2 % (c) The University of Glasgow 2006
3 % (c) The AQUA Project, Glasgow University, 1996-1998
6 TcTyClsDecls: Typecheck type and class declarations
10 tcTyAndClassDecls, tcFamInstDecl
13 #include "HsVersions.h"
47 import Data.List ( partition, elemIndex )
48 import Control.Monad ( mplus )
52 %************************************************************************
54 \subsection{Type checking for type and class declarations}
56 %************************************************************************
60 Consider a mutually-recursive group, binding
61 a type constructor T and a class C.
63 Step 1: getInitialKind
64 Construct a KindEnv by binding T and C to a kind variable
67 In that environment, do a kind check
69 Step 3: Zonk the kinds
71 Step 4: buildTyConOrClass
72 Construct an environment binding T to a TyCon and C to a Class.
73 a) Their kinds comes from zonking the relevant kind variable
74 b) Their arity (for synonyms) comes direct from the decl
75 c) The funcional dependencies come from the decl
76 d) The rest comes a knot-tied binding of T and C, returned from Step 4
77 e) The variances of the tycons in the group is calculated from
81 In this environment, walk over the decls, constructing the TyCons and Classes.
82 This uses in a strict way items (a)-(c) above, which is why they must
83 be constructed in Step 4. Feed the results back to Step 4.
84 For this step, pass the is-recursive flag as the wimp-out flag
88 Step 6: Extend environment
89 We extend the type environment with bindings not only for the TyCons and Classes,
90 but also for their "implicit Ids" like data constructors and class selectors
92 Step 7: checkValidTyCl
93 For a recursive group only, check all the decls again, just
94 to check all the side conditions on validity. We could not
95 do this before because we were in a mutually recursive knot.
97 Identification of recursive TyCons
98 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
99 The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
102 Identifying a TyCon as recursive serves two purposes
104 1. Avoid infinite types. Non-recursive newtypes are treated as
105 "transparent", like type synonyms, after the type checker. If we did
106 this for all newtypes, we'd get infinite types. So we figure out for
107 each newtype whether it is "recursive", and add a coercion if so. In
108 effect, we are trying to "cut the loops" by identifying a loop-breaker.
110 2. Avoid infinite unboxing. This is nothing to do with newtypes.
114 Well, this function diverges, but we don't want the strictness analyser
115 to diverge. But the strictness analyser will diverge because it looks
116 deeper and deeper into the structure of T. (I believe there are
117 examples where the function does something sane, and the strictness
118 analyser still diverges, but I can't see one now.)
120 Now, concerning (1), the FC2 branch currently adds a coercion for ALL
121 newtypes. I did this as an experiment, to try to expose cases in which
122 the coercions got in the way of optimisations. If it turns out that we
123 can indeed always use a coercion, then we don't risk recursive types,
124 and don't need to figure out what the loop breakers are.
126 For newtype *families* though, we will always have a coercion, so they
127 are always loop breakers! So you can easily adjust the current
128 algorithm by simply treating all newtype families as loop breakers (and
129 indeed type families). I think.
132 tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
133 -> TcM TcGblEnv -- Input env extended by types and classes
134 -- and their implicit Ids,DataCons
135 tcTyAndClassDecls boot_details allDecls
136 = do { -- Omit instances of type families; they are handled together
137 -- with the *heads* of class instances
138 ; let decls = filter (not . isFamInstDecl . unLoc) allDecls
140 -- First check for cyclic type synonysm or classes
141 -- See notes with checkCycleErrs
142 ; checkCycleErrs decls
144 ; traceTc (text "tcTyAndCl" <+> ppr mod)
145 ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
146 do { let { -- Seperate ordinary synonyms from all other type and
147 -- class declarations and add all associated type
148 -- declarations from type classes. The latter is
149 -- required so that the temporary environment for the
150 -- knot includes all associated family declarations.
151 ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
153 ; alg_at_decls = concatMap addATs alg_decls
155 -- Extend the global env with the knot-tied results
156 -- for data types and classes
158 -- We must populate the environment with the loop-tied
159 -- T's right away, because the kind checker may "fault
160 -- in" some type constructors that recursively
162 ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss
163 ; tcExtendRecEnv gbl_things $ do
165 -- Kind-check the declarations
166 { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
168 ; let { -- Calculate rec-flag
169 ; calc_rec = calcRecFlags boot_details rec_alg_tyclss
170 ; tc_decl = addLocM (tcTyClDecl calc_rec) }
172 -- Type-check the type synonyms, and extend the envt
173 ; syn_tycons <- tcSynDecls kc_syn_decls
174 ; tcExtendGlobalEnv syn_tycons $ do
176 -- Type-check the data types and classes
177 { alg_tyclss <- mappM tc_decl kc_alg_decls
178 ; return (syn_tycons, concat alg_tyclss)
180 -- Finished with knot-tying now
181 -- Extend the environment with the finished things
182 ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
184 -- Perform the validity check
185 { traceTc (text "ready for validity check")
186 ; mappM_ (addLocM checkValidTyCl) decls
187 ; traceTc (text "done")
189 -- Add the implicit things;
190 -- we want them in the environment because
191 -- they may be mentioned in interface files
192 -- NB: All associated types and their implicit things will be added a
193 -- second time here. This doesn't matter as the definitions are
195 ; let { implicit_things = concatMap implicitTyThings alg_tyclss }
196 ; traceTc ((text "Adding" <+> ppr alg_tyclss)
197 $$ (text "and" <+> ppr implicit_things))
198 ; tcExtendGlobalEnv implicit_things getGblEnv
201 -- Pull associated types out of class declarations, to tie them into the
203 -- NB: We put them in the same place in the list as `tcTyClDecl' will
204 -- eventually put the matching `TyThing's. That's crucial; otherwise,
205 -- the two argument lists of `mkGlobalThings' don't match up.
206 addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats
209 mkGlobalThings :: [LTyClDecl Name] -- The decls
210 -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
212 -- Driven by the Decls, and treating the TyThings lazily
213 -- make a TypeEnv for the new things
214 mkGlobalThings decls things
215 = map mk_thing (decls `zipLazy` things)
217 mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
219 mk_thing (L _ decl, ~(ATyCon tc))
220 = (tcdName decl, ATyCon tc)
224 %************************************************************************
226 \subsection{Type checking family instances}
228 %************************************************************************
230 Family instances are somewhat of a hybrid. They are processed together with
231 class instance heads, but can contain data constructors and hence they share a
232 lot of kinding and type checking code with ordinary algebraic data types (and
236 tcFamInstDecl :: LTyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
237 tcFamInstDecl (L loc decl)
238 = -- Prime error recovery, set source location
239 recoverM (returnM Nothing) $
242 do { -- type families require -ftype-families and can't be in an
244 ; gla_exts <- doptM Opt_TypeFamilies
245 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
246 ; checkTc gla_exts $ badFamInstDecl (tcdLName decl)
247 ; checkTc (not is_boot) $ badBootFamInstDeclErr
249 -- perform kind and type checking
250 ; tcFamInstDecl1 decl
253 tcFamInstDecl1 :: TyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
256 tcFamInstDecl1 (decl@TySynonym {tcdLName = L loc tc_name})
257 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
258 do { -- check that the family declaration is for a synonym
259 unless (isSynTyCon family) $
260 addErr (wrongKindOfFamily family)
262 ; -- (1) kind check the right hand side of the type equation
263 ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
265 -- (2) type check type equation
266 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
267 ; t_typats <- mappM tcHsKindedType k_typats
268 ; t_rhs <- tcHsKindedType k_rhs
270 -- (3) construct representation tycon
271 ; rep_tc_name <- newFamInstTyConName tc_name loc
272 ; tycon <- buildSynTyCon rep_tc_name t_tvs (SynonymTyCon t_rhs)
273 (Just (family, t_typats))
275 ; return $ Just (ATyCon tycon)
278 -- "newtype instance" and "data instance"
279 tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
281 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
282 do { -- check that the family declaration is for the right kind
283 unless (isAlgTyCon family) $
284 addErr (wrongKindOfFamily family)
286 ; -- (1) kind check the data declaration as usual
287 ; k_decl <- kcDataDecl decl k_tvs
288 ; let k_ctxt = tcdCtxt k_decl
289 k_cons = tcdCons k_decl
291 -- result kind must be '*' (otherwise, we have too few patterns)
292 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
294 -- (2) type check indexed data type declaration
295 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
296 ; unbox_strict <- doptM Opt_UnboxStrictFields
298 -- Check that we don't use GADT syntax for indexed types
299 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
301 -- Check that a newtype has exactly one constructor
302 ; checkTc (new_or_data == DataType || isSingleton k_cons) $
303 newtypeConError tc_name (length k_cons)
305 ; t_typats <- mappM tcHsKindedType k_typats
306 ; stupid_theta <- tcHsKindedContext k_ctxt
308 -- (3) construct representation tycon
309 ; rep_tc_name <- newFamInstTyConName tc_name loc
310 ; tycon <- fixM (\ tycon -> do
311 { data_cons <- mappM (addLocM (tcConDecl unbox_strict tycon t_tvs))
315 DataType -> return (mkDataTyConRhs data_cons)
316 NewType -> ASSERT( isSingleton data_cons )
317 mkNewTyConRhs tc_name tycon (head data_cons)
318 ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive
319 False h98_syntax (Just (family, t_typats))
320 -- We always assume that indexed types are recursive. Why?
321 -- (1) Due to their open nature, we can never be sure that a
322 -- further instance might not introduce a new recursive
323 -- dependency. (2) They are always valid loop breakers as
324 -- they involve a coercion.
328 ; return $ Just (ATyCon tycon)
331 h98_syntax = case cons of -- All constructors have same shape
332 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
335 -- Kind checking of indexed types
338 -- Kind check type patterns and kind annotate the embedded type variables.
340 -- * Here we check that a type instance matches its kind signature, but we do
341 -- not check whether there is a pattern for each type index; the latter
342 -- check is only required for type functions.
344 kcIdxTyPats :: TyClDecl Name
345 -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
346 -- ^^kinded tvs ^^kinded ty pats ^^res kind
348 kcIdxTyPats decl thing_inside
349 = kcHsTyVars (tcdTyVars decl) $ \tvs ->
350 do { family <- tcLookupLocatedTyCon (tcdLName decl)
351 ; let { (kinds, resKind) = splitKindFunTys (tyConKind family)
352 ; hs_typats = fromJust $ tcdTyPats decl }
354 -- we may not have more parameters than the kind indicates
355 ; checkTc (length kinds >= length hs_typats) $
356 tooManyParmsErr (tcdLName decl)
358 -- type functions can have a higher-kinded result
359 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
360 ; typats <- TcRnMonad.zipWithM kcCheckHsType hs_typats kinds
361 ; thing_inside tvs typats resultKind family
367 %************************************************************************
371 %************************************************************************
373 We need to kind check all types in the mutually recursive group
374 before we know the kind of the type variables. For example:
377 op :: D b => a -> b -> b
380 bop :: (Monad c) => ...
382 Here, the kind of the locally-polymorphic type variable "b"
383 depends on *all the uses of class D*. For example, the use of
384 Monad c in bop's type signature means that D must have kind Type->Type.
386 However type synonyms work differently. They can have kinds which don't
387 just involve (->) and *:
388 type R = Int# -- Kind #
389 type S a = Array# a -- Kind * -> #
390 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
391 So we must infer their kinds from their right-hand sides *first* and then
392 use them, whereas for the mutually recursive data types D we bring into
393 scope kind bindings D -> k, where k is a kind variable, and do inference.
397 This treatment of type synonyms only applies to Haskell 98-style synonyms.
398 General type functions can be recursive, and hence, appear in `alg_decls'.
400 The kind of a type family is solely determinded by its kind signature;
401 hence, only kind signatures participate in the construction of the initial
402 kind environment (as constructed by `getInitialKind'). In fact, we ignore
403 instances of families altogether in the following. However, we need to
404 include the kinds of associated families into the construction of the
405 initial kind environment. (This is handled by `allDecls').
408 kcTyClDecls syn_decls alg_decls
409 = do { -- First extend the kind env with each data type, class, and
410 -- indexed type, mapping them to a type variable
411 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
412 ; alg_kinds <- mappM getInitialKind initialKindDecls
413 ; tcExtendKindEnv alg_kinds $ do
415 -- Now kind-check the type synonyms, in dependency order
416 -- We do these differently to data type and classes,
417 -- because a type synonym can be an unboxed type
419 -- and a kind variable can't unify with UnboxedTypeKind
420 -- So we infer their kinds in dependency order
421 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
422 ; tcExtendKindEnv syn_kinds $ do
424 -- Now kind-check the data type, class, and kind signatures,
425 -- returning kind-annotated decls; we don't kind-check
426 -- instances of indexed types yet, but leave this to
428 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
429 (filter (not . isFamInstDecl . unLoc) alg_decls)
431 ; return (kc_syn_decls, kc_alg_decls) }}}
433 -- get all declarations relevant for determining the initial kind
435 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
438 allDecls decl | isFamInstDecl decl = []
441 ------------------------------------------------------------------------
442 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
443 -- Only for data type, class, and indexed type declarations
444 -- Get as much info as possible from the data, class, or indexed type decl,
445 -- so as to maximise usefulness of error messages
447 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
448 ; res_kind <- mk_res_kind decl
449 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
451 mk_arg_kind (UserTyVar _) = newKindVar
452 mk_arg_kind (KindedTyVar _ kind) = return kind
454 mk_res_kind (TyFamily { tcdKind = Just kind }) = return kind
455 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
456 -- On GADT-style declarations we allow a kind signature
457 -- data T :: *->* where { ... }
458 mk_res_kind other = return liftedTypeKind
462 kcSynDecls :: [SCC (LTyClDecl Name)]
463 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
464 [(Name,TcKind)]) -- Kind bindings
467 kcSynDecls (group : groups)
468 = do { (decl, nk) <- kcSynDecl group
469 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
470 ; return (decl:decls, nk:nks) }
473 kcSynDecl :: SCC (LTyClDecl Name)
474 -> TcM (LTyClDecl Name, -- Kind-annotated decls
475 (Name,TcKind)) -- Kind bindings
476 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
477 = tcAddDeclCtxt decl $
478 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
479 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
480 <+> brackets (ppr k_tvs))
481 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
482 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
483 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
484 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
485 (unLoc (tcdLName decl), tc_kind)) })
487 kcSynDecl (CyclicSCC decls)
488 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
489 -- of out-of-scope tycons
491 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
493 ------------------------------------------------------------------------
494 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
495 -- Not used for type synonyms (see kcSynDecl)
497 kcTyClDecl decl@(TyData {})
498 = ASSERT( not . isFamInstDecl $ decl ) -- must not be a family instance
499 kcTyClDeclBody decl $
502 kcTyClDecl decl@(TyFamily {tcdKind = kind})
503 = kcTyClDeclBody decl $ \ tvs' ->
504 return (decl {tcdTyVars = tvs',
505 tcdKind = kind `mplus` Just liftedTypeKind})
506 -- default result kind is '*'
508 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
509 = kcTyClDeclBody decl $ \ tvs' ->
510 do { is_boot <- tcIsHsBoot
511 ; ctxt' <- kcHsContext ctxt
512 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
513 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
514 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
517 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
518 ; return (TypeSig nm op_ty') }
519 kc_sig other_sig = return other_sig
521 kcTyClDecl decl@(ForeignType {})
524 kcTyClDeclBody :: TyClDecl Name
525 -> ([LHsTyVarBndr Name] -> TcM a)
527 -- getInitialKind has made a suitably-shaped kind for the type or class
528 -- Unpack it, and attribute those kinds to the type variables
529 -- Extend the env with bindings for the tyvars, taken from
530 -- the kind of the tycon/class. Give it to the thing inside, and
531 -- check the result kind matches
532 kcTyClDeclBody decl thing_inside
533 = tcAddDeclCtxt decl $
534 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
535 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
536 (kinds, _) = splitKindFunTys tc_kind
537 hs_tvs = tcdTyVars decl
538 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
539 [ L loc (KindedTyVar (hsTyVarName tv) k)
540 | (L loc tv, k) <- zip hs_tvs kinds]
541 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
543 -- Kind check a data declaration, assuming that we already extended the
544 -- kind environment with the type variables of the left-hand side (these
545 -- kinded type variables are also passed as the second parameter).
547 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
548 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
550 = do { ctxt' <- kcHsContext ctxt
551 ; cons' <- mappM (wrapLocM kc_con_decl) cons
552 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
554 -- doc comments are typechecked to Nothing here
555 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res _) = do
556 kcHsTyVars ex_tvs $ \ex_tvs' -> do
557 ex_ctxt' <- kcHsContext ex_ctxt
558 details' <- kc_con_details details
560 ResTyH98 -> return ResTyH98
561 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
562 return (ConDecl name expl ex_tvs' ex_ctxt' details' res' Nothing)
564 kc_con_details (PrefixCon btys)
565 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
566 kc_con_details (InfixCon bty1 bty2)
567 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
568 kc_con_details (RecCon fields)
569 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
571 kc_field (ConDeclField fld bty d) = do { bty' <- kc_larg_ty bty
572 ; return (ConDeclField fld bty' d) }
574 kc_larg_ty bty = case new_or_data of
575 DataType -> kcHsSigType bty
576 NewType -> kcHsLiftedSigType bty
577 -- Can't allow an unlifted type for newtypes, because we're effectively
578 -- going to remove the constructor while coercing it to a lifted type.
579 -- And newtypes can't be bang'd
583 %************************************************************************
585 \subsection{Type checking}
587 %************************************************************************
590 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
591 tcSynDecls [] = return []
592 tcSynDecls (decl : decls)
593 = do { syn_tc <- addLocM tcSynDecl decl
594 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
595 ; return (syn_tc : syn_tcs) }
599 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
600 = tcTyVarBndrs tvs $ \ tvs' -> do
601 { traceTc (text "tcd1" <+> ppr tc_name)
602 ; rhs_ty' <- tcHsKindedType rhs_ty
603 ; tycon <- buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty') Nothing
604 ; return (ATyCon tycon)
608 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
610 tcTyClDecl calc_isrec decl
611 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
613 -- "type family" declarations
614 tcTyClDecl1 _calc_isrec
615 (TyFamily {tcdFlavour = TypeFamily,
616 tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = Just kind})
617 -- NB: kind at latest
620 = tcTyVarBndrs tvs $ \ tvs' -> do
621 { traceTc (text "type family: " <+> ppr tc_name)
622 ; idx_tys <- doptM Opt_TypeFamilies
624 -- Check that we don't use families without -ftype-families
625 ; checkTc idx_tys $ badFamInstDecl tc_name
627 ; tycon <- buildSynTyCon tc_name tvs' (OpenSynTyCon kind Nothing) Nothing
628 ; return [ATyCon tycon]
631 -- "newtype family" or "data family" declaration
632 tcTyClDecl1 _calc_isrec
633 (TyFamily {tcdFlavour = DataFamily,
634 tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = mb_kind})
635 = tcTyVarBndrs tvs $ \ tvs' -> do
636 { traceTc (text "data family: " <+> ppr tc_name)
637 ; extra_tvs <- tcDataKindSig mb_kind
638 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
640 ; idx_tys <- doptM Opt_TypeFamilies
642 -- Check that we don't use families without -ftype-families
643 ; checkTc idx_tys $ badFamInstDecl tc_name
645 ; tycon <- buildAlgTyCon tc_name final_tvs []
646 mkOpenDataTyConRhs Recursive False True Nothing
647 ; return [ATyCon tycon]
650 -- "newtype" and "data"
651 tcTyClDecl1 calc_isrec
652 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
653 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
654 = tcTyVarBndrs tvs $ \ tvs' -> do
655 { extra_tvs <- tcDataKindSig mb_ksig
656 ; let final_tvs = tvs' ++ extra_tvs
657 ; stupid_theta <- tcHsKindedContext ctxt
658 ; want_generic <- doptM Opt_Generics
659 ; unbox_strict <- doptM Opt_UnboxStrictFields
660 ; gla_exts <- doptM Opt_GlasgowExts
661 ; gadt_ok <- doptM Opt_GADTs
662 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
664 -- Check that we don't use GADT syntax in H98 world
665 ; checkTc (gadt_ok || h98_syntax) (badGadtDecl tc_name)
667 -- Check that we don't use kind signatures without Glasgow extensions
668 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
670 -- Check that the stupid theta is empty for a GADT-style declaration
671 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
673 -- Check that there's at least one condecl,
674 -- or else we're reading an hs-boot file, or -fglasgow-exts
675 ; checkTc (not (null cons) || gla_exts || is_boot)
676 (emptyConDeclsErr tc_name)
678 -- Check that a newtype has exactly one constructor
679 ; checkTc (new_or_data == DataType || isSingleton cons)
680 (newtypeConError tc_name (length cons))
682 ; tycon <- fixM (\ tycon -> do
683 { data_cons <- mappM (addLocM (tcConDecl unbox_strict tycon final_tvs))
686 if null cons && is_boot -- In a hs-boot file, empty cons means
687 then return AbstractTyCon -- "don't know"; hence Abstract
688 else case new_or_data of
689 DataType -> return (mkDataTyConRhs data_cons)
691 ASSERT( isSingleton data_cons )
692 mkNewTyConRhs tc_name tycon (head data_cons)
693 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
694 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
696 ; return [ATyCon tycon]
699 is_rec = calc_isrec tc_name
700 h98_syntax = case cons of -- All constructors have same shape
701 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
704 tcTyClDecl1 calc_isrec
705 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
706 tcdCtxt = ctxt, tcdMeths = meths,
707 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
708 = tcTyVarBndrs tvs $ \ tvs' -> do
709 { ctxt' <- tcHsKindedContext ctxt
710 ; fds' <- mappM (addLocM tc_fundep) fundeps
711 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
712 ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
713 ; sig_stuff <- tcClassSigs class_name sigs meths
714 ; clas <- fixM (\ clas ->
715 let -- This little knot is just so we can get
716 -- hold of the name of the class TyCon, which we
717 -- need to look up its recursiveness
718 tycon_name = tyConName (classTyCon clas)
719 tc_isrec = calc_isrec tycon_name
721 buildClass class_name tvs' ctxt' fds' ats'
723 ; return (AClass clas : ats')
724 -- NB: Order is important due to the call to `mkGlobalThings' when
725 -- tying the the type and class declaration type checking knot.
728 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
729 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
730 ; return (tvs1', tvs2') }
732 -- For each AT argument compute the position of the corresponding class
733 -- parameter in the class head. This will later serve as a permutation
734 -- vector when checking the validity of instance declarations.
735 setTyThingPoss [ATyCon tycon] atTyVars =
736 let classTyVars = hsLTyVarNames tvs
738 . map (`elemIndex` classTyVars)
741 -- There will be no Nothing, as we already passed renaming
743 ATyCon (setTyConArgPoss tycon poss)
744 setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
746 tcTyClDecl1 calc_isrec
747 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
748 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
750 -----------------------------------
751 tcConDecl :: Bool -- True <=> -funbox-strict_fields
756 tcConDecl unbox_strict tycon tc_tvs -- Data types
757 (ConDecl name _ tvs ctxt details res_ty _)
758 = tcTyVarBndrs tvs $ \ tvs' -> do
759 { ctxt' <- tcHsKindedContext ctxt
760 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
762 -- Tiresome: tidy the tyvar binders, since tc_tvs and tvs' may have the same OccNames
763 tc_datacon is_infix field_lbls btys
764 = do { let bangs = map getBangStrictness btys
765 ; arg_tys <- mappM tcHsBangType btys
766 ; buildDataCon (unLoc name) is_infix
767 (argStrictness unbox_strict bangs arg_tys)
768 (map unLoc field_lbls)
769 univ_tvs ex_tvs eq_preds ctxt' arg_tys
771 -- NB: we put data_tc, the type constructor gotten from the
772 -- constructor type signature into the data constructor;
773 -- that way checkValidDataCon can complain if it's wrong.
776 PrefixCon btys -> tc_datacon False [] btys
777 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
778 RecCon fields -> tc_datacon False field_names btys
780 field_names = map cd_fld_name fields
781 btys = map cd_fld_type fields
784 tcResultType :: TyCon
785 -> [TyVar] -- data T a b c = ...
786 -> [TyVar] -- where MkT :: forall a b c. ...
788 -> TcM ([TyVar], -- Universal
789 [TyVar], -- Existential (distinct OccNames from univs)
790 [(TyVar,Type)], -- Equality predicates
791 TyCon) -- TyCon given in the ResTy
792 -- We don't check that the TyCon given in the ResTy is
793 -- the same as the parent tycon, becuase we are in the middle
794 -- of a recursive knot; so it's postponed until checkValidDataCon
796 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
797 = return (tc_tvs, dc_tvs, [], decl_tycon)
798 -- In H98 syntax the dc_tvs are the existential ones
799 -- data T a b c = forall d e. MkT ...
800 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
802 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
803 -- E.g. data T a b c where
804 -- MkT :: forall x y z. T (x,y) z z
806 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
808 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
810 ; let univ_tvs = choose_univs [] tidy_tc_tvs res_tys
811 -- Each univ_tv is either a dc_tv or a tc_tv
812 ex_tvs = dc_tvs `minusList` univ_tvs
813 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
815 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
817 -- choose_univs uses the res_ty itself if it's a type variable
818 -- and hasn't already been used; otherwise it uses one of the tc_tvs
819 choose_univs used tc_tvs []
820 = ASSERT( null tc_tvs ) []
821 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
822 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
823 = tv : choose_univs (tv:used) tc_tvs res_tys
825 = tc_tv : choose_univs used tc_tvs res_tys
827 -- NB: tc_tvs and dc_tvs are distinct, but
828 -- we want them to be *visibly* distinct, both for
829 -- interface files and general confusion. So rename
830 -- the tc_tvs, since they are not used yet (no
831 -- consequential renaming needed)
832 init_occ_env = initTidyOccEnv (map getOccName dc_tvs)
833 (_, tidy_tc_tvs) = mapAccumL tidy_one init_occ_env tc_tvs
834 tidy_one env tv = (env', setTyVarName tv (tidyNameOcc name occ'))
837 (env', occ') = tidyOccName env (getOccName name)
840 argStrictness :: Bool -- True <=> -funbox-strict_fields
842 -> [TcType] -> [StrictnessMark]
843 argStrictness unbox_strict bangs arg_tys
844 = ASSERT( length bangs == length arg_tys )
845 zipWith (chooseBoxingStrategy unbox_strict) arg_tys bangs
847 -- We attempt to unbox/unpack a strict field when either:
848 -- (i) The field is marked '!!', or
849 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
851 -- We have turned off unboxing of newtypes because coercions make unboxing
852 -- and reboxing more complicated
853 chooseBoxingStrategy :: Bool -> TcType -> HsBang -> StrictnessMark
854 chooseBoxingStrategy unbox_strict_fields arg_ty bang
856 HsNoBang -> NotMarkedStrict
857 HsStrict | unbox_strict_fields
858 && can_unbox arg_ty -> MarkedUnboxed
859 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
860 other -> MarkedStrict
862 -- we can unbox if the type is a chain of newtypes with a product tycon
864 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
866 Just (arg_tycon, tycon_args) ->
867 not (isRecursiveTyCon arg_tycon) && -- Note [Recusive unboxing]
868 isProductTyCon arg_tycon &&
869 (if isNewTyCon arg_tycon then
870 can_unbox (newTyConInstRhs arg_tycon tycon_args)
874 Note [Recursive unboxing]
875 ~~~~~~~~~~~~~~~~~~~~~~~~~
876 Be careful not to try to unbox this!
878 But it's the *argument* type that matters. This is fine:
880 because Int is non-recursive.
882 %************************************************************************
884 \subsection{Dependency analysis}
886 %************************************************************************
888 Validity checking is done once the mutually-recursive knot has been
889 tied, so we can look at things freely.
892 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
893 checkCycleErrs tyclss
897 = do { mappM_ recClsErr cls_cycles
898 ; failM } -- Give up now, because later checkValidTyCl
899 -- will loop if the synonym is recursive
901 cls_cycles = calcClassCycles tyclss
903 checkValidTyCl :: TyClDecl Name -> TcM ()
904 -- We do the validity check over declarations, rather than TyThings
905 -- only so that we can add a nice context with tcAddDeclCtxt
907 = tcAddDeclCtxt decl $
908 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
909 ; traceTc (text "Validity of" <+> ppr thing)
911 ATyCon tc -> checkValidTyCon tc
912 AClass cl -> checkValidClass cl
913 ; traceTc (text "Done validity of" <+> ppr thing)
916 -------------------------
917 -- For data types declared with record syntax, we require
918 -- that each constructor that has a field 'f'
919 -- (a) has the same result type
920 -- (b) has the same type for 'f'
921 -- module alpha conversion of the quantified type variables
922 -- of the constructor.
924 checkValidTyCon :: TyCon -> TcM ()
927 = case synTyConRhs tc of
928 OpenSynTyCon _ _ -> return ()
929 SynonymTyCon ty -> checkValidType syn_ctxt ty
931 = -- Check the context on the data decl
932 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
934 -- Check arg types of data constructors
935 mappM_ (checkValidDataCon tc) data_cons `thenM_`
937 -- Check that fields with the same name share a type
938 mappM_ check_fields groups
941 syn_ctxt = TySynCtxt name
943 data_cons = tyConDataCons tc
945 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
946 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
947 get_fields con = dataConFieldLabels con `zip` repeat con
948 -- dataConFieldLabels may return the empty list, which is fine
950 -- See Note [GADT record selectors] in MkId.lhs
951 -- We must check (a) that the named field has the same
952 -- type in each constructor
953 -- (b) that those constructors have the same result type
955 -- However, the constructors may have differently named type variable
956 -- and (worse) we don't know how the correspond to each other. E.g.
957 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
958 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
960 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
961 -- result type against other candidates' types BOTH WAYS ROUND.
962 -- If they magically agrees, take the substitution and
963 -- apply them to the latter ones, and see if they match perfectly.
964 check_fields fields@((label, con1) : other_fields)
965 -- These fields all have the same name, but are from
966 -- different constructors in the data type
967 = recoverM (return ()) $ mapM_ checkOne other_fields
968 -- Check that all the fields in the group have the same type
969 -- NB: this check assumes that all the constructors of a given
970 -- data type use the same type variables
972 (tvs1, _, _, res1) = dataConSig con1
974 fty1 = dataConFieldType con1 label
976 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
977 = do { checkFieldCompat label con1 con2 ts1 res1 res2 fty1 fty2
978 ; checkFieldCompat label con2 con1 ts2 res2 res1 fty2 fty1 }
980 (tvs2, _, _, res2) = dataConSig con2
982 fty2 = dataConFieldType con2 label
984 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
985 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
986 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
988 mb_subst1 = tcMatchTy tvs1 res1 res2
989 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
991 -------------------------------
992 checkValidDataCon :: TyCon -> DataCon -> TcM ()
993 checkValidDataCon tc con
994 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
995 addErrCtxt (dataConCtxt con) $
996 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
997 ; checkValidType ctxt (dataConUserType con)
998 ; ifM (isNewTyCon tc) (checkNewDataCon con)
1001 ctxt = ConArgCtxt (dataConName con)
1003 -------------------------------
1004 checkNewDataCon :: DataCon -> TcM ()
1005 -- Checks for the data constructor of a newtype
1007 = do { checkTc (isSingleton arg_tys) (newtypeFieldErr con (length arg_tys))
1009 ; checkTc (null eq_spec) (newtypePredError con)
1010 -- Return type is (T a b c)
1011 ; checkTc (null ex_tvs && null theta) (newtypeExError con)
1013 ; checkTc (not (any isMarkedStrict (dataConStrictMarks con)))
1014 (newtypeStrictError con)
1018 (_univ_tvs, ex_tvs, eq_spec, theta, arg_tys, _res_ty) = dataConFullSig con
1020 -------------------------------
1021 checkValidClass :: Class -> TcM ()
1023 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
1024 gla_exts <- doptM Opt_GlasgowExts
1026 -- Check that the class is unary, unless GlaExs
1027 ; checkTc (notNull tyvars) (nullaryClassErr cls)
1028 ; checkTc (gla_exts || unary) (classArityErr cls)
1030 -- Check the super-classes
1031 ; checkValidTheta (ClassSCCtxt (className cls)) theta
1033 -- Check the class operations
1034 ; mappM_ (check_op gla_exts) op_stuff
1036 -- Check that if the class has generic methods, then the
1037 -- class has only one parameter. We can't do generic
1038 -- multi-parameter type classes!
1039 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
1042 (tyvars, theta, _, op_stuff) = classBigSig cls
1043 unary = isSingleton tyvars
1044 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
1046 check_op gla_exts (sel_id, dm)
1047 = addErrCtxt (classOpCtxt sel_id tau) $ do
1048 { checkValidTheta SigmaCtxt (tail theta)
1049 -- The 'tail' removes the initial (C a) from the
1050 -- class itself, leaving just the method type
1052 ; checkValidType (FunSigCtxt op_name) tau
1054 -- Check that the type mentions at least one of
1055 -- the class type variables...or at least one reachable
1056 -- from one of the class variables. Example: tc223
1057 -- class Error e => Game b mv e | b -> mv e where
1058 -- newBoard :: MonadState b m => m ()
1059 -- Here, MonadState has a fundep m->b, so newBoard is fine
1060 ; let grown_tyvars = grow theta (mkVarSet tyvars)
1061 ; checkTc (tyVarsOfType tau `intersectsVarSet` grown_tyvars)
1062 (noClassTyVarErr cls sel_id)
1064 -- Check that for a generic method, the type of
1065 -- the method is sufficiently simple
1066 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1067 (badGenericMethodType op_name op_ty)
1070 op_name = idName sel_id
1071 op_ty = idType sel_id
1072 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1073 (_,theta2,tau2) = tcSplitSigmaTy tau1
1074 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1075 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1076 -- Ugh! The function might have a type like
1077 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1078 -- With -fglasgow-exts, we want to allow this, even though the inner
1079 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1080 -- in the context of a for-all must mention at least one quantified
1081 -- type variable. What a mess!
1084 ---------------------------------------------------------------------
1085 resultTypeMisMatch field_name con1 con2
1086 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1087 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1088 nest 2 $ ptext SLIT("but have different result types")]
1089 fieldTypeMisMatch field_name con1 con2
1090 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1091 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1093 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1095 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1096 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1099 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1102 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1103 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1105 noClassTyVarErr clas op
1106 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1107 ptext SLIT("mentions none of the type variables of the class") <+>
1108 ppr clas <+> hsep (map ppr (classTyVars clas))]
1110 genericMultiParamErr clas
1111 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1112 ptext SLIT("cannot have generic methods")
1114 badGenericMethodType op op_ty
1115 = hang (ptext SLIT("Generic method type is too complex"))
1116 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1117 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1120 = setSrcSpan (getLoc (head sorted_decls)) $
1121 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1122 nest 2 (vcat (map ppr_decl sorted_decls))])
1124 sorted_decls = sortLocated syn_decls
1125 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1128 = setSrcSpan (getLoc (head sorted_decls)) $
1129 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1130 nest 2 (vcat (map ppr_decl sorted_decls))])
1132 sorted_decls = sortLocated cls_decls
1133 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1135 sortLocated :: [Located a] -> [Located a]
1136 sortLocated things = sortLe le things
1138 le (L l1 _) (L l2 _) = l1 <= l2
1140 badDataConTyCon data_con
1141 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1142 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1143 2 (ptext SLIT("instead of its parent type"))
1146 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1147 , nest 2 (parens $ ptext SLIT("Use -X=GADT to allow GADTs")) ]
1149 badStupidTheta tc_name
1150 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1152 newtypeConError tycon n
1153 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1154 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1157 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1158 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1160 newtypeStrictError con
1161 = sep [ptext SLIT("A newtype constructor cannot have a strictness annotation,"),
1162 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1164 newtypePredError con
1165 = sep [ptext SLIT("A newtype constructor must have a return type of form T a1 ... an"),
1166 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does not")]
1168 newtypeFieldErr con_name n_flds
1169 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1170 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1172 badSigTyDecl tc_name
1173 = vcat [ ptext SLIT("Illegal kind signature") <+>
1174 quotes (ppr tc_name)
1175 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow kind signatures")) ]
1177 badFamInstDecl tc_name
1178 = vcat [ ptext SLIT("Illegal family instance for") <+>
1179 quotes (ppr tc_name)
1180 , nest 2 (parens $ ptext SLIT("Use -X=TypeFamilies to allow indexed type families")) ]
1182 badGadtIdxTyDecl tc_name
1183 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1184 quotes (ppr tc_name)
1185 , nest 2 (parens $ ptext SLIT("Family instances can not yet use GADT declarations")) ]
1187 tooManyParmsErr tc_name
1188 = ptext SLIT("Family instance has too many parameters:") <+>
1189 quotes (ppr tc_name)
1191 tooFewParmsErr tc_name
1192 = ptext SLIT("Family instance has too few parameters:") <+>
1193 quotes (ppr tc_name)
1195 badBootFamInstDeclErr =
1196 ptext SLIT("Illegal family instance in hs-boot file")
1198 wrongKindOfFamily family =
1199 ptext SLIT("Wrong category of family instance; declaration was for a") <+>
1202 kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
1203 | isAlgTyCon family = ptext SLIT("data type")
1204 | otherwise = pprPanic "wrongKindOfFamily" (ppr family)
1206 emptyConDeclsErr tycon
1207 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1208 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]