2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcTyClsDecls]{Typecheck type and class declarations}
8 tcTyAndClassDecls, tcIdxTyInstDecl
11 #include "HsVersions.h"
13 import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
14 ConDecl(..), Sig(..), NewOrData(..), ResType(..),
15 tyClDeclTyVars, isSynDecl, isClassDecl, isIdxTyDecl,
16 isKindSigDecl, hsConArgs, LTyClDecl, tcdName,
17 hsTyVarName, LHsTyVarBndr, LHsType, HsType(..),
20 import HsTypes ( HsBang(..), getBangStrictness )
21 import BasicTypes ( RecFlag(..), StrictnessMark(..) )
22 import HscTypes ( implicitTyThings, ModDetails )
23 import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon,
24 mkDataTyConRhs, mkNewTyConRhs )
26 import TcEnv ( TyThing(..),
27 tcLookupLocated, tcLookupLocatedGlobal,
28 tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs,
29 tcExtendRecEnv, tcLookupTyVar, InstInfo )
30 import TcTyDecls ( calcRecFlags, calcClassCycles, calcSynCycles )
31 import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
32 import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
33 kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
34 kcHsSigType, tcHsBangType, tcLHsConResTy,
35 tcDataKindSig, kcCheckHsType )
36 import TcMType ( newKindVar, checkValidTheta, checkValidType,
38 UserTypeCtxt(..), SourceTyCtxt(..) )
39 import TcType ( TcKind, TcType, Type, tyVarsOfType, mkPhiTy,
40 mkArrowKind, liftedTypeKind, mkTyVarTys,
41 tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe )
42 import Type ( PredType(..), splitTyConApp_maybe, mkTyVarTy,
43 newTyConInstRhs, isLiftedTypeKind, Kind
44 -- pprParendType, pprThetaArrow
46 import Generics ( validGenericMethodType, canDoGenerics )
47 import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars )
48 import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon, OpenDataTyCon,
50 SynTyConRhs( OpenSynTyCon, SynonymTyCon ),
51 tyConDataCons, mkForeignTyCon, isProductTyCon,
52 isRecursiveTyCon, isOpenTyCon,
53 tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName,
54 isNewTyCon, tyConKind )
55 import DataCon ( DataCon, dataConUserType, dataConName,
56 dataConFieldLabels, dataConTyCon, dataConAllTyVars,
57 dataConFieldType, dataConResTys )
58 import Var ( TyVar, idType, idName )
59 import VarSet ( elemVarSet, mkVarSet )
60 import Name ( Name, getSrcLoc )
62 import Maybe ( isJust, fromJust, isNothing )
63 import Maybes ( expectJust )
64 import Unify ( tcMatchTys, tcMatchTyX )
65 import Util ( zipLazy, isSingleton, notNull, sortLe )
66 import List ( partition )
67 import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan )
68 import ListSetOps ( equivClasses, minusList )
69 import List ( delete )
70 import Digraph ( SCC(..) )
71 import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
72 Opt_UnboxStrictFields ) )
76 %************************************************************************
78 \subsection{Type checking for type and class declarations}
80 %************************************************************************
84 Consider a mutually-recursive group, binding
85 a type constructor T and a class C.
87 Step 1: getInitialKind
88 Construct a KindEnv by binding T and C to a kind variable
91 In that environment, do a kind check
93 Step 3: Zonk the kinds
95 Step 4: buildTyConOrClass
96 Construct an environment binding T to a TyCon and C to a Class.
97 a) Their kinds comes from zonking the relevant kind variable
98 b) Their arity (for synonyms) comes direct from the decl
99 c) The funcional dependencies come from the decl
100 d) The rest comes a knot-tied binding of T and C, returned from Step 4
101 e) The variances of the tycons in the group is calculated from
105 In this environment, walk over the decls, constructing the TyCons and Classes.
106 This uses in a strict way items (a)-(c) above, which is why they must
107 be constructed in Step 4. Feed the results back to Step 4.
108 For this step, pass the is-recursive flag as the wimp-out flag
112 Step 6: Extend environment
113 We extend the type environment with bindings not only for the TyCons and Classes,
114 but also for their "implicit Ids" like data constructors and class selectors
116 Step 7: checkValidTyCl
117 For a recursive group only, check all the decls again, just
118 to check all the side conditions on validity. We could not
119 do this before because we were in a mutually recursive knot.
121 Identification of recursive TyCons
122 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
123 The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
126 Identifying a TyCon as recursive serves two purposes
128 1. Avoid infinite types. Non-recursive newtypes are treated as
129 "transparent", like type synonyms, after the type checker. If we did
130 this for all newtypes, we'd get infinite types. So we figure out for
131 each newtype whether it is "recursive", and add a coercion if so. In
132 effect, we are trying to "cut the loops" by identifying a loop-breaker.
134 2. Avoid infinite unboxing. This is nothing to do with newtypes.
138 Well, this function diverges, but we don't want the strictness analyser
139 to diverge. But the strictness analyser will diverge because it looks
140 deeper and deeper into the structure of T. (I believe there are
141 examples where the function does something sane, and the strictness
142 analyser still diverges, but I can't see one now.)
144 Now, concerning (1), the FC2 branch currently adds a coercion for ALL
145 newtypes. I did this as an experiment, to try to expose cases in which
146 the coercions got in the way of optimisations. If it turns out that we
147 can indeed always use a coercion, then we don't risk recursive types,
148 and don't need to figure out what the loop breakers are.
150 For newtype *families* though, we will always have a coercion, so they
151 are always loop breakers! So you can easily adjust the current
152 algorithm by simply treating all newtype families as loop breakers (and
153 indeed type families). I think.
156 tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
157 -> TcM TcGblEnv -- Input env extended by types and classes
158 -- and their implicit Ids,DataCons
159 tcTyAndClassDecls boot_details allDecls
160 = do { -- Omit instances of indexed types; they are handled together
161 -- with the *heads* of class instances
162 ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
164 -- First check for cyclic type synonysm or classes
165 -- See notes with checkCycleErrs
166 ; checkCycleErrs decls
168 ; traceTc (text "tcTyAndCl" <+> ppr mod)
169 ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
170 do { let { -- Seperate ordinary synonyms from all other type and
171 -- class declarations and add all associated type
172 -- declarations from type classes. The latter is
173 -- required so that the temporary environment for the
174 -- knot includes all associated family declarations.
175 ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
177 ; alg_at_decls = concatMap addATs alg_decls
179 -- Extend the global env with the knot-tied results
180 -- for data types and classes
182 -- We must populate the environment with the loop-tied
183 -- T's right away, because the kind checker may "fault
184 -- in" some type constructors that recursively
186 ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss
187 ; tcExtendRecEnv gbl_things $ do
189 -- Kind-check the declarations
190 { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
192 ; let { -- Calculate rec-flag
193 ; calc_rec = calcRecFlags boot_details rec_alg_tyclss
194 ; tc_decl = addLocM (tcTyClDecl calc_rec) }
195 -- Type-check the type synonyms, and extend the envt
196 ; syn_tycons <- tcSynDecls kc_syn_decls
197 ; tcExtendGlobalEnv syn_tycons $ do
199 -- Type-check the data types and classes
200 { alg_tyclss <- mappM tc_decl kc_alg_decls
201 ; return (syn_tycons, concat alg_tyclss)
203 -- Finished with knot-tying now
204 -- Extend the environment with the finished things
205 ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
207 -- Perform the validity check
208 { traceTc (text "ready for validity check")
209 ; mappM_ (addLocM checkValidTyCl) decls
210 ; traceTc (text "done")
212 -- Add the implicit things;
213 -- we want them in the environment because
214 -- they may be mentioned in interface files
215 ; let { implicit_things = concatMap implicitTyThings alg_tyclss }
216 ; traceTc ((text "Adding" <+> ppr alg_tyclss)
217 $$ (text "and" <+> ppr implicit_things))
218 ; tcExtendGlobalEnv implicit_things getGblEnv
221 addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats
224 mkGlobalThings :: [LTyClDecl Name] -- The decls
225 -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
227 -- Driven by the Decls, and treating the TyThings lazily
228 -- make a TypeEnv for the new things
229 mkGlobalThings decls things
230 = map mk_thing (decls `zipLazy` things)
232 mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
234 mk_thing (L _ decl, ~(ATyCon tc))
235 = (tcdName decl, ATyCon tc)
239 %************************************************************************
241 \subsection{Type checking instances of indexed types}
243 %************************************************************************
245 Instances of indexed types are somewhat of a hybrid. They are processed
246 together with class instance heads, but can contain data constructors and hence
247 they share a lot of kinding and type checking code with ordinary algebraic
248 data types (and GADTs).
251 tcIdxTyInstDecl :: LTyClDecl Name
252 -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
253 tcIdxTyInstDecl (L loc decl)
254 = -- Prime error recovery, set source location
255 recoverM (returnM (Nothing, Nothing)) $
258 do { -- indexed data types require -fglasgow-exts and can't be in an
260 ; gla_exts <- doptM Opt_GlasgowExts
261 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
262 ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
263 ; checkTc (not is_boot) $ badBootTyIdxDeclErr
265 -- perform kind and type checking
266 ; tcIdxTyInstDecl1 decl
269 tcIdxTyInstDecl1 :: TyClDecl Name
270 -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
272 tcIdxTyInstDecl1 (decl@TySynonym {})
273 = kcIdxTyPats decl $ \k_tvs k_typats resKind _ ->
274 do { -- (1) kind check the right hand side of the type equation
275 ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
277 -- (2) type check type equation
278 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
279 ; t_typats <- mappM tcHsKindedType k_typats
280 ; t_rhs <- tcHsKindedType k_rhs
282 -- construct type rewrite rule
283 -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
284 ; return (Nothing, Nothing) -- !!!TODO: need InstInfo for eq axioms
287 tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
289 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
290 do { -- (1) kind check the data declaration as usual
291 ; k_decl <- kcDataDecl decl k_tvs
292 ; let k_ctxt = tcdCtxt k_decl
293 k_cons = tcdCons k_decl
295 -- result kind must be '*' (otherwise, we have too few patterns)
296 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
298 -- (2) type check indexed data type declaration
299 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
300 ; unbox_strict <- doptM Opt_UnboxStrictFields
302 -- Check that we don't use GADT syntax for indexed types
303 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
305 -- Check that a newtype has exactly one constructor
306 ; checkTc (new_or_data == DataType || isSingleton k_cons) $
307 newtypeConError tc_name (length k_cons)
309 ; t_typats <- mappM tcHsKindedType k_typats
310 ; stupid_theta <- tcHsKindedContext k_ctxt
312 ; tycon <- fixM (\ tycon -> do
313 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
314 tycon t_tvs (Just t_typats)))
318 DataType -> return (mkDataTyConRhs data_cons)
320 ASSERT( isSingleton data_cons )
321 mkNewTyConRhs tc_name tycon (head data_cons)
322 ; buildAlgTyCon tc_name t_tvs stupid_theta tc_rhs Recursive
323 False h98_syntax (Just family)
324 -- We always assume that indexed types are recursive. Why?
325 -- (1) Due to their open nature, we can never be sure that a
326 -- further instance might not introduce a new recursive
327 -- dependency. (2) They are always valid loop breakers as
328 -- they involve a coercion.
332 -- !!!TODO: missing eq axiom
333 ; return (Nothing, Just (ATyCon tycon))
336 h98_syntax = case cons of -- All constructors have same shape
337 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
340 -- Kind checking of indexed types
343 -- Kind check type patterns and kind annotate the embedded type variables.
345 -- * Here we check that a type instance matches its kind signature, but we do
346 -- not check whether there is a pattern for each type index; the latter
347 -- check is only required for type functions.
349 kcIdxTyPats :: TyClDecl Name
350 -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
351 -- ^^kinded tvs ^^kinded ty pats ^^res kind
353 kcIdxTyPats decl thing_inside
354 = kcHsTyVars (tcdTyVars decl) $ \tvs ->
355 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
356 ; let { family = case tc_ty_thing of
357 AGlobal (ATyCon family) -> family
358 ; (kinds, resKind) = splitKindFunTys (tyConKind family)
359 ; hs_typats = fromJust $ tcdTyPats decl }
361 -- we may not have more parameters than the kind indicates
362 ; checkTc (length kinds >= length hs_typats) $
363 tooManyParmsErr (tcdLName decl)
365 -- type functions can have a higher-kinded result
366 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
367 ; typats <- zipWithM kcCheckHsType hs_typats kinds
368 ; thing_inside tvs typats resultKind family
374 %************************************************************************
378 %************************************************************************
380 We need to kind check all types in the mutually recursive group
381 before we know the kind of the type variables. For example:
384 op :: D b => a -> b -> b
387 bop :: (Monad c) => ...
389 Here, the kind of the locally-polymorphic type variable "b"
390 depends on *all the uses of class D*. For example, the use of
391 Monad c in bop's type signature means that D must have kind Type->Type.
393 However type synonyms work differently. They can have kinds which don't
394 just involve (->) and *:
395 type R = Int# -- Kind #
396 type S a = Array# a -- Kind * -> #
397 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
398 So we must infer their kinds from their right-hand sides *first* and then
399 use them, whereas for the mutually recursive data types D we bring into
400 scope kind bindings D -> k, where k is a kind variable, and do inference.
404 This treatment of type synonyms only applies to Haskell 98-style synonyms.
405 General type functions can be recursive, and hence, appear in `alg_decls'.
407 The kind of an indexed type is solely determinded by its kind signature;
408 hence, only kind signatures participate in the construction of the initial
409 kind environment (as constructed by `getInitialKind'). In fact, we ignore
410 instances of indexed types altogether in the following. However, we need to
411 include the kind signatures of associated types into the construction of the
412 initial kind environment. (This is handled by `allDecls').
415 kcTyClDecls syn_decls alg_decls
416 = do { -- First extend the kind env with each data type, class, and
417 -- indexed type, mapping them to a type variable
418 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
419 ; alg_kinds <- mappM getInitialKind initialKindDecls
420 ; tcExtendKindEnv alg_kinds $ do
422 -- Now kind-check the type synonyms, in dependency order
423 -- We do these differently to data type and classes,
424 -- because a type synonym can be an unboxed type
426 -- and a kind variable can't unify with UnboxedTypeKind
427 -- So we infer their kinds in dependency order
428 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
429 ; tcExtendKindEnv syn_kinds $ do
431 -- Now kind-check the data type, class, and kind signatures,
432 -- returning kind-annotated decls; we don't kind-check
433 -- instances of indexed types yet, but leave this to
435 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
436 (filter (not . isIdxTyDecl . unLoc) alg_decls)
438 ; return (kc_syn_decls, kc_alg_decls) }}}
440 -- get all declarations relevant for determining the initial kind
442 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
445 allDecls decl | isIdxTyDecl decl = []
448 ------------------------------------------------------------------------
449 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
450 -- Only for data type, class, and indexed type declarations
451 -- Get as much info as possible from the data, class, or indexed type decl,
452 -- so as to maximise usefulness of error messages
454 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
455 ; res_kind <- mk_res_kind decl
456 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
458 mk_arg_kind (UserTyVar _) = newKindVar
459 mk_arg_kind (KindedTyVar _ kind) = return kind
461 mk_res_kind (TyFunction { tcdKind = kind }) = return kind
462 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
463 -- On GADT-style and data signature declarations we allow a kind
465 -- data T :: *->* where { ... }
466 mk_res_kind other = return liftedTypeKind
470 kcSynDecls :: [SCC (LTyClDecl Name)]
471 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
472 [(Name,TcKind)]) -- Kind bindings
475 kcSynDecls (group : groups)
476 = do { (decl, nk) <- kcSynDecl group
477 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
478 ; return (decl:decls, nk:nks) }
481 kcSynDecl :: SCC (LTyClDecl Name)
482 -> TcM (LTyClDecl Name, -- Kind-annotated decls
483 (Name,TcKind)) -- Kind bindings
484 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
485 = tcAddDeclCtxt decl $
486 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
487 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
488 <+> brackets (ppr k_tvs))
489 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
490 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
491 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
492 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
493 (unLoc (tcdLName decl), tc_kind)) })
495 kcSynDecl (CyclicSCC decls)
496 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
497 -- of out-of-scope tycons
499 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
501 ------------------------------------------------------------------------
502 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
503 -- Not used for type synonyms (see kcSynDecl)
505 kcTyClDecl decl@(TyData {})
506 = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
507 kcTyClDeclBody decl $
510 kcTyClDecl decl@(TyFunction {})
511 = kcTyClDeclBody decl $ \ tvs' ->
512 return (decl {tcdTyVars = tvs'})
514 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
515 = kcTyClDeclBody decl $ \ tvs' ->
516 do { is_boot <- tcIsHsBoot
517 ; ctxt' <- kcHsContext ctxt
518 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
519 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
520 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
523 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
524 ; return (TypeSig nm op_ty') }
525 kc_sig other_sig = return other_sig
527 kcTyClDecl decl@(ForeignType {})
530 kcTyClDeclBody :: TyClDecl Name
531 -> ([LHsTyVarBndr Name] -> TcM a)
533 -- getInitialKind has made a suitably-shaped kind for the type or class
534 -- Unpack it, and attribute those kinds to the type variables
535 -- Extend the env with bindings for the tyvars, taken from
536 -- the kind of the tycon/class. Give it to the thing inside, and
537 -- check the result kind matches
538 kcTyClDeclBody decl thing_inside
539 = tcAddDeclCtxt decl $
540 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
541 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
542 (kinds, _) = splitKindFunTys tc_kind
543 hs_tvs = tcdTyVars decl
544 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
545 [ L loc (KindedTyVar (hsTyVarName tv) k)
546 | (L loc tv, k) <- zip hs_tvs kinds]
547 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
549 -- Kind check a data declaration, assuming that we already extended the
550 -- kind environment with the type variables of the left-hand side (these
551 -- kinded type variables are also passed as the second parameter).
553 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
554 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
556 = do { ctxt' <- kcHsContext ctxt
557 ; cons' <- mappM (wrapLocM kc_con_decl) cons
558 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
560 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do
561 kcHsTyVars ex_tvs $ \ex_tvs' -> do
562 ex_ctxt' <- kcHsContext ex_ctxt
563 details' <- kc_con_details details
565 ResTyH98 -> return ResTyH98
566 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
567 return (ConDecl name expl ex_tvs' ex_ctxt' details' res')
569 kc_con_details (PrefixCon btys)
570 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
571 kc_con_details (InfixCon bty1 bty2)
572 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
573 kc_con_details (RecCon fields)
574 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
576 kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') }
578 kc_larg_ty bty = case new_or_data of
579 DataType -> kcHsSigType bty
580 NewType -> kcHsLiftedSigType bty
581 -- Can't allow an unlifted type for newtypes, because we're effectively
582 -- going to remove the constructor while coercing it to a lifted type.
583 -- And newtypes can't be bang'd
587 %************************************************************************
589 \subsection{Type checking}
591 %************************************************************************
594 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
595 tcSynDecls [] = return []
596 tcSynDecls (decl : decls)
597 = do { syn_tc <- addLocM tcSynDecl decl
598 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
599 ; return (syn_tc : syn_tcs) }
602 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
603 = tcTyVarBndrs tvs $ \ tvs' -> do
604 { traceTc (text "tcd1" <+> ppr tc_name)
605 ; rhs_ty' <- tcHsKindedType rhs_ty
606 ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
609 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
611 tcTyClDecl calc_isrec decl
612 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
614 -- kind signature for a type function
615 tcTyClDecl1 _calc_isrec
616 (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
617 = tcTyVarBndrs tvs $ \ tvs' -> do
618 { gla_exts <- doptM Opt_GlasgowExts
620 -- Check that we don't use kind signatures without Glasgow extensions
621 ; checkTc gla_exts $ badSigTyDecl tc_name
623 ; return [ATyCon (buildSynTyCon tc_name tvs' (OpenSynTyCon kind))]
626 -- kind signature for an indexed data type
627 tcTyClDecl1 _calc_isrec
628 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
629 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = []})
630 = tcTyVarBndrs tvs $ \ tvs' -> do
631 { extra_tvs <- tcDataKindSig mb_ksig
632 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
634 ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
635 ; gla_exts <- doptM Opt_GlasgowExts
637 -- Check that we don't use kind signatures without Glasgow extensions
638 ; checkTc gla_exts $ badSigTyDecl tc_name
640 ; tycon <- buildAlgTyCon tc_name final_tvs []
642 DataType -> OpenDataTyCon
643 NewType -> OpenNewTyCon)
644 Recursive False True Nothing
645 ; return [ATyCon tycon]
648 tcTyClDecl1 calc_isrec
649 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
650 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
651 = tcTyVarBndrs tvs $ \ tvs' -> do
652 { extra_tvs <- tcDataKindSig mb_ksig
653 ; let final_tvs = tvs' ++ extra_tvs
654 ; stupid_theta <- tcHsKindedContext ctxt
655 ; want_generic <- doptM Opt_Generics
656 ; unbox_strict <- doptM Opt_UnboxStrictFields
657 ; gla_exts <- doptM Opt_GlasgowExts
658 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
660 -- Check that we don't use GADT syntax in H98 world
661 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
663 -- Check that we don't use kind signatures without Glasgow extensions
664 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
666 -- Check that the stupid theta is empty for a GADT-style declaration
667 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
669 -- Check that there's at least one condecl,
670 -- or else we're reading an hs-boot file, or -fglasgow-exts
671 ; checkTc (not (null cons) || gla_exts || is_boot)
672 (emptyConDeclsErr tc_name)
674 -- Check that a newtype has exactly one constructor
675 ; checkTc (new_or_data == DataType || isSingleton cons)
676 (newtypeConError tc_name (length cons))
678 ; tycon <- fixM (\ tycon -> do
679 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
680 tycon final_tvs Nothing))
683 if null cons && is_boot -- In a hs-boot file, empty cons means
684 then return AbstractTyCon -- "don't know"; hence Abstract
685 else case new_or_data of
686 DataType -> return (mkDataTyConRhs data_cons)
688 ASSERT( isSingleton data_cons )
689 mkNewTyConRhs tc_name tycon (head data_cons)
690 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
691 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
693 ; return [ATyCon tycon]
696 is_rec = calc_isrec tc_name
697 h98_syntax = case cons of -- All constructors have same shape
698 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
701 tcTyClDecl1 calc_isrec
702 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
703 tcdCtxt = ctxt, tcdMeths = meths,
704 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
705 = tcTyVarBndrs tvs $ \ tvs' -> do
706 { ctxt' <- tcHsKindedContext ctxt
707 ; fds' <- mappM (addLocM tc_fundep) fundeps
708 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
709 ; let ats' = concat atss
710 ; sig_stuff <- tcClassSigs class_name sigs meths
711 ; clas <- fixM (\ clas ->
712 let -- This little knot is just so we can get
713 -- hold of the name of the class TyCon, which we
714 -- need to look up its recursiveness
715 tycon_name = tyConName (classTyCon clas)
716 tc_isrec = calc_isrec tycon_name
718 buildClass class_name tvs' ctxt' fds' ats'
720 ; return (AClass clas : ats')
721 -- NB: Order is important due to the call to `mkGlobalThings' when
722 -- tying the the type and class declaration type checking knot.
725 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
726 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
727 ; return (tvs1', tvs2') }
730 tcTyClDecl1 calc_isrec
731 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
732 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
734 -----------------------------------
735 tcConDecl :: Bool -- True <=> -funbox-strict_fields
738 -> Maybe [Type] -- Just ts <=> type patterns of instance type
742 tcConDecl unbox_strict NewType tycon tc_tvs mb_typats -- Newtypes
743 (ConDecl name _ ex_tvs ex_ctxt details ResTyH98)
744 = do { let tc_datacon field_lbls arg_ty
745 = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
746 ; buildDataCon (unLoc name) False {- Prefix -}
748 (map unLoc field_lbls)
749 tc_tvs [] -- No existentials
750 [] [] -- No equalities, predicates
755 -- Check that a newtype has no existential stuff
756 ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
759 PrefixCon [arg_ty] -> tc_datacon [] arg_ty
760 RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty
762 failWithTc (newtypeFieldErr name (length (hsConArgs details)))
763 -- Check that the constructor has exactly one field
766 tcConDecl unbox_strict DataType tycon tc_tvs mb_typats -- Data types
767 (ConDecl name _ tvs ctxt details res_ty)
768 = tcTyVarBndrs tvs $ \ tvs' -> do
769 { ctxt' <- tcHsKindedContext ctxt
770 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
772 tc_datacon is_infix field_lbls btys
773 = do { let bangs = map getBangStrictness btys
774 ; arg_tys <- mappM tcHsBangType btys
775 ; buildDataCon (unLoc name) is_infix
776 (argStrictness unbox_strict tycon bangs arg_tys)
777 (map unLoc field_lbls)
778 univ_tvs ex_tvs eq_preds ctxt' arg_tys
781 -- NB: we put data_tc, the type constructor gotten from the
782 -- constructor type signature into the data constructor;
783 -- that way checkValidDataCon can complain if it's wrong.
786 PrefixCon btys -> tc_datacon False [] btys
787 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
788 RecCon fields -> tc_datacon False field_names btys
790 (field_names, btys) = unzip fields
794 tcResultType :: TyCon
795 -> [TyVar] -- data T a b c = ...
796 -> [TyVar] -- where MkT :: forall a b c. ...
798 -> TcM ([TyVar], -- Universal
799 [TyVar], -- Existential
800 [(TyVar,Type)], -- Equality predicates
801 TyCon) -- TyCon given in the ResTy
802 -- We don't check that the TyCon given in the ResTy is
803 -- the same as the parent tycon, becuase we are in the middle
804 -- of a recursive knot; so it's postponed until checkValidDataCon
806 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
807 = return (tc_tvs, dc_tvs, [], decl_tycon)
808 -- In H98 syntax the dc_tvs are the existential ones
809 -- data T a b c = forall d e. MkT ...
810 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
812 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
813 -- E.g. data T a b c where
814 -- MkT :: forall x y z. T (x,y) z z
816 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
818 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
819 -- NB: tc_tvs and dc_tvs are distinct
820 ; let univ_tvs = choose_univs [] tc_tvs res_tys
821 -- Each univ_tv is either a dc_tv or a tc_tv
822 ex_tvs = dc_tvs `minusList` univ_tvs
823 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
825 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
827 -- choose_univs uses the res_ty itself if it's a type variable
828 -- and hasn't already been used; otherwise it uses one of the tc_tvs
829 choose_univs used tc_tvs []
830 = ASSERT( null tc_tvs ) []
831 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
832 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
833 = tv : choose_univs (tv:used) tc_tvs res_tys
835 = tc_tv : choose_univs used tc_tvs res_tys
838 argStrictness :: Bool -- True <=> -funbox-strict_fields
840 -> [TcType] -> [StrictnessMark]
841 argStrictness unbox_strict tycon bangs arg_tys
842 = ASSERT( length bangs == length arg_tys )
843 zipWith (chooseBoxingStrategy unbox_strict tycon) arg_tys bangs
845 -- We attempt to unbox/unpack a strict field when either:
846 -- (i) The field is marked '!!', or
847 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
849 -- We have turned off unboxing of newtypes because coercions make unboxing
850 -- and reboxing more complicated
851 chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark
852 chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang
854 HsNoBang -> NotMarkedStrict
855 HsStrict | unbox_strict_fields
856 && can_unbox arg_ty -> MarkedUnboxed
857 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
858 other -> MarkedStrict
860 -- we can unbox if the type is a chain of newtypes with a product tycon
862 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
864 Just (arg_tycon, tycon_args) ->
865 not (isRecursiveTyCon tycon) &&
866 isProductTyCon arg_tycon &&
867 (if isNewTyCon arg_tycon then
868 can_unbox (newTyConInstRhs arg_tycon tycon_args)
872 %************************************************************************
874 \subsection{Dependency analysis}
876 %************************************************************************
878 Validity checking is done once the mutually-recursive knot has been
879 tied, so we can look at things freely.
882 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
883 checkCycleErrs tyclss
887 = do { mappM_ recClsErr cls_cycles
888 ; failM } -- Give up now, because later checkValidTyCl
889 -- will loop if the synonym is recursive
891 cls_cycles = calcClassCycles tyclss
893 checkValidTyCl :: TyClDecl Name -> TcM ()
894 -- We do the validity check over declarations, rather than TyThings
895 -- only so that we can add a nice context with tcAddDeclCtxt
897 = tcAddDeclCtxt decl $
898 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
899 ; traceTc (text "Validity of" <+> ppr thing)
901 ATyCon tc -> checkValidTyCon tc
902 AClass cl -> checkValidClass cl
903 ; traceTc (text "Done validity of" <+> ppr thing)
906 -------------------------
907 -- For data types declared with record syntax, we require
908 -- that each constructor that has a field 'f'
909 -- (a) has the same result type
910 -- (b) has the same type for 'f'
911 -- module alpha conversion of the quantified type variables
912 -- of the constructor.
914 checkValidTyCon :: TyCon -> TcM ()
917 = case synTyConRhs tc of
918 OpenSynTyCon _ -> return ()
919 SynonymTyCon ty -> checkValidType syn_ctxt ty
921 = -- Check the context on the data decl
922 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
924 -- Check arg types of data constructors
925 mappM_ (checkValidDataCon tc) data_cons `thenM_`
927 -- Check that fields with the same name share a type
928 mappM_ check_fields groups
931 syn_ctxt = TySynCtxt name
933 data_cons = tyConDataCons tc
935 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
936 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
937 get_fields con = dataConFieldLabels con `zip` repeat con
938 -- dataConFieldLabels may return the empty list, which is fine
940 -- See Note [GADT record selectors] in MkId.lhs
941 -- We must check (a) that the named field has the same
942 -- type in each constructor
943 -- (b) that those constructors have the same result type
945 -- However, the constructors may have differently named type variable
946 -- and (worse) we don't know how the correspond to each other. E.g.
947 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
948 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
950 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
951 -- result type against other candidates' types BOTH WAYS ROUND.
952 -- If they magically agrees, take the substitution and
953 -- apply them to the latter ones, and see if they match perfectly.
954 check_fields fields@((label, con1) : other_fields)
955 -- These fields all have the same name, but are from
956 -- different constructors in the data type
957 = recoverM (return ()) $ mapM_ checkOne other_fields
958 -- Check that all the fields in the group have the same type
959 -- NB: this check assumes that all the constructors of a given
960 -- data type use the same type variables
962 tvs1 = mkVarSet (dataConAllTyVars con1)
963 res1 = dataConResTys con1
964 fty1 = dataConFieldType con1 label
966 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
967 = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
968 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
970 tvs2 = mkVarSet (dataConAllTyVars con2)
971 res2 = dataConResTys con2
972 fty2 = dataConFieldType con2 label
974 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
975 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
976 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
978 mb_subst1 = tcMatchTys tvs1 res1 res2
979 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
981 -------------------------------
982 checkValidDataCon :: TyCon -> DataCon -> TcM ()
983 checkValidDataCon tc con
984 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
985 addErrCtxt (dataConCtxt con) $
986 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
987 ; checkValidType ctxt (dataConUserType con) }
989 ctxt = ConArgCtxt (dataConName con)
991 -------------------------------
992 checkValidClass :: Class -> TcM ()
994 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
995 gla_exts <- doptM Opt_GlasgowExts
997 -- Check that the class is unary, unless GlaExs
998 ; checkTc (notNull tyvars) (nullaryClassErr cls)
999 ; checkTc (gla_exts || unary) (classArityErr cls)
1001 -- Check the super-classes
1002 ; checkValidTheta (ClassSCCtxt (className cls)) theta
1004 -- Check the class operations
1005 ; mappM_ (check_op gla_exts) op_stuff
1007 -- Check that if the class has generic methods, then the
1008 -- class has only one parameter. We can't do generic
1009 -- multi-parameter type classes!
1010 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
1013 (tyvars, theta, _, op_stuff) = classBigSig cls
1014 unary = isSingleton tyvars
1015 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
1017 check_op gla_exts (sel_id, dm)
1018 = addErrCtxt (classOpCtxt sel_id tau) $ do
1019 { checkValidTheta SigmaCtxt (tail theta)
1020 -- The 'tail' removes the initial (C a) from the
1021 -- class itself, leaving just the method type
1023 ; checkValidType (FunSigCtxt op_name) tau
1025 -- Check that the type mentions at least one of
1026 -- the class type variables
1027 ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
1028 (noClassTyVarErr cls sel_id)
1030 -- Check that for a generic method, the type of
1031 -- the method is sufficiently simple
1032 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1033 (badGenericMethodType op_name op_ty)
1036 op_name = idName sel_id
1037 op_ty = idType sel_id
1038 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1039 (_,theta2,tau2) = tcSplitSigmaTy tau1
1040 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1041 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1042 -- Ugh! The function might have a type like
1043 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1044 -- With -fglasgow-exts, we want to allow this, even though the inner
1045 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1046 -- in the context of a for-all must mention at least one quantified
1047 -- type variable. What a mess!
1050 ---------------------------------------------------------------------
1051 resultTypeMisMatch field_name con1 con2
1052 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1053 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1054 nest 2 $ ptext SLIT("but have different result types")]
1055 fieldTypeMisMatch field_name con1 con2
1056 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1057 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1059 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1061 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1062 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1065 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1068 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1069 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1071 noClassTyVarErr clas op
1072 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1073 ptext SLIT("mentions none of the type variables of the class") <+>
1074 ppr clas <+> hsep (map ppr (classTyVars clas))]
1076 genericMultiParamErr clas
1077 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1078 ptext SLIT("cannot have generic methods")
1080 badGenericMethodType op op_ty
1081 = hang (ptext SLIT("Generic method type is too complex"))
1082 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1083 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1086 = setSrcSpan (getLoc (head sorted_decls)) $
1087 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1088 nest 2 (vcat (map ppr_decl sorted_decls))])
1090 sorted_decls = sortLocated syn_decls
1091 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1094 = setSrcSpan (getLoc (head sorted_decls)) $
1095 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1096 nest 2 (vcat (map ppr_decl sorted_decls))])
1098 sorted_decls = sortLocated cls_decls
1099 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1101 sortLocated :: [Located a] -> [Located a]
1102 sortLocated things = sortLe le things
1104 le (L l1 _) (L l2 _) = l1 <= l2
1106 badDataConTyCon data_con
1107 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1108 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1109 2 (ptext SLIT("instead of its parent type"))
1112 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1113 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
1115 badStupidTheta tc_name
1116 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1118 newtypeConError tycon n
1119 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1120 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1123 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1124 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1126 newtypeFieldErr con_name n_flds
1127 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1128 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1130 badSigTyDecl tc_name
1131 = vcat [ ptext SLIT("Illegal kind signature") <+>
1132 quotes (ppr tc_name)
1133 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1135 badKindSigCtxt tc_name
1136 = vcat [ ptext SLIT("Illegal context in kind signature") <+>
1137 quotes (ppr tc_name)
1138 , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ]
1140 badIdxTyDecl tc_name
1141 = vcat [ ptext SLIT("Illegal indexed type instance for") <+>
1142 quotes (ppr tc_name)
1143 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1145 badGadtIdxTyDecl tc_name
1146 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1147 quotes (ppr tc_name)
1148 , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ]
1150 tooManyParmsErr tc_name
1151 = ptext SLIT("Indexed type instance has too many parameters:") <+>
1152 quotes (ppr tc_name)
1154 tooFewParmsErr tc_name
1155 = ptext SLIT("Indexed type instance has too few parameters:") <+>
1156 quotes (ppr tc_name)
1158 badBootTyIdxDeclErr = ptext SLIT("Illegal indexed type instance in hs-boot file")
1160 emptyConDeclsErr tycon
1161 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1162 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]