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(..), HsRecField(..), Sig(..), NewOrData(..), ResType(..),
15 tyClDeclTyVars, isSynDecl, isIdxTyDecl,
16 isKindSigDecl, hsConArgs, LTyClDecl, tcdName,
17 hsTyVarName, LHsTyVarBndr, LHsType
19 import HsTypes ( HsBang(..), getBangStrictness, hsLTyVarNames )
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,
28 tcExtendKindEnvTvs, newFamInstTyConName,
29 tcExtendRecEnv, tcLookupTyVar, tcLookupLocatedTyCon )
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,
41 tcSplitSigmaTy, tcGetTyVar_maybe )
42 import Type ( splitTyConApp_maybe,
43 newTyConInstRhs, isLiftedTypeKind, Kind,
44 splitKindFunTys, mkArrowKinds
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,
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, tyVarName, setTyVarName )
61 import VarSet ( elemVarSet, mkVarSet )
62 import Name ( Name, getSrcLoc, tidyNameOcc, getOccName )
63 import OccName ( initTidyOccEnv, tidyOccName )
65 import Maybe ( isJust, fromJust, isNothing, catMaybes )
66 import Maybes ( expectJust )
67 import Monad ( unless )
68 import Unify ( tcMatchTys, tcMatchTyX )
69 import Util ( zipLazy, isSingleton, notNull, sortLe, mapAccumL )
70 import List ( partition, elemIndex )
71 import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan,
73 import ListSetOps ( equivClasses, minusList )
74 import Digraph ( SCC(..) )
75 import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
76 Opt_UnboxStrictFields, Opt_IndexedTypes ) )
80 %************************************************************************
82 \subsection{Type checking for type and class declarations}
84 %************************************************************************
88 Consider a mutually-recursive group, binding
89 a type constructor T and a class C.
91 Step 1: getInitialKind
92 Construct a KindEnv by binding T and C to a kind variable
95 In that environment, do a kind check
97 Step 3: Zonk the kinds
99 Step 4: buildTyConOrClass
100 Construct an environment binding T to a TyCon and C to a Class.
101 a) Their kinds comes from zonking the relevant kind variable
102 b) Their arity (for synonyms) comes direct from the decl
103 c) The funcional dependencies come from the decl
104 d) The rest comes a knot-tied binding of T and C, returned from Step 4
105 e) The variances of the tycons in the group is calculated from
109 In this environment, walk over the decls, constructing the TyCons and Classes.
110 This uses in a strict way items (a)-(c) above, which is why they must
111 be constructed in Step 4. Feed the results back to Step 4.
112 For this step, pass the is-recursive flag as the wimp-out flag
116 Step 6: Extend environment
117 We extend the type environment with bindings not only for the TyCons and Classes,
118 but also for their "implicit Ids" like data constructors and class selectors
120 Step 7: checkValidTyCl
121 For a recursive group only, check all the decls again, just
122 to check all the side conditions on validity. We could not
123 do this before because we were in a mutually recursive knot.
125 Identification of recursive TyCons
126 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
127 The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
130 Identifying a TyCon as recursive serves two purposes
132 1. Avoid infinite types. Non-recursive newtypes are treated as
133 "transparent", like type synonyms, after the type checker. If we did
134 this for all newtypes, we'd get infinite types. So we figure out for
135 each newtype whether it is "recursive", and add a coercion if so. In
136 effect, we are trying to "cut the loops" by identifying a loop-breaker.
138 2. Avoid infinite unboxing. This is nothing to do with newtypes.
142 Well, this function diverges, but we don't want the strictness analyser
143 to diverge. But the strictness analyser will diverge because it looks
144 deeper and deeper into the structure of T. (I believe there are
145 examples where the function does something sane, and the strictness
146 analyser still diverges, but I can't see one now.)
148 Now, concerning (1), the FC2 branch currently adds a coercion for ALL
149 newtypes. I did this as an experiment, to try to expose cases in which
150 the coercions got in the way of optimisations. If it turns out that we
151 can indeed always use a coercion, then we don't risk recursive types,
152 and don't need to figure out what the loop breakers are.
154 For newtype *families* though, we will always have a coercion, so they
155 are always loop breakers! So you can easily adjust the current
156 algorithm by simply treating all newtype families as loop breakers (and
157 indeed type families). I think.
160 tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
161 -> TcM TcGblEnv -- Input env extended by types and classes
162 -- and their implicit Ids,DataCons
163 tcTyAndClassDecls boot_details allDecls
164 = do { -- Omit instances of indexed types; they are handled together
165 -- with the *heads* of class instances
166 ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
168 -- First check for cyclic type synonysm or classes
169 -- See notes with checkCycleErrs
170 ; checkCycleErrs decls
172 ; traceTc (text "tcTyAndCl" <+> ppr mod)
173 ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
174 do { let { -- Seperate ordinary synonyms from all other type and
175 -- class declarations and add all associated type
176 -- declarations from type classes. The latter is
177 -- required so that the temporary environment for the
178 -- knot includes all associated family declarations.
179 ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
181 ; alg_at_decls = concatMap addATs alg_decls
183 -- Extend the global env with the knot-tied results
184 -- for data types and classes
186 -- We must populate the environment with the loop-tied
187 -- T's right away, because the kind checker may "fault
188 -- in" some type constructors that recursively
190 ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss
191 ; tcExtendRecEnv gbl_things $ do
193 -- Kind-check the declarations
194 { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
196 ; let { -- Calculate rec-flag
197 ; calc_rec = calcRecFlags boot_details rec_alg_tyclss
198 ; tc_decl = addLocM (tcTyClDecl calc_rec) }
200 -- Type-check the type synonyms, and extend the envt
201 ; syn_tycons <- tcSynDecls kc_syn_decls
202 ; tcExtendGlobalEnv syn_tycons $ do
204 -- Type-check the data types and classes
205 { alg_tyclss <- mappM tc_decl kc_alg_decls
206 ; return (syn_tycons, concat alg_tyclss)
208 -- Finished with knot-tying now
209 -- Extend the environment with the finished things
210 ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
212 -- Perform the validity check
213 { traceTc (text "ready for validity check")
214 ; mappM_ (addLocM checkValidTyCl) decls
215 ; traceTc (text "done")
217 -- Add the implicit things;
218 -- we want them in the environment because
219 -- they may be mentioned in interface files
220 -- NB: All associated types and their implicit things will be added a
221 -- second time here. This doesn't matter as the definitions are
223 ; let { implicit_things = concatMap implicitTyThings alg_tyclss }
224 ; traceTc ((text "Adding" <+> ppr alg_tyclss)
225 $$ (text "and" <+> ppr implicit_things))
226 ; tcExtendGlobalEnv implicit_things getGblEnv
229 -- Pull associated types out of class declarations, to tie them into the
231 -- NB: We put them in the same place in the list as `tcTyClDecl' will
232 -- eventually put the matching `TyThing's. That's crucial; otherwise,
233 -- the two argument lists of `mkGlobalThings' don't match up.
234 addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats
237 mkGlobalThings :: [LTyClDecl Name] -- The decls
238 -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
240 -- Driven by the Decls, and treating the TyThings lazily
241 -- make a TypeEnv for the new things
242 mkGlobalThings decls things
243 = map mk_thing (decls `zipLazy` things)
245 mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
247 mk_thing (L _ decl, ~(ATyCon tc))
248 = (tcdName decl, ATyCon tc)
252 %************************************************************************
254 \subsection{Type checking instances of indexed types}
256 %************************************************************************
258 Instances of indexed types are somewhat of a hybrid. They are processed
259 together with class instance heads, but can contain data constructors and hence
260 they share a lot of kinding and type checking code with ordinary algebraic
261 data types (and GADTs).
264 tcIdxTyInstDecl :: LTyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
265 tcIdxTyInstDecl (L loc decl)
266 = -- Prime error recovery, set source location
267 recoverM (returnM Nothing) $
270 do { -- indexed data types require -findexed-types and can't be in an
272 ; gla_exts <- doptM Opt_IndexedTypes
273 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
274 ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
275 ; checkTc (not is_boot) $ badBootTyIdxDeclErr
277 -- perform kind and type checking
278 ; tcIdxTyInstDecl1 decl
281 tcIdxTyInstDecl1 :: TyClDecl Name -> TcM (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 -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
298 ; return Nothing -- !!!TODO: need TyThing for indexed synonym
301 tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
303 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
304 do { -- check that the family declaration is for the right kind
305 unless (new_or_data == NewType && isNewTyCon family ||
306 new_or_data == DataType && isDataTyCon family) $
307 addErr (wrongKindOfFamily family)
309 ; -- (1) kind check the data declaration as usual
310 ; k_decl <- kcDataDecl decl k_tvs
311 ; let k_ctxt = tcdCtxt k_decl
312 k_cons = tcdCons k_decl
314 -- result kind must be '*' (otherwise, we have too few patterns)
315 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
317 -- (2) type check indexed data type declaration
318 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
319 ; unbox_strict <- doptM Opt_UnboxStrictFields
321 -- Check that we don't use GADT syntax for indexed types
322 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
324 -- Check that a newtype has exactly one constructor
325 ; checkTc (new_or_data == DataType || isSingleton k_cons) $
326 newtypeConError tc_name (length k_cons)
328 ; t_typats <- mappM tcHsKindedType k_typats
329 ; stupid_theta <- tcHsKindedContext k_ctxt
331 ; rep_tc_name <- newFamInstTyConName tc_name (srcSpanStart loc)
332 ; tycon <- fixM (\ tycon -> do
333 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
338 DataType -> return (mkDataTyConRhs data_cons)
339 NewType -> ASSERT( isSingleton data_cons )
340 mkNewTyConRhs tc_name tycon (head data_cons)
341 ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive
342 False h98_syntax (Just (family, t_typats))
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 $ 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 { family <- tcLookupLocatedTyCon (tcdLName decl)
374 ; let { (kinds, resKind) = splitKindFunTys (tyConKind family)
375 ; hs_typats = fromJust $ tcdTyPats decl }
377 -- we may not have more parameters than the kind indicates
378 ; checkTc (length kinds >= length hs_typats) $
379 tooManyParmsErr (tcdLName decl)
381 -- type functions can have a higher-kinded result
382 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
383 ; typats <- zipWithM kcCheckHsType hs_typats kinds
384 ; thing_inside tvs typats resultKind family
390 %************************************************************************
394 %************************************************************************
396 We need to kind check all types in the mutually recursive group
397 before we know the kind of the type variables. For example:
400 op :: D b => a -> b -> b
403 bop :: (Monad c) => ...
405 Here, the kind of the locally-polymorphic type variable "b"
406 depends on *all the uses of class D*. For example, the use of
407 Monad c in bop's type signature means that D must have kind Type->Type.
409 However type synonyms work differently. They can have kinds which don't
410 just involve (->) and *:
411 type R = Int# -- Kind #
412 type S a = Array# a -- Kind * -> #
413 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
414 So we must infer their kinds from their right-hand sides *first* and then
415 use them, whereas for the mutually recursive data types D we bring into
416 scope kind bindings D -> k, where k is a kind variable, and do inference.
420 This treatment of type synonyms only applies to Haskell 98-style synonyms.
421 General type functions can be recursive, and hence, appear in `alg_decls'.
423 The kind of an indexed type is solely determinded by its kind signature;
424 hence, only kind signatures participate in the construction of the initial
425 kind environment (as constructed by `getInitialKind'). In fact, we ignore
426 instances of indexed types altogether in the following. However, we need to
427 include the kind signatures of associated types into the construction of the
428 initial kind environment. (This is handled by `allDecls').
431 kcTyClDecls syn_decls alg_decls
432 = do { -- First extend the kind env with each data type, class, and
433 -- indexed type, mapping them to a type variable
434 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
435 ; alg_kinds <- mappM getInitialKind initialKindDecls
436 ; tcExtendKindEnv alg_kinds $ do
438 -- Now kind-check the type synonyms, in dependency order
439 -- We do these differently to data type and classes,
440 -- because a type synonym can be an unboxed type
442 -- and a kind variable can't unify with UnboxedTypeKind
443 -- So we infer their kinds in dependency order
444 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
445 ; tcExtendKindEnv syn_kinds $ do
447 -- Now kind-check the data type, class, and kind signatures,
448 -- returning kind-annotated decls; we don't kind-check
449 -- instances of indexed types yet, but leave this to
451 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
452 (filter (not . isIdxTyDecl . unLoc) alg_decls)
454 ; return (kc_syn_decls, kc_alg_decls) }}}
456 -- get all declarations relevant for determining the initial kind
458 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
461 allDecls decl | isIdxTyDecl decl = []
464 ------------------------------------------------------------------------
465 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
466 -- Only for data type, class, and indexed type declarations
467 -- Get as much info as possible from the data, class, or indexed type decl,
468 -- so as to maximise usefulness of error messages
470 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
471 ; res_kind <- mk_res_kind decl
472 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
474 mk_arg_kind (UserTyVar _) = newKindVar
475 mk_arg_kind (KindedTyVar _ kind) = return kind
477 mk_res_kind (TyFunction { tcdKind = kind }) = return kind
478 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
479 -- On GADT-style and data signature declarations we allow a kind
481 -- data T :: *->* where { ... }
482 mk_res_kind other = return liftedTypeKind
486 kcSynDecls :: [SCC (LTyClDecl Name)]
487 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
488 [(Name,TcKind)]) -- Kind bindings
491 kcSynDecls (group : groups)
492 = do { (decl, nk) <- kcSynDecl group
493 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
494 ; return (decl:decls, nk:nks) }
497 kcSynDecl :: SCC (LTyClDecl Name)
498 -> TcM (LTyClDecl Name, -- Kind-annotated decls
499 (Name,TcKind)) -- Kind bindings
500 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
501 = tcAddDeclCtxt decl $
502 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
503 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
504 <+> brackets (ppr k_tvs))
505 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
506 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
507 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
508 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
509 (unLoc (tcdLName decl), tc_kind)) })
511 kcSynDecl (CyclicSCC decls)
512 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
513 -- of out-of-scope tycons
515 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
517 ------------------------------------------------------------------------
518 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
519 -- Not used for type synonyms (see kcSynDecl)
521 kcTyClDecl decl@(TyData {})
522 = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
523 kcTyClDeclBody decl $
526 kcTyClDecl decl@(TyFunction {})
527 = kcTyClDeclBody decl $ \ tvs' ->
528 return (decl {tcdTyVars = tvs'})
530 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
531 = kcTyClDeclBody decl $ \ tvs' ->
532 do { is_boot <- tcIsHsBoot
533 ; ctxt' <- kcHsContext ctxt
534 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
535 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
536 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
539 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
540 ; return (TypeSig nm op_ty') }
541 kc_sig other_sig = return other_sig
543 kcTyClDecl decl@(ForeignType {})
546 kcTyClDeclBody :: TyClDecl Name
547 -> ([LHsTyVarBndr Name] -> TcM a)
549 -- getInitialKind has made a suitably-shaped kind for the type or class
550 -- Unpack it, and attribute those kinds to the type variables
551 -- Extend the env with bindings for the tyvars, taken from
552 -- the kind of the tycon/class. Give it to the thing inside, and
553 -- check the result kind matches
554 kcTyClDeclBody decl thing_inside
555 = tcAddDeclCtxt decl $
556 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
557 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
558 (kinds, _) = splitKindFunTys tc_kind
559 hs_tvs = tcdTyVars decl
560 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
561 [ L loc (KindedTyVar (hsTyVarName tv) k)
562 | (L loc tv, k) <- zip hs_tvs kinds]
563 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
565 -- Kind check a data declaration, assuming that we already extended the
566 -- kind environment with the type variables of the left-hand side (these
567 -- kinded type variables are also passed as the second parameter).
569 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
570 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
572 = do { ctxt' <- kcHsContext ctxt
573 ; cons' <- mappM (wrapLocM kc_con_decl) cons
574 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
576 -- doc comments are typechecked to Nothing here
577 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res _) = do
578 kcHsTyVars ex_tvs $ \ex_tvs' -> do
579 ex_ctxt' <- kcHsContext ex_ctxt
580 details' <- kc_con_details details
582 ResTyH98 -> return ResTyH98
583 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
584 return (ConDecl name expl ex_tvs' ex_ctxt' details' res' Nothing)
586 kc_con_details (PrefixCon btys)
587 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
588 kc_con_details (InfixCon bty1 bty2)
589 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
590 kc_con_details (RecCon fields)
591 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
593 kc_field (HsRecField fld bty d) = do { bty' <- kc_larg_ty bty ; return (HsRecField fld bty' d) }
595 kc_larg_ty bty = case new_or_data of
596 DataType -> kcHsSigType bty
597 NewType -> kcHsLiftedSigType bty
598 -- Can't allow an unlifted type for newtypes, because we're effectively
599 -- going to remove the constructor while coercing it to a lifted type.
600 -- And newtypes can't be bang'd
604 %************************************************************************
606 \subsection{Type checking}
608 %************************************************************************
611 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
612 tcSynDecls [] = return []
613 tcSynDecls (decl : decls)
614 = do { syn_tc <- addLocM tcSynDecl decl
615 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
616 ; return (syn_tc : syn_tcs) }
619 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
620 = tcTyVarBndrs tvs $ \ tvs' -> do
621 { traceTc (text "tcd1" <+> ppr tc_name)
622 ; rhs_ty' <- tcHsKindedType rhs_ty
623 ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
626 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
628 tcTyClDecl calc_isrec decl
629 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
631 -- kind signature for a type function
632 tcTyClDecl1 _calc_isrec
633 (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
634 = tcTyVarBndrs tvs $ \ tvs' -> do
635 { traceTc (text "type family: " <+> ppr tc_name)
636 ; gla_exts <- doptM Opt_IndexedTypes
638 -- Check that we don't use kind signatures without Glasgow extensions
639 ; checkTc gla_exts $ badSigTyDecl tc_name
641 ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)]
644 -- kind signature for an indexed data type
645 tcTyClDecl1 _calc_isrec
646 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
647 tcdLName = L _ tc_name, tcdKindSig = Just ksig, tcdCons = []})
648 = tcTyVarBndrs tvs $ \ tvs' -> do
649 { traceTc (text "data/newtype family: " <+> ppr tc_name)
650 ; extra_tvs <- tcDataKindSig (Just ksig)
651 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
653 ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
654 ; gla_exts <- doptM Opt_IndexedTypes
656 -- Check that we don't use kind signatures without Glasgow extensions
657 ; checkTc gla_exts $ badSigTyDecl tc_name
659 ; tycon <- buildAlgTyCon tc_name final_tvs []
661 DataType -> OpenDataTyCon
662 NewType -> OpenNewTyCon)
663 Recursive False True Nothing
664 ; return [ATyCon tycon]
667 tcTyClDecl1 calc_isrec
668 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
669 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
670 = tcTyVarBndrs tvs $ \ tvs' -> do
671 { extra_tvs <- tcDataKindSig mb_ksig
672 ; let final_tvs = tvs' ++ extra_tvs
673 ; stupid_theta <- tcHsKindedContext ctxt
674 ; want_generic <- doptM Opt_Generics
675 ; unbox_strict <- doptM Opt_UnboxStrictFields
676 ; gla_exts <- doptM Opt_GlasgowExts
677 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
679 -- Check that we don't use GADT syntax in H98 world
680 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
682 -- Check that we don't use kind signatures without Glasgow extensions
683 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
685 -- Check that the stupid theta is empty for a GADT-style declaration
686 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
688 -- Check that there's at least one condecl,
689 -- or else we're reading an hs-boot file, or -fglasgow-exts
690 ; checkTc (not (null cons) || gla_exts || is_boot)
691 (emptyConDeclsErr tc_name)
693 -- Check that a newtype has exactly one constructor
694 ; checkTc (new_or_data == DataType || isSingleton cons)
695 (newtypeConError tc_name (length cons))
697 ; tycon <- fixM (\ tycon -> do
698 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
702 if null cons && is_boot -- In a hs-boot file, empty cons means
703 then return AbstractTyCon -- "don't know"; hence Abstract
704 else case new_or_data of
705 DataType -> return (mkDataTyConRhs data_cons)
707 ASSERT( isSingleton data_cons )
708 mkNewTyConRhs tc_name tycon (head data_cons)
709 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
710 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
712 ; return [ATyCon tycon]
715 is_rec = calc_isrec tc_name
716 h98_syntax = case cons of -- All constructors have same shape
717 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
720 tcTyClDecl1 calc_isrec
721 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
722 tcdCtxt = ctxt, tcdMeths = meths,
723 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
724 = tcTyVarBndrs tvs $ \ tvs' -> do
725 { ctxt' <- tcHsKindedContext ctxt
726 ; fds' <- mappM (addLocM tc_fundep) fundeps
727 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
728 ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
729 ; sig_stuff <- tcClassSigs class_name sigs meths
730 ; clas <- fixM (\ clas ->
731 let -- This little knot is just so we can get
732 -- hold of the name of the class TyCon, which we
733 -- need to look up its recursiveness
734 tycon_name = tyConName (classTyCon clas)
735 tc_isrec = calc_isrec tycon_name
737 buildClass class_name tvs' ctxt' fds' ats'
739 ; return (AClass clas : ats')
740 -- NB: Order is important due to the call to `mkGlobalThings' when
741 -- tying the the type and class declaration type checking knot.
744 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
745 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
746 ; return (tvs1', tvs2') }
748 -- For each AT argument compute the position of the corresponding class
749 -- parameter in the class head. This will later serve as a permutation
750 -- vector when checking the validity of instance declarations.
751 setTyThingPoss [ATyCon tycon] atTyVars =
752 let classTyVars = hsLTyVarNames tvs
754 . map (`elemIndex` classTyVars)
757 -- There will be no Nothing, as we already passed renaming
759 ATyCon (setTyConArgPoss tycon poss)
760 setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
762 tcTyClDecl1 calc_isrec
763 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
764 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
766 -----------------------------------
767 tcConDecl :: Bool -- True <=> -funbox-strict_fields
773 tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
774 (ConDecl name _ ex_tvs ex_ctxt details ResTyH98 _)
775 = do { let tc_datacon field_lbls arg_ty
776 = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
777 ; buildDataCon (unLoc name) False {- Prefix -}
779 (map unLoc field_lbls)
780 tc_tvs [] -- No existentials
781 [] [] -- No equalities, predicates
785 -- Check that a newtype has no existential stuff
786 ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
789 PrefixCon [arg_ty] -> tc_datacon [] arg_ty
790 RecCon [HsRecField field_lbl arg_ty _] -> tc_datacon [field_lbl] arg_ty
792 failWithTc (newtypeFieldErr name (length (hsConArgs details)))
793 -- Check that the constructor has exactly one field
796 tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
797 (ConDecl name _ tvs ctxt details res_ty _)
798 = tcTyVarBndrs tvs $ \ tvs' -> do
799 { ctxt' <- tcHsKindedContext ctxt
800 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
802 -- Tiresome: tidy the tyvar binders, since tc_tvs and tvs' may have the same OccNames
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 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 [ (n, t) | HsRecField n t _ <- 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 (distinct OccNames from univs)
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
850 ; let univ_tvs = choose_univs [] tidy_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
867 -- NB: tc_tvs and dc_tvs are distinct, but
868 -- we want them to be *visibly* distinct, both for
869 -- interface files and general confusion. So rename
870 -- the tc_tvs, since they are not used yet (no
871 -- consequential renaming needed)
872 init_occ_env = initTidyOccEnv (map getOccName dc_tvs)
873 (_, tidy_tc_tvs) = mapAccumL tidy_one init_occ_env tc_tvs
874 tidy_one env tv = (env', setTyVarName tv (tidyNameOcc name occ'))
877 (env', occ') = tidyOccName env (getOccName name)
880 argStrictness :: Bool -- True <=> -funbox-strict_fields
882 -> [TcType] -> [StrictnessMark]
883 argStrictness unbox_strict bangs arg_tys
884 = ASSERT( length bangs == length arg_tys )
885 zipWith (chooseBoxingStrategy unbox_strict) arg_tys bangs
887 -- We attempt to unbox/unpack a strict field when either:
888 -- (i) The field is marked '!!', or
889 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
891 -- We have turned off unboxing of newtypes because coercions make unboxing
892 -- and reboxing more complicated
893 chooseBoxingStrategy :: Bool -> TcType -> HsBang -> StrictnessMark
894 chooseBoxingStrategy unbox_strict_fields arg_ty bang
896 HsNoBang -> NotMarkedStrict
897 HsStrict | unbox_strict_fields
898 && can_unbox arg_ty -> MarkedUnboxed
899 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
900 other -> MarkedStrict
902 -- we can unbox if the type is a chain of newtypes with a product tycon
904 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
906 Just (arg_tycon, tycon_args) ->
907 not (isRecursiveTyCon arg_tycon) && -- Note [Recusive unboxing]
908 isProductTyCon arg_tycon &&
909 (if isNewTyCon arg_tycon then
910 can_unbox (newTyConInstRhs arg_tycon tycon_args)
914 Note [Recursive unboxing]
915 ~~~~~~~~~~~~~~~~~~~~~~~~~
916 Be careful not to try to unbox this!
918 But it's the *argument* type that matters. This is fine:
920 because Int is non-recursive.
922 %************************************************************************
924 \subsection{Dependency analysis}
926 %************************************************************************
928 Validity checking is done once the mutually-recursive knot has been
929 tied, so we can look at things freely.
932 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
933 checkCycleErrs tyclss
937 = do { mappM_ recClsErr cls_cycles
938 ; failM } -- Give up now, because later checkValidTyCl
939 -- will loop if the synonym is recursive
941 cls_cycles = calcClassCycles tyclss
943 checkValidTyCl :: TyClDecl Name -> TcM ()
944 -- We do the validity check over declarations, rather than TyThings
945 -- only so that we can add a nice context with tcAddDeclCtxt
947 = tcAddDeclCtxt decl $
948 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
949 ; traceTc (text "Validity of" <+> ppr thing)
951 ATyCon tc -> checkValidTyCon tc
952 AClass cl -> checkValidClass cl
953 ; traceTc (text "Done validity of" <+> ppr thing)
956 -------------------------
957 -- For data types declared with record syntax, we require
958 -- that each constructor that has a field 'f'
959 -- (a) has the same result type
960 -- (b) has the same type for 'f'
961 -- module alpha conversion of the quantified type variables
962 -- of the constructor.
964 checkValidTyCon :: TyCon -> TcM ()
967 = case synTyConRhs tc of
968 OpenSynTyCon _ -> return ()
969 SynonymTyCon ty -> checkValidType syn_ctxt ty
971 = -- Check the context on the data decl
972 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
974 -- Check arg types of data constructors
975 mappM_ (checkValidDataCon tc) data_cons `thenM_`
977 -- Check that fields with the same name share a type
978 mappM_ check_fields groups
981 syn_ctxt = TySynCtxt name
983 data_cons = tyConDataCons tc
985 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
986 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
987 get_fields con = dataConFieldLabels con `zip` repeat con
988 -- dataConFieldLabels may return the empty list, which is fine
990 -- See Note [GADT record selectors] in MkId.lhs
991 -- We must check (a) that the named field has the same
992 -- type in each constructor
993 -- (b) that those constructors have the same result type
995 -- However, the constructors may have differently named type variable
996 -- and (worse) we don't know how the correspond to each other. E.g.
997 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
998 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
1000 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
1001 -- result type against other candidates' types BOTH WAYS ROUND.
1002 -- If they magically agrees, take the substitution and
1003 -- apply them to the latter ones, and see if they match perfectly.
1004 check_fields fields@((label, con1) : other_fields)
1005 -- These fields all have the same name, but are from
1006 -- different constructors in the data type
1007 = recoverM (return ()) $ mapM_ checkOne other_fields
1008 -- Check that all the fields in the group have the same type
1009 -- NB: this check assumes that all the constructors of a given
1010 -- data type use the same type variables
1012 tvs1 = mkVarSet (dataConAllTyVars con1)
1013 res1 = dataConResTys con1
1014 fty1 = dataConFieldType con1 label
1016 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
1017 = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
1018 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
1020 tvs2 = mkVarSet (dataConAllTyVars con2)
1021 res2 = dataConResTys con2
1022 fty2 = dataConFieldType con2 label
1024 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
1025 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
1026 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
1028 mb_subst1 = tcMatchTys tvs1 res1 res2
1029 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
1031 -------------------------------
1032 checkValidDataCon :: TyCon -> DataCon -> TcM ()
1033 checkValidDataCon tc con
1034 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
1035 addErrCtxt (dataConCtxt con) $
1036 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
1037 ; checkValidType ctxt (dataConUserType con) }
1039 ctxt = ConArgCtxt (dataConName con)
1041 -------------------------------
1042 checkValidClass :: Class -> TcM ()
1044 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
1045 gla_exts <- doptM Opt_GlasgowExts
1047 -- Check that the class is unary, unless GlaExs
1048 ; checkTc (notNull tyvars) (nullaryClassErr cls)
1049 ; checkTc (gla_exts || unary) (classArityErr cls)
1051 -- Check the super-classes
1052 ; checkValidTheta (ClassSCCtxt (className cls)) theta
1054 -- Check the class operations
1055 ; mappM_ (check_op gla_exts) op_stuff
1057 -- Check that if the class has generic methods, then the
1058 -- class has only one parameter. We can't do generic
1059 -- multi-parameter type classes!
1060 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
1063 (tyvars, theta, _, op_stuff) = classBigSig cls
1064 unary = isSingleton tyvars
1065 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
1067 check_op gla_exts (sel_id, dm)
1068 = addErrCtxt (classOpCtxt sel_id tau) $ do
1069 { checkValidTheta SigmaCtxt (tail theta)
1070 -- The 'tail' removes the initial (C a) from the
1071 -- class itself, leaving just the method type
1073 ; checkValidType (FunSigCtxt op_name) tau
1075 -- Check that the type mentions at least one of
1076 -- the class type variables
1077 ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
1078 (noClassTyVarErr cls sel_id)
1080 -- Check that for a generic method, the type of
1081 -- the method is sufficiently simple
1082 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1083 (badGenericMethodType op_name op_ty)
1086 op_name = idName sel_id
1087 op_ty = idType sel_id
1088 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1089 (_,theta2,tau2) = tcSplitSigmaTy tau1
1090 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1091 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1092 -- Ugh! The function might have a type like
1093 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1094 -- With -fglasgow-exts, we want to allow this, even though the inner
1095 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1096 -- in the context of a for-all must mention at least one quantified
1097 -- type variable. What a mess!
1100 ---------------------------------------------------------------------
1101 resultTypeMisMatch field_name con1 con2
1102 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1103 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1104 nest 2 $ ptext SLIT("but have different result types")]
1105 fieldTypeMisMatch field_name con1 con2
1106 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1107 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1109 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1111 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1112 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1115 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1118 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1119 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1121 noClassTyVarErr clas op
1122 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1123 ptext SLIT("mentions none of the type variables of the class") <+>
1124 ppr clas <+> hsep (map ppr (classTyVars clas))]
1126 genericMultiParamErr clas
1127 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1128 ptext SLIT("cannot have generic methods")
1130 badGenericMethodType op op_ty
1131 = hang (ptext SLIT("Generic method type is too complex"))
1132 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1133 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1136 = setSrcSpan (getLoc (head sorted_decls)) $
1137 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1138 nest 2 (vcat (map ppr_decl sorted_decls))])
1140 sorted_decls = sortLocated syn_decls
1141 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1144 = setSrcSpan (getLoc (head sorted_decls)) $
1145 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1146 nest 2 (vcat (map ppr_decl sorted_decls))])
1148 sorted_decls = sortLocated cls_decls
1149 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1151 sortLocated :: [Located a] -> [Located a]
1152 sortLocated things = sortLe le things
1154 le (L l1 _) (L l2 _) = l1 <= l2
1156 badDataConTyCon data_con
1157 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1158 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1159 2 (ptext SLIT("instead of its parent type"))
1162 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1163 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
1165 badStupidTheta tc_name
1166 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1168 newtypeConError tycon n
1169 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1170 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1173 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1174 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1176 newtypeFieldErr con_name n_flds
1177 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1178 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1180 badSigTyDecl tc_name
1181 = vcat [ ptext SLIT("Illegal kind signature") <+>
1182 quotes (ppr tc_name)
1183 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1185 badKindSigCtxt tc_name
1186 = vcat [ ptext SLIT("Illegal context in kind signature") <+>
1187 quotes (ppr tc_name)
1188 , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ]
1190 badIdxTyDecl tc_name
1191 = vcat [ ptext SLIT("Illegal indexed type instance for") <+>
1192 quotes (ppr tc_name)
1193 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1195 badGadtIdxTyDecl tc_name
1196 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1197 quotes (ppr tc_name)
1198 , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ]
1200 tooManyParmsErr tc_name
1201 = ptext SLIT("Indexed type instance has too many parameters:") <+>
1202 quotes (ppr tc_name)
1204 tooFewParmsErr tc_name
1205 = ptext SLIT("Indexed type instance has too few parameters:") <+>
1206 quotes (ppr tc_name)
1208 badBootTyIdxDeclErr =
1209 ptext SLIT("Illegal indexed type instance in hs-boot file")
1211 wrongKindOfFamily family =
1212 ptext SLIT("Wrong category of type instance; declaration was for a") <+>
1215 kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
1216 | isDataTyCon family = ptext SLIT("data type")
1217 | isNewTyCon family = ptext SLIT("newtype")
1219 emptyConDeclsErr tycon
1220 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1221 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]