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 CoreSyn ( RuleName )
43 import {- Kind parts of -} Type ( Kind, pprKind )
44 import BasicTypes ( Activation(..), DeprecTxt )
45 import ForeignCall ( CCallTarget(..), DNCallSpec, CCallConv, Safety,
46 CExportSpec(..), CLabelString )
49 import Class ( FunDep, pprFundeps )
52 import SrcLoc ( Located(..), unLoc, noLoc )
54 import Maybe ( isJust )
58 %************************************************************************
60 \subsection[HsDecl]{Declarations}
62 %************************************************************************
65 type LHsDecl id = Located (HsDecl id)
72 | DefD (DefaultDecl id)
73 | ForD (ForeignDecl id)
74 | DeprecD (DeprecDecl id)
76 | SpliceD (SpliceDecl id)
78 -- NB: all top-level fixity decls are contained EITHER
80 -- OR in the ClassDecls in TyClDs
83 -- a) data constructors
84 -- b) class methods (but they can be also done in the
85 -- signatures of class decls)
86 -- c) imported functions (that have an IfacSig)
89 -- The latter is for class methods only
91 -- A [HsDecl] is categorised into a HsGroup before being
92 -- fed to the renamer.
95 hs_valds :: HsValBinds id,
96 hs_tyclds :: [LTyClDecl id],
97 hs_instds :: [LInstDecl id],
99 hs_fixds :: [LFixitySig id],
100 -- Snaffled out of both top-level fixity signatures,
101 -- and those in class declarations
103 hs_defds :: [LDefaultDecl id],
104 hs_fords :: [LForeignDecl id],
105 hs_depds :: [LDeprecDecl id],
106 hs_ruleds :: [LRuleDecl id]
109 emptyGroup, emptyRdrGroup, emptyRnGroup :: HsGroup a
110 emptyRdrGroup = emptyGroup { hs_valds = emptyValBindsIn }
111 emptyRnGroup = emptyGroup { hs_valds = emptyValBindsOut }
113 emptyGroup = HsGroup { hs_tyclds = [], hs_instds = [],
114 hs_fixds = [], hs_defds = [], hs_fords = [],
115 hs_depds = [], hs_ruleds = [],
116 hs_valds = error "emptyGroup hs_valds: Can't happen" }
118 appendGroups :: HsGroup a -> HsGroup a -> HsGroup a
121 hs_valds = val_groups1,
130 hs_valds = val_groups2,
140 hs_valds = val_groups1 `plusHsValBinds` val_groups2,
141 hs_tyclds = tyclds1 ++ tyclds2,
142 hs_instds = instds1 ++ instds2,
143 hs_fixds = fixds1 ++ fixds2,
144 hs_defds = defds1 ++ defds2,
145 hs_fords = fords1 ++ fords2,
146 hs_depds = depds1 ++ depds2,
147 hs_ruleds = rulds1 ++ rulds2 }
151 instance OutputableBndr name => Outputable (HsDecl name) where
152 ppr (TyClD dcl) = ppr dcl
153 ppr (ValD binds) = ppr binds
154 ppr (DefD def) = ppr def
155 ppr (InstD inst) = ppr inst
156 ppr (ForD fd) = ppr fd
157 ppr (SigD sd) = ppr sd
158 ppr (RuleD rd) = ppr rd
159 ppr (DeprecD dd) = ppr dd
160 ppr (SpliceD dd) = ppr dd
162 instance OutputableBndr name => Outputable (HsGroup name) where
163 ppr (HsGroup { hs_valds = val_decls,
164 hs_tyclds = tycl_decls,
165 hs_instds = inst_decls,
166 hs_fixds = fix_decls,
167 hs_depds = deprec_decls,
168 hs_fords = foreign_decls,
169 hs_defds = default_decls,
170 hs_ruleds = rule_decls })
171 = vcat [ppr_ds fix_decls, ppr_ds default_decls,
172 ppr_ds deprec_decls, ppr_ds rule_decls,
174 ppr_ds tycl_decls, ppr_ds inst_decls,
175 ppr_ds foreign_decls]
178 ppr_ds ds = text "" $$ vcat (map ppr ds)
180 data SpliceDecl id = SpliceDecl (Located (HsExpr id)) -- Top level splice
182 instance OutputableBndr name => Outputable (SpliceDecl name) where
183 ppr (SpliceDecl e) = ptext SLIT("$") <> parens (pprExpr (unLoc e))
187 %************************************************************************
189 \subsection[TyDecl]{@data@, @newtype@ or @type@ (synonym) type declaration}
191 %************************************************************************
193 --------------------------------
195 --------------------------------
197 Here is the story about the implicit names that go with type, class,
198 and instance decls. It's a bit tricky, so pay attention!
200 "Implicit" (or "system") binders
201 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
202 Each data type decl defines
203 a worker name for each constructor
204 to-T and from-T convertors
205 Each class decl defines
206 a tycon for the class
207 a data constructor for that tycon
208 the worker for that constructor
209 a selector for each superclass
211 All have occurrence names that are derived uniquely from their parent
214 None of these get separate definitions in an interface file; they are
215 fully defined by the data or class decl. But they may *occur* in
216 interface files, of course. Any such occurrence must haul in the
217 relevant type or class decl.
220 - Ensure they "point to" the parent data/class decl
221 when loading that decl from an interface file
222 (See RnHiFiles.getSysBinders)
224 - When typechecking the decl, we build the implicit TyCons and Ids.
225 When doing so we look them up in the name cache (RnEnv.lookupSysName),
226 to ensure correct module and provenance is set
228 These are the two places that we have to conjure up the magic derived
229 names. (The actual magic is in OccName.mkWorkerOcc, etc.)
233 - Occurrence name is derived uniquely from the method name
236 - If there is a default method name at all, it's recorded in
237 the ClassOpSig (in HsBinds), in the DefMeth field.
238 (DefMeth is defined in Class.lhs)
240 Source-code class decls and interface-code class decls are treated subtly
241 differently, which has given me a great deal of confusion over the years.
242 Here's the deal. (We distinguish the two cases because source-code decls
243 have (Just binds) in the tcdMeths field, whereas interface decls have Nothing.
245 In *source-code* class declarations:
247 - When parsing, every ClassOpSig gets a DefMeth with a suitable RdrName
248 This is done by RdrHsSyn.mkClassOpSigDM
250 - The renamer renames it to a Name
252 - During typechecking, we generate a binding for each $dm for
253 which there's a programmer-supplied default method:
258 We generate a binding for $dmop1 but not for $dmop2.
259 The Class for Foo has a NoDefMeth for op2 and a DefMeth for op1.
260 The Name for $dmop2 is simply discarded.
262 In *interface-file* class declarations:
263 - When parsing, we see if there's an explicit programmer-supplied default method
264 because there's an '=' sign to indicate it:
266 op1 = :: <type> -- NB the '='
268 We use this info to generate a DefMeth with a suitable RdrName for op1,
269 and a NoDefMeth for op2
270 - The interface file has a separate definition for $dmop1, with unfolding etc.
271 - The renamer renames it to a Name.
272 - The renamer treats $dmop1 as a free variable of the declaration, so that
273 the binding for $dmop1 will be sucked in. (See RnHsSyn.tyClDeclFVs)
274 This doesn't happen for source code class decls, because they *bind* the default method.
278 Each instance declaration gives rise to one dictionary function binding.
280 The type checker makes up new source-code instance declarations
281 (e.g. from 'deriving' or generic default methods --- see
282 TcInstDcls.tcInstDecls1). So we can't generate the names for
283 dictionary functions in advance (we don't know how many we need).
285 On the other hand for interface-file instance declarations, the decl
286 specifies the name of the dictionary function, and it has a binding elsewhere
287 in the interface file:
288 instance {Eq Int} = dEqInt
289 dEqInt :: {Eq Int} <pragma info>
291 So again we treat source code and interface file code slightly differently.
294 - Source code instance decls have a Nothing in the (Maybe name) field
295 (see data InstDecl below)
297 - The typechecker makes up a Local name for the dict fun for any source-code
298 instance decl, whether it comes from a source-code instance decl, or whether
299 the instance decl is derived from some other construct (e.g. 'deriving').
301 - The occurrence name it chooses is derived from the instance decl (just for
302 documentation really) --- e.g. dNumInt. Two dict funs may share a common
303 occurrence name, but will have different uniques. E.g.
304 instance Foo [Int] where ...
305 instance Foo [Bool] where ...
306 These might both be dFooList
308 - The CoreTidy phase externalises the name, and ensures the occurrence name is
309 unique (this isn't special to dict funs). So we'd get dFooList and dFooList1.
311 - We can take this relaxed approach (changing the occurrence name later)
312 because dict fun Ids are not captured in a TyCon or Class (unlike default
313 methods, say). Instead, they are kept separately in the InstEnv. This
314 makes it easy to adjust them after compiling a module. (Once we've finished
315 compiling that module, they don't change any more.)
319 - The instance decl gives the dict fun name, so the InstDecl has a (Just name)
320 in the (Maybe name) field.
322 - RnHsSyn.instDeclFVs treats the dict fun name as free in the decl, so that we
323 suck in the dfun binding
327 -- TyClDecls are precisely the kind of declarations that can
328 -- appear in interface files; or (internally) in GHC's interface
329 -- for a module. That's why (despite the misnomer) IfaceSig and ForeignType
330 -- are both in TyClDecl
332 -- Representation of indexed types
333 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
334 -- Kind signatures of indexed types come in two flavours:
336 -- * kind signatures for type functions: variant `TyFunction' and
338 -- * kind signatures for indexed data types and newtypes : variant `TyData'
339 -- iff a kind is present in `tcdKindSig' and there are no constructors in
342 -- Indexed types are represented by 'TyData' and 'TySynonym' using the field
343 -- 'tcdTyPats::Maybe [LHsType name]', with the following meaning:
345 -- * If it is 'Nothing', we have a *vanilla* data type declaration or type
346 -- synonym declaration and 'tcdVars' contains the type parameters of the
349 -- * If it is 'Just pats', we have the definition of an indexed type Then,
350 -- 'pats' are type patterns for the type-indexes of the type constructor
351 -- and 'tcdVars' are the variables in those patterns. Hence, the arity of
352 -- the indexed type (ie, the number of indexes) is 'length tcdTyPats' and
353 -- *not* 'length tcdVars'.
355 -- In both cases, 'tcdVars' collects all variables we need to quantify over.
357 type LTyClDecl name = Located (TyClDecl name)
361 tcdLName :: Located name,
362 tcdExtName :: Maybe FastString,
366 | TyData { tcdND :: NewOrData,
367 tcdCtxt :: LHsContext name, -- Context
368 tcdLName :: Located name, -- Type constructor
369 tcdTyVars :: [LHsTyVarBndr name], -- Type variables
370 tcdTyPats :: Maybe [LHsType name], -- Type patterns
371 tcdKindSig:: Maybe Kind, -- Optional kind sig;
374 -- indexed type sigs)
376 tcdCons :: [LConDecl name], -- Data constructors
377 -- For data T a = T1 | T2 a the LConDecls all have ResTyH98
378 -- For data T a where { T1 :: T a } the LConDecls all have ResTyGADT
380 tcdDerivs :: Maybe [LHsType name]
381 -- Derivings; Nothing => not specified
382 -- Just [] => derive exactly what is asked
383 -- These "types" must be of form
384 -- forall ab. C ty1 ty2
385 -- Typically the foralls and ty args are empty, but they
386 -- are non-empty for the newtype-deriving case
389 | TyFunction {tcdLName :: Located name, -- type constructor
390 tcdTyVars :: [LHsTyVarBndr name], -- type variables
391 tcdIso :: Bool, -- injective type?
392 tcdKind :: Kind -- result kind
395 | TySynonym { tcdLName :: Located name, -- type constructor
396 tcdTyVars :: [LHsTyVarBndr name], -- type variables
397 tcdTyPats :: Maybe [LHsType name], -- Type patterns
398 -- 'Nothing' => vanilla
400 tcdSynRhs :: LHsType name -- synonym expansion
403 | ClassDecl { tcdCtxt :: LHsContext name, -- Context...
404 tcdLName :: Located name, -- Name of the class
405 tcdTyVars :: [LHsTyVarBndr name], -- Class type variables
406 tcdFDs :: [Located (FunDep name)], -- Functional deps
407 tcdSigs :: [LSig name], -- Methods' signatures
408 tcdMeths :: LHsBinds name, -- Default methods
409 tcdATs :: [LTyClDecl name] -- Associated types; ie
416 = NewType -- "newtype Blah ..."
417 | DataType -- "data Blah ..."
418 deriving( Eq ) -- Needed because Demand derives Eq
424 isTFunDecl, isDataDecl, isSynDecl, isClassDecl, isKindSigDecl, isIdxTyDecl ::
425 TyClDecl name -> Bool
427 -- type function kind signature
428 isTFunDecl (TyFunction {}) = True
429 isTFunDecl other = False
431 -- vanilla Haskell type synonym
432 isSynDecl (TySynonym {tcdTyPats = Nothing}) = True
433 isSynDecl other = False
435 -- type equation (of a type function)
436 isTEqnDecl (TySynonym {tcdTyPats = Just _}) = True
437 isTEqnDecl other = False
439 isDataDecl (TyData {}) = True
440 isDataDecl other = False
442 isClassDecl (ClassDecl {}) = True
443 isClassDecl other = False
445 -- kind signature (for an indexed type)
446 isKindSigDecl (TyFunction {} ) = True
447 isKindSigDecl (TyData {tcdKindSig = Just _,
448 tcdCons = [] }) = True
449 isKindSigDecl other = False
451 -- definition of an instance of an indexed type
453 | isSynDecl tydecl || isDataDecl tydecl = isJust (tcdTyPats tydecl)
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}) = [name]
471 tyClDeclNames (ForeignType {tcdLName = name}) = [name]
473 tyClDeclNames (ClassDecl {tcdLName = cls_name, tcdSigs = sigs, tcdATs = ats})
475 concatMap (tyClDeclNames . unLoc) ats ++ [n | L _ (TypeSig n _) <- sigs]
477 tyClDeclNames (TyData {tcdLName = tc_name, tcdCons = cons})
478 = tc_name : conDeclsNames (map unLoc cons)
480 tyClDeclTyVars (TyFunction {tcdTyVars = tvs}) = tvs
481 tyClDeclTyVars (TySynonym {tcdTyVars = tvs}) = tvs
482 tyClDeclTyVars (TyData {tcdTyVars = tvs}) = tvs
483 tyClDeclTyVars (ClassDecl {tcdTyVars = tvs}) = tvs
484 tyClDeclTyVars (ForeignType {}) = []
488 countTyClDecls :: [TyClDecl name] -> (Int, Int, Int, Int, Int, Int)
489 -- class, synonym decls, type function signatures,
490 -- type function equations, data, newtype
492 = (count isClassDecl decls,
493 count isSynDecl decls,
494 count isTFunDecl decls,
495 count isTEqnDecl decls,
496 count isDataTy decls,
499 isDataTy TyData{tcdND=DataType} = True
502 isNewTy TyData{tcdND=NewType} = True
507 instance OutputableBndr name
508 => Outputable (TyClDecl name) where
510 ppr (ForeignType {tcdLName = ltycon})
511 = hsep [ptext SLIT("foreign import type dotnet"), ppr ltycon]
513 ppr (TyFunction {tcdLName = ltycon, tcdTyVars = tyvars, tcdIso = iso,
515 = typeMaybeIso <+> pp_decl_head [] ltycon tyvars Nothing <+>
516 dcolon <+> pprKind kind
518 typeMaybeIso = if iso
519 then ptext SLIT("type iso")
520 else ptext SLIT("type")
522 ppr (TySynonym {tcdLName = ltycon, tcdTyVars = tyvars, tcdTyPats = typats,
523 tcdSynRhs = mono_ty})
524 = hang (ptext SLIT("type") <+> pp_decl_head [] ltycon tyvars typats <+>
528 ppr (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = ltycon,
529 tcdTyVars = tyvars, tcdTyPats = typats, tcdKindSig = mb_sig,
530 tcdCons = condecls, tcdDerivs = derivings})
531 = pp_tydecl (ppr new_or_data <+>
532 pp_decl_head (unLoc context) ltycon tyvars typats <+>
534 (pp_condecls condecls)
537 ppr_sig Nothing = empty
538 ppr_sig (Just kind) = dcolon <+> pprKind kind
540 ppr (ClassDecl {tcdCtxt = context, tcdLName = lclas, tcdTyVars = tyvars,
542 tcdSigs = sigs, tcdMeths = methods, tcdATs = ats})
543 | null sigs && null ats -- No "where" part
546 | otherwise -- Laid out
547 = sep [hsep [top_matter, ptext SLIT("where {")],
548 nest 4 (sep [ sep (map ppr_semi ats)
549 , sep (map ppr_semi sigs)
550 , pprLHsBinds methods
553 top_matter = ptext SLIT("class")
554 <+> pp_decl_head (unLoc context) lclas tyvars Nothing
555 <+> pprFundeps (map unLoc fds)
556 ppr_semi decl = ppr decl <> semi
558 pp_decl_head :: OutputableBndr name
561 -> [LHsTyVarBndr name]
562 -> Maybe [LHsType name]
564 pp_decl_head context thing tyvars Nothing -- no explicit type patterns
565 = hsep [pprHsContext context, ppr thing, interppSP tyvars]
566 pp_decl_head context thing _ (Just typats) -- explicit type patterns
567 = hsep [ pprHsContext context, ppr thing
568 , hsep (map (pprParendHsType.unLoc) typats)]
570 pp_condecls cs@(L _ ConDecl{ con_res = ResTyGADT _ } : _) -- In GADT syntax
571 = hang (ptext SLIT("where")) 2 (vcat (map ppr cs))
572 pp_condecls cs -- In H98 syntax
573 = equals <+> sep (punctuate (ptext SLIT(" |")) (map ppr cs))
575 pp_tydecl pp_head pp_decl_rhs derivings
576 = hang pp_head 4 (sep [
580 Just ds -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
583 instance Outputable NewOrData where
584 ppr NewType = ptext SLIT("newtype")
585 ppr DataType = ptext SLIT("data")
589 %************************************************************************
591 \subsection[ConDecl]{A data-constructor declaration}
593 %************************************************************************
596 type LConDecl name = Located (ConDecl name)
598 -- data T b = forall a. Eq a => MkT a b
599 -- MkT :: forall b a. Eq a => MkT a b
602 -- MkT1 :: Int -> T Int
604 -- data T = Int `MkT` Int
608 -- Int `MkT` Int :: T Int
612 { con_name :: Located name -- Constructor name; this is used for the
613 -- DataCon itself, and for the user-callable wrapper Id
615 , con_explicit :: HsExplicitForAll -- Is there an user-written forall? (cf. HStypes.HsForAllTy)
617 , con_qvars :: [LHsTyVarBndr name] -- ResTyH98: the constructor's existential type variables
618 -- ResTyGADT: all the constructor's quantified type variables
620 , con_cxt :: LHsContext name -- The context. This *does not* include the
621 -- "stupid theta" which lives only in the TyData decl
623 , con_details :: HsConDetails name (LBangType name) -- The main payload
625 , con_res :: ResType name -- Result type of the constructor
629 = ResTyH98 -- Constructor was declared using Haskell 98 syntax
630 | ResTyGADT (LHsType name) -- Constructor was declared using GADT-style syntax,
631 -- and here is its result type
635 conDeclsNames :: Eq name => [ConDecl name] -> [Located name]
636 -- See tyClDeclNames for what this does
637 -- The function is boringly complicated because of the records
638 -- And since we only have equality, we have to be a little careful
640 = snd (foldl do_one ([], []) cons)
642 do_one (flds_seen, acc) (ConDecl { con_name = lname, con_details = RecCon flds })
643 = (map unLoc new_flds ++ flds_seen, lname : [f | f <- new_flds] ++ acc)
645 new_flds = [ f | (f,_) <- flds, not (unLoc f `elem` flds_seen) ]
647 do_one (flds_seen, acc) c
648 = (flds_seen, (con_name c):acc)
650 conDetailsTys details = map getBangType (hsConArgs details)
655 instance (OutputableBndr name) => Outputable (ConDecl name) where
658 pprConDecl (ConDecl con expl tvs cxt details ResTyH98)
659 = sep [pprHsForAll expl tvs cxt, ppr_details con details]
661 ppr_details con (InfixCon t1 t2) = hsep [ppr t1, pprHsVar con, ppr t2]
662 ppr_details con (PrefixCon tys) = hsep (pprHsVar con : map ppr tys)
663 ppr_details con (RecCon fields) = ppr con <+> ppr_fields fields
665 pprConDecl (ConDecl con expl tvs cxt (PrefixCon arg_tys) (ResTyGADT res_ty))
666 = ppr con <+> dcolon <+>
667 sep [pprHsForAll expl tvs cxt, ppr (foldr mk_fun_ty res_ty arg_tys)]
669 mk_fun_ty a b = noLoc (HsFunTy a b)
670 pprConDecl (ConDecl con expl tvs cxt (RecCon fields) (ResTyGADT res_ty))
671 = sep [pprHsForAll expl tvs cxt, ppr con <+> ppr fields <+> dcolon <+> ppr res_ty]
673 ppr_fields fields = braces (sep (punctuate comma (map ppr_field fields)))
674 ppr_field (n, ty) = ppr n <+> dcolon <+> ppr ty
677 %************************************************************************
679 \subsection[InstDecl]{An instance declaration
681 %************************************************************************
684 type LInstDecl name = Located (InstDecl name)
687 = InstDecl (LHsType name) -- Context => Class Instance-type
688 -- Using a polytype means that the renamer conveniently
689 -- figures out the quantified type variables for us.
691 [LSig name] -- User-supplied pragmatic info
692 [LTyClDecl name]-- Associated types (ie, 'TyData' and
695 instance (OutputableBndr name) => Outputable (InstDecl name) where
697 ppr (InstDecl inst_ty binds uprags ats)
698 = vcat [hsep [ptext SLIT("instance"), ppr inst_ty, ptext SLIT("where")],
701 nest 4 (pprLHsBinds binds) ]
703 -- Extract the declarations of associated types from an instance
705 instDeclATs :: InstDecl name -> [LTyClDecl name]
706 instDeclATs (InstDecl _ _ _ ats) = ats
709 %************************************************************************
711 \subsection[DefaultDecl]{A @default@ declaration}
713 %************************************************************************
715 There can only be one default declaration per module, but it is hard
716 for the parser to check that; we pass them all through in the abstract
717 syntax, and that restriction must be checked in the front end.
720 type LDefaultDecl name = Located (DefaultDecl name)
722 data DefaultDecl name
723 = DefaultDecl [LHsType name]
725 instance (OutputableBndr name)
726 => Outputable (DefaultDecl name) where
728 ppr (DefaultDecl tys)
729 = ptext SLIT("default") <+> parens (interpp'SP tys)
732 %************************************************************************
734 \subsection{Foreign function interface declaration}
736 %************************************************************************
740 -- foreign declarations are distinguished as to whether they define or use a
743 -- * the Boolean value indicates whether the pre-standard deprecated syntax
746 type LForeignDecl name = Located (ForeignDecl name)
748 data ForeignDecl name
749 = ForeignImport (Located name) (LHsType name) ForeignImport -- defines name
750 | ForeignExport (Located name) (LHsType name) ForeignExport -- uses name
752 -- Specification Of an imported external entity in dependence on the calling
755 data ForeignImport = -- import of a C entity
757 -- * the two strings specifying a header file or library
758 -- may be empty, which indicates the absence of a
759 -- header or object specification (both are not used
760 -- in the case of `CWrapper' and when `CFunction'
761 -- has a dynamic target)
763 -- * the calling convention is irrelevant for code
764 -- generation in the case of `CLabel', but is needed
765 -- for pretty printing
767 -- * `Safety' is irrelevant for `CLabel' and `CWrapper'
769 CImport CCallConv -- ccall or stdcall
770 Safety -- safe or unsafe
771 FastString -- name of C header
772 FastString -- name of library object
773 CImportSpec -- details of the C entity
775 -- import of a .NET function
777 | DNImport DNCallSpec
779 -- details of an external C entity
781 data CImportSpec = CLabel CLabelString -- import address of a C label
782 | CFunction CCallTarget -- static or dynamic function
783 | CWrapper -- wrapper to expose closures
786 -- specification of an externally exported entity in dependence on the calling
789 data ForeignExport = CExport CExportSpec -- contains the calling convention
790 | DNExport -- presently unused
792 -- abstract type imported from .NET
794 data FoType = DNType -- In due course we'll add subtype stuff
795 deriving (Eq) -- Used for equality instance for TyClDecl
798 -- pretty printing of foreign declarations
801 instance OutputableBndr name => Outputable (ForeignDecl name) where
802 ppr (ForeignImport n ty fimport) =
803 ptext SLIT("foreign import") <+> ppr fimport <+>
804 ppr n <+> dcolon <+> ppr ty
805 ppr (ForeignExport n ty fexport) =
806 ptext SLIT("foreign export") <+> ppr fexport <+>
807 ppr n <+> dcolon <+> ppr ty
809 instance Outputable ForeignImport where
810 ppr (DNImport spec) =
811 ptext SLIT("dotnet") <+> ppr spec
812 ppr (CImport cconv safety header lib spec) =
813 ppr cconv <+> ppr safety <+>
814 char '"' <> pprCEntity header lib spec <> char '"'
816 pprCEntity header lib (CLabel lbl) =
817 ptext SLIT("static") <+> ftext header <+> char '&' <>
818 pprLib lib <> ppr lbl
819 pprCEntity header lib (CFunction (StaticTarget lbl)) =
820 ptext SLIT("static") <+> ftext header <+> char '&' <>
821 pprLib lib <> ppr lbl
822 pprCEntity header lib (CFunction (DynamicTarget)) =
823 ptext SLIT("dynamic")
824 pprCEntity _ _ (CWrapper) = ptext SLIT("wrapper")
826 pprLib lib | nullFS lib = empty
827 | otherwise = char '[' <> ppr lib <> char ']'
829 instance Outputable ForeignExport where
830 ppr (CExport (CExportStatic lbl cconv)) =
831 ppr cconv <+> char '"' <> ppr lbl <> char '"'
833 ptext SLIT("dotnet") <+> ptext SLIT("\"<unused>\"")
835 instance Outputable FoType where
836 ppr DNType = ptext SLIT("type dotnet")
840 %************************************************************************
842 \subsection{Transformation rules}
844 %************************************************************************
847 type LRuleDecl name = Located (RuleDecl name)
850 = HsRule -- Source rule
851 RuleName -- Rule name
853 [RuleBndr name] -- Forall'd vars; after typechecking this includes tyvars
854 (Located (HsExpr name)) -- LHS
855 NameSet -- Free-vars from the LHS
856 (Located (HsExpr name)) -- RHS
857 NameSet -- Free-vars from the RHS
860 = RuleBndr (Located name)
861 | RuleBndrSig (Located name) (LHsType name)
863 collectRuleBndrSigTys :: [RuleBndr name] -> [LHsType name]
864 collectRuleBndrSigTys bndrs = [ty | RuleBndrSig _ ty <- bndrs]
866 instance OutputableBndr name => Outputable (RuleDecl name) where
867 ppr (HsRule name act ns lhs fv_lhs rhs fv_rhs)
868 = sep [text "{-# RULES" <+> doubleQuotes (ftext name) <+> ppr act,
869 nest 4 (pp_forall <+> pprExpr (unLoc lhs)),
870 nest 4 (equals <+> pprExpr (unLoc rhs) <+> text "#-}") ]
872 pp_forall | null ns = empty
873 | otherwise = text "forall" <+> fsep (map ppr ns) <> dot
875 instance OutputableBndr name => Outputable (RuleBndr name) where
876 ppr (RuleBndr name) = ppr name
877 ppr (RuleBndrSig name ty) = ppr name <> dcolon <> ppr ty
881 %************************************************************************
883 \subsection[DeprecDecl]{Deprecations}
885 %************************************************************************
887 We use exported entities for things to deprecate.
890 type LDeprecDecl name = Located (DeprecDecl name)
892 data DeprecDecl name = Deprecation name DeprecTxt
894 instance OutputableBndr name => Outputable (DeprecDecl name) where
895 ppr (Deprecation thing txt)
896 = hsep [text "{-# DEPRECATED", ppr thing, doubleQuotes (ppr txt), text "#-}"]