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
19 import HsTypes ( HsBang(..), getBangStrictness )
20 import BasicTypes ( RecFlag(..), StrictnessMark(..) )
21 import HscTypes ( implicitTyThings, ModDetails )
22 import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon,
23 mkDataTyConRhs, mkNewTyConRhs )
25 import TcEnv ( TyThing(..),
26 tcLookupLocated, tcLookupLocatedGlobal,
27 tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs,
28 tcExtendRecEnv, tcLookupTyVar, InstInfo )
29 import TcTyDecls ( calcRecFlags, calcClassCycles, calcSynCycles )
30 import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
31 import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
32 kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
33 kcHsSigType, tcHsBangType, tcLHsConResTy,
34 tcDataKindSig, kcCheckHsType )
35 import TcMType ( newKindVar, checkValidTheta, checkValidType,
37 UserTypeCtxt(..), SourceTyCtxt(..) )
38 import TcType ( TcKind, TcType, Type, tyVarsOfType, mkPhiTy,
39 mkArrowKind, liftedTypeKind, mkTyVarTys,
40 tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe )
41 import Type ( PredType(..), splitTyConApp_maybe, mkTyVarTy,
42 newTyConInstRhs, isLiftedTypeKind, Kind
43 -- pprParendType, pprThetaArrow
45 import Generics ( validGenericMethodType, canDoGenerics )
46 import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars )
47 import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon ),
48 tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon,
49 tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName,
51 import DataCon ( DataCon, dataConUserType, dataConName,
52 dataConFieldLabels, dataConTyCon, dataConAllTyVars,
53 dataConFieldType, dataConResTys )
54 import Var ( TyVar, idType, idName )
55 import VarSet ( elemVarSet, mkVarSet )
56 import Name ( Name, getSrcLoc )
58 import Maybe ( isJust, fromJust, isNothing )
59 import Maybes ( expectJust )
60 import Unify ( tcMatchTys, tcMatchTyX )
61 import Util ( zipLazy, isSingleton, notNull, sortLe )
62 import List ( partition )
63 import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan )
64 import ListSetOps ( equivClasses, minusList )
65 import List ( delete )
66 import Digraph ( SCC(..) )
67 import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
68 Opt_UnboxStrictFields ) )
72 %************************************************************************
74 \subsection{Type checking for type and class declarations}
76 %************************************************************************
80 Consider a mutually-recursive group, binding
81 a type constructor T and a class C.
83 Step 1: getInitialKind
84 Construct a KindEnv by binding T and C to a kind variable
87 In that environment, do a kind check
89 Step 3: Zonk the kinds
91 Step 4: buildTyConOrClass
92 Construct an environment binding T to a TyCon and C to a Class.
93 a) Their kinds comes from zonking the relevant kind variable
94 b) Their arity (for synonyms) comes direct from the decl
95 c) The funcional dependencies come from the decl
96 d) The rest comes a knot-tied binding of T and C, returned from Step 4
97 e) The variances of the tycons in the group is calculated from
101 In this environment, walk over the decls, constructing the TyCons and Classes.
102 This uses in a strict way items (a)-(c) above, which is why they must
103 be constructed in Step 4. Feed the results back to Step 4.
104 For this step, pass the is-recursive flag as the wimp-out flag
108 Step 6: Extend environment
109 We extend the type environment with bindings not only for the TyCons and Classes,
110 but also for their "implicit Ids" like data constructors and class selectors
112 Step 7: checkValidTyCl
113 For a recursive group only, check all the decls again, just
114 to check all the side conditions on validity. We could not
115 do this before because we were in a mutually recursive knot.
117 Identification of recursive TyCons
118 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
119 The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
122 Identifying a TyCon as recursive serves two purposes
124 1. Avoid infinite types. Non-recursive newtypes are treated as
125 "transparent", like type synonyms, after the type checker. If we did
126 this for all newtypes, we'd get infinite types. So we figure out for
127 each newtype whether it is "recursive", and add a coercion if so. In
128 effect, we are trying to "cut the loops" by identifying a loop-breaker.
130 2. Avoid infinite unboxing. This is nothing to do with newtypes.
134 Well, this function diverges, but we don't want the strictness analyser
135 to diverge. But the strictness analyser will diverge because it looks
136 deeper and deeper into the structure of T. (I believe there are
137 examples where the function does something sane, and the strictness
138 analyser still diverges, but I can't see one now.)
140 Now, concerning (1), the FC2 branch currently adds a coercion for ALL
141 newtypes. I did this as an experiment, to try to expose cases in which
142 the coercions got in the way of optimisations. If it turns out that we
143 can indeed always use a coercion, then we don't risk recursive types,
144 and don't need to figure out what the loop breakers are.
146 For newtype *families* though, we will always have a coercion, so they
147 are always loop breakers! So you can easily adjust the current
148 algorithm by simply treating all newtype families as loop breakers (and
149 indeed type families). I think.
152 tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
153 -> TcM TcGblEnv -- Input env extended by types and classes
154 -- and their implicit Ids,DataCons
155 tcTyAndClassDecls boot_details allDecls
156 = do { -- Omit instances of indexed types; they are handled together
157 -- with the *heads* of class instances
158 ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
160 -- First check for cyclic type synonysm or classes
161 -- See notes with checkCycleErrs
162 ; checkCycleErrs decls
164 ; traceTc (text "tcTyAndCl" <+> ppr mod)
165 ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
166 do { let { -- Calculate variances and rec-flag
167 ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
169 -- Extend the global env with the knot-tied results
170 -- for data types and classes
172 -- We must populate the environment with the loop-tied T's right
173 -- away, because the kind checker may "fault in" some type
174 -- constructors that recursively mention T
175 ; let { gbl_things = mkGlobalThings alg_decls rec_alg_tyclss }
176 ; tcExtendRecEnv gbl_things $ do
178 -- Kind-check the declarations
179 { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
181 ; let { calc_rec = calcRecFlags boot_details rec_alg_tyclss
182 ; tc_decl = addLocM (tcTyClDecl calc_rec) }
183 -- Type-check the type synonyms, and extend the envt
184 ; syn_tycons <- tcSynDecls kc_syn_decls
185 ; tcExtendGlobalEnv syn_tycons $ do
187 -- Type-check the data types and classes
188 { alg_tyclss <- mappM tc_decl kc_alg_decls
189 ; return (syn_tycons, alg_tyclss)
191 -- Finished with knot-tying now
192 -- Extend the environment with the finished things
193 ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
195 -- Perform the validity check
196 { traceTc (text "ready for validity check")
197 ; mappM_ (addLocM checkValidTyCl) decls
198 ; traceTc (text "done")
200 -- Add the implicit things;
201 -- we want them in the environment because
202 -- they may be mentioned in interface files
203 ; let { implicit_things = concatMap implicitTyThings alg_tyclss }
204 ; traceTc ((text "Adding" <+> ppr alg_tyclss) $$ (text "and" <+> ppr implicit_things))
205 ; tcExtendGlobalEnv implicit_things getGblEnv
208 mkGlobalThings :: [LTyClDecl Name] -- The decls
209 -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
211 -- Driven by the Decls, and treating the TyThings lazily
212 -- make a TypeEnv for the new things
213 mkGlobalThings decls things
214 = map mk_thing (decls `zipLazy` things)
216 mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
218 mk_thing (L _ decl, ~(ATyCon tc))
219 = (tcdName decl, ATyCon tc)
223 %************************************************************************
225 \subsection{Type checking instances of indexed types}
227 %************************************************************************
229 Instances of indexed types are somewhat of a hybrid. They are processed
230 together with class instance heads, but can contain data constructors and hence
231 they share a lot of kinding and type checking code with ordinary algebraic
232 data types (and GADTs).
235 tcIdxTyInstDecl :: LTyClDecl Name -> TcM (Maybe InstInfo) -- Nothing if error
236 tcIdxTyInstDecl (L loc decl)
237 = -- Prime error recovery, set source location
238 recoverM (returnM Nothing) $
241 do { -- indexed data types require -fglasgow-exts and can't be in an
243 ; gla_exts <- doptM Opt_GlasgowExts
244 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
245 ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
246 ; checkTc (not is_boot) $ badBootTyIdxDeclErr
248 -- perform kind and type checking
249 ; tcIdxTyInstDecl1 decl
252 tcIdxTyInstDecl1 :: TyClDecl Name -> TcM (Maybe InstInfo) -- Nothing if error
254 tcIdxTyInstDecl1 (decl@TySynonym {})
255 = kcIdxTyPats decl $ \k_tvs k_typats resKind ->
256 do { -- kind check the right hand side of the type equation
257 ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
259 -- type check type equation
260 ; tcTyVarBndrs k_tvs $ \t_tvs -> do {
261 ; t_typats <- mappM tcHsKindedType k_typats
262 ; t_rhs <- tcHsKindedType k_rhs
264 -- construct type rewrite rule
265 -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
266 ; return Nothing -- !!!TODO: need InstInfo for indexed types
269 tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L _ tc_name,
271 = kcIdxTyPats decl $ \k_tvs k_typats resKind ->
272 do { -- kind check the data declaration as usual
273 ; k_decl <- kcDataDecl decl k_tvs
274 ; k_typats <- mappM tcHsKindedType k_typats
275 ; let k_ctxt = tcdCtxt decl
276 k_cons = tcdCons decl
278 -- result kind must be '*' (otherwise, we have too few patterns)
279 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
281 -- type check indexed data type declaration
282 ; tcTyVarBndrs k_tvs $ \t_tvs -> do {
283 ; unbox_strict <- doptM Opt_UnboxStrictFields
285 -- Check that we don't use GADT syntax for indexed types
286 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
288 -- Check that a newtype has exactly one constructor
289 ; checkTc (new_or_data == DataType || isSingleton cons) $
290 newtypeConError tc_name (length cons)
292 ; stupid_theta <- tcHsKindedContext k_ctxt
293 ; tycon <- fixM (\ tycon -> do
294 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
299 DataType -> return (mkDataTyConRhs data_cons)
301 ASSERT( isSingleton data_cons )
302 mkNewTyConRhs tc_name tycon (head data_cons)
303 --vvvvvvv !!! need a new derived tc_name here
304 ; buildAlgTyCon tc_name t_tvs stupid_theta tc_rhs Recursive
306 -- We always assume that indexed types are recursive. Why?
307 -- (1) Due to their open nature, we can never be sure that a
308 -- further instance might not introduce a new recursive
309 -- dependency. (2) They are always valid loop breakers as
310 -- they involve a coercion.
314 -- !!!twofold: (1) (ATyCon tycon) and (2) an equality axiom
315 ; return Nothing -- !!!TODO: need InstInfo for indexed types
318 h98_syntax = case cons of -- All constructors have same shape
319 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
322 -- Kind checking of indexed types
325 -- Kind check type patterns and kind annotate the embedded type variables.
327 -- * Here we check that a type instance matches its kind signature, but we do
328 -- not check whether there is a pattern for each type index; the latter
329 -- check is only required for type functions.
331 kcIdxTyPats :: TyClDecl Name
332 -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TcM a)
333 -- ^^kinded tvs ^^kinded ty pats ^^res kind
335 kcIdxTyPats decl thing_inside
336 = kcHsTyVars (tcdTyVars decl) $ \tvs ->
337 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
338 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
339 (kinds, resKind) = splitKindFunTys tc_kind
340 hs_typats = fromJust $ tcdTyPats decl
342 -- we may not have more parameters than the kind indicates
343 ; checkTc (length kinds >= length hs_typats) $
344 tooManyParmsErr (tcdLName decl)
346 -- type functions can have a higher-kinded result
347 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
348 ; typats <- zipWithM kcCheckHsType hs_typats kinds
349 ; thing_inside tvs typats resultKind
354 %************************************************************************
358 %************************************************************************
360 We need to kind check all types in the mutually recursive group
361 before we know the kind of the type variables. For example:
364 op :: D b => a -> b -> b
367 bop :: (Monad c) => ...
369 Here, the kind of the locally-polymorphic type variable "b"
370 depends on *all the uses of class D*. For example, the use of
371 Monad c in bop's type signature means that D must have kind Type->Type.
373 However type synonyms work differently. They can have kinds which don't
374 just involve (->) and *:
375 type R = Int# -- Kind #
376 type S a = Array# a -- Kind * -> #
377 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
378 So we must infer their kinds from their right-hand sides *first* and then
379 use them, whereas for the mutually recursive data types D we bring into
380 scope kind bindings D -> k, where k is a kind variable, and do inference.
384 This treatment of type synonyms only applies to Haskell 98-style synonyms.
385 General type functions can be recursive, and hence, appear in `alg_decls'.
387 The kind of an indexed type is solely determinded by its kind signature;
388 hence, only kind signatures participate in the construction of the initial
389 kind environment (as constructed by `getInitialKind'). In fact, we ignore
390 instances of indexed types altogether in the following. However, we need to
391 include the kind signatures of associated types into the construction of the
392 initial kind environment. (This is handled by `allDecls').
395 kcTyClDecls syn_decls alg_decls
396 = do { -- First extend the kind env with each data type, class, and
397 -- indexed type, mapping them to a type variable
398 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
399 ; alg_kinds <- mappM getInitialKind initialKindDecls
400 ; tcExtendKindEnv alg_kinds $ do
402 -- Now kind-check the type synonyms, in dependency order
403 -- We do these differently to data type and classes,
404 -- because a type synonym can be an unboxed type
406 -- and a kind variable can't unify with UnboxedTypeKind
407 -- So we infer their kinds in dependency order
408 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
409 ; tcExtendKindEnv syn_kinds $ do
411 -- Now kind-check the data type, class, and kind signatures,
412 -- returning kind-annotated decls; we don't kind-check
413 -- instances of indexed types yet, but leave this to
415 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
416 (filter (not . isIdxTyDecl . unLoc) alg_decls)
418 ; return (kc_syn_decls, kc_alg_decls) }}}
420 -- get all declarations relevant for determining the initial kind
422 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
425 allDecls decl | isIdxTyDecl decl = []
428 ------------------------------------------------------------------------
429 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
430 -- Only for data type, class, and indexed type declarations
431 -- Get as much info as possible from the data, class, or indexed type decl,
432 -- so as to maximise usefulness of error messages
434 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
435 ; res_kind <- mk_res_kind decl
436 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
438 mk_arg_kind (UserTyVar _) = newKindVar
439 mk_arg_kind (KindedTyVar _ kind) = return kind
441 mk_res_kind (TyFunction { tcdKind = kind }) = return kind
442 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
443 -- On GADT-style and data signature declarations we allow a kind
445 -- data T :: *->* where { ... }
446 mk_res_kind other = return liftedTypeKind
450 kcSynDecls :: [SCC (LTyClDecl Name)]
451 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
452 [(Name,TcKind)]) -- Kind bindings
455 kcSynDecls (group : groups)
456 = do { (decl, nk) <- kcSynDecl group
457 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
458 ; return (decl:decls, nk:nks) }
461 kcSynDecl :: SCC (LTyClDecl Name)
462 -> TcM (LTyClDecl Name, -- Kind-annotated decls
463 (Name,TcKind)) -- Kind bindings
464 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
465 = tcAddDeclCtxt decl $
466 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
467 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
468 <+> brackets (ppr k_tvs))
469 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
470 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
471 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
472 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
473 (unLoc (tcdLName decl), tc_kind)) })
475 kcSynDecl (CyclicSCC decls)
476 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
477 -- of out-of-scope tycons
479 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
481 ------------------------------------------------------------------------
482 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
483 -- Not used for type synonyms (see kcSynDecl)
485 kcTyClDecl decl@(TyData {})
486 = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
487 kcTyClDeclBody decl $
490 kcTyClDecl decl@(TyFunction {})
491 = kcTyClDeclBody decl $ \ tvs' ->
492 return (decl {tcdTyVars = tvs'})
494 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
495 = kcTyClDeclBody decl $ \ tvs' ->
496 do { is_boot <- tcIsHsBoot
497 ; ctxt' <- kcHsContext ctxt
498 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
499 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
500 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
503 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
504 ; return (TypeSig nm op_ty') }
505 kc_sig other_sig = return other_sig
507 kcTyClDecl decl@(ForeignType {})
510 kcTyClDeclBody :: TyClDecl Name
511 -> ([LHsTyVarBndr Name] -> TcM a)
513 -- getInitialKind has made a suitably-shaped kind for the type or class
514 -- Unpack it, and attribute those kinds to the type variables
515 -- Extend the env with bindings for the tyvars, taken from
516 -- the kind of the tycon/class. Give it to the thing inside, and
517 -- check the result kind matches
518 kcTyClDeclBody decl thing_inside
519 = tcAddDeclCtxt decl $
520 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
521 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
522 (kinds, _) = splitKindFunTys tc_kind
523 hs_tvs = tcdTyVars decl
524 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
525 [ L loc (KindedTyVar (hsTyVarName tv) k)
526 | (L loc tv, k) <- zip hs_tvs kinds]
527 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
529 -- Kind check a data declaration, assuming that we already extended the
530 -- kind environment with the type variables of the left-hand side (these
531 -- kinded type variables are also passed as the second parameter).
533 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
534 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
536 = do { ctxt' <- kcHsContext ctxt
537 ; cons' <- mappM (wrapLocM kc_con_decl) cons
538 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
540 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do
541 kcHsTyVars ex_tvs $ \ex_tvs' -> do
542 ex_ctxt' <- kcHsContext ex_ctxt
543 details' <- kc_con_details details
545 ResTyH98 -> return ResTyH98
546 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
547 return (ConDecl name expl ex_tvs' ex_ctxt' details' res')
549 kc_con_details (PrefixCon btys)
550 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
551 kc_con_details (InfixCon bty1 bty2)
552 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
553 kc_con_details (RecCon fields)
554 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
556 kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') }
558 kc_larg_ty bty = case new_or_data of
559 DataType -> kcHsSigType bty
560 NewType -> kcHsLiftedSigType bty
561 -- Can't allow an unlifted type for newtypes, because we're effectively
562 -- going to remove the constructor while coercing it to a lifted type.
563 -- And newtypes can't be bang'd
567 %************************************************************************
569 \subsection{Type checking}
571 %************************************************************************
574 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
575 tcSynDecls [] = return []
576 tcSynDecls (decl : decls)
577 = do { syn_tc <- addLocM tcSynDecl decl
578 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
579 ; return (syn_tc : syn_tcs) }
582 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
583 = tcTyVarBndrs tvs $ \ tvs' -> do
584 { traceTc (text "tcd1" <+> ppr tc_name)
585 ; rhs_ty' <- tcHsKindedType rhs_ty
586 ; return (ATyCon (buildSynTyCon tc_name tvs' rhs_ty')) }
589 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM TyThing
591 tcTyClDecl calc_isrec decl
592 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
594 -- kind signature for a type functions
595 tcTyClDecl1 _calc_isrec
596 (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
597 = tcKindSigDecl tc_name tvs kind
599 -- kind signature for an indexed data type
600 tcTyClDecl1 _calc_isrec
601 (TyData {tcdCtxt = ctxt, tcdTyVars = tvs,
602 tcdLName = L _ tc_name, tcdKindSig = Just kind, tcdCons = []})
604 { checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
605 ; tcKindSigDecl tc_name tvs kind
608 tcTyClDecl1 calc_isrec
609 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
610 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
611 = tcTyVarBndrs tvs $ \ tvs' -> do
612 { extra_tvs <- tcDataKindSig mb_ksig
613 ; let final_tvs = tvs' ++ extra_tvs
614 ; stupid_theta <- tcHsKindedContext ctxt
615 ; want_generic <- doptM Opt_Generics
616 ; unbox_strict <- doptM Opt_UnboxStrictFields
617 ; gla_exts <- doptM Opt_GlasgowExts
618 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
620 -- Check that we don't use GADT syntax in H98 world
621 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
623 -- Check that we don't use kind signatures without Glasgow extensions
624 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
626 -- Check that the stupid theta is empty for a GADT-style declaration
627 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
629 -- Check that there's at least one condecl,
630 -- or else we're reading an hs-boot file, or -fglasgow-exts
631 ; checkTc (not (null cons) || gla_exts || is_boot)
632 (emptyConDeclsErr tc_name)
634 -- Check that a newtype has exactly one constructor
635 ; checkTc (new_or_data == DataType || isSingleton cons)
636 (newtypeConError tc_name (length cons))
638 ; tycon <- fixM (\ tycon -> do
639 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
643 if null cons && is_boot -- In a hs-boot file, empty cons means
644 then return AbstractTyCon -- "don't know"; hence Abstract
645 else case new_or_data of
646 DataType -> return (mkDataTyConRhs data_cons)
648 ASSERT( isSingleton data_cons )
649 mkNewTyConRhs tc_name tycon (head data_cons)
650 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
651 (want_generic && canDoGenerics data_cons) h98_syntax
653 ; return (ATyCon tycon)
656 is_rec = calc_isrec tc_name
657 h98_syntax = case cons of -- All constructors have same shape
658 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
661 tcTyClDecl1 calc_isrec
662 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
663 tcdCtxt = ctxt, tcdMeths = meths,
664 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
665 = tcTyVarBndrs tvs $ \ tvs' -> do
666 { ctxt' <- tcHsKindedContext ctxt
667 ; fds' <- mappM (addLocM tc_fundep) fundeps
668 ; ats' <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
669 -- ^^^^ !!!TODO: what to do with this? Need to generate FC tyfun decls.
670 ; sig_stuff <- tcClassSigs class_name sigs meths
671 ; clas <- fixM (\ clas ->
672 let -- This little knot is just so we can get
673 -- hold of the name of the class TyCon, which we
674 -- need to look up its recursiveness
675 tycon_name = tyConName (classTyCon clas)
676 tc_isrec = calc_isrec tycon_name
678 buildClass class_name tvs' ctxt' fds'
680 ; return (AClass clas) }
682 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
683 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
684 ; return (tvs1', tvs2') }
687 tcTyClDecl1 calc_isrec
688 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
689 = returnM (ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0))
691 -----------------------------------
692 tcKindSigDecl :: Name -> [LHsTyVarBndr Name] -> Kind -> TcM TyThing
693 tcKindSigDecl tc_name tvs kind
694 = tcTyVarBndrs tvs $ \ tvs' -> do
695 { gla_exts <- doptM Opt_GlasgowExts
697 -- Check that we don't use kind signatures without Glasgow extensions
698 ; checkTc gla_exts $ badSigTyDecl tc_name
701 -- We need to extend TyCon.TyCon with a new variant representing indexed
702 -- type constructors (ie, IdxTyCon). We will use them for both indexed
703 -- data types as well as type functions. In the case of indexed *data*
704 -- types, they are *abstract*; ie, won't be rewritten. OR do we just want
705 -- to make another variant of AlgTyCon (after all synonyms are also
707 -- We need an additional argument to this functions, which determines
708 -- whether the type constructor is abstract.
709 ; tycon <- error "TcTyClsDecls.tcKindSigDecl: IdxTyCon not implemented yet."
710 ; return (ATyCon tycon)
713 -----------------------------------
714 tcConDecl :: Bool -- True <=> -funbox-strict_fields
715 -> NewOrData -> TyCon -> [TyVar]
716 -> ConDecl Name -> TcM DataCon
718 tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
719 (ConDecl name _ ex_tvs ex_ctxt details ResTyH98)
720 = do { let tc_datacon field_lbls arg_ty
721 = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
722 ; buildDataCon (unLoc name) False {- Prefix -}
724 (map unLoc field_lbls)
725 tc_tvs [] -- No existentials
726 [] [] -- No equalities, predicates
730 -- Check that a newtype has no existential stuff
731 ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
734 PrefixCon [arg_ty] -> tc_datacon [] arg_ty
735 RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty
736 other -> failWithTc (newtypeFieldErr name (length (hsConArgs details)))
737 -- Check that the constructor has exactly one field
740 tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
741 (ConDecl name _ tvs ctxt details res_ty)
742 = tcTyVarBndrs tvs $ \ tvs' -> do
743 { ctxt' <- tcHsKindedContext ctxt
744 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
746 tc_datacon is_infix field_lbls btys
747 = do { let bangs = map getBangStrictness btys
748 ; arg_tys <- mappM tcHsBangType btys
749 ; buildDataCon (unLoc name) is_infix
750 (argStrictness unbox_strict tycon bangs arg_tys)
751 (map unLoc field_lbls)
752 univ_tvs ex_tvs eq_preds ctxt' arg_tys
754 -- NB: we put data_tc, the type constructor gotten from the constructor
755 -- type signature into the data constructor; that way
756 -- checkValidDataCon can complain if it's wrong.
759 PrefixCon btys -> tc_datacon False [] btys
760 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
761 RecCon fields -> tc_datacon False field_names btys
763 (field_names, btys) = unzip fields
767 tcResultType :: TyCon
768 -> [TyVar] -- data T a b c = ...
769 -> [TyVar] -- where MkT :: forall a b c. ...
771 -> TcM ([TyVar], -- Universal
772 [TyVar], -- Existential
773 [(TyVar,Type)], -- Equality predicates
774 TyCon) -- TyCon given in the ResTy
775 -- We don't check that the TyCon given in the ResTy is
776 -- the same as the parent tycon, becuase we are in the middle
777 -- of a recursive knot; so it's postponed until checkValidDataCon
779 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
780 = return (tc_tvs, dc_tvs, [], decl_tycon)
781 -- In H98 syntax the dc_tvs are the existential ones
782 -- data T a b c = forall d e. MkT ...
783 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
785 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
786 -- E.g. data T a b c where
787 -- MkT :: forall x y z. T (x,y) z z
789 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
791 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
792 -- NB: tc_tvs and dc_tvs are distinct
793 ; let univ_tvs = choose_univs [] tc_tvs res_tys
794 -- Each univ_tv is either a dc_tv or a tc_tv
795 ex_tvs = dc_tvs `minusList` univ_tvs
796 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
798 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
800 -- choose_univs uses the res_ty itself if it's a type variable
801 -- and hasn't already been used; otherwise it uses one of the tc_tvs
802 choose_univs used tc_tvs []
803 = ASSERT( null tc_tvs ) []
804 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
805 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
806 = tv : choose_univs (tv:used) tc_tvs res_tys
808 = tc_tv : choose_univs used tc_tvs res_tys
811 argStrictness :: Bool -- True <=> -funbox-strict_fields
813 -> [TcType] -> [StrictnessMark]
814 argStrictness unbox_strict tycon bangs arg_tys
815 = ASSERT( length bangs == length arg_tys )
816 zipWith (chooseBoxingStrategy unbox_strict tycon) arg_tys bangs
818 -- We attempt to unbox/unpack a strict field when either:
819 -- (i) The field is marked '!!', or
820 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
822 -- We have turned off unboxing of newtypes because coercions make unboxing
823 -- and reboxing more complicated
824 chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark
825 chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang
827 HsNoBang -> NotMarkedStrict
828 HsStrict | unbox_strict_fields
829 && can_unbox arg_ty -> MarkedUnboxed
830 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
831 other -> MarkedStrict
833 -- we can unbox if the type is a chain of newtypes with a product tycon
835 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
837 Just (arg_tycon, tycon_args) ->
838 not (isRecursiveTyCon tycon) &&
839 isProductTyCon arg_tycon &&
840 (if isNewTyCon arg_tycon then
841 can_unbox (newTyConInstRhs arg_tycon tycon_args)
845 %************************************************************************
847 \subsection{Dependency analysis}
849 %************************************************************************
851 Validity checking is done once the mutually-recursive knot has been
852 tied, so we can look at things freely.
855 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
856 checkCycleErrs tyclss
860 = do { mappM_ recClsErr cls_cycles
861 ; failM } -- Give up now, because later checkValidTyCl
862 -- will loop if the synonym is recursive
864 cls_cycles = calcClassCycles tyclss
866 checkValidTyCl :: TyClDecl Name -> TcM ()
867 -- We do the validity check over declarations, rather than TyThings
868 -- only so that we can add a nice context with tcAddDeclCtxt
870 = tcAddDeclCtxt decl $
871 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
872 ; traceTc (text "Validity of" <+> ppr thing)
874 ATyCon tc -> checkValidTyCon tc
875 AClass cl -> checkValidClass cl
876 ; traceTc (text "Done validity of" <+> ppr thing)
879 -------------------------
880 -- For data types declared with record syntax, we require
881 -- that each constructor that has a field 'f'
882 -- (a) has the same result type
883 -- (b) has the same type for 'f'
884 -- module alpha conversion of the quantified type variables
885 -- of the constructor.
887 checkValidTyCon :: TyCon -> TcM ()
890 = checkValidType syn_ctxt syn_rhs
892 = -- Check the context on the data decl
893 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
895 -- Check arg types of data constructors
896 mappM_ (checkValidDataCon tc) data_cons `thenM_`
898 -- Check that fields with the same name share a type
899 mappM_ check_fields groups
902 syn_ctxt = TySynCtxt name
904 syn_rhs = synTyConRhs tc
905 data_cons = tyConDataCons tc
907 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
908 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
909 get_fields con = dataConFieldLabels con `zip` repeat con
910 -- dataConFieldLabels may return the empty list, which is fine
912 -- See Note [GADT record selectors] in MkId.lhs
913 -- We must check (a) that the named field has the same
914 -- type in each constructor
915 -- (b) that those constructors have the same result type
917 -- However, the constructors may have differently named type variable
918 -- and (worse) we don't know how the correspond to each other. E.g.
919 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
920 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
922 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
923 -- result type against other candidates' types BOTH WAYS ROUND.
924 -- If they magically agrees, take the substitution and
925 -- apply them to the latter ones, and see if they match perfectly.
926 check_fields fields@((label, con1) : other_fields)
927 -- These fields all have the same name, but are from
928 -- different constructors in the data type
929 = recoverM (return ()) $ mapM_ checkOne other_fields
930 -- Check that all the fields in the group have the same type
931 -- NB: this check assumes that all the constructors of a given
932 -- data type use the same type variables
934 tvs1 = mkVarSet (dataConAllTyVars con1)
935 res1 = dataConResTys con1
936 fty1 = dataConFieldType con1 label
938 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
939 = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
940 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
942 tvs2 = mkVarSet (dataConAllTyVars con2)
943 res2 = dataConResTys con2
944 fty2 = dataConFieldType con2 label
946 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
947 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
948 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
950 mb_subst1 = tcMatchTys tvs1 res1 res2
951 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
953 -------------------------------
954 checkValidDataCon :: TyCon -> DataCon -> TcM ()
955 checkValidDataCon tc con
956 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
957 addErrCtxt (dataConCtxt con) $
958 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
959 ; checkValidType ctxt (dataConUserType con) }
961 ctxt = ConArgCtxt (dataConName con)
963 -------------------------------
964 checkValidClass :: Class -> TcM ()
966 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
967 gla_exts <- doptM Opt_GlasgowExts
969 -- Check that the class is unary, unless GlaExs
970 ; checkTc (notNull tyvars) (nullaryClassErr cls)
971 ; checkTc (gla_exts || unary) (classArityErr cls)
973 -- Check the super-classes
974 ; checkValidTheta (ClassSCCtxt (className cls)) theta
976 -- Check the class operations
977 ; mappM_ (check_op gla_exts) op_stuff
979 -- Check that if the class has generic methods, then the
980 -- class has only one parameter. We can't do generic
981 -- multi-parameter type classes!
982 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
985 (tyvars, theta, _, op_stuff) = classBigSig cls
986 unary = isSingleton tyvars
987 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
989 check_op gla_exts (sel_id, dm)
990 = addErrCtxt (classOpCtxt sel_id tau) $ do
991 { checkValidTheta SigmaCtxt (tail theta)
992 -- The 'tail' removes the initial (C a) from the
993 -- class itself, leaving just the method type
995 ; checkValidType (FunSigCtxt op_name) tau
997 -- Check that the type mentions at least one of
998 -- the class type variables
999 ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
1000 (noClassTyVarErr cls sel_id)
1002 -- Check that for a generic method, the type of
1003 -- the method is sufficiently simple
1004 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1005 (badGenericMethodType op_name op_ty)
1008 op_name = idName sel_id
1009 op_ty = idType sel_id
1010 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1011 (_,theta2,tau2) = tcSplitSigmaTy tau1
1012 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1013 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1014 -- Ugh! The function might have a type like
1015 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1016 -- With -fglasgow-exts, we want to allow this, even though the inner
1017 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1018 -- in the context of a for-all must mention at least one quantified
1019 -- type variable. What a mess!
1022 ---------------------------------------------------------------------
1023 resultTypeMisMatch field_name con1 con2
1024 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1025 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1026 nest 2 $ ptext SLIT("but have different result types")]
1027 fieldTypeMisMatch field_name con1 con2
1028 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1029 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1031 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1033 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1034 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1037 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1040 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1041 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1043 noClassTyVarErr clas op
1044 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1045 ptext SLIT("mentions none of the type variables of the class") <+>
1046 ppr clas <+> hsep (map ppr (classTyVars clas))]
1048 genericMultiParamErr clas
1049 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1050 ptext SLIT("cannot have generic methods")
1052 badGenericMethodType op op_ty
1053 = hang (ptext SLIT("Generic method type is too complex"))
1054 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1055 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1058 = setSrcSpan (getLoc (head sorted_decls)) $
1059 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1060 nest 2 (vcat (map ppr_decl sorted_decls))])
1062 sorted_decls = sortLocated syn_decls
1063 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1066 = setSrcSpan (getLoc (head sorted_decls)) $
1067 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1068 nest 2 (vcat (map ppr_decl sorted_decls))])
1070 sorted_decls = sortLocated cls_decls
1071 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1073 sortLocated :: [Located a] -> [Located a]
1074 sortLocated things = sortLe le things
1076 le (L l1 _) (L l2 _) = l1 <= l2
1078 badDataConTyCon data_con
1079 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1080 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1081 2 (ptext SLIT("instead of its parent type"))
1084 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1085 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
1087 badStupidTheta tc_name
1088 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1090 newtypeConError tycon n
1091 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1092 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1095 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1096 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1098 newtypeFieldErr con_name n_flds
1099 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1100 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1102 badSigTyDecl tc_name
1103 = vcat [ ptext SLIT("Illegal kind signature") <+>
1104 quotes (ppr tc_name)
1105 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1107 badKindSigCtxt tc_name
1108 = vcat [ ptext SLIT("Illegal context in kind signature") <+>
1109 quotes (ppr tc_name)
1110 , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ]
1112 badIdxTyDecl tc_name
1113 = vcat [ ptext SLIT("Illegal indexed type instance for") <+>
1114 quotes (ppr tc_name)
1115 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1117 badGadtIdxTyDecl tc_name
1118 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1119 quotes (ppr tc_name)
1120 , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ]
1122 tooManyParmsErr tc_name
1123 = ptext SLIT("Indexed type instance has too many parameters:") <+>
1124 quotes (ppr tc_name)
1126 tooFewParmsErr tc_name
1127 = ptext SLIT("Indexed type instance has too few parameters:") <+>
1128 quotes (ppr tc_name)
1130 badBootTyIdxDeclErr = ptext SLIT("Illegal indexed type instance in hs-boot file")
1132 emptyConDeclsErr tycon
1133 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1134 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]