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, 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, isDataTyCon, tyConKind,
56 import DataCon ( DataCon, dataConUserType, dataConName,
57 dataConFieldLabels, dataConTyCon, dataConAllTyVars,
58 dataConFieldType, dataConResTys )
59 import Var ( TyVar, idType, idName )
60 import VarSet ( elemVarSet, mkVarSet )
61 import Name ( Name, getSrcLoc )
63 import Maybe ( isJust, fromJust, isNothing, catMaybes )
64 import Maybes ( expectJust )
65 import Monad ( unless )
66 import Unify ( tcMatchTys, tcMatchTyX )
67 import Util ( zipLazy, isSingleton, notNull, sortLe )
68 import List ( partition, elemIndex )
69 import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan )
70 import ListSetOps ( equivClasses, minusList )
71 import Digraph ( SCC(..) )
72 import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
73 Opt_UnboxStrictFields ) )
77 %************************************************************************
79 \subsection{Type checking for type and class declarations}
81 %************************************************************************
85 Consider a mutually-recursive group, binding
86 a type constructor T and a class C.
88 Step 1: getInitialKind
89 Construct a KindEnv by binding T and C to a kind variable
92 In that environment, do a kind check
94 Step 3: Zonk the kinds
96 Step 4: buildTyConOrClass
97 Construct an environment binding T to a TyCon and C to a Class.
98 a) Their kinds comes from zonking the relevant kind variable
99 b) Their arity (for synonyms) comes direct from the decl
100 c) The funcional dependencies come from the decl
101 d) The rest comes a knot-tied binding of T and C, returned from Step 4
102 e) The variances of the tycons in the group is calculated from
106 In this environment, walk over the decls, constructing the TyCons and Classes.
107 This uses in a strict way items (a)-(c) above, which is why they must
108 be constructed in Step 4. Feed the results back to Step 4.
109 For this step, pass the is-recursive flag as the wimp-out flag
113 Step 6: Extend environment
114 We extend the type environment with bindings not only for the TyCons and Classes,
115 but also for their "implicit Ids" like data constructors and class selectors
117 Step 7: checkValidTyCl
118 For a recursive group only, check all the decls again, just
119 to check all the side conditions on validity. We could not
120 do this before because we were in a mutually recursive knot.
122 Identification of recursive TyCons
123 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
124 The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
127 Identifying a TyCon as recursive serves two purposes
129 1. Avoid infinite types. Non-recursive newtypes are treated as
130 "transparent", like type synonyms, after the type checker. If we did
131 this for all newtypes, we'd get infinite types. So we figure out for
132 each newtype whether it is "recursive", and add a coercion if so. In
133 effect, we are trying to "cut the loops" by identifying a loop-breaker.
135 2. Avoid infinite unboxing. This is nothing to do with newtypes.
139 Well, this function diverges, but we don't want the strictness analyser
140 to diverge. But the strictness analyser will diverge because it looks
141 deeper and deeper into the structure of T. (I believe there are
142 examples where the function does something sane, and the strictness
143 analyser still diverges, but I can't see one now.)
145 Now, concerning (1), the FC2 branch currently adds a coercion for ALL
146 newtypes. I did this as an experiment, to try to expose cases in which
147 the coercions got in the way of optimisations. If it turns out that we
148 can indeed always use a coercion, then we don't risk recursive types,
149 and don't need to figure out what the loop breakers are.
151 For newtype *families* though, we will always have a coercion, so they
152 are always loop breakers! So you can easily adjust the current
153 algorithm by simply treating all newtype families as loop breakers (and
154 indeed type families). I think.
157 tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
158 -> TcM TcGblEnv -- Input env extended by types and classes
159 -- and their implicit Ids,DataCons
160 tcTyAndClassDecls boot_details allDecls
161 = do { -- Omit instances of indexed types; they are handled together
162 -- with the *heads* of class instances
163 ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
165 -- First check for cyclic type synonysm or classes
166 -- See notes with checkCycleErrs
167 ; checkCycleErrs decls
169 ; traceTc (text "tcTyAndCl" <+> ppr mod)
170 ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
171 do { let { -- Seperate ordinary synonyms from all other type and
172 -- class declarations and add all associated type
173 -- declarations from type classes. The latter is
174 -- required so that the temporary environment for the
175 -- knot includes all associated family declarations.
176 ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
178 ; alg_at_decls = concatMap addATs alg_decls
180 -- Extend the global env with the knot-tied results
181 -- for data types and classes
183 -- We must populate the environment with the loop-tied
184 -- T's right away, because the kind checker may "fault
185 -- in" some type constructors that recursively
187 ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss
188 ; tcExtendRecEnv gbl_things $ do
190 -- Kind-check the declarations
191 { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
193 ; let { -- Calculate rec-flag
194 ; calc_rec = calcRecFlags boot_details rec_alg_tyclss
195 ; tc_decl = addLocM (tcTyClDecl calc_rec) }
196 -- Type-check the type synonyms, and extend the envt
197 ; syn_tycons <- tcSynDecls kc_syn_decls
198 ; tcExtendGlobalEnv syn_tycons $ do
200 -- Type-check the data types and classes
201 { alg_tyclss <- mappM tc_decl kc_alg_decls
202 ; return (syn_tycons, concat alg_tyclss)
204 -- Finished with knot-tying now
205 -- Extend the environment with the finished things
206 ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
208 -- Perform the validity check
209 { traceTc (text "ready for validity check")
210 ; mappM_ (addLocM checkValidTyCl) decls
211 ; traceTc (text "done")
213 -- Add the implicit things;
214 -- we want them in the environment because
215 -- they may be mentioned in interface files
216 -- NB: All associated types and their implicit things will be added a
217 -- second time here. This doesn't matter as the definitions are
219 ; let { implicit_things = concatMap implicitTyThings alg_tyclss }
220 ; traceTc ((text "Adding" <+> ppr alg_tyclss)
221 $$ (text "and" <+> ppr implicit_things))
222 ; tcExtendGlobalEnv implicit_things getGblEnv
225 -- Pull associated types out of class declarations, to tie them into the
227 -- NB: We put them in the same place in the list as `tcTyClDecl' will
228 -- eventually put the matching `TyThing's. That's crucial; otherwise,
229 -- the two argument lists of `mkGlobalThings' don't match up.
230 addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats
233 mkGlobalThings :: [LTyClDecl Name] -- The decls
234 -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
236 -- Driven by the Decls, and treating the TyThings lazily
237 -- make a TypeEnv for the new things
238 mkGlobalThings decls things
239 = map mk_thing (decls `zipLazy` things)
241 mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
243 mk_thing (L _ decl, ~(ATyCon tc))
244 = (tcdName decl, ATyCon tc)
248 %************************************************************************
250 \subsection{Type checking instances of indexed types}
252 %************************************************************************
254 Instances of indexed types are somewhat of a hybrid. They are processed
255 together with class instance heads, but can contain data constructors and hence
256 they share a lot of kinding and type checking code with ordinary algebraic
257 data types (and GADTs).
260 tcIdxTyInstDecl :: LTyClDecl Name
261 -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
262 tcIdxTyInstDecl (L loc decl)
263 = -- Prime error recovery, set source location
264 recoverM (returnM (Nothing, Nothing)) $
267 do { -- indexed data types require -fglasgow-exts and can't be in an
269 ; gla_exts <- doptM Opt_GlasgowExts
270 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
271 ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
272 ; checkTc (not is_boot) $ badBootTyIdxDeclErr
274 -- perform kind and type checking
275 ; tcIdxTyInstDecl1 decl
278 tcIdxTyInstDecl1 :: TyClDecl Name
279 -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
281 tcIdxTyInstDecl1 (decl@TySynonym {})
282 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
283 do { -- check that the family declaration is for a synonym
284 unless (isSynTyCon family) $
285 addErr (wrongKindOfFamily family)
287 ; -- (1) kind check the right hand side of the type equation
288 ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
290 -- (2) type check type equation
291 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
292 ; t_typats <- mappM tcHsKindedType k_typats
293 ; t_rhs <- tcHsKindedType k_rhs
295 -- construct type rewrite rule
296 -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
297 ; return (Nothing, Nothing) -- !!!TODO: need InstInfo for eq axioms
300 tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
302 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
303 do { -- check that the family declaration is for the right kind
304 unless (new_or_data == NewType && isNewTyCon family ||
305 new_or_data == DataType && isDataTyCon family) $
306 addErr (wrongKindOfFamily family)
308 ; -- (1) kind check the data declaration as usual
309 ; k_decl <- kcDataDecl decl k_tvs
310 ; let k_ctxt = tcdCtxt k_decl
311 k_cons = tcdCons k_decl
313 -- result kind must be '*' (otherwise, we have too few patterns)
314 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
316 -- (2) type check indexed data type declaration
317 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
318 ; unbox_strict <- doptM Opt_UnboxStrictFields
320 -- Check that we don't use GADT syntax for indexed types
321 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
323 -- Check that a newtype has exactly one constructor
324 ; checkTc (new_or_data == DataType || isSingleton k_cons) $
325 newtypeConError tc_name (length k_cons)
327 ; t_typats <- mappM tcHsKindedType k_typats
328 ; stupid_theta <- tcHsKindedContext k_ctxt
330 ; index <- nextDFunIndex -- to generate unique names
331 ; tycon <- fixM (\ tycon -> do
332 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
337 DataType -> return (mkDataTyConRhs data_cons)
339 ASSERT( isSingleton data_cons )
340 mkNewTyConRhs tc_name tycon (head data_cons)
341 ; buildAlgTyCon tc_name t_tvs stupid_theta tc_rhs Recursive
342 False h98_syntax (Just (family, t_typats, index))
343 -- We always assume that indexed types are recursive. Why?
344 -- (1) Due to their open nature, we can never be sure that a
345 -- further instance might not introduce a new recursive
346 -- dependency. (2) They are always valid loop breakers as
347 -- they involve a coercion.
351 ; return (Nothing, Just (ATyCon tycon))
354 h98_syntax = case cons of -- All constructors have same shape
355 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
358 -- Kind checking of indexed types
361 -- Kind check type patterns and kind annotate the embedded type variables.
363 -- * Here we check that a type instance matches its kind signature, but we do
364 -- not check whether there is a pattern for each type index; the latter
365 -- check is only required for type functions.
367 kcIdxTyPats :: TyClDecl Name
368 -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
369 -- ^^kinded tvs ^^kinded ty pats ^^res kind
371 kcIdxTyPats decl thing_inside
372 = kcHsTyVars (tcdTyVars decl) $ \tvs ->
373 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
374 ; let { family = case tc_ty_thing of
375 AGlobal (ATyCon family) -> family
376 ; (kinds, resKind) = splitKindFunTys (tyConKind family)
377 ; hs_typats = fromJust $ tcdTyPats decl }
379 -- we may not have more parameters than the kind indicates
380 ; checkTc (length kinds >= length hs_typats) $
381 tooManyParmsErr (tcdLName decl)
383 -- type functions can have a higher-kinded result
384 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
385 ; typats <- zipWithM kcCheckHsType hs_typats kinds
386 ; thing_inside tvs typats resultKind family
392 %************************************************************************
396 %************************************************************************
398 We need to kind check all types in the mutually recursive group
399 before we know the kind of the type variables. For example:
402 op :: D b => a -> b -> b
405 bop :: (Monad c) => ...
407 Here, the kind of the locally-polymorphic type variable "b"
408 depends on *all the uses of class D*. For example, the use of
409 Monad c in bop's type signature means that D must have kind Type->Type.
411 However type synonyms work differently. They can have kinds which don't
412 just involve (->) and *:
413 type R = Int# -- Kind #
414 type S a = Array# a -- Kind * -> #
415 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
416 So we must infer their kinds from their right-hand sides *first* and then
417 use them, whereas for the mutually recursive data types D we bring into
418 scope kind bindings D -> k, where k is a kind variable, and do inference.
422 This treatment of type synonyms only applies to Haskell 98-style synonyms.
423 General type functions can be recursive, and hence, appear in `alg_decls'.
425 The kind of an indexed type is solely determinded by its kind signature;
426 hence, only kind signatures participate in the construction of the initial
427 kind environment (as constructed by `getInitialKind'). In fact, we ignore
428 instances of indexed types altogether in the following. However, we need to
429 include the kind signatures of associated types into the construction of the
430 initial kind environment. (This is handled by `allDecls').
433 kcTyClDecls syn_decls alg_decls
434 = do { -- First extend the kind env with each data type, class, and
435 -- indexed type, mapping them to a type variable
436 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
437 ; alg_kinds <- mappM getInitialKind initialKindDecls
438 ; tcExtendKindEnv alg_kinds $ do
440 -- Now kind-check the type synonyms, in dependency order
441 -- We do these differently to data type and classes,
442 -- because a type synonym can be an unboxed type
444 -- and a kind variable can't unify with UnboxedTypeKind
445 -- So we infer their kinds in dependency order
446 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
447 ; tcExtendKindEnv syn_kinds $ do
449 -- Now kind-check the data type, class, and kind signatures,
450 -- returning kind-annotated decls; we don't kind-check
451 -- instances of indexed types yet, but leave this to
453 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
454 (filter (not . isIdxTyDecl . unLoc) alg_decls)
456 ; return (kc_syn_decls, kc_alg_decls) }}}
458 -- get all declarations relevant for determining the initial kind
460 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
463 allDecls decl | isIdxTyDecl decl = []
466 ------------------------------------------------------------------------
467 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
468 -- Only for data type, class, and indexed type declarations
469 -- Get as much info as possible from the data, class, or indexed type decl,
470 -- so as to maximise usefulness of error messages
472 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
473 ; res_kind <- mk_res_kind decl
474 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
476 mk_arg_kind (UserTyVar _) = newKindVar
477 mk_arg_kind (KindedTyVar _ kind) = return kind
479 mk_res_kind (TyFunction { tcdKind = kind }) = return kind
480 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
481 -- On GADT-style and data signature declarations we allow a kind
483 -- data T :: *->* where { ... }
484 mk_res_kind other = return liftedTypeKind
488 kcSynDecls :: [SCC (LTyClDecl Name)]
489 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
490 [(Name,TcKind)]) -- Kind bindings
493 kcSynDecls (group : groups)
494 = do { (decl, nk) <- kcSynDecl group
495 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
496 ; return (decl:decls, nk:nks) }
499 kcSynDecl :: SCC (LTyClDecl Name)
500 -> TcM (LTyClDecl Name, -- Kind-annotated decls
501 (Name,TcKind)) -- Kind bindings
502 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
503 = tcAddDeclCtxt decl $
504 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
505 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
506 <+> brackets (ppr k_tvs))
507 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
508 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
509 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
510 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
511 (unLoc (tcdLName decl), tc_kind)) })
513 kcSynDecl (CyclicSCC decls)
514 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
515 -- of out-of-scope tycons
517 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
519 ------------------------------------------------------------------------
520 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
521 -- Not used for type synonyms (see kcSynDecl)
523 kcTyClDecl decl@(TyData {})
524 = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
525 kcTyClDeclBody decl $
528 kcTyClDecl decl@(TyFunction {})
529 = kcTyClDeclBody decl $ \ tvs' ->
530 return (decl {tcdTyVars = tvs'})
532 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
533 = kcTyClDeclBody decl $ \ tvs' ->
534 do { is_boot <- tcIsHsBoot
535 ; ctxt' <- kcHsContext ctxt
536 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
537 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
538 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
541 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
542 ; return (TypeSig nm op_ty') }
543 kc_sig other_sig = return other_sig
545 kcTyClDecl decl@(ForeignType {})
548 kcTyClDeclBody :: TyClDecl Name
549 -> ([LHsTyVarBndr Name] -> TcM a)
551 -- getInitialKind has made a suitably-shaped kind for the type or class
552 -- Unpack it, and attribute those kinds to the type variables
553 -- Extend the env with bindings for the tyvars, taken from
554 -- the kind of the tycon/class. Give it to the thing inside, and
555 -- check the result kind matches
556 kcTyClDeclBody decl thing_inside
557 = tcAddDeclCtxt decl $
558 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
559 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
560 (kinds, _) = splitKindFunTys tc_kind
561 hs_tvs = tcdTyVars decl
562 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
563 [ L loc (KindedTyVar (hsTyVarName tv) k)
564 | (L loc tv, k) <- zip hs_tvs kinds]
565 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
567 -- Kind check a data declaration, assuming that we already extended the
568 -- kind environment with the type variables of the left-hand side (these
569 -- kinded type variables are also passed as the second parameter).
571 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
572 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
574 = do { ctxt' <- kcHsContext ctxt
575 ; cons' <- mappM (wrapLocM kc_con_decl) cons
576 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
578 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do
579 kcHsTyVars ex_tvs $ \ex_tvs' -> do
580 ex_ctxt' <- kcHsContext ex_ctxt
581 details' <- kc_con_details details
583 ResTyH98 -> return ResTyH98
584 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
585 return (ConDecl name expl ex_tvs' ex_ctxt' details' res')
587 kc_con_details (PrefixCon btys)
588 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
589 kc_con_details (InfixCon bty1 bty2)
590 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
591 kc_con_details (RecCon fields)
592 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
594 kc_field (fld, bty) = do { bty' <- kc_larg_ty bty ; return (fld, bty') }
596 kc_larg_ty bty = case new_or_data of
597 DataType -> kcHsSigType bty
598 NewType -> kcHsLiftedSigType bty
599 -- Can't allow an unlifted type for newtypes, because we're effectively
600 -- going to remove the constructor while coercing it to a lifted type.
601 -- And newtypes can't be bang'd
605 %************************************************************************
607 \subsection{Type checking}
609 %************************************************************************
612 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
613 tcSynDecls [] = return []
614 tcSynDecls (decl : decls)
615 = do { syn_tc <- addLocM tcSynDecl decl
616 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
617 ; return (syn_tc : syn_tcs) }
620 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
621 = tcTyVarBndrs tvs $ \ tvs' -> do
622 { traceTc (text "tcd1" <+> ppr tc_name)
623 ; rhs_ty' <- tcHsKindedType rhs_ty
624 ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
627 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
629 tcTyClDecl calc_isrec decl
630 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
632 -- kind signature for a type function
633 tcTyClDecl1 _calc_isrec
634 (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
635 = tcTyVarBndrs tvs $ \ tvs' -> do
636 { traceTc (text "type family: " <+> ppr tc_name)
637 ; gla_exts <- doptM Opt_GlasgowExts
639 -- Check that we don't use kind signatures without Glasgow extensions
640 ; checkTc gla_exts $ badSigTyDecl tc_name
642 ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)]
645 -- kind signature for an indexed data type
646 tcTyClDecl1 _calc_isrec
647 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
648 tcdLName = L _ tc_name, tcdKindSig = Just ksig, tcdCons = []})
649 = tcTyVarBndrs tvs $ \ tvs' -> do
650 { traceTc (text "data/newtype family: " <+> ppr tc_name)
651 ; extra_tvs <- tcDataKindSig (Just ksig)
652 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
654 ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
655 ; gla_exts <- doptM Opt_GlasgowExts
657 -- Check that we don't use kind signatures without Glasgow extensions
658 ; checkTc gla_exts $ badSigTyDecl tc_name
660 ; tycon <- buildAlgTyCon tc_name final_tvs []
662 DataType -> OpenDataTyCon
663 NewType -> OpenNewTyCon)
664 Recursive False True Nothing
665 ; return [ATyCon tycon]
668 tcTyClDecl1 calc_isrec
669 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
670 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
671 = tcTyVarBndrs tvs $ \ tvs' -> do
672 { extra_tvs <- tcDataKindSig mb_ksig
673 ; let final_tvs = tvs' ++ extra_tvs
674 ; stupid_theta <- tcHsKindedContext ctxt
675 ; want_generic <- doptM Opt_Generics
676 ; unbox_strict <- doptM Opt_UnboxStrictFields
677 ; gla_exts <- doptM Opt_GlasgowExts
678 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
680 -- Check that we don't use GADT syntax in H98 world
681 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
683 -- Check that we don't use kind signatures without Glasgow extensions
684 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
686 -- Check that the stupid theta is empty for a GADT-style declaration
687 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
689 -- Check that there's at least one condecl,
690 -- or else we're reading an hs-boot file, or -fglasgow-exts
691 ; checkTc (not (null cons) || gla_exts || is_boot)
692 (emptyConDeclsErr tc_name)
694 -- Check that a newtype has exactly one constructor
695 ; checkTc (new_or_data == DataType || isSingleton cons)
696 (newtypeConError tc_name (length cons))
698 ; tycon <- fixM (\ tycon -> do
699 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
703 if null cons && is_boot -- In a hs-boot file, empty cons means
704 then return AbstractTyCon -- "don't know"; hence Abstract
705 else case new_or_data of
706 DataType -> return (mkDataTyConRhs data_cons)
708 ASSERT( isSingleton data_cons )
709 mkNewTyConRhs tc_name tycon (head data_cons)
710 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
711 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
713 ; return [ATyCon tycon]
716 is_rec = calc_isrec tc_name
717 h98_syntax = case cons of -- All constructors have same shape
718 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
721 tcTyClDecl1 calc_isrec
722 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
723 tcdCtxt = ctxt, tcdMeths = meths,
724 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
725 = tcTyVarBndrs tvs $ \ tvs' -> do
726 { ctxt' <- tcHsKindedContext ctxt
727 ; fds' <- mappM (addLocM tc_fundep) fundeps
728 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
729 ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
730 ; sig_stuff <- tcClassSigs class_name sigs meths
731 ; clas <- fixM (\ clas ->
732 let -- This little knot is just so we can get
733 -- hold of the name of the class TyCon, which we
734 -- need to look up its recursiveness
735 tycon_name = tyConName (classTyCon clas)
736 tc_isrec = calc_isrec tycon_name
738 buildClass class_name tvs' ctxt' fds' ats'
740 ; return (AClass clas : ats')
741 -- NB: Order is important due to the call to `mkGlobalThings' when
742 -- tying the the type and class declaration type checking knot.
745 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
746 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
747 ; return (tvs1', tvs2') }
749 -- For each AT argument compute the position of the corresponding class
750 -- parameter in the class head. This will later serve as a permutation
751 -- vector when checking the validity of instance declarations.
752 setTyThingPoss [ATyCon tycon] atTyVars =
753 let classTyVars = hsLTyVarNames tvs
755 . map (`elemIndex` classTyVars)
758 -- There will be no Nothing, as we already passed renaming
760 ATyCon (setTyConArgPoss tycon poss)
761 setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
763 tcTyClDecl1 calc_isrec
764 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
765 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
767 -----------------------------------
768 tcConDecl :: Bool -- True <=> -funbox-strict_fields
774 tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
775 (ConDecl name _ ex_tvs ex_ctxt details ResTyH98)
776 = do { let tc_datacon field_lbls arg_ty
777 = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
778 ; buildDataCon (unLoc name) False {- Prefix -}
780 (map unLoc field_lbls)
781 tc_tvs [] -- No existentials
782 [] [] -- No equalities, predicates
786 -- Check that a newtype has no existential stuff
787 ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
790 PrefixCon [arg_ty] -> tc_datacon [] arg_ty
791 RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty
793 failWithTc (newtypeFieldErr name (length (hsConArgs details)))
794 -- Check that the constructor has exactly one field
797 tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
798 (ConDecl name _ tvs ctxt details res_ty)
799 = tcTyVarBndrs tvs $ \ tvs' -> do
800 { ctxt' <- tcHsKindedContext ctxt
801 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
803 tc_datacon is_infix field_lbls btys
804 = do { let bangs = map getBangStrictness btys
805 ; arg_tys <- mappM tcHsBangType btys
806 ; buildDataCon (unLoc name) is_infix
807 (argStrictness unbox_strict tycon bangs arg_tys)
808 (map unLoc field_lbls)
809 univ_tvs ex_tvs eq_preds ctxt' arg_tys
811 -- NB: we put data_tc, the type constructor gotten from the
812 -- constructor type signature into the data constructor;
813 -- that way checkValidDataCon can complain if it's wrong.
816 PrefixCon btys -> tc_datacon False [] btys
817 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
818 RecCon fields -> tc_datacon False field_names btys
820 (field_names, btys) = unzip fields
824 tcResultType :: TyCon
825 -> [TyVar] -- data T a b c = ...
826 -> [TyVar] -- where MkT :: forall a b c. ...
828 -> TcM ([TyVar], -- Universal
829 [TyVar], -- Existential
830 [(TyVar,Type)], -- Equality predicates
831 TyCon) -- TyCon given in the ResTy
832 -- We don't check that the TyCon given in the ResTy is
833 -- the same as the parent tycon, becuase we are in the middle
834 -- of a recursive knot; so it's postponed until checkValidDataCon
836 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
837 = return (tc_tvs, dc_tvs, [], decl_tycon)
838 -- In H98 syntax the dc_tvs are the existential ones
839 -- data T a b c = forall d e. MkT ...
840 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
842 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
843 -- E.g. data T a b c where
844 -- MkT :: forall x y z. T (x,y) z z
846 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
848 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
849 -- NB: tc_tvs and dc_tvs are distinct
850 ; let univ_tvs = choose_univs [] tc_tvs res_tys
851 -- Each univ_tv is either a dc_tv or a tc_tv
852 ex_tvs = dc_tvs `minusList` univ_tvs
853 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
855 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
857 -- choose_univs uses the res_ty itself if it's a type variable
858 -- and hasn't already been used; otherwise it uses one of the tc_tvs
859 choose_univs used tc_tvs []
860 = ASSERT( null tc_tvs ) []
861 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
862 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
863 = tv : choose_univs (tv:used) tc_tvs res_tys
865 = tc_tv : choose_univs used tc_tvs res_tys
868 argStrictness :: Bool -- True <=> -funbox-strict_fields
870 -> [TcType] -> [StrictnessMark]
871 argStrictness unbox_strict tycon bangs arg_tys
872 = ASSERT( length bangs == length arg_tys )
873 zipWith (chooseBoxingStrategy unbox_strict tycon) arg_tys bangs
875 -- We attempt to unbox/unpack a strict field when either:
876 -- (i) The field is marked '!!', or
877 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
879 -- We have turned off unboxing of newtypes because coercions make unboxing
880 -- and reboxing more complicated
881 chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark
882 chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang
884 HsNoBang -> NotMarkedStrict
885 HsStrict | unbox_strict_fields
886 && can_unbox arg_ty -> MarkedUnboxed
887 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
888 other -> MarkedStrict
890 -- we can unbox if the type is a chain of newtypes with a product tycon
892 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
894 Just (arg_tycon, tycon_args) ->
895 not (isRecursiveTyCon tycon) &&
896 isProductTyCon arg_tycon &&
897 (if isNewTyCon arg_tycon then
898 can_unbox (newTyConInstRhs arg_tycon tycon_args)
902 %************************************************************************
904 \subsection{Dependency analysis}
906 %************************************************************************
908 Validity checking is done once the mutually-recursive knot has been
909 tied, so we can look at things freely.
912 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
913 checkCycleErrs tyclss
917 = do { mappM_ recClsErr cls_cycles
918 ; failM } -- Give up now, because later checkValidTyCl
919 -- will loop if the synonym is recursive
921 cls_cycles = calcClassCycles tyclss
923 checkValidTyCl :: TyClDecl Name -> TcM ()
924 -- We do the validity check over declarations, rather than TyThings
925 -- only so that we can add a nice context with tcAddDeclCtxt
927 = tcAddDeclCtxt decl $
928 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
929 ; traceTc (text "Validity of" <+> ppr thing)
931 ATyCon tc -> checkValidTyCon tc
932 AClass cl -> checkValidClass cl
933 ; traceTc (text "Done validity of" <+> ppr thing)
936 -------------------------
937 -- For data types declared with record syntax, we require
938 -- that each constructor that has a field 'f'
939 -- (a) has the same result type
940 -- (b) has the same type for 'f'
941 -- module alpha conversion of the quantified type variables
942 -- of the constructor.
944 checkValidTyCon :: TyCon -> TcM ()
947 = case synTyConRhs tc of
948 OpenSynTyCon _ -> return ()
949 SynonymTyCon ty -> checkValidType syn_ctxt ty
951 = -- Check the context on the data decl
952 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
954 -- Check arg types of data constructors
955 mappM_ (checkValidDataCon tc) data_cons `thenM_`
957 -- Check that fields with the same name share a type
958 mappM_ check_fields groups
961 syn_ctxt = TySynCtxt name
963 data_cons = tyConDataCons tc
965 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
966 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
967 get_fields con = dataConFieldLabels con `zip` repeat con
968 -- dataConFieldLabels may return the empty list, which is fine
970 -- See Note [GADT record selectors] in MkId.lhs
971 -- We must check (a) that the named field has the same
972 -- type in each constructor
973 -- (b) that those constructors have the same result type
975 -- However, the constructors may have differently named type variable
976 -- and (worse) we don't know how the correspond to each other. E.g.
977 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
978 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
980 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
981 -- result type against other candidates' types BOTH WAYS ROUND.
982 -- If they magically agrees, take the substitution and
983 -- apply them to the latter ones, and see if they match perfectly.
984 check_fields fields@((label, con1) : other_fields)
985 -- These fields all have the same name, but are from
986 -- different constructors in the data type
987 = recoverM (return ()) $ mapM_ checkOne other_fields
988 -- Check that all the fields in the group have the same type
989 -- NB: this check assumes that all the constructors of a given
990 -- data type use the same type variables
992 tvs1 = mkVarSet (dataConAllTyVars con1)
993 res1 = dataConResTys con1
994 fty1 = dataConFieldType con1 label
996 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
997 = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
998 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
1000 tvs2 = mkVarSet (dataConAllTyVars con2)
1001 res2 = dataConResTys con2
1002 fty2 = dataConFieldType con2 label
1004 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
1005 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
1006 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
1008 mb_subst1 = tcMatchTys tvs1 res1 res2
1009 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
1011 -------------------------------
1012 checkValidDataCon :: TyCon -> DataCon -> TcM ()
1013 checkValidDataCon tc con
1014 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
1015 addErrCtxt (dataConCtxt con) $
1016 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
1017 ; checkValidType ctxt (dataConUserType con) }
1019 ctxt = ConArgCtxt (dataConName con)
1021 -------------------------------
1022 checkValidClass :: Class -> TcM ()
1024 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
1025 gla_exts <- doptM Opt_GlasgowExts
1027 -- Check that the class is unary, unless GlaExs
1028 ; checkTc (notNull tyvars) (nullaryClassErr cls)
1029 ; checkTc (gla_exts || unary) (classArityErr cls)
1031 -- Check the super-classes
1032 ; checkValidTheta (ClassSCCtxt (className cls)) theta
1034 -- Check the class operations
1035 ; mappM_ (check_op gla_exts) op_stuff
1037 -- Check that if the class has generic methods, then the
1038 -- class has only one parameter. We can't do generic
1039 -- multi-parameter type classes!
1040 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
1043 (tyvars, theta, _, op_stuff) = classBigSig cls
1044 unary = isSingleton tyvars
1045 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
1047 check_op gla_exts (sel_id, dm)
1048 = addErrCtxt (classOpCtxt sel_id tau) $ do
1049 { checkValidTheta SigmaCtxt (tail theta)
1050 -- The 'tail' removes the initial (C a) from the
1051 -- class itself, leaving just the method type
1053 ; checkValidType (FunSigCtxt op_name) tau
1055 -- Check that the type mentions at least one of
1056 -- the class type variables
1057 ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
1058 (noClassTyVarErr cls sel_id)
1060 -- Check that for a generic method, the type of
1061 -- the method is sufficiently simple
1062 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1063 (badGenericMethodType op_name op_ty)
1066 op_name = idName sel_id
1067 op_ty = idType sel_id
1068 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1069 (_,theta2,tau2) = tcSplitSigmaTy tau1
1070 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1071 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1072 -- Ugh! The function might have a type like
1073 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1074 -- With -fglasgow-exts, we want to allow this, even though the inner
1075 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1076 -- in the context of a for-all must mention at least one quantified
1077 -- type variable. What a mess!
1080 ---------------------------------------------------------------------
1081 resultTypeMisMatch field_name con1 con2
1082 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1083 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1084 nest 2 $ ptext SLIT("but have different result types")]
1085 fieldTypeMisMatch field_name con1 con2
1086 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1087 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1089 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1091 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1092 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1095 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1098 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1099 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1101 noClassTyVarErr clas op
1102 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1103 ptext SLIT("mentions none of the type variables of the class") <+>
1104 ppr clas <+> hsep (map ppr (classTyVars clas))]
1106 genericMultiParamErr clas
1107 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1108 ptext SLIT("cannot have generic methods")
1110 badGenericMethodType op op_ty
1111 = hang (ptext SLIT("Generic method type is too complex"))
1112 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1113 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1116 = setSrcSpan (getLoc (head sorted_decls)) $
1117 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1118 nest 2 (vcat (map ppr_decl sorted_decls))])
1120 sorted_decls = sortLocated syn_decls
1121 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1124 = setSrcSpan (getLoc (head sorted_decls)) $
1125 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1126 nest 2 (vcat (map ppr_decl sorted_decls))])
1128 sorted_decls = sortLocated cls_decls
1129 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1131 sortLocated :: [Located a] -> [Located a]
1132 sortLocated things = sortLe le things
1134 le (L l1 _) (L l2 _) = l1 <= l2
1136 badDataConTyCon data_con
1137 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1138 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1139 2 (ptext SLIT("instead of its parent type"))
1142 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1143 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
1145 badStupidTheta tc_name
1146 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1148 newtypeConError tycon n
1149 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1150 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1153 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1154 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1156 newtypeFieldErr con_name n_flds
1157 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1158 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1160 badSigTyDecl tc_name
1161 = vcat [ ptext SLIT("Illegal kind signature") <+>
1162 quotes (ppr tc_name)
1163 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1165 badKindSigCtxt tc_name
1166 = vcat [ ptext SLIT("Illegal context in kind signature") <+>
1167 quotes (ppr tc_name)
1168 , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ]
1170 badIdxTyDecl tc_name
1171 = vcat [ ptext SLIT("Illegal indexed type instance for") <+>
1172 quotes (ppr tc_name)
1173 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1175 badGadtIdxTyDecl tc_name
1176 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1177 quotes (ppr tc_name)
1178 , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ]
1180 tooManyParmsErr tc_name
1181 = ptext SLIT("Indexed type instance has too many parameters:") <+>
1182 quotes (ppr tc_name)
1184 tooFewParmsErr tc_name
1185 = ptext SLIT("Indexed type instance has too few parameters:") <+>
1186 quotes (ppr tc_name)
1188 badBootTyIdxDeclErr =
1189 ptext SLIT("Illegal indexed type instance in hs-boot file")
1191 wrongKindOfFamily family =
1192 ptext SLIT("Wrong category of type instance; declaration was for a") <+>
1195 kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
1196 | isDataTyCon family = ptext SLIT("data type")
1197 | isNewTyCon family = ptext SLIT("newtype")
1199 emptyConDeclsErr tycon
1200 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1201 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]