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, hsLTyVarNames )
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,
29 tcExtendKindEnvTvs, newFamInstTyConName,
30 tcExtendRecEnv, tcLookupTyVar, InstInfo )
31 import TcTyDecls ( calcRecFlags, calcClassCycles, calcSynCycles )
32 import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
33 import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
34 kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
35 kcHsSigType, tcHsBangType, tcLHsConResTy,
36 tcDataKindSig, kcCheckHsType )
37 import TcMType ( newKindVar, checkValidTheta, checkValidType,
39 UserTypeCtxt(..), SourceTyCtxt(..) )
40 import TcType ( TcKind, TcType, Type, tyVarsOfType, mkPhiTy,
41 mkArrowKind, liftedTypeKind, mkTyVarTys,
42 tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe )
43 import Type ( PredType(..), splitTyConApp_maybe, mkTyVarTy,
44 newTyConInstRhs, isLiftedTypeKind, Kind
45 -- pprParendType, pprThetaArrow
47 import Generics ( validGenericMethodType, canDoGenerics )
48 import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars )
49 import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon, OpenDataTyCon,
51 SynTyConRhs( OpenSynTyCon, SynonymTyCon ),
52 tyConDataCons, mkForeignTyCon, isProductTyCon,
53 isRecursiveTyCon, isOpenTyCon,
54 tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName,
55 isNewTyCon, isDataTyCon, tyConKind,
57 import DataCon ( DataCon, dataConUserType, dataConName,
58 dataConFieldLabels, dataConTyCon, dataConAllTyVars,
59 dataConFieldType, dataConResTys )
60 import Var ( TyVar, idType, idName )
61 import VarSet ( elemVarSet, mkVarSet )
62 import Name ( Name, getSrcLoc )
64 import Maybe ( isJust, fromJust, isNothing, catMaybes )
65 import Maybes ( expectJust )
66 import Monad ( unless )
67 import Unify ( tcMatchTys, tcMatchTyX )
68 import Util ( zipLazy, isSingleton, notNull, sortLe )
69 import List ( partition, elemIndex )
70 import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan,
72 import ListSetOps ( equivClasses, minusList )
73 import Digraph ( SCC(..) )
74 import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
75 Opt_UnboxStrictFields, Opt_IndexedTypes ) )
79 %************************************************************************
81 \subsection{Type checking for type and class declarations}
83 %************************************************************************
87 Consider a mutually-recursive group, binding
88 a type constructor T and a class C.
90 Step 1: getInitialKind
91 Construct a KindEnv by binding T and C to a kind variable
94 In that environment, do a kind check
96 Step 3: Zonk the kinds
98 Step 4: buildTyConOrClass
99 Construct an environment binding T to a TyCon and C to a Class.
100 a) Their kinds comes from zonking the relevant kind variable
101 b) Their arity (for synonyms) comes direct from the decl
102 c) The funcional dependencies come from the decl
103 d) The rest comes a knot-tied binding of T and C, returned from Step 4
104 e) The variances of the tycons in the group is calculated from
108 In this environment, walk over the decls, constructing the TyCons and Classes.
109 This uses in a strict way items (a)-(c) above, which is why they must
110 be constructed in Step 4. Feed the results back to Step 4.
111 For this step, pass the is-recursive flag as the wimp-out flag
115 Step 6: Extend environment
116 We extend the type environment with bindings not only for the TyCons and Classes,
117 but also for their "implicit Ids" like data constructors and class selectors
119 Step 7: checkValidTyCl
120 For a recursive group only, check all the decls again, just
121 to check all the side conditions on validity. We could not
122 do this before because we were in a mutually recursive knot.
124 Identification of recursive TyCons
125 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
126 The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
129 Identifying a TyCon as recursive serves two purposes
131 1. Avoid infinite types. Non-recursive newtypes are treated as
132 "transparent", like type synonyms, after the type checker. If we did
133 this for all newtypes, we'd get infinite types. So we figure out for
134 each newtype whether it is "recursive", and add a coercion if so. In
135 effect, we are trying to "cut the loops" by identifying a loop-breaker.
137 2. Avoid infinite unboxing. This is nothing to do with newtypes.
141 Well, this function diverges, but we don't want the strictness analyser
142 to diverge. But the strictness analyser will diverge because it looks
143 deeper and deeper into the structure of T. (I believe there are
144 examples where the function does something sane, and the strictness
145 analyser still diverges, but I can't see one now.)
147 Now, concerning (1), the FC2 branch currently adds a coercion for ALL
148 newtypes. I did this as an experiment, to try to expose cases in which
149 the coercions got in the way of optimisations. If it turns out that we
150 can indeed always use a coercion, then we don't risk recursive types,
151 and don't need to figure out what the loop breakers are.
153 For newtype *families* though, we will always have a coercion, so they
154 are always loop breakers! So you can easily adjust the current
155 algorithm by simply treating all newtype families as loop breakers (and
156 indeed type families). I think.
159 tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
160 -> TcM TcGblEnv -- Input env extended by types and classes
161 -- and their implicit Ids,DataCons
162 tcTyAndClassDecls boot_details allDecls
163 = do { -- Omit instances of indexed types; they are handled together
164 -- with the *heads* of class instances
165 ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
167 -- First check for cyclic type synonysm or classes
168 -- See notes with checkCycleErrs
169 ; checkCycleErrs decls
171 ; traceTc (text "tcTyAndCl" <+> ppr mod)
172 ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
173 do { let { -- Seperate ordinary synonyms from all other type and
174 -- class declarations and add all associated type
175 -- declarations from type classes. The latter is
176 -- required so that the temporary environment for the
177 -- knot includes all associated family declarations.
178 ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
180 ; alg_at_decls = concatMap addATs alg_decls
182 -- Extend the global env with the knot-tied results
183 -- for data types and classes
185 -- We must populate the environment with the loop-tied
186 -- T's right away, because the kind checker may "fault
187 -- in" some type constructors that recursively
189 ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss
190 ; tcExtendRecEnv gbl_things $ do
192 -- Kind-check the declarations
193 { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
195 ; let { -- Calculate rec-flag
196 ; calc_rec = calcRecFlags boot_details rec_alg_tyclss
197 ; tc_decl = addLocM (tcTyClDecl calc_rec) }
198 -- Type-check the type synonyms, and extend the envt
199 ; syn_tycons <- tcSynDecls kc_syn_decls
200 ; tcExtendGlobalEnv syn_tycons $ do
202 -- Type-check the data types and classes
203 { alg_tyclss <- mappM tc_decl kc_alg_decls
204 ; return (syn_tycons, concat alg_tyclss)
206 -- Finished with knot-tying now
207 -- Extend the environment with the finished things
208 ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
210 -- Perform the validity check
211 { traceTc (text "ready for validity check")
212 ; mappM_ (addLocM checkValidTyCl) decls
213 ; traceTc (text "done")
215 -- Add the implicit things;
216 -- we want them in the environment because
217 -- they may be mentioned in interface files
218 -- NB: All associated types and their implicit things will be added a
219 -- second time here. This doesn't matter as the definitions are
221 ; let { implicit_things = concatMap implicitTyThings alg_tyclss }
222 ; traceTc ((text "Adding" <+> ppr alg_tyclss)
223 $$ (text "and" <+> ppr implicit_things))
224 ; tcExtendGlobalEnv implicit_things getGblEnv
227 -- Pull associated types out of class declarations, to tie them into the
229 -- NB: We put them in the same place in the list as `tcTyClDecl' will
230 -- eventually put the matching `TyThing's. That's crucial; otherwise,
231 -- the two argument lists of `mkGlobalThings' don't match up.
232 addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats
235 mkGlobalThings :: [LTyClDecl Name] -- The decls
236 -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
238 -- Driven by the Decls, and treating the TyThings lazily
239 -- make a TypeEnv for the new things
240 mkGlobalThings decls things
241 = map mk_thing (decls `zipLazy` things)
243 mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
245 mk_thing (L _ decl, ~(ATyCon tc))
246 = (tcdName decl, ATyCon tc)
250 %************************************************************************
252 \subsection{Type checking instances of indexed types}
254 %************************************************************************
256 Instances of indexed types are somewhat of a hybrid. They are processed
257 together with class instance heads, but can contain data constructors and hence
258 they share a lot of kinding and type checking code with ordinary algebraic
259 data types (and GADTs).
262 tcIdxTyInstDecl :: LTyClDecl Name
263 -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
264 tcIdxTyInstDecl (L loc decl)
265 = -- Prime error recovery, set source location
266 recoverM (returnM (Nothing, Nothing)) $
269 do { -- indexed data types require -findexed-types and can't be in an
271 ; gla_exts <- doptM Opt_IndexedTypes
272 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
273 ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
274 ; checkTc (not is_boot) $ badBootTyIdxDeclErr
276 -- perform kind and type checking
277 ; tcIdxTyInstDecl1 decl
280 tcIdxTyInstDecl1 :: TyClDecl Name
281 -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
283 tcIdxTyInstDecl1 (decl@TySynonym {})
284 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
285 do { -- check that the family declaration is for a synonym
286 unless (isSynTyCon family) $
287 addErr (wrongKindOfFamily family)
289 ; -- (1) kind check the right hand side of the type equation
290 ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
292 -- (2) type check type equation
293 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
294 ; t_typats <- mappM tcHsKindedType k_typats
295 ; t_rhs <- tcHsKindedType k_rhs
297 -- construct type rewrite rule
298 -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
299 ; return (Nothing, Nothing) -- !!!TODO: need InstInfo for eq axioms
302 tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
304 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
305 do { -- check that the family declaration is for the right kind
306 unless (new_or_data == NewType && isNewTyCon family ||
307 new_or_data == DataType && isDataTyCon family) $
308 addErr (wrongKindOfFamily family)
310 ; -- (1) kind check the data declaration as usual
311 ; k_decl <- kcDataDecl decl k_tvs
312 ; let k_ctxt = tcdCtxt k_decl
313 k_cons = tcdCons k_decl
315 -- result kind must be '*' (otherwise, we have too few patterns)
316 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
318 -- (2) type check indexed data type declaration
319 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
320 ; unbox_strict <- doptM Opt_UnboxStrictFields
322 -- Check that we don't use GADT syntax for indexed types
323 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
325 -- Check that a newtype has exactly one constructor
326 ; checkTc (new_or_data == DataType || isSingleton k_cons) $
327 newtypeConError tc_name (length k_cons)
329 ; t_typats <- mappM tcHsKindedType k_typats
330 ; stupid_theta <- tcHsKindedContext k_ctxt
332 ; rep_tc_name <- newFamInstTyConName tc_name (srcSpanStart loc)
333 ; tycon <- fixM (\ tycon -> do
334 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
339 DataType -> return (mkDataTyConRhs data_cons)
340 NewType -> ASSERT( isSingleton data_cons )
341 mkNewTyConRhs tc_name tycon (head data_cons)
342 ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive
343 False h98_syntax (Just (family, t_typats))
344 -- We always assume that indexed types are recursive. Why?
345 -- (1) Due to their open nature, we can never be sure that a
346 -- further instance might not introduce a new recursive
347 -- dependency. (2) They are always valid loop breakers as
348 -- they involve a coercion.
352 ; return (Nothing, Just (ATyCon tycon))
355 h98_syntax = case cons of -- All constructors have same shape
356 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
359 -- Kind checking of indexed types
362 -- Kind check type patterns and kind annotate the embedded type variables.
364 -- * Here we check that a type instance matches its kind signature, but we do
365 -- not check whether there is a pattern for each type index; the latter
366 -- check is only required for type functions.
368 kcIdxTyPats :: TyClDecl Name
369 -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
370 -- ^^kinded tvs ^^kinded ty pats ^^res kind
372 kcIdxTyPats decl thing_inside
373 = kcHsTyVars (tcdTyVars decl) $ \tvs ->
374 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
375 ; let { family = case tc_ty_thing of
376 AGlobal (ATyCon family) -> family
377 ; (kinds, resKind) = splitKindFunTys (tyConKind family)
378 ; hs_typats = fromJust $ tcdTyPats decl }
380 -- we may not have more parameters than the kind indicates
381 ; checkTc (length kinds >= length hs_typats) $
382 tooManyParmsErr (tcdLName decl)
384 -- type functions can have a higher-kinded result
385 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
386 ; typats <- zipWithM kcCheckHsType hs_typats kinds
387 ; thing_inside tvs typats resultKind family
393 %************************************************************************
397 %************************************************************************
399 We need to kind check all types in the mutually recursive group
400 before we know the kind of the type variables. For example:
403 op :: D b => a -> b -> b
406 bop :: (Monad c) => ...
408 Here, the kind of the locally-polymorphic type variable "b"
409 depends on *all the uses of class D*. For example, the use of
410 Monad c in bop's type signature means that D must have kind Type->Type.
412 However type synonyms work differently. They can have kinds which don't
413 just involve (->) and *:
414 type R = Int# -- Kind #
415 type S a = Array# a -- Kind * -> #
416 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
417 So we must infer their kinds from their right-hand sides *first* and then
418 use them, whereas for the mutually recursive data types D we bring into
419 scope kind bindings D -> k, where k is a kind variable, and do inference.
423 This treatment of type synonyms only applies to Haskell 98-style synonyms.
424 General type functions can be recursive, and hence, appear in `alg_decls'.
426 The kind of an indexed type is solely determinded by its kind signature;
427 hence, only kind signatures participate in the construction of the initial
428 kind environment (as constructed by `getInitialKind'). In fact, we ignore
429 instances of indexed types altogether in the following. However, we need to
430 include the kind signatures of associated types into the construction of the
431 initial kind environment. (This is handled by `allDecls').
434 kcTyClDecls syn_decls alg_decls
435 = do { -- First extend the kind env with each data type, class, and
436 -- indexed type, mapping them to a type variable
437 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
438 ; alg_kinds <- mappM getInitialKind initialKindDecls
439 ; tcExtendKindEnv alg_kinds $ do
441 -- Now kind-check the type synonyms, in dependency order
442 -- We do these differently to data type and classes,
443 -- because a type synonym can be an unboxed type
445 -- and a kind variable can't unify with UnboxedTypeKind
446 -- So we infer their kinds in dependency order
447 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
448 ; tcExtendKindEnv syn_kinds $ do
450 -- Now kind-check the data type, class, and kind signatures,
451 -- returning kind-annotated decls; we don't kind-check
452 -- instances of indexed types yet, but leave this to
454 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
455 (filter (not . isIdxTyDecl . unLoc) alg_decls)
457 ; return (kc_syn_decls, kc_alg_decls) }}}
459 -- get all declarations relevant for determining the initial kind
461 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
464 allDecls decl | isIdxTyDecl decl = []
467 ------------------------------------------------------------------------
468 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
469 -- Only for data type, class, and indexed type declarations
470 -- Get as much info as possible from the data, class, or indexed type decl,
471 -- so as to maximise usefulness of error messages
473 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
474 ; res_kind <- mk_res_kind decl
475 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
477 mk_arg_kind (UserTyVar _) = newKindVar
478 mk_arg_kind (KindedTyVar _ kind) = return kind
480 mk_res_kind (TyFunction { tcdKind = kind }) = return kind
481 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
482 -- On GADT-style and data signature declarations we allow a kind
484 -- data T :: *->* where { ... }
485 mk_res_kind other = return liftedTypeKind
489 kcSynDecls :: [SCC (LTyClDecl Name)]
490 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
491 [(Name,TcKind)]) -- Kind bindings
494 kcSynDecls (group : groups)
495 = do { (decl, nk) <- kcSynDecl group
496 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
497 ; return (decl:decls, nk:nks) }
500 kcSynDecl :: SCC (LTyClDecl Name)
501 -> TcM (LTyClDecl Name, -- Kind-annotated decls
502 (Name,TcKind)) -- Kind bindings
503 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
504 = tcAddDeclCtxt decl $
505 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
506 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
507 <+> brackets (ppr k_tvs))
508 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
509 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
510 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
511 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
512 (unLoc (tcdLName decl), tc_kind)) })
514 kcSynDecl (CyclicSCC decls)
515 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
516 -- of out-of-scope tycons
518 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
520 ------------------------------------------------------------------------
521 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
522 -- Not used for type synonyms (see kcSynDecl)
524 kcTyClDecl decl@(TyData {})
525 = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
526 kcTyClDeclBody decl $
529 kcTyClDecl decl@(TyFunction {})
530 = kcTyClDeclBody decl $ \ tvs' ->
531 return (decl {tcdTyVars = tvs'})
533 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
534 = kcTyClDeclBody decl $ \ tvs' ->
535 do { is_boot <- tcIsHsBoot
536 ; ctxt' <- kcHsContext ctxt
537 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
538 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
539 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
542 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
543 ; return (TypeSig nm op_ty') }
544 kc_sig other_sig = return other_sig
546 kcTyClDecl decl@(ForeignType {})
549 kcTyClDeclBody :: TyClDecl Name
550 -> ([LHsTyVarBndr Name] -> TcM a)
552 -- getInitialKind has made a suitably-shaped kind for the type or class
553 -- Unpack it, and attribute those kinds to the type variables
554 -- Extend the env with bindings for the tyvars, taken from
555 -- the kind of the tycon/class. Give it to the thing inside, and
556 -- check the result kind matches
557 kcTyClDeclBody decl thing_inside
558 = tcAddDeclCtxt decl $
559 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
560 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
561 (kinds, _) = splitKindFunTys tc_kind
562 hs_tvs = tcdTyVars decl
563 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
564 [ L loc (KindedTyVar (hsTyVarName tv) k)
565 | (L loc tv, k) <- zip hs_tvs kinds]
566 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
568 -- Kind check a data declaration, assuming that we already extended the
569 -- kind environment with the type variables of the left-hand side (these
570 -- kinded type variables are also passed as the second parameter).
572 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
573 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
575 = do { ctxt' <- kcHsContext ctxt
576 ; cons' <- mappM (wrapLocM kc_con_decl) cons
577 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
579 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do
580 kcHsTyVars ex_tvs $ \ex_tvs' -> do
581 ex_ctxt' <- kcHsContext ex_ctxt
582 details' <- kc_con_details details
584 ResTyH98 -> return ResTyH98
585 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
586 return (ConDecl name expl ex_tvs' ex_ctxt' details' res')
588 kc_con_details (PrefixCon btys)
589 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
590 kc_con_details (InfixCon bty1 bty2)
591 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
592 kc_con_details (RecCon fields)
593 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
595 kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') }
597 kc_larg_ty bty = case new_or_data of
598 DataType -> kcHsSigType bty
599 NewType -> kcHsLiftedSigType bty
600 -- Can't allow an unlifted type for newtypes, because we're effectively
601 -- going to remove the constructor while coercing it to a lifted type.
602 -- And newtypes can't be bang'd
606 %************************************************************************
608 \subsection{Type checking}
610 %************************************************************************
613 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
614 tcSynDecls [] = return []
615 tcSynDecls (decl : decls)
616 = do { syn_tc <- addLocM tcSynDecl decl
617 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
618 ; return (syn_tc : syn_tcs) }
621 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
622 = tcTyVarBndrs tvs $ \ tvs' -> do
623 { traceTc (text "tcd1" <+> ppr tc_name)
624 ; rhs_ty' <- tcHsKindedType rhs_ty
625 ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
628 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
630 tcTyClDecl calc_isrec decl
631 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
633 -- kind signature for a type function
634 tcTyClDecl1 _calc_isrec
635 (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
636 = tcTyVarBndrs tvs $ \ tvs' -> do
637 { traceTc (text "type family: " <+> ppr tc_name)
638 ; gla_exts <- doptM Opt_IndexedTypes
640 -- Check that we don't use kind signatures without Glasgow extensions
641 ; checkTc gla_exts $ badSigTyDecl tc_name
643 ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)]
646 -- kind signature for an indexed data type
647 tcTyClDecl1 _calc_isrec
648 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
649 tcdLName = L _ tc_name, tcdKindSig = Just ksig, tcdCons = []})
650 = tcTyVarBndrs tvs $ \ tvs' -> do
651 { traceTc (text "data/newtype family: " <+> ppr tc_name)
652 ; extra_tvs <- tcDataKindSig (Just ksig)
653 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
655 ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
656 ; gla_exts <- doptM Opt_IndexedTypes
658 -- Check that we don't use kind signatures without Glasgow extensions
659 ; checkTc gla_exts $ badSigTyDecl tc_name
661 ; tycon <- buildAlgTyCon tc_name final_tvs []
663 DataType -> OpenDataTyCon
664 NewType -> OpenNewTyCon)
665 Recursive False True Nothing
666 ; return [ATyCon tycon]
669 tcTyClDecl1 calc_isrec
670 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
671 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
672 = tcTyVarBndrs tvs $ \ tvs' -> do
673 { extra_tvs <- tcDataKindSig mb_ksig
674 ; let final_tvs = tvs' ++ extra_tvs
675 ; stupid_theta <- tcHsKindedContext ctxt
676 ; want_generic <- doptM Opt_Generics
677 ; unbox_strict <- doptM Opt_UnboxStrictFields
678 ; gla_exts <- doptM Opt_GlasgowExts
679 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
681 -- Check that we don't use GADT syntax in H98 world
682 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
684 -- Check that we don't use kind signatures without Glasgow extensions
685 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
687 -- Check that the stupid theta is empty for a GADT-style declaration
688 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
690 -- Check that there's at least one condecl,
691 -- or else we're reading an hs-boot file, or -fglasgow-exts
692 ; checkTc (not (null cons) || gla_exts || is_boot)
693 (emptyConDeclsErr tc_name)
695 -- Check that a newtype has exactly one constructor
696 ; checkTc (new_or_data == DataType || isSingleton cons)
697 (newtypeConError tc_name (length cons))
699 ; tycon <- fixM (\ tycon -> do
700 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
704 if null cons && is_boot -- In a hs-boot file, empty cons means
705 then return AbstractTyCon -- "don't know"; hence Abstract
706 else case new_or_data of
707 DataType -> return (mkDataTyConRhs data_cons)
709 ASSERT( isSingleton data_cons )
710 mkNewTyConRhs tc_name tycon (head data_cons)
711 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
712 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
714 ; return [ATyCon tycon]
717 is_rec = calc_isrec tc_name
718 h98_syntax = case cons of -- All constructors have same shape
719 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
722 tcTyClDecl1 calc_isrec
723 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
724 tcdCtxt = ctxt, tcdMeths = meths,
725 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
726 = tcTyVarBndrs tvs $ \ tvs' -> do
727 { ctxt' <- tcHsKindedContext ctxt
728 ; fds' <- mappM (addLocM tc_fundep) fundeps
729 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
730 ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
731 ; sig_stuff <- tcClassSigs class_name sigs meths
732 ; clas <- fixM (\ clas ->
733 let -- This little knot is just so we can get
734 -- hold of the name of the class TyCon, which we
735 -- need to look up its recursiveness
736 tycon_name = tyConName (classTyCon clas)
737 tc_isrec = calc_isrec tycon_name
739 buildClass class_name tvs' ctxt' fds' ats'
741 ; return (AClass clas : ats')
742 -- NB: Order is important due to the call to `mkGlobalThings' when
743 -- tying the the type and class declaration type checking knot.
746 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
747 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
748 ; return (tvs1', tvs2') }
750 -- For each AT argument compute the position of the corresponding class
751 -- parameter in the class head. This will later serve as a permutation
752 -- vector when checking the validity of instance declarations.
753 setTyThingPoss [ATyCon tycon] atTyVars =
754 let classTyVars = hsLTyVarNames tvs
756 . map (`elemIndex` classTyVars)
759 -- There will be no Nothing, as we already passed renaming
761 ATyCon (setTyConArgPoss tycon poss)
762 setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
764 tcTyClDecl1 calc_isrec
765 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
766 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
768 -----------------------------------
769 tcConDecl :: Bool -- True <=> -funbox-strict_fields
775 tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
776 (ConDecl name _ ex_tvs ex_ctxt details ResTyH98)
777 = do { let tc_datacon field_lbls arg_ty
778 = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
779 ; buildDataCon (unLoc name) False {- Prefix -}
781 (map unLoc field_lbls)
782 tc_tvs [] -- No existentials
783 [] [] -- No equalities, predicates
787 -- Check that a newtype has no existential stuff
788 ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
791 PrefixCon [arg_ty] -> tc_datacon [] arg_ty
792 RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty
794 failWithTc (newtypeFieldErr name (length (hsConArgs details)))
795 -- Check that the constructor has exactly one field
798 tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
799 (ConDecl name _ tvs ctxt details res_ty)
800 = tcTyVarBndrs tvs $ \ tvs' -> do
801 { ctxt' <- tcHsKindedContext ctxt
802 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
804 tc_datacon is_infix field_lbls btys
805 = do { let bangs = map getBangStrictness btys
806 ; arg_tys <- mappM tcHsBangType btys
807 ; buildDataCon (unLoc name) is_infix
808 (argStrictness unbox_strict tycon bangs arg_tys)
809 (map unLoc field_lbls)
810 univ_tvs ex_tvs eq_preds ctxt' arg_tys
812 -- NB: we put data_tc, the type constructor gotten from the
813 -- constructor type signature into the data constructor;
814 -- that way checkValidDataCon can complain if it's wrong.
817 PrefixCon btys -> tc_datacon False [] btys
818 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
819 RecCon fields -> tc_datacon False field_names btys
821 (field_names, btys) = unzip fields
825 tcResultType :: TyCon
826 -> [TyVar] -- data T a b c = ...
827 -> [TyVar] -- where MkT :: forall a b c. ...
829 -> TcM ([TyVar], -- Universal
830 [TyVar], -- Existential
831 [(TyVar,Type)], -- Equality predicates
832 TyCon) -- TyCon given in the ResTy
833 -- We don't check that the TyCon given in the ResTy is
834 -- the same as the parent tycon, becuase we are in the middle
835 -- of a recursive knot; so it's postponed until checkValidDataCon
837 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
838 = return (tc_tvs, dc_tvs, [], decl_tycon)
839 -- In H98 syntax the dc_tvs are the existential ones
840 -- data T a b c = forall d e. MkT ...
841 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
843 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
844 -- E.g. data T a b c where
845 -- MkT :: forall x y z. T (x,y) z z
847 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
849 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
850 -- NB: tc_tvs and dc_tvs are distinct
851 ; let univ_tvs = choose_univs [] tc_tvs res_tys
852 -- Each univ_tv is either a dc_tv or a tc_tv
853 ex_tvs = dc_tvs `minusList` univ_tvs
854 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
856 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
858 -- choose_univs uses the res_ty itself if it's a type variable
859 -- and hasn't already been used; otherwise it uses one of the tc_tvs
860 choose_univs used tc_tvs []
861 = ASSERT( null tc_tvs ) []
862 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
863 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
864 = tv : choose_univs (tv:used) tc_tvs res_tys
866 = tc_tv : choose_univs used tc_tvs res_tys
869 argStrictness :: Bool -- True <=> -funbox-strict_fields
871 -> [TcType] -> [StrictnessMark]
872 argStrictness unbox_strict tycon bangs arg_tys
873 = ASSERT( length bangs == length arg_tys )
874 zipWith (chooseBoxingStrategy unbox_strict tycon) arg_tys bangs
876 -- We attempt to unbox/unpack a strict field when either:
877 -- (i) The field is marked '!!', or
878 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
880 -- We have turned off unboxing of newtypes because coercions make unboxing
881 -- and reboxing more complicated
882 chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark
883 chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang
885 HsNoBang -> NotMarkedStrict
886 HsStrict | unbox_strict_fields
887 && can_unbox arg_ty -> MarkedUnboxed
888 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
889 other -> MarkedStrict
891 -- we can unbox if the type is a chain of newtypes with a product tycon
893 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
895 Just (arg_tycon, tycon_args) ->
896 not (isRecursiveTyCon tycon) &&
897 isProductTyCon arg_tycon &&
898 (if isNewTyCon arg_tycon then
899 can_unbox (newTyConInstRhs arg_tycon tycon_args)
903 %************************************************************************
905 \subsection{Dependency analysis}
907 %************************************************************************
909 Validity checking is done once the mutually-recursive knot has been
910 tied, so we can look at things freely.
913 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
914 checkCycleErrs tyclss
918 = do { mappM_ recClsErr cls_cycles
919 ; failM } -- Give up now, because later checkValidTyCl
920 -- will loop if the synonym is recursive
922 cls_cycles = calcClassCycles tyclss
924 checkValidTyCl :: TyClDecl Name -> TcM ()
925 -- We do the validity check over declarations, rather than TyThings
926 -- only so that we can add a nice context with tcAddDeclCtxt
928 = tcAddDeclCtxt decl $
929 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
930 ; traceTc (text "Validity of" <+> ppr thing)
932 ATyCon tc -> checkValidTyCon tc
933 AClass cl -> checkValidClass cl
934 ; traceTc (text "Done validity of" <+> ppr thing)
937 -------------------------
938 -- For data types declared with record syntax, we require
939 -- that each constructor that has a field 'f'
940 -- (a) has the same result type
941 -- (b) has the same type for 'f'
942 -- module alpha conversion of the quantified type variables
943 -- of the constructor.
945 checkValidTyCon :: TyCon -> TcM ()
948 = case synTyConRhs tc of
949 OpenSynTyCon _ -> return ()
950 SynonymTyCon ty -> checkValidType syn_ctxt ty
952 = -- Check the context on the data decl
953 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
955 -- Check arg types of data constructors
956 mappM_ (checkValidDataCon tc) data_cons `thenM_`
958 -- Check that fields with the same name share a type
959 mappM_ check_fields groups
962 syn_ctxt = TySynCtxt name
964 data_cons = tyConDataCons tc
966 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
967 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
968 get_fields con = dataConFieldLabels con `zip` repeat con
969 -- dataConFieldLabels may return the empty list, which is fine
971 -- See Note [GADT record selectors] in MkId.lhs
972 -- We must check (a) that the named field has the same
973 -- type in each constructor
974 -- (b) that those constructors have the same result type
976 -- However, the constructors may have differently named type variable
977 -- and (worse) we don't know how the correspond to each other. E.g.
978 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
979 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
981 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
982 -- result type against other candidates' types BOTH WAYS ROUND.
983 -- If they magically agrees, take the substitution and
984 -- apply them to the latter ones, and see if they match perfectly.
985 check_fields fields@((label, con1) : other_fields)
986 -- These fields all have the same name, but are from
987 -- different constructors in the data type
988 = recoverM (return ()) $ mapM_ checkOne other_fields
989 -- Check that all the fields in the group have the same type
990 -- NB: this check assumes that all the constructors of a given
991 -- data type use the same type variables
993 tvs1 = mkVarSet (dataConAllTyVars con1)
994 res1 = dataConResTys con1
995 fty1 = dataConFieldType con1 label
997 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
998 = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
999 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
1001 tvs2 = mkVarSet (dataConAllTyVars con2)
1002 res2 = dataConResTys con2
1003 fty2 = dataConFieldType con2 label
1005 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
1006 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
1007 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
1009 mb_subst1 = tcMatchTys tvs1 res1 res2
1010 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
1012 -------------------------------
1013 checkValidDataCon :: TyCon -> DataCon -> TcM ()
1014 checkValidDataCon tc con
1015 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
1016 addErrCtxt (dataConCtxt con) $
1017 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
1018 ; checkValidType ctxt (dataConUserType con) }
1020 ctxt = ConArgCtxt (dataConName con)
1022 -------------------------------
1023 checkValidClass :: Class -> TcM ()
1025 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
1026 gla_exts <- doptM Opt_GlasgowExts
1028 -- Check that the class is unary, unless GlaExs
1029 ; checkTc (notNull tyvars) (nullaryClassErr cls)
1030 ; checkTc (gla_exts || unary) (classArityErr cls)
1032 -- Check the super-classes
1033 ; checkValidTheta (ClassSCCtxt (className cls)) theta
1035 -- Check the class operations
1036 ; mappM_ (check_op gla_exts) op_stuff
1038 -- Check that if the class has generic methods, then the
1039 -- class has only one parameter. We can't do generic
1040 -- multi-parameter type classes!
1041 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
1044 (tyvars, theta, _, op_stuff) = classBigSig cls
1045 unary = isSingleton tyvars
1046 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
1048 check_op gla_exts (sel_id, dm)
1049 = addErrCtxt (classOpCtxt sel_id tau) $ do
1050 { checkValidTheta SigmaCtxt (tail theta)
1051 -- The 'tail' removes the initial (C a) from the
1052 -- class itself, leaving just the method type
1054 ; checkValidType (FunSigCtxt op_name) tau
1056 -- Check that the type mentions at least one of
1057 -- the class type variables
1058 ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
1059 (noClassTyVarErr cls sel_id)
1061 -- Check that for a generic method, the type of
1062 -- the method is sufficiently simple
1063 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1064 (badGenericMethodType op_name op_ty)
1067 op_name = idName sel_id
1068 op_ty = idType sel_id
1069 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1070 (_,theta2,tau2) = tcSplitSigmaTy tau1
1071 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1072 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1073 -- Ugh! The function might have a type like
1074 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1075 -- With -fglasgow-exts, we want to allow this, even though the inner
1076 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1077 -- in the context of a for-all must mention at least one quantified
1078 -- type variable. What a mess!
1081 ---------------------------------------------------------------------
1082 resultTypeMisMatch field_name con1 con2
1083 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1084 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1085 nest 2 $ ptext SLIT("but have different result types")]
1086 fieldTypeMisMatch field_name con1 con2
1087 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1088 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1090 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1092 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1093 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1096 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1099 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1100 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1102 noClassTyVarErr clas op
1103 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1104 ptext SLIT("mentions none of the type variables of the class") <+>
1105 ppr clas <+> hsep (map ppr (classTyVars clas))]
1107 genericMultiParamErr clas
1108 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1109 ptext SLIT("cannot have generic methods")
1111 badGenericMethodType op op_ty
1112 = hang (ptext SLIT("Generic method type is too complex"))
1113 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1114 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1117 = setSrcSpan (getLoc (head sorted_decls)) $
1118 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1119 nest 2 (vcat (map ppr_decl sorted_decls))])
1121 sorted_decls = sortLocated syn_decls
1122 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1125 = setSrcSpan (getLoc (head sorted_decls)) $
1126 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1127 nest 2 (vcat (map ppr_decl sorted_decls))])
1129 sorted_decls = sortLocated cls_decls
1130 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1132 sortLocated :: [Located a] -> [Located a]
1133 sortLocated things = sortLe le things
1135 le (L l1 _) (L l2 _) = l1 <= l2
1137 badDataConTyCon data_con
1138 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1139 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1140 2 (ptext SLIT("instead of its parent type"))
1143 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1144 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
1146 badStupidTheta tc_name
1147 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1149 newtypeConError tycon n
1150 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1151 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1154 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1155 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1157 newtypeFieldErr con_name n_flds
1158 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1159 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1161 badSigTyDecl tc_name
1162 = vcat [ ptext SLIT("Illegal kind signature") <+>
1163 quotes (ppr tc_name)
1164 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1166 badKindSigCtxt tc_name
1167 = vcat [ ptext SLIT("Illegal context in kind signature") <+>
1168 quotes (ppr tc_name)
1169 , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ]
1171 badIdxTyDecl tc_name
1172 = vcat [ ptext SLIT("Illegal indexed type instance for") <+>
1173 quotes (ppr tc_name)
1174 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1176 badGadtIdxTyDecl tc_name
1177 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1178 quotes (ppr tc_name)
1179 , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ]
1181 tooManyParmsErr tc_name
1182 = ptext SLIT("Indexed type instance has too many parameters:") <+>
1183 quotes (ppr tc_name)
1185 tooFewParmsErr tc_name
1186 = ptext SLIT("Indexed type instance has too few parameters:") <+>
1187 quotes (ppr tc_name)
1189 badBootTyIdxDeclErr =
1190 ptext SLIT("Illegal indexed type instance in hs-boot file")
1192 wrongKindOfFamily family =
1193 ptext SLIT("Wrong category of type instance; declaration was for a") <+>
1196 kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
1197 | isDataTyCon family = ptext SLIT("data type")
1198 | isNewTyCon family = ptext SLIT("newtype")
1200 emptyConDeclsErr tycon
1201 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1202 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]