2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[HsDecls]{Abstract syntax: global declarations}
6 Definitions for: @TyDecl@ and @oCnDecl@, @ClassDecl@,
7 @InstDecl@, @DefaultDecl@ and @ForeignDecl@.
11 HsDecl(..), LHsDecl, TyClDecl(..), LTyClDecl,
12 InstDecl(..), LInstDecl, NewOrData(..),
13 RuleDecl(..), LRuleDecl, RuleBndr(..),
14 DefaultDecl(..), LDefaultDecl, SpliceDecl(..),
15 ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
16 CImportSpec(..), FoType(..),
17 ConDecl(..), ResType(..), LConDecl,
18 DeprecDecl(..), LDeprecDecl,
19 HsGroup(..), emptyRdrGroup, emptyRnGroup, appendGroups,
20 tcdName, tyClDeclNames, tyClDeclTyVars,
21 isClassDecl, isTFunDecl, isSynDecl, isDataDecl, isKindSigDecl,
26 collectRuleBndrSigTys,
29 #include "HsVersions.h"
32 import {-# SOURCE #-} HsExpr( HsExpr, pprExpr )
33 -- Because Expr imports Decls via HsBracket
35 import HsBinds ( HsValBinds(..), HsBind, LHsBinds, plusHsValBinds,
36 Sig(..), LSig, LFixitySig, pprLHsBinds,
37 emptyValBindsIn, emptyValBindsOut )
38 import HsPat ( HsConDetails(..), hsConArgs )
39 import HsImpExp ( pprHsVar )
41 import NameSet ( NameSet )
42 import HscTypes ( DeprecTxt )
43 import CoreSyn ( RuleName )
44 import Kind ( Kind, pprKind )
45 import BasicTypes ( Activation(..) )
46 import ForeignCall ( CCallTarget(..), DNCallSpec, CCallConv, Safety,
47 CExportSpec(..), CLabelString )
50 import FunDeps ( pprFundeps )
51 import Class ( FunDep )
54 import SrcLoc ( Located(..), unLoc, noLoc )
56 import Maybe ( isJust )
60 %************************************************************************
62 \subsection[HsDecl]{Declarations}
64 %************************************************************************
67 type LHsDecl id = Located (HsDecl id)
74 | DefD (DefaultDecl id)
75 | ForD (ForeignDecl id)
76 | DeprecD (DeprecDecl id)
78 | SpliceD (SpliceDecl id)
80 -- NB: all top-level fixity decls are contained EITHER
82 -- OR in the ClassDecls in TyClDs
85 -- a) data constructors
86 -- b) class methods (but they can be also done in the
87 -- signatures of class decls)
88 -- c) imported functions (that have an IfacSig)
91 -- The latter is for class methods only
93 -- A [HsDecl] is categorised into a HsGroup before being
94 -- fed to the renamer.
97 hs_valds :: HsValBinds id,
98 hs_tyclds :: [LTyClDecl id],
99 hs_instds :: [LInstDecl id],
101 hs_fixds :: [LFixitySig id],
102 -- Snaffled out of both top-level fixity signatures,
103 -- and those in class declarations
105 hs_defds :: [LDefaultDecl id],
106 hs_fords :: [LForeignDecl id],
107 hs_depds :: [LDeprecDecl id],
108 hs_ruleds :: [LRuleDecl id]
111 emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup a
112 emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
113 emptyRnGroup = emptyGroup { hs_valds = emptyValBindsOut }
115 emptyGroup = HsGroup { hs_tyclds = [], hs_instds = [],
116 hs_fixds = [], hs_defds = [], hs_fords = [],
117 hs_depds = [], hs_ruleds = [],
118 hs_valds = error "emptyGroup hs_valds: Can't happen" }
120 appendGroups :: HsGroup a -> HsGroup a -> HsGroup a
123 hs_valds = val_groups1,
132 hs_valds = val_groups2,
142 hs_valds = val_groups1 `plusHsValBinds` val_groups2,
143 hs_tyclds = tyclds1 ++ tyclds2,
144 hs_instds = instds1 ++ instds2,
145 hs_fixds = fixds1 ++ fixds2,
146 hs_defds = defds1 ++ defds2,
147 hs_fords = fords1 ++ fords2,
148 hs_depds = depds1 ++ depds2,
149 hs_ruleds = rulds1 ++ rulds2 }
153 instance OutputableBndr name => Outputable (HsDecl name) where
154 ppr (TyClD dcl) = ppr dcl
155 ppr (ValD binds) = ppr binds
156 ppr (DefD def) = ppr def
157 ppr (InstD inst) = ppr inst
158 ppr (ForD fd) = ppr fd
159 ppr (SigD sd) = ppr sd
160 ppr (RuleD rd) = ppr rd
161 ppr (DeprecD dd) = ppr dd
162 ppr (SpliceD dd) = ppr dd
164 instance OutputableBndr name => Outputable (HsGroup name) where
165 ppr (HsGroup { hs_valds = val_decls,
166 hs_tyclds = tycl_decls,
167 hs_instds = inst_decls,
168 hs_fixds = fix_decls,
169 hs_depds = deprec_decls,
170 hs_fords = foreign_decls,
171 hs_defds = default_decls,
172 hs_ruleds = rule_decls })
173 = vcat [ppr_ds fix_decls, ppr_ds default_decls,
174 ppr_ds deprec_decls, ppr_ds rule_decls,
176 ppr_ds tycl_decls, ppr_ds inst_decls,
177 ppr_ds foreign_decls]
180 ppr_ds ds = text "" $$ vcat (map ppr ds)
182 data SpliceDecl id = SpliceDecl (Located (HsExpr id)) -- Top level splice
184 instance OutputableBndr name => Outputable (SpliceDecl name) where
185 ppr (SpliceDecl e) = ptext SLIT("$") <> parens (pprExpr (unLoc e))
189 %************************************************************************
191 \subsection[TyDecl]{@data@, @newtype@ or @type@ (synonym) type declaration}
193 %************************************************************************
195 --------------------------------
197 --------------------------------
199 Here is the story about the implicit names that go with type, class,
200 and instance decls. It's a bit tricky, so pay attention!
202 "Implicit" (or "system") binders
203 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
204 Each data type decl defines
205 a worker name for each constructor
206 to-T and from-T convertors
207 Each class decl defines
208 a tycon for the class
209 a data constructor for that tycon
210 the worker for that constructor
211 a selector for each superclass
213 All have occurrence names that are derived uniquely from their parent
216 None of these get separate definitions in an interface file; they are
217 fully defined by the data or class decl. But they may *occur* in
218 interface files, of course. Any such occurrence must haul in the
219 relevant type or class decl.
222 - Ensure they "point to" the parent data/class decl
223 when loading that decl from an interface file
224 (See RnHiFiles.getSysBinders)
226 - When typechecking the decl, we build the implicit TyCons and Ids.
227 When doing so we look them up in the name cache (RnEnv.lookupSysName),
228 to ensure correct module and provenance is set
230 These are the two places that we have to conjure up the magic derived
231 names. (The actual magic is in OccName.mkWorkerOcc, etc.)
235 - Occurrence name is derived uniquely from the method name
238 - If there is a default method name at all, it's recorded in
239 the ClassOpSig (in HsBinds), in the DefMeth field.
240 (DefMeth is defined in Class.lhs)
242 Source-code class decls and interface-code class decls are treated subtly
243 differently, which has given me a great deal of confusion over the years.
244 Here's the deal. (We distinguish the two cases because source-code decls
245 have (Just binds) in the tcdMeths field, whereas interface decls have Nothing.
247 In *source-code* class declarations:
249 - When parsing, every ClassOpSig gets a DefMeth with a suitable RdrName
250 This is done by RdrHsSyn.mkClassOpSigDM
252 - The renamer renames it to a Name
254 - During typechecking, we generate a binding for each $dm for
255 which there's a programmer-supplied default method:
260 We generate a binding for $dmop1 but not for $dmop2.
261 The Class for Foo has a NoDefMeth for op2 and a DefMeth for op1.
262 The Name for $dmop2 is simply discarded.
264 In *interface-file* class declarations:
265 - When parsing, we see if there's an explicit programmer-supplied default method
266 because there's an '=' sign to indicate it:
268 op1 = :: <type> -- NB the '='
270 We use this info to generate a DefMeth with a suitable RdrName for op1,
271 and a NoDefMeth for op2
272 - The interface file has a separate definition for $dmop1, with unfolding etc.
273 - The renamer renames it to a Name.
274 - The renamer treats $dmop1 as a free variable of the declaration, so that
275 the binding for $dmop1 will be sucked in. (See RnHsSyn.tyClDeclFVs)
276 This doesn't happen for source code class decls, because they *bind* the default method.
280 Each instance declaration gives rise to one dictionary function binding.
282 The type checker makes up new source-code instance declarations
283 (e.g. from 'deriving' or generic default methods --- see
284 TcInstDcls.tcInstDecls1). So we can't generate the names for
285 dictionary functions in advance (we don't know how many we need).
287 On the other hand for interface-file instance declarations, the decl
288 specifies the name of the dictionary function, and it has a binding elsewhere
289 in the interface file:
290 instance {Eq Int} = dEqInt
291 dEqInt :: {Eq Int} <pragma info>
293 So again we treat source code and interface file code slightly differently.
296 - Source code instance decls have a Nothing in the (Maybe name) field
297 (see data InstDecl below)
299 - The typechecker makes up a Local name for the dict fun for any source-code
300 instance decl, whether it comes from a source-code instance decl, or whether
301 the instance decl is derived from some other construct (e.g. 'deriving').
303 - The occurrence name it chooses is derived from the instance decl (just for
304 documentation really) --- e.g. dNumInt. Two dict funs may share a common
305 occurrence name, but will have different uniques. E.g.
306 instance Foo [Int] where ...
307 instance Foo [Bool] where ...
308 These might both be dFooList
310 - The CoreTidy phase externalises the name, and ensures the occurrence name is
311 unique (this isn't special to dict funs). So we'd get dFooList and dFooList1.
313 - We can take this relaxed approach (changing the occurrence name later)
314 because dict fun Ids are not captured in a TyCon or Class (unlike default
315 methods, say). Instead, they are kept separately in the InstEnv. This
316 makes it easy to adjust them after compiling a module. (Once we've finished
317 compiling that module, they don't change any more.)
321 - The instance decl gives the dict fun name, so the InstDecl has a (Just name)
322 in the (Maybe name) field.
324 - RnHsSyn.instDeclFVs treats the dict fun name as free in the decl, so that we
325 suck in the dfun binding
329 -- TyClDecls are precisely the kind of declarations that can
330 -- appear in interface files; or (internally) in GHC's interface
331 -- for a module. That's why (despite the misnomer) IfaceSig and ForeignType
332 -- are both in TyClDecl
334 -- Representation of indexed types
335 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
336 -- Kind signatures of indexed types come in two flavours:
338 -- * kind signatures for type functions: variant `TyFunction' and
340 -- * kind signatures for indexed data types and newtypes : variant `TyData'
341 -- iff a kind is present in `tcdKindSig' and there are no constructors in
344 -- Indexed types are represented by 'TyData' and 'TySynonym' using the field
345 -- 'tcdTyPats::Maybe [LHsType name]', with the following meaning:
347 -- * If it is 'Nothing', we have a *vanilla* data type declaration or type
348 -- synonym declaration and 'tcdVars' contains the type parameters of the
351 -- * If it is 'Just pats', we have the definition of an indexed type Then,
352 -- 'pats' are type patterns for the type-indexes of the type constructor
353 -- and 'tcdVars' are the variables in those patterns. Hence, the arity of
354 -- the indexed type (ie, the number of indexes) is 'length tcdTyPats' and
355 -- *not* 'length tcdVars'.
357 -- In both cases, 'tcdVars' collects all variables we need to quantify over.
359 type LTyClDecl name = Located (TyClDecl name)
363 tcdLName :: Located name,
364 tcdExtName :: Maybe FastString,
368 | TyData { tcdND :: NewOrData,
369 tcdCtxt :: LHsContext name, -- Context
370 tcdLName :: Located name, -- Type constructor
371 tcdTyVars :: [LHsTyVarBndr name], -- Type variables
372 tcdTyPats :: Maybe [LHsType name], -- Type patterns
373 tcdKindSig:: Maybe Kind, -- Optional kind sig;
376 -- indexed type sigs)
378 tcdCons :: [LConDecl name], -- Data constructors
379 -- For data T a = T1 | T2 a the LConDecls all have ResTyH98
380 -- For data T a where { T1 :: T a } the LConDecls all have ResTyGADT
382 tcdDerivs :: Maybe [LHsType name]
383 -- Derivings; Nothing => not specified
384 -- Just [] => derive exactly what is asked
385 -- These "types" must be of form
386 -- forall ab. C ty1 ty2
387 -- Typically the foralls and ty args are empty, but they
388 -- are non-empty for the newtype-deriving case
391 | TyFunction {tcdLName :: Located name, -- type constructor
392 tcdTyVars :: [LHsTyVarBndr name], -- type variables
393 tcdIso :: Bool, -- injective type?
394 tcdKind :: Kind -- result kind
397 | TySynonym { tcdLName :: Located name, -- type constructor
398 tcdTyVars :: [LHsTyVarBndr name], -- type variables
399 tcdTyPats :: Maybe [LHsType name], -- Type patterns
400 -- 'Nothing' => vanilla
402 tcdSynRhs :: LHsType name -- synonym expansion
405 | ClassDecl { tcdCtxt :: LHsContext name, -- Context...
406 tcdLName :: Located name, -- Name of the class
407 tcdTyVars :: [LHsTyVarBndr name], -- Class type variables
408 tcdFDs :: [Located (FunDep name)], -- Functional deps
409 tcdSigs :: [LSig name], -- Methods' signatures
410 tcdMeths :: LHsBinds name, -- Default methods
411 tcdATs :: [LTyClDecl name] -- Associated types; ie
418 = NewType -- "newtype Blah ..."
419 | DataType -- "data Blah ..."
420 deriving( Eq ) -- Needed because Demand derives Eq
426 isTFunDecl, isDataDecl, isSynDecl, isClassDecl, isKindSigDecl, isIdxTyDecl ::
427 TyClDecl name -> Bool
429 -- type function kind signature
430 isTFunDecl (TyFunction {}) = True
431 isTFunDecl other = False
433 -- vanilla Haskell type synonym
434 isSynDecl (TySynonym {tcdTyPats = Nothing}) = True
435 isSynDecl other = False
437 -- type equation (of a type function)
438 isTEqnDecl (TySynonym {tcdTyPats = Just _}) = True
439 isTEqnDecl other = False
441 isDataDecl (TyData {}) = True
442 isDataDecl other = False
444 isClassDecl (ClassDecl {}) = True
445 isClassDecl other = False
447 -- kind signature (for an indexed type)
448 isKindSigDecl (TyFunction {} ) = True
449 isKindSigDecl (TyData {tcdKindSig = Just _,
450 tcdCons = [] }) = True
451 isKindSigDecl other = False
453 -- definition of an instance of an indexed type
454 isIdxTyDecl = isJust . tcdTyPats
460 tcdName :: TyClDecl name -> name
461 tcdName decl = unLoc (tcdLName decl)
463 tyClDeclNames :: Eq name => TyClDecl name -> [Located name]
464 -- Returns all the *binding* names of the decl, along with their SrcLocs
465 -- The first one is guaranteed to be the name of the decl
466 -- For record fields, the first one counts as the SrcLoc
467 -- We use the equality to filter out duplicate field names
469 tyClDeclNames (TyFunction {tcdLName = name}) = [name]
470 tyClDeclNames (TySynonym {tcdLName = name,
471 tcdTyPats= Nothing}) = [name]
472 tyClDeclNames (TySynonym {} ) = [] -- type equation
473 tyClDeclNames (ForeignType {tcdLName = name}) = [name]
475 tyClDeclNames (ClassDecl {tcdLName = cls_name, tcdSigs = sigs, tcdATs = ats})
477 concatMap (tyClDeclNames . unLoc) ats ++ [n | L _ (TypeSig n _) <- sigs]
479 tyClDeclNames (TyData {tcdLName = tc_name, tcdCons = cons})
480 = tc_name : conDeclsNames (map unLoc cons)
482 tyClDeclTyVars (TyFunction {tcdTyVars = tvs}) = tvs
483 tyClDeclTyVars (TySynonym {tcdTyVars = tvs}) = tvs
484 tyClDeclTyVars (TyData {tcdTyVars = tvs}) = tvs
485 tyClDeclTyVars (ClassDecl {tcdTyVars = tvs}) = tvs
486 tyClDeclTyVars (ForeignType {}) = []
490 countTyClDecls :: [TyClDecl name] -> (Int, Int, Int, Int, Int, Int)
491 -- class, synonym decls, type function signatures,
492 -- type function equations, data, newtype
494 = (count isClassDecl decls,
495 count isSynDecl decls,
496 count isTFunDecl decls,
497 count isTEqnDecl decls,
498 count isDataTy decls,
501 isDataTy TyData{tcdND=DataType} = True
504 isNewTy TyData{tcdND=NewType} = True
509 instance OutputableBndr name
510 => Outputable (TyClDecl name) where
512 ppr (ForeignType {tcdLName = ltycon})
513 = hsep [ptext SLIT("foreign import type dotnet"), ppr ltycon]
515 ppr (TyFunction {tcdLName = ltycon, tcdTyVars = tyvars, tcdIso = iso,
517 = typeMaybeIso <+> pp_decl_head [] ltycon tyvars Nothing <+>
518 dcolon <+> pprKind kind
520 typeMaybeIso = if iso
521 then ptext SLIT("type iso")
522 else ptext SLIT("type")
524 ppr (TySynonym {tcdLName = ltycon, tcdTyVars = tyvars, tcdTyPats = typats,
525 tcdSynRhs = mono_ty})
526 = hang (ptext SLIT("type") <+> pp_decl_head [] ltycon tyvars typats <+>
530 ppr (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = ltycon,
531 tcdTyVars = tyvars, tcdTyPats = typats, tcdKindSig = mb_sig,
532 tcdCons = condecls, tcdDerivs = derivings})
533 = pp_tydecl (ppr new_or_data <+>
534 pp_decl_head (unLoc context) ltycon tyvars typats <+>
536 (pp_condecls condecls)
539 ppr_sig Nothing = empty
540 ppr_sig (Just kind) = dcolon <+> pprKind kind
542 ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars,
544 tcdSigs = sigs, tcdMeths = methods, tcdATs = ats})
545 | null sigs && null ats -- No "where" part
548 | otherwise -- Laid out
549 = sep [hsep [top_matter, ptext SLIT("where {")],
550 nest 4 (sep [ sep (map ppr_semi ats)
551 , sep (map ppr_semi sigs)
552 , pprLHsBinds methods
555 top_matter = ptext SLIT("class")
556 <+> pp_decl_head (unLoc context) lclas tyvars Nothing
557 <+> pprFundeps (map unLoc fds)
558 ppr_semi decl = ppr decl <> semi
560 pp_decl_head :: OutputableBndr name
563 -> [LHsTyVarBndr name]
564 -> Maybe [LHsType name]
566 pp_decl_head context thing tyvars Nothing -- no explicit type patterns
567 = hsep [pprHsContext context, ppr thing, interppSP tyvars]
568 pp_decl_head context thing _ (Just typats) -- explicit type patterns
569 = hsep [ pprHsContext context, ppr thing
570 , hsep (map (pprParendHsType.unLoc) typats)]
572 pp_condecls cs@(L _ ConDecl{ con_res = ResTyGADT _ } : _) -- In GADT syntax
573 = hang (ptext SLIT("where")) 2 (vcat (map ppr cs))
574 pp_condecls cs -- In H98 syntax
575 = equals <+> sep (punctuate (ptext SLIT(" |")) (map ppr cs))
577 pp_tydecl pp_head pp_decl_rhs derivings
578 = hang pp_head 4 (sep [
582 Just ds -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
585 instance Outputable NewOrData where
586 ppr NewType = ptext SLIT("newtype")
587 ppr DataType = ptext SLIT("data")
591 %************************************************************************
593 \subsection[ConDecl]{A data-constructor declaration}
595 %************************************************************************
598 type LConDecl name = Located (ConDecl name)
600 -- data T b = forall a. Eq a => MkT a b
601 -- MkT :: forall b a. Eq a => MkT a b
604 -- MkT1 :: Int -> T Int
606 -- data T = Int `MkT` Int
610 -- Int `MkT` Int :: T Int
614 { con_name :: Located name -- Constructor name; this is used for the
615 -- DataCon itself, and for the user-callable wrapper Id
617 , con_explicit :: HsExplicitForAll -- Is there an user-written forall? (cf. HStypes.HsForAllTy)
619 , con_qvars :: [LHsTyVarBndr name] -- ResTyH98: the constructor's existential type variables
620 -- ResTyGADT: all the constructor's quantified type variables
622 , con_cxt :: LHsContext name -- The context. This *does not* include the
623 -- "stupid theta" which lives only in the TyData decl
625 , con_details :: HsConDetails name (LBangType name) -- The main payload
627 , con_res :: ResType name -- Result type of the constructor
631 = ResTyH98 -- Constructor was declared using Haskell 98 syntax
632 | ResTyGADT (LHsType name) -- Constructor was declared using GADT-style syntax,
633 -- and here is its result type
637 conDeclsNames :: Eq name => [ConDecl name] -> [Located name]
638 -- See tyClDeclNames for what this does
639 -- The function is boringly complicated because of the records
640 -- And since we only have equality, we have to be a little careful
642 = snd (foldl do_one ([], []) cons)
644 do_one (flds_seen, acc) (ConDecl { con_name = lname, con_details = RecCon flds })
645 = (map unLoc new_flds ++ flds_seen, lname : [f | f <- new_flds] ++ acc)
647 new_flds = [ f | (f,_) <- flds, not (unLoc f `elem` flds_seen) ]
649 do_one (flds_seen, acc) c
650 = (flds_seen, (con_name c):acc)
652 conDetailsTys details = map getBangType (hsConArgs details)
657 instance (OutputableBndr name) => Outputable (ConDecl name) where
660 pprConDecl (ConDecl con expl tvs cxt details ResTyH98)
661 = sep [pprHsForAll expl tvs cxt, ppr_details con details]
663 ppr_details con (InfixCon t1 t2) = hsep [ppr t1, pprHsVar con, ppr t2]
664 ppr_details con (PrefixCon tys) = hsep (pprHsVar con : map ppr tys)
665 ppr_details con (RecCon fields) = ppr con <+> ppr_fields fields
667 pprConDecl (ConDecl con expl tvs cxt (PrefixCon arg_tys) (ResTyGADT res_ty))
668 = ppr con <+> dcolon <+>
669 sep [pprHsForAll expl tvs cxt, ppr (foldr mk_fun_ty res_ty arg_tys)]
671 mk_fun_ty a b = noLoc (HsFunTy a b)
672 pprConDecl (ConDecl con expl tvs cxt (RecCon fields) (ResTyGADT res_ty))
673 = sep [pprHsForAll expl tvs cxt, ppr con <+> ppr fields <+> dcolon <+> ppr res_ty]
675 ppr_fields fields = braces (sep (punctuate comma (map ppr_field fields)))
676 ppr_field (n, ty) = ppr n <+> dcolon <+> ppr ty
679 %************************************************************************
681 \subsection[InstDecl]{An instance declaration
683 %************************************************************************
686 type LInstDecl name = Located (InstDecl name)
689 = InstDecl (LHsType name) -- Context => Class Instance-type
690 -- Using a polytype means that the renamer conveniently
691 -- figures out the quantified type variables for us.
693 [LSig name] -- User-supplied pragmatic info
694 [LTyClDecl name]-- Associated types (ie, 'TyData' and
697 instance (OutputableBndr name) => Outputable (InstDecl name) where
699 ppr (InstDecl inst_ty binds uprags ats)
700 = vcat [hsep [ptext SLIT("instance"), ppr inst_ty, ptext SLIT("where")],
703 nest 4 (pprLHsBinds binds) ]
705 -- Extract the declarations of associated types from an instance
707 instDeclATs :: InstDecl name -> [LTyClDecl name]
708 instDeclATs (InstDecl _ _ _ ats) = ats
711 %************************************************************************
713 \subsection[DefaultDecl]{A @default@ declaration}
715 %************************************************************************
717 There can only be one default declaration per module, but it is hard
718 for the parser to check that; we pass them all through in the abstract
719 syntax, and that restriction must be checked in the front end.
722 type LDefaultDecl name = Located (DefaultDecl name)
724 data DefaultDecl name
725 = DefaultDecl [LHsType name]
727 instance (OutputableBndr name)
728 => Outputable (DefaultDecl name) where
730 ppr (DefaultDecl tys)
731 = ptext SLIT("default") <+> parens (interpp'SP tys)
734 %************************************************************************
736 \subsection{Foreign function interface declaration}
738 %************************************************************************
742 -- foreign declarations are distinguished as to whether they define or use a
745 -- * the Boolean value indicates whether the pre-standard deprecated syntax
748 type LForeignDecl name = Located (ForeignDecl name)
750 data ForeignDecl name
751 = ForeignImport (Located name) (LHsType name) ForeignImport -- defines name
752 | ForeignExport (Located name) (LHsType name) ForeignExport -- uses name
754 -- Specification Of an imported external entity in dependence on the calling
757 data ForeignImport = -- import of a C entity
759 -- * the two strings specifying a header file or library
760 -- may be empty, which indicates the absence of a
761 -- header or object specification (both are not used
762 -- in the case of `CWrapper' and when `CFunction'
763 -- has a dynamic target)
765 -- * the calling convention is irrelevant for code
766 -- generation in the case of `CLabel', but is needed
767 -- for pretty printing
769 -- * `Safety' is irrelevant for `CLabel' and `CWrapper'
771 CImport CCallConv -- ccall or stdcall
772 Safety -- safe or unsafe
773 FastString -- name of C header
774 FastString -- name of library object
775 CImportSpec -- details of the C entity
777 -- import of a .NET function
779 | DNImport DNCallSpec
781 -- details of an external C entity
783 data CImportSpec = CLabel CLabelString -- import address of a C label
784 | CFunction CCallTarget -- static or dynamic function
785 | CWrapper -- wrapper to expose closures
788 -- specification of an externally exported entity in dependence on the calling
791 data ForeignExport = CExport CExportSpec -- contains the calling convention
792 | DNExport -- presently unused
794 -- abstract type imported from .NET
796 data FoType = DNType -- In due course we'll add subtype stuff
797 deriving (Eq) -- Used for equality instance for TyClDecl
800 -- pretty printing of foreign declarations
803 instance OutputableBndr name => Outputable (ForeignDecl name) where
804 ppr (ForeignImport n ty fimport) =
805 ptext SLIT("foreign import") <+> ppr fimport <+>
806 ppr n <+> dcolon <+> ppr ty
807 ppr (ForeignExport n ty fexport) =
808 ptext SLIT("foreign export") <+> ppr fexport <+>
809 ppr n <+> dcolon <+> ppr ty
811 instance Outputable ForeignImport where
812 ppr (DNImport spec) =
813 ptext SLIT("dotnet") <+> ppr spec
814 ppr (CImport cconv safety header lib spec) =
815 ppr cconv <+> ppr safety <+>
816 char '"' <> pprCEntity header lib spec <> char '"'
818 pprCEntity header lib (CLabel lbl) =
819 ptext SLIT("static") <+> ftext header <+> char '&' <>
820 pprLib lib <> ppr lbl
821 pprCEntity header lib (CFunction (StaticTarget lbl)) =
822 ptext SLIT("static") <+> ftext header <+> char '&' <>
823 pprLib lib <> ppr lbl
824 pprCEntity header lib (CFunction (DynamicTarget)) =
825 ptext SLIT("dynamic")
826 pprCEntity _ _ (CWrapper) = ptext SLIT("wrapper")
828 pprLib lib | nullFS lib = empty
829 | otherwise = char '[' <> ppr lib <> char ']'
831 instance Outputable ForeignExport where
832 ppr (CExport (CExportStatic lbl cconv)) =
833 ppr cconv <+> char '"' <> ppr lbl <> char '"'
835 ptext SLIT("dotnet") <+> ptext SLIT("\"<unused>\"")
837 instance Outputable FoType where
838 ppr DNType = ptext SLIT("type dotnet")
842 %************************************************************************
844 \subsection{Transformation rules}
846 %************************************************************************
849 type LRuleDecl name = Located (RuleDecl name)
852 = HsRule -- Source rule
853 RuleName -- Rule name
855 [RuleBndr name] -- Forall'd vars; after typechecking this includes tyvars
856 (Located (HsExpr name)) -- LHS
857 NameSet -- Free-vars from the LHS
858 (Located (HsExpr name)) -- RHS
859 NameSet -- Free-vars from the RHS
862 = RuleBndr (Located name)
863 | RuleBndrSig (Located name) (LHsType name)
865 collectRuleBndrSigTys :: [RuleBndr name] -> [LHsType name]
866 collectRuleBndrSigTys bndrs = [ty | RuleBndrSig _ ty <- bndrs]
868 instance OutputableBndr name => Outputable (RuleDecl name) where
869 ppr (HsRule name act ns lhs fv_lhs rhs fv_rhs)
870 = sep [text "{-# RULES" <+> doubleQuotes (ftext name) <+> ppr act,
871 nest 4 (pp_forall <+> pprExpr (unLoc lhs)),
872 nest 4 (equals <+> pprExpr (unLoc rhs) <+> text "#-}") ]
874 pp_forall | null ns = empty
875 | otherwise = text "forall" <+> fsep (map ppr ns) <> dot
877 instance OutputableBndr name => Outputable (RuleBndr name) where
878 ppr (RuleBndr name) = ppr name
879 ppr (RuleBndrSig name ty) = ppr name <> dcolon <> ppr ty
883 %************************************************************************
885 \subsection[DeprecDecl]{Deprecations}
887 %************************************************************************
889 We use exported entities for things to deprecate.
892 type LDeprecDecl name = Located (DeprecDecl name)
894 data DeprecDecl name = Deprecation name DeprecTxt
896 instance OutputableBndr name => Outputable (DeprecDecl name) where
897 ppr (Deprecation thing txt)
898 = hsep [text "{-# DEPRECATED", ppr thing, doubleQuotes (ppr txt), text "#-}"]