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(..),
16 RuleDecl(..), LRuleDecl, RuleBndr(..),
17 DefaultDecl(..), LDefaultDecl, SpliceDecl(..),
18 ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
19 CImportSpec(..), FoType(..),
20 ConDecl(..), ResType(..), LConDecl,
21 DocDecl(..), LDocDecl, docDeclDoc,
22 DeprecDecl(..), LDeprecDecl,
23 HsGroup(..), emptyRdrGroup, emptyRnGroup, appendGroups,
24 tcdName, tyClDeclNames, tyClDeclTyVars,
25 isClassDecl, isSynDecl, isDataDecl, isTypeDecl, isFamilyDecl,
30 collectRuleBndrSigTys,
33 #include "HsVersions.h"
36 import {-# SOURCE #-} HsExpr( HsExpr, pprExpr )
37 -- Because Expr imports Decls via HsBracket
46 import {- Kind parts of -} Type
57 import Data.Maybe ( isJust )
60 %************************************************************************
62 \subsection[HsDecl]{Declarations}
64 %************************************************************************
67 type LHsDecl id = Located (HsDecl id)
72 | DerivD (DerivDecl id)
75 | DefD (DefaultDecl id)
76 | ForD (ForeignDecl id)
77 | DeprecD (DeprecDecl id)
79 | SpliceD (SpliceDecl id)
83 -- NB: all top-level fixity decls are contained EITHER
85 -- OR in the ClassDecls in TyClDs
88 -- a) data constructors
89 -- b) class methods (but they can be also done in the
90 -- signatures of class decls)
91 -- c) imported functions (that have an IfacSig)
94 -- The latter is for class methods only
96 -- A [HsDecl] is categorised into a HsGroup before being
97 -- fed to the renamer.
100 hs_valds :: HsValBinds id,
101 hs_tyclds :: [LTyClDecl id],
102 hs_instds :: [LInstDecl id],
103 hs_derivds :: [LDerivDecl id],
105 hs_fixds :: [LFixitySig id],
106 -- Snaffled out of both top-level fixity signatures,
107 -- and those in class declarations
109 hs_defds :: [LDefaultDecl id],
110 hs_fords :: [LForeignDecl id],
111 hs_depds :: [LDeprecDecl id],
112 hs_ruleds :: [LRuleDecl id],
114 hs_docs :: [LDocDecl id]
117 emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup a
118 emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
119 emptyRnGroup = emptyGroup { hs_valds = emptyValBindsOut }
121 emptyGroup = HsGroup { hs_tyclds = [], hs_instds = [], hs_derivds = [],
122 hs_fixds = [], hs_defds = [], hs_fords = [],
123 hs_depds = [], hs_ruleds = [],
124 hs_valds = error "emptyGroup hs_valds: Can't happen",
127 appendGroups :: HsGroup a -> HsGroup a -> HsGroup a
130 hs_valds = val_groups1,
133 hs_derivds = derivds1,
141 hs_valds = val_groups2,
144 hs_derivds = derivds2,
153 hs_valds = val_groups1 `plusHsValBinds` val_groups2,
154 hs_tyclds = tyclds1 ++ tyclds2,
155 hs_instds = instds1 ++ instds2,
156 hs_derivds = derivds1 ++ derivds2,
157 hs_fixds = fixds1 ++ fixds2,
158 hs_defds = defds1 ++ defds2,
159 hs_fords = fords1 ++ fords2,
160 hs_depds = depds1 ++ depds2,
161 hs_ruleds = rulds1 ++ rulds2,
162 hs_docs = docs1 ++ docs2 }
166 instance OutputableBndr name => Outputable (HsDecl name) where
167 ppr (TyClD dcl) = ppr dcl
168 ppr (ValD binds) = ppr binds
169 ppr (DefD def) = ppr def
170 ppr (InstD inst) = ppr inst
171 ppr (DerivD deriv) = ppr deriv
172 ppr (ForD fd) = ppr fd
173 ppr (SigD sd) = ppr sd
174 ppr (RuleD rd) = ppr rd
175 ppr (DeprecD dd) = ppr dd
176 ppr (SpliceD dd) = ppr dd
177 ppr (DocD doc) = ppr doc
179 instance OutputableBndr name => Outputable (HsGroup name) where
180 ppr (HsGroup { hs_valds = val_decls,
181 hs_tyclds = tycl_decls,
182 hs_instds = inst_decls,
183 hs_derivds = deriv_decls,
184 hs_fixds = fix_decls,
185 hs_depds = deprec_decls,
186 hs_fords = foreign_decls,
187 hs_defds = default_decls,
188 hs_ruleds = rule_decls })
189 = vcat [ppr_ds fix_decls, ppr_ds default_decls,
190 ppr_ds deprec_decls, ppr_ds rule_decls,
192 ppr_ds tycl_decls, ppr_ds inst_decls,
194 ppr_ds foreign_decls]
197 ppr_ds ds = text "" $$ vcat (map ppr ds)
199 data SpliceDecl id = SpliceDecl (Located (HsExpr id)) -- Top level splice
201 instance OutputableBndr name => Outputable (SpliceDecl name) where
202 ppr (SpliceDecl e) = ptext SLIT("$") <> parens (pprExpr (unLoc e))
206 %************************************************************************
208 \subsection[TyDecl]{@data@, @newtype@ or @type@ (synonym) type declaration}
210 %************************************************************************
212 --------------------------------
214 --------------------------------
216 Here is the story about the implicit names that go with type, class,
217 and instance decls. It's a bit tricky, so pay attention!
219 "Implicit" (or "system") binders
220 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
221 Each data type decl defines
222 a worker name for each constructor
223 to-T and from-T convertors
224 Each class decl defines
225 a tycon for the class
226 a data constructor for that tycon
227 the worker for that constructor
228 a selector for each superclass
230 All have occurrence names that are derived uniquely from their parent
233 None of these get separate definitions in an interface file; they are
234 fully defined by the data or class decl. But they may *occur* in
235 interface files, of course. Any such occurrence must haul in the
236 relevant type or class decl.
239 - Ensure they "point to" the parent data/class decl
240 when loading that decl from an interface file
241 (See RnHiFiles.getSysBinders)
243 - When typechecking the decl, we build the implicit TyCons and Ids.
244 When doing so we look them up in the name cache (RnEnv.lookupSysName),
245 to ensure correct module and provenance is set
247 These are the two places that we have to conjure up the magic derived
248 names. (The actual magic is in OccName.mkWorkerOcc, etc.)
252 - Occurrence name is derived uniquely from the method name
255 - If there is a default method name at all, it's recorded in
256 the ClassOpSig (in HsBinds), in the DefMeth field.
257 (DefMeth is defined in Class.lhs)
259 Source-code class decls and interface-code class decls are treated subtly
260 differently, which has given me a great deal of confusion over the years.
261 Here's the deal. (We distinguish the two cases because source-code decls
262 have (Just binds) in the tcdMeths field, whereas interface decls have Nothing.
264 In *source-code* class declarations:
266 - When parsing, every ClassOpSig gets a DefMeth with a suitable RdrName
267 This is done by RdrHsSyn.mkClassOpSigDM
269 - The renamer renames it to a Name
271 - During typechecking, we generate a binding for each $dm for
272 which there's a programmer-supplied default method:
277 We generate a binding for $dmop1 but not for $dmop2.
278 The Class for Foo has a NoDefMeth for op2 and a DefMeth for op1.
279 The Name for $dmop2 is simply discarded.
281 In *interface-file* class declarations:
282 - When parsing, we see if there's an explicit programmer-supplied default method
283 because there's an '=' sign to indicate it:
285 op1 = :: <type> -- NB the '='
287 We use this info to generate a DefMeth with a suitable RdrName for op1,
288 and a NoDefMeth for op2
289 - The interface file has a separate definition for $dmop1, with unfolding etc.
290 - The renamer renames it to a Name.
291 - The renamer treats $dmop1 as a free variable of the declaration, so that
292 the binding for $dmop1 will be sucked in. (See RnHsSyn.tyClDeclFVs)
293 This doesn't happen for source code class decls, because they *bind* the default method.
297 Each instance declaration gives rise to one dictionary function binding.
299 The type checker makes up new source-code instance declarations
300 (e.g. from 'deriving' or generic default methods --- see
301 TcInstDcls.tcInstDecls1). So we can't generate the names for
302 dictionary functions in advance (we don't know how many we need).
304 On the other hand for interface-file instance declarations, the decl
305 specifies the name of the dictionary function, and it has a binding elsewhere
306 in the interface file:
307 instance {Eq Int} = dEqInt
308 dEqInt :: {Eq Int} <pragma info>
310 So again we treat source code and interface file code slightly differently.
313 - Source code instance decls have a Nothing in the (Maybe name) field
314 (see data InstDecl below)
316 - The typechecker makes up a Local name for the dict fun for any source-code
317 instance decl, whether it comes from a source-code instance decl, or whether
318 the instance decl is derived from some other construct (e.g. 'deriving').
320 - The occurrence name it chooses is derived from the instance decl (just for
321 documentation really) --- e.g. dNumInt. Two dict funs may share a common
322 occurrence name, but will have different uniques. E.g.
323 instance Foo [Int] where ...
324 instance Foo [Bool] where ...
325 These might both be dFooList
327 - The CoreTidy phase externalises the name, and ensures the occurrence name is
328 unique (this isn't special to dict funs). So we'd get dFooList and dFooList1.
330 - We can take this relaxed approach (changing the occurrence name later)
331 because dict fun Ids are not captured in a TyCon or Class (unlike default
332 methods, say). Instead, they are kept separately in the InstEnv. This
333 makes it easy to adjust them after compiling a module. (Once we've finished
334 compiling that module, they don't change any more.)
338 - The instance decl gives the dict fun name, so the InstDecl has a (Just name)
339 in the (Maybe name) field.
341 - RnHsSyn.instDeclFVs treats the dict fun name as free in the decl, so that we
342 suck in the dfun binding
346 -- Representation of indexed types
347 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
348 -- Family kind signatures are represented by the variant `TyFamily'. It
349 -- covers "type family", "newtype family", and "data family" declarations,
350 -- distinguished by the value of the field `tcdFlavour'.
352 -- Indexed types are represented by 'TyData' and 'TySynonym' using the field
353 -- 'tcdTyPats::Maybe [LHsType name]', with the following meaning:
355 -- * If it is 'Nothing', we have a *vanilla* data type declaration or type
356 -- synonym declaration and 'tcdVars' contains the type parameters of the
359 -- * If it is 'Just pats', we have the definition of an indexed type. Then,
360 -- 'pats' are type patterns for the type-indexes of the type constructor
361 -- and 'tcdTyVars' are the variables in those patterns. Hence, the arity of
362 -- the indexed type (ie, the number of indexes) is 'length tcdTyPats' and
363 -- *not* 'length tcdVars'.
365 -- In both cases, 'tcdVars' collects all variables we need to quantify over.
367 type LTyClDecl name = Located (TyClDecl name)
371 tcdLName :: Located name,
372 tcdExtName :: Maybe FastString,
376 -- type/data/newtype family T :: *->*
377 | TyFamily { tcdFlavour:: FamilyFlavour, -- type, new, or data
378 tcdLName :: Located name, -- type constructor
379 tcdTyVars :: [LHsTyVarBndr name], -- type variables
380 tcdKind :: Maybe Kind -- result kind
383 -- Declares a data type or newtype, giving its construcors
384 -- data/newtype T a = <constrs>
385 -- data/newtype instance T [a] = <constrs>
386 | TyData { tcdND :: NewOrData,
387 tcdCtxt :: LHsContext name, -- Context
388 tcdLName :: Located name, -- Type constructor
390 tcdTyVars :: [LHsTyVarBndr name], -- Type variables
392 tcdTyPats :: Maybe [LHsType name], -- Type patterns
393 -- Just [t1..tn] for data instance T t1..tn = ...
394 -- in this case tcdTyVars = fv( tcdTyPats )
395 -- Nothing for everything else
397 tcdKindSig:: Maybe Kind, -- Optional kind sig
398 -- (Just k) for a GADT-style 'data', or 'data
399 -- instance' decl with explicit kind sig
401 tcdCons :: [LConDecl name], -- Data constructors
402 -- For data T a = T1 | T2 a the LConDecls all have ResTyH98
403 -- For data T a where { T1 :: T a } the LConDecls all have ResTyGADT
405 tcdDerivs :: Maybe [LHsType name]
406 -- Derivings; Nothing => not specified
407 -- Just [] => derive exactly what is asked
408 -- These "types" must be of form
409 -- forall ab. C ty1 ty2
410 -- Typically the foralls and ty args are empty, but they
411 -- are non-empty for the newtype-deriving case
414 | TySynonym { tcdLName :: Located name, -- type constructor
415 tcdTyVars :: [LHsTyVarBndr name], -- type variables
416 tcdTyPats :: Maybe [LHsType name], -- Type patterns
417 -- See comments for tcdTyPats in TyData
418 -- 'Nothing' => vanilla type synonym
420 tcdSynRhs :: LHsType name -- synonym expansion
423 | ClassDecl { tcdCtxt :: LHsContext name, -- Context...
424 tcdLName :: Located name, -- Name of the class
425 tcdTyVars :: [LHsTyVarBndr name], -- Class type variables
426 tcdFDs :: [Located (FunDep name)], -- Functional deps
427 tcdSigs :: [LSig name], -- Methods' signatures
428 tcdMeths :: LHsBinds name, -- Default methods
429 tcdATs :: [LTyClDecl name], -- Associated types; ie
433 tcdDocs :: [LDocDecl name] -- Haddock docs
437 = NewType -- "newtype Blah ..."
438 | DataType -- "data Blah ..."
439 deriving( Eq ) -- Needed because Demand derives Eq
442 = TypeFamily -- "type family ..."
443 | DataFamily NewOrData -- "newtype family ..." or "data family ..."
449 isDataDecl, isTypeDecl, isSynDecl, isClassDecl, isFamilyDecl, isFamInstDecl ::
450 TyClDecl name -> Bool
452 -- data/newtype or data/newtype instance declaration
453 isDataDecl (TyData {}) = True
454 isDataDecl _other = False
456 -- type or type instance declaration
457 isTypeDecl (TySynonym {}) = True
458 isTypeDecl _other = False
460 -- vanilla Haskell type synonym (ie, not a type instance)
461 isSynDecl (TySynonym {tcdTyPats = Nothing}) = True
462 isSynDecl _other = False
465 isClassDecl (ClassDecl {}) = True
466 isClassDecl other = False
468 -- type family declaration
469 isFamilyDecl (TyFamily {}) = True
470 isFamilyDecl _other = False
472 -- family instance (types, newtypes, and data types)
475 || isDataDecl tydecl = isJust (tcdTyPats tydecl)
482 tcdName :: TyClDecl name -> name
483 tcdName decl = unLoc (tcdLName decl)
485 tyClDeclNames :: Eq name => TyClDecl name -> [Located name]
486 -- Returns all the *binding* names of the decl, along with their SrcLocs
487 -- The first one is guaranteed to be the name of the decl
488 -- For record fields, the first one counts as the SrcLoc
489 -- We use the equality to filter out duplicate field names
491 tyClDeclNames (TyFamily {tcdLName = name}) = [name]
492 tyClDeclNames (TySynonym {tcdLName = name}) = [name]
493 tyClDeclNames (ForeignType {tcdLName = name}) = [name]
495 tyClDeclNames (ClassDecl {tcdLName = cls_name, tcdSigs = sigs, tcdATs = ats})
497 concatMap (tyClDeclNames . unLoc) ats ++ [n | L _ (TypeSig n _) <- sigs]
499 tyClDeclNames (TyData {tcdLName = tc_name, tcdCons = cons})
500 = tc_name : conDeclsNames (map unLoc cons)
502 tyClDeclTyVars (TyFamily {tcdTyVars = tvs}) = tvs
503 tyClDeclTyVars (TySynonym {tcdTyVars = tvs}) = tvs
504 tyClDeclTyVars (TyData {tcdTyVars = tvs}) = tvs
505 tyClDeclTyVars (ClassDecl {tcdTyVars = tvs}) = tvs
506 tyClDeclTyVars (ForeignType {}) = []
510 countTyClDecls :: [TyClDecl name] -> (Int, Int, Int, Int, Int, Int)
511 -- class, synonym decls, data, newtype, family decls, family instances
513 = (count isClassDecl decls,
514 count isSynDecl decls, -- excluding...
515 count isDataTy decls, -- ...family...
516 count isNewTy decls, -- ...instances
517 count isFamilyDecl decls,
518 count isFamInstDecl decls)
520 isDataTy TyData{tcdND = DataType, tcdTyPats = Nothing} = True
523 isNewTy TyData{tcdND = NewType, tcdTyPats = Nothing} = True
528 instance OutputableBndr name
529 => Outputable (TyClDecl name) where
531 ppr (ForeignType {tcdLName = ltycon})
532 = hsep [ptext SLIT("foreign import type dotnet"), ppr ltycon]
534 ppr (TyFamily {tcdFlavour = flavour, tcdLName = ltycon,
535 tcdTyVars = tyvars, tcdKind = mb_kind})
536 = pp_flavour <+> pp_decl_head [] ltycon tyvars Nothing <+> pp_kind
538 pp_flavour = case flavour of
539 TypeFamily -> ptext SLIT("type family")
540 DataFamily NewType -> ptext SLIT("newtype family")
541 DataFamily DataType -> ptext SLIT("data family")
543 pp_kind = case mb_kind of
545 Just kind -> dcolon <+> pprKind kind
547 ppr (TySynonym {tcdLName = ltycon, tcdTyVars = tyvars, tcdTyPats = typats,
548 tcdSynRhs = mono_ty})
549 = hang (ptext SLIT("type") <+>
550 (if isJust typats then ptext SLIT("instance") else empty) <+>
551 pp_decl_head [] ltycon tyvars typats <+>
555 ppr (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = ltycon,
556 tcdTyVars = tyvars, tcdTyPats = typats, tcdKindSig = mb_sig,
557 tcdCons = condecls, tcdDerivs = derivings})
558 = pp_tydecl (null condecls && isJust mb_sig)
560 (if isJust typats then ptext SLIT("instance") else empty) <+>
561 pp_decl_head (unLoc context) ltycon tyvars typats <+>
563 (pp_condecls condecls)
566 ppr_sig Nothing = empty
567 ppr_sig (Just kind) = dcolon <+> pprKind kind
569 ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars,
571 tcdSigs = sigs, tcdMeths = methods, tcdATs = ats})
572 | null sigs && null ats -- No "where" part
575 | otherwise -- Laid out
576 = sep [hsep [top_matter, ptext SLIT("where {")],
577 nest 4 (sep [ sep (map ppr_semi ats)
578 , sep (map ppr_semi sigs)
579 , pprLHsBinds methods
582 top_matter = ptext SLIT("class")
583 <+> pp_decl_head (unLoc context) lclas tyvars Nothing
584 <+> pprFundeps (map unLoc fds)
585 ppr_semi decl = ppr decl <> semi
587 pp_decl_head :: OutputableBndr name
590 -> [LHsTyVarBndr name]
591 -> Maybe [LHsType name]
593 pp_decl_head context thing tyvars Nothing -- no explicit type patterns
594 = hsep [pprHsContext context, ppr thing, interppSP tyvars]
595 pp_decl_head context thing _ (Just typats) -- explicit type patterns
596 = hsep [ pprHsContext context, ppr thing
597 , hsep (map (pprParendHsType.unLoc) typats)]
599 pp_condecls cs@(L _ ConDecl{ con_res = ResTyGADT _ } : _) -- In GADT syntax
600 = hang (ptext SLIT("where")) 2 (vcat (map ppr cs))
601 pp_condecls cs -- In H98 syntax
602 = equals <+> sep (punctuate (ptext SLIT(" |")) (map ppr cs))
604 pp_tydecl True pp_head pp_decl_rhs derivings
606 pp_tydecl False pp_head pp_decl_rhs derivings
607 = hang pp_head 4 (sep [
611 Just ds -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
614 instance Outputable NewOrData where
615 ppr NewType = ptext SLIT("newtype")
616 ppr DataType = ptext SLIT("data")
620 %************************************************************************
622 \subsection[ConDecl]{A data-constructor declaration}
624 %************************************************************************
627 type LConDecl name = Located (ConDecl name)
629 -- data T b = forall a. Eq a => MkT a b
630 -- MkT :: forall b a. Eq a => MkT a b
633 -- MkT1 :: Int -> T Int
635 -- data T = Int `MkT` Int
639 -- Int `MkT` Int :: T Int
643 { con_name :: Located name -- Constructor name; this is used for the
644 -- DataCon itself, and for the user-callable wrapper Id
646 , con_explicit :: HsExplicitForAll -- Is there an user-written forall? (cf. HStypes.HsForAllTy)
648 , con_qvars :: [LHsTyVarBndr name] -- ResTyH98: the constructor's existential type variables
649 -- ResTyGADT: all the constructor's quantified type variables
651 , con_cxt :: LHsContext name -- The context. This *does not* include the
652 -- "stupid theta" which lives only in the TyData decl
654 , con_details :: HsConDetails name (LBangType name) -- The main payload
656 , con_res :: ResType name -- Result type of the constructor
658 , con_doc :: Maybe (LHsDoc name) -- A possible Haddock comment
662 = ResTyH98 -- Constructor was declared using Haskell 98 syntax
663 | ResTyGADT (LHsType name) -- Constructor was declared using GADT-style syntax,
664 -- and here is its result type
668 conDeclsNames :: Eq name => [ConDecl name] -> [Located name]
669 -- See tyClDeclNames for what this does
670 -- The function is boringly complicated because of the records
671 -- And since we only have equality, we have to be a little careful
673 = snd (foldl do_one ([], []) cons)
675 do_one (flds_seen, acc) (ConDecl { con_name = lname, con_details = RecCon flds })
676 = (map unLoc new_flds ++ flds_seen, lname : [f | f <- new_flds] ++ acc)
678 new_flds = [ f | (HsRecField f _ _) <- flds, not (unLoc f `elem` flds_seen) ]
680 do_one (flds_seen, acc) c
681 = (flds_seen, (con_name c):acc)
683 conDetailsTys details = map getBangType (hsConArgs details)
688 instance (OutputableBndr name) => Outputable (ConDecl name) where
691 pprConDecl (ConDecl con expl tvs cxt details ResTyH98 doc)
692 = sep [ppr_mbDoc doc, pprHsForAll expl tvs cxt, ppr_details con details]
694 ppr_details con (InfixCon t1 t2) = hsep [ppr t1, pprHsVar con, ppr t2]
695 ppr_details con (PrefixCon tys) = hsep (pprHsVar con : map ppr tys)
696 ppr_details con (RecCon fields) = ppr con <+> ppr_fields fields
698 pprConDecl (ConDecl con expl tvs cxt (PrefixCon arg_tys) (ResTyGADT res_ty) _)
699 = ppr con <+> dcolon <+>
700 sep [pprHsForAll expl tvs cxt, ppr (foldr mk_fun_ty res_ty arg_tys)]
702 mk_fun_ty a b = noLoc (HsFunTy a b)
704 pprConDecl (ConDecl con expl tvs cxt (RecCon fields) (ResTyGADT res_ty) _)
705 = sep [pprHsForAll expl tvs cxt, ppr con <+> ppr_fields fields <+> dcolon <+> ppr res_ty]
707 ppr_fields fields = braces (sep (punctuate comma (map ppr fields)))
710 %************************************************************************
712 \subsection[InstDecl]{An instance declaration
714 %************************************************************************
717 type LInstDecl name = Located (InstDecl name)
720 = InstDecl (LHsType name) -- Context => Class Instance-type
721 -- Using a polytype means that the renamer conveniently
722 -- figures out the quantified type variables for us.
724 [LSig name] -- User-supplied pragmatic info
725 [LTyClDecl name]-- Associated types (ie, 'TyData' and
728 instance (OutputableBndr name) => Outputable (InstDecl name) where
730 ppr (InstDecl inst_ty binds uprags ats)
731 = vcat [hsep [ptext SLIT("instance"), ppr inst_ty, ptext SLIT("where")],
734 nest 4 (pprLHsBinds binds) ]
736 -- Extract the declarations of associated types from an instance
738 instDeclATs :: InstDecl name -> [LTyClDecl name]
739 instDeclATs (InstDecl _ _ _ ats) = ats
742 %************************************************************************
744 \subsection[DerivDecl]{A stand-alone instance deriving declaration
746 %************************************************************************
749 type LDerivDecl name = Located (DerivDecl name)
751 data DerivDecl name = DerivDecl (LHsType name)
753 instance (OutputableBndr name) => Outputable (DerivDecl name) where
755 = hsep [ptext SLIT("derived instance"), ppr ty]
758 %************************************************************************
760 \subsection[DefaultDecl]{A @default@ declaration}
762 %************************************************************************
764 There can only be one default declaration per module, but it is hard
765 for the parser to check that; we pass them all through in the abstract
766 syntax, and that restriction must be checked in the front end.
769 type LDefaultDecl name = Located (DefaultDecl name)
771 data DefaultDecl name
772 = DefaultDecl [LHsType name]
774 instance (OutputableBndr name)
775 => Outputable (DefaultDecl name) where
777 ppr (DefaultDecl tys)
778 = ptext SLIT("default") <+> parens (interpp'SP tys)
781 %************************************************************************
783 \subsection{Foreign function interface declaration}
785 %************************************************************************
789 -- foreign declarations are distinguished as to whether they define or use a
792 -- * the Boolean value indicates whether the pre-standard deprecated syntax
795 type LForeignDecl name = Located (ForeignDecl name)
797 data ForeignDecl name
798 = ForeignImport (Located name) (LHsType name) ForeignImport -- defines name
799 | ForeignExport (Located name) (LHsType name) ForeignExport -- uses name
801 -- Specification Of an imported external entity in dependence on the calling
804 data ForeignImport = -- import of a C entity
806 -- * the two strings specifying a header file or library
807 -- may be empty, which indicates the absence of a
808 -- header or object specification (both are not used
809 -- in the case of `CWrapper' and when `CFunction'
810 -- has a dynamic target)
812 -- * the calling convention is irrelevant for code
813 -- generation in the case of `CLabel', but is needed
814 -- for pretty printing
816 -- * `Safety' is irrelevant for `CLabel' and `CWrapper'
818 CImport CCallConv -- ccall or stdcall
819 Safety -- safe or unsafe
820 FastString -- name of C header
821 FastString -- name of library object
822 CImportSpec -- details of the C entity
824 -- import of a .NET function
826 | DNImport DNCallSpec
828 -- details of an external C entity
830 data CImportSpec = CLabel CLabelString -- import address of a C label
831 | CFunction CCallTarget -- static or dynamic function
832 | CWrapper -- wrapper to expose closures
835 -- specification of an externally exported entity in dependence on the calling
838 data ForeignExport = CExport CExportSpec -- contains the calling convention
839 | DNExport -- presently unused
841 -- abstract type imported from .NET
843 data FoType = DNType -- In due course we'll add subtype stuff
844 deriving (Eq) -- Used for equality instance for TyClDecl
847 -- pretty printing of foreign declarations
850 instance OutputableBndr name => Outputable (ForeignDecl name) where
851 ppr (ForeignImport n ty fimport) =
852 ptext SLIT("foreign import") <+> ppr fimport <+>
853 ppr n <+> dcolon <+> ppr ty
854 ppr (ForeignExport n ty fexport) =
855 ptext SLIT("foreign export") <+> ppr fexport <+>
856 ppr n <+> dcolon <+> ppr ty
858 instance Outputable ForeignImport where
859 ppr (DNImport spec) =
860 ptext SLIT("dotnet") <+> ppr spec
861 ppr (CImport cconv safety header lib spec) =
862 ppr cconv <+> ppr safety <+>
863 char '"' <> pprCEntity header lib spec <> char '"'
865 pprCEntity header lib (CLabel lbl) =
866 ptext SLIT("static") <+> ftext header <+> char '&' <>
867 pprLib lib <> ppr lbl
868 pprCEntity header lib (CFunction (StaticTarget lbl)) =
869 ptext SLIT("static") <+> ftext header <+> char '&' <>
870 pprLib lib <> ppr lbl
871 pprCEntity header lib (CFunction (DynamicTarget)) =
872 ptext SLIT("dynamic")
873 pprCEntity _ _ (CWrapper) = ptext SLIT("wrapper")
875 pprLib lib | nullFS lib = empty
876 | otherwise = char '[' <> ppr lib <> char ']'
878 instance Outputable ForeignExport where
879 ppr (CExport (CExportStatic lbl cconv)) =
880 ppr cconv <+> char '"' <> ppr lbl <> char '"'
882 ptext SLIT("dotnet") <+> ptext SLIT("\"<unused>\"")
884 instance Outputable FoType where
885 ppr DNType = ptext SLIT("type dotnet")
889 %************************************************************************
891 \subsection{Transformation rules}
893 %************************************************************************
896 type LRuleDecl name = Located (RuleDecl name)
899 = HsRule -- Source rule
900 RuleName -- Rule name
902 [RuleBndr name] -- Forall'd vars; after typechecking this includes tyvars
903 (Located (HsExpr name)) -- LHS
904 NameSet -- Free-vars from the LHS
905 (Located (HsExpr name)) -- RHS
906 NameSet -- Free-vars from the RHS
909 = RuleBndr (Located name)
910 | RuleBndrSig (Located name) (LHsType name)
912 collectRuleBndrSigTys :: [RuleBndr name] -> [LHsType name]
913 collectRuleBndrSigTys bndrs = [ty | RuleBndrSig _ ty <- bndrs]
915 instance OutputableBndr name => Outputable (RuleDecl name) where
916 ppr (HsRule name act ns lhs fv_lhs rhs fv_rhs)
917 = sep [text "{-# RULES" <+> doubleQuotes (ftext name) <+> ppr act,
918 nest 4 (pp_forall <+> pprExpr (unLoc lhs)),
919 nest 4 (equals <+> pprExpr (unLoc rhs) <+> text "#-}") ]
921 pp_forall | null ns = empty
922 | otherwise = text "forall" <+> fsep (map ppr ns) <> dot
924 instance OutputableBndr name => Outputable (RuleBndr name) where
925 ppr (RuleBndr name) = ppr name
926 ppr (RuleBndrSig name ty) = ppr name <> dcolon <> ppr ty
929 %************************************************************************
931 \subsection[DocDecl]{Document comments}
933 %************************************************************************
937 type LDocDecl name = Located (DocDecl name)
940 = DocCommentNext (HsDoc name)
941 | DocCommentPrev (HsDoc name)
942 | DocCommentNamed String (HsDoc name)
943 | DocGroup Int (HsDoc name)
945 -- Okay, I need to reconstruct the document comments, but for now:
946 instance Outputable (DocDecl name) where
947 ppr _ = text "<document comment>"
949 docDeclDoc (DocCommentNext d) = d
950 docDeclDoc (DocCommentPrev d) = d
951 docDeclDoc (DocCommentNamed _ d) = d
952 docDeclDoc (DocGroup _ d) = d
956 %************************************************************************
958 \subsection[DeprecDecl]{Deprecations}
960 %************************************************************************
962 We use exported entities for things to deprecate.
965 type LDeprecDecl name = Located (DeprecDecl name)
967 data DeprecDecl name = Deprecation name DeprecTxt
969 instance OutputableBndr name => Outputable (DeprecDecl name) where
970 ppr (Deprecation thing txt)
971 = hsep [text "{-# DEPRECATED", ppr thing, doubleQuotes (ppr txt), text "#-}"]