
704 \subsection[InstDecl]{An instance declaration
706 %************************************************************************
709 type LInstDecl name = Located (InstDecl name)
712 = InstDecl (LHsType name) -- Context => Class Instance-type
713 -- Using a polytype means that the renamer conveniently
714 -- figures out the quantified type variables for us.
716 [LSig name] -- User-supplied pragmatic info
717 [LTyClDecl name]-- Associated types (ie, 'TyData' and
720 instance (OutputableBndr name) => Outputable (InstDecl name) where
722 ppr (InstDecl inst_ty binds uprags ats)
723 = vcat [hsep [ptext SLIT("instance"), ppr inst_ty, ptext SLIT("where")],
726 nest 4 (pprLHsBinds binds) ]
728 -- Extract the declarations of associated types from an instance
730 instDeclATs :: InstDecl name -> [LTyClDecl name]
731 instDeclATs (InstDecl _ _ _ ats) = ats
734 %************************************************************************
736 \subsection[DerivDecl]{A stand-alone instance deriving declaration
738 %************************************************************************
741 type LDerivDecl name = Located (DerivDecl name)
744 = DerivDecl (LHsType name) (Located name)
746 instance (OutputableBndr name) => Outputable (DerivDecl name) where
748 = hsep [ptext SLIT("deriving"), ppr ty, ptext SLIT("for"), ppr n]
751 %************************************************************************
753 \subsection[DefaultDecl]{A @default@ declaration}
755 %************************************************************************
757 There can only be one default declaration per module, but it is hard
758 for the parser to check that; we pass them all through in the abstract
759 syntax, and that restriction must be checked in the front end.
762 type LDefaultDecl name = Located (DefaultDecl name)
764 data DefaultDecl name
765 = DefaultDecl [LHsType name]
767 instance (OutputableBndr name)
768 => Outputable (DefaultDecl name) where
770 ppr (DefaultDecl tys)
771 = ptext SLIT("default") <+> parens (interpp'SP tys)
774 %************************************************************************
776 \subsection{Foreign function interface declaration}
778 %************************************************************************
782 -- foreign declarations are distinguished as to whether they define or use a
785 -- * the Boolean value indicates whether the pre-standard deprecated syntax
788 type LForeignDecl name = Located (ForeignDecl name)
790 data ForeignDecl name
791 = ForeignImport (Located name) (LHsType name) ForeignImport -- defines name
792 | ForeignExport (Located name) (LHsType name) ForeignExport -- uses name
794 -- Specification Of an imported external entity in dependence on the calling
797 data ForeignImport = -- import of a C entity
799 -- * the two strings specifying a header file or library
800 -- may be empty, which indicates the absence of a
801 -- header or object specification (both are not used
802 -- in the case of `CWrapper' and when `CFunction'
803 -- has a dynamic target)
805 -- * the calling convention is irrelevant for code
806 -- generation in the case of `CLabel', but is needed
807 -- for pretty printing
809 -- * `Safety' is irrelevant for `CLabel' and `CWrapper'
811 CImport CCallConv -- ccall or stdcall
812 Safety -- safe or unsafe
813 FastString -- name of C header
814 FastString -- name of library object
815 CImportSpec -- details of the C entity
817 -- import of a .NET function
819 | DNImport DNCallSpec
821 -- details of an external C entity
823 data CImportSpec = CLabel CLabelString -- import address of a C label
824 | CFunction CCallTarget -- static or dynamic function
825 | CWrapper -- wrapper to expose closures
828 -- specification of an externally exported entity in dependence on the calling
831 data ForeignExport = CExport CExportSpec -- contains the calling convention
832 | DNExport -- presently unused
834 -- abstract type imported from .NET
836 data FoType = DNType -- In due course we'll add subtype stuff
837 deriving (Eq) -- Used for equality instance for TyClDecl
840 -- pretty printing of foreign declarations
843 instance OutputableBndr name => Outputable (ForeignDecl name) where
844 ppr (ForeignImport n ty fimport) =
845 ptext SLIT("foreign import") <+> ppr fimport <+>
846 ppr n <+> dcolon <+> ppr ty
847 ppr (ForeignExport n ty fexport) =
848 ptext SLIT("foreign export") <+> ppr fexport <+>
849 ppr n <+> dcolon <+> ppr ty
851 instance Outputable ForeignImport where
852 ppr (DNImport spec) =
853 ptext SLIT("dotnet") <+> ppr spec
854 ppr (CImport cconv safety header lib spec) =
855 ppr cconv <+> ppr safety <+>
856 char '"' <> pprCEntity header lib spec <> char '"'
858 pprCEntity header lib (CLabel lbl) =
859 ptext SLIT("static") <+> ftext header <+> char '&' <>
860 pprLib lib <> ppr lbl
861 pprCEntity header lib (CFunction (StaticTarget lbl)) =
862 ptext SLIT("static") <+> ftext header <+> char '&' <>
863 pprLib lib <> ppr lbl
864 pprCEntity header lib (CFunction (DynamicTarget)) =
865 ptext SLIT("dynamic")
866 pprCEntity _ _ (CWrapper) = ptext SLIT("wrapper")
868 pprLib lib | nullFS lib = empty
869 | otherwise = char '[' <> ppr lib <> char ']'
871 instance Outputable ForeignExport where
872 ppr (CExport (CExportStatic lbl cconv)) =
873 ppr cconv <+> char '"' <> ppr lbl <> char '"'
875 ptext SLIT("dotnet") <+> ptext SLIT("\"<unused>\"")
877 instance Outputable FoType where
878 ppr DNType = ptext SLIT("type dotnet")
882 %************************************************************************
884 \subsection{Transformation rules}
886 %************************************************************************
889 type LRuleDecl name = Located (RuleDecl name)
892 = HsRule -- Source rule
893 RuleName -- Rule name
895 [RuleBndr name] -- Forall'd vars; after typechecking this includes tyvars
896 (Located (HsExpr name)) -- LHS
897 NameSet -- Free-vars from the LHS
898 (Located (HsExpr name)) -- RHS
899 NameSet -- Free-vars from the RHS
902 = RuleBndr (Located name)
903 | RuleBndrSig (Located name) (LHsType name)
905 collectRuleBndrSigTys :: [RuleBndr name] -> [LHsType name]
906 collectRuleBndrSigTys bndrs = [ty | RuleBndrSig _ ty <- bndrs]
908 instance OutputableBndr name => Outputable (RuleDecl name) where
909 ppr (HsRule name act ns lhs fv_lhs rhs fv_rhs)
910 = sep [text "{-# RULES" <+> doubleQuotes (ftext name) <+> ppr act,
911 nest 4 (pp_forall <+> pprExpr (unLoc lhs)),
912 nest 4 (equals <+> pprExpr (unLoc rhs) <+> text "#-}") ]
914 pp_forall | null ns = empty
915 | otherwise = text "forall" <+> fsep (map ppr ns) <> dot
917 instance OutputableBndr name => Outputable (RuleBndr name) where
918 ppr (RuleBndr name) = ppr name
919 ppr (RuleBndrSig name ty) = ppr name <> dcolon <> ppr ty
922 %************************************************************************
924 \subsection[DocDecl]{Document comments}
926 %************************************************************************
930 -- source code entities, for representing the module structure
933 | DocEntity (DocDecl name)
935 type LDocDecl name = Located (DocDecl name)
938 = DocCommentNext (HsDoc name)
939 | DocCommentPrev (HsDoc name)
940 | DocCommentNamed String (HsDoc name)
941 | DocGroup Int (HsDoc name)
943 -- Okay, I need to reconstruct the document comments, but for now:
944 instance Outputable (DocDecl name) where
945 ppr _ = text "<document comment>"
947 docDeclDoc (DocCommentNext d) = d
948 docDeclDoc (DocCommentPrev d) = d
949 docDeclDoc (DocCommentNamed _ d) = d
950 docDeclDoc (DocGroup _ d) = d
954 %************************************************************************
956 \subsection[DeprecDecl]{Deprecations}
958 %************************************************************************
960 We use exported entities for things to deprecate.
963 type LDeprecDecl name = Located (DeprecDecl name)
965 data DeprecDecl name = Deprecation name DeprecTxt
967 instance OutputableBndr name => Outputable (DeprecDecl name) where
968 ppr (Deprecation thing txt)
969 = hsep [text "{-# DEPRECATED", ppr thing, doubleQuotes (ppr txt), text "#-}"]