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 (HsRecField fld bty d) = do { bty' <- kc_larg_ty bty ; return (HsRecField fld bty' d) }
573 kc_larg_ty bty = case new_or_data of
574 DataType -> kcHsSigType bty
575 NewType -> kcHsLiftedSigType bty
576 -- Can't allow an unlifted type for newtypes, because we're effectively
577 -- going to remove the constructor while coercing it to a lifted type.
578 -- And newtypes can't be bang'd
582 %************************************************************************
584 \subsection{Type checking}
586 %************************************************************************
589 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
590 tcSynDecls [] = return []
591 tcSynDecls (decl : decls)
592 = do { syn_tc <- addLocM tcSynDecl decl
593 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
594 ; return (syn_tc : syn_tcs) }
598 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
599 = tcTyVarBndrs tvs $ \ tvs' -> do
600 { traceTc (text "tcd1" <+> ppr tc_name)
601 ; rhs_ty' <- tcHsKindedType rhs_ty
602 ; tycon <- buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty') Nothing
603 ; return (ATyCon tycon)
607 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
609 tcTyClDecl calc_isrec decl
610 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
612 -- "type family" declarations
613 tcTyClDecl1 _calc_isrec
614 (TyFamily {tcdFlavour = TypeFamily,
615 tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = Just kind})
616 -- NB: kind at latest
619 = tcTyVarBndrs tvs $ \ tvs' -> do
620 { traceTc (text "type family: " <+> ppr tc_name)
621 ; idx_tys <- doptM Opt_TypeFamilies
623 -- Check that we don't use families without -ftype-families
624 ; checkTc idx_tys $ badFamInstDecl tc_name
626 ; tycon <- buildSynTyCon tc_name tvs' (OpenSynTyCon kind Nothing) Nothing
627 ; return [ATyCon tycon]
630 -- "newtype family" or "data family" declaration
631 tcTyClDecl1 _calc_isrec
632 (TyFamily {tcdFlavour = DataFamily,
633 tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = mb_kind})
634 = tcTyVarBndrs tvs $ \ tvs' -> do
635 { traceTc (text "data family: " <+> ppr tc_name)
636 ; extra_tvs <- tcDataKindSig mb_kind
637 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
639 ; idx_tys <- doptM Opt_TypeFamilies
641 -- Check that we don't use families without -ftype-families
642 ; checkTc idx_tys $ badFamInstDecl tc_name
644 ; tycon <- buildAlgTyCon tc_name final_tvs []
645 mkOpenDataTyConRhs Recursive False True Nothing
646 ; return [ATyCon tycon]
649 -- "newtype" and "data"
650 tcTyClDecl1 calc_isrec
651 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
652 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
653 = tcTyVarBndrs tvs $ \ tvs' -> do
654 { extra_tvs <- tcDataKindSig mb_ksig
655 ; let final_tvs = tvs' ++ extra_tvs
656 ; stupid_theta <- tcHsKindedContext ctxt
657 ; want_generic <- doptM Opt_Generics
658 ; unbox_strict <- doptM Opt_UnboxStrictFields
659 ; gla_exts <- doptM Opt_GlasgowExts
660 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
662 -- Check that we don't use GADT syntax in H98 world
663 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
665 -- Check that we don't use kind signatures without Glasgow extensions
666 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
668 -- Check that the stupid theta is empty for a GADT-style declaration
669 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
671 -- Check that there's at least one condecl,
672 -- or else we're reading an hs-boot file, or -fglasgow-exts
673 ; checkTc (not (null cons) || gla_exts || is_boot)
674 (emptyConDeclsErr tc_name)
676 -- Check that a newtype has exactly one constructor
677 ; checkTc (new_or_data == DataType || isSingleton cons)
678 (newtypeConError tc_name (length cons))
680 ; tycon <- fixM (\ tycon -> do
681 { data_cons <- mappM (addLocM (tcConDecl unbox_strict tycon final_tvs))
684 if null cons && is_boot -- In a hs-boot file, empty cons means
685 then return AbstractTyCon -- "don't know"; hence Abstract
686 else case new_or_data of
687 DataType -> return (mkDataTyConRhs data_cons)
689 ASSERT( isSingleton data_cons )
690 mkNewTyConRhs tc_name tycon (head data_cons)
691 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
692 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
694 ; return [ATyCon tycon]
697 is_rec = calc_isrec tc_name
698 h98_syntax = case cons of -- All constructors have same shape
699 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
702 tcTyClDecl1 calc_isrec
703 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
704 tcdCtxt = ctxt, tcdMeths = meths,
705 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
706 = tcTyVarBndrs tvs $ \ tvs' -> do
707 { ctxt' <- tcHsKindedContext ctxt
708 ; fds' <- mappM (addLocM tc_fundep) fundeps
709 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
710 ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
711 ; sig_stuff <- tcClassSigs class_name sigs meths
712 ; clas <- fixM (\ clas ->
713 let -- This little knot is just so we can get
714 -- hold of the name of the class TyCon, which we
715 -- need to look up its recursiveness
716 tycon_name = tyConName (classTyCon clas)
717 tc_isrec = calc_isrec tycon_name
719 buildClass class_name tvs' ctxt' fds' ats'
721 ; return (AClass clas : ats')
722 -- NB: Order is important due to the call to `mkGlobalThings' when
723 -- tying the the type and class declaration type checking knot.
726 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
727 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
728 ; return (tvs1', tvs2') }
730 -- For each AT argument compute the position of the corresponding class
731 -- parameter in the class head. This will later serve as a permutation
732 -- vector when checking the validity of instance declarations.
733 setTyThingPoss [ATyCon tycon] atTyVars =
734 let classTyVars = hsLTyVarNames tvs
736 . map (`elemIndex` classTyVars)
739 -- There will be no Nothing, as we already passed renaming
741 ATyCon (setTyConArgPoss tycon poss)
742 setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
744 tcTyClDecl1 calc_isrec
745 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
746 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
748 -----------------------------------
749 tcConDecl :: Bool -- True <=> -funbox-strict_fields
754 tcConDecl unbox_strict tycon tc_tvs -- Data types
755 (ConDecl name _ tvs ctxt details res_ty _)
756 = tcTyVarBndrs tvs $ \ tvs' -> do
757 { ctxt' <- tcHsKindedContext ctxt
758 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
760 -- Tiresome: tidy the tyvar binders, since tc_tvs and tvs' may have the same OccNames
761 tc_datacon is_infix field_lbls btys
762 = do { let bangs = map getBangStrictness btys
763 ; arg_tys <- mappM tcHsBangType btys
764 ; buildDataCon (unLoc name) is_infix
765 (argStrictness unbox_strict bangs arg_tys)
766 (map unLoc field_lbls)
767 univ_tvs ex_tvs eq_preds ctxt' arg_tys
769 -- NB: we put data_tc, the type constructor gotten from the
770 -- constructor type signature into the data constructor;
771 -- that way checkValidDataCon can complain if it's wrong.
774 PrefixCon btys -> tc_datacon False [] btys
775 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
776 RecCon fields -> tc_datacon False field_names btys
778 (field_names, btys) = unzip [ (n, t) | HsRecField n t _ <- fields ]
782 tcResultType :: TyCon
783 -> [TyVar] -- data T a b c = ...
784 -> [TyVar] -- where MkT :: forall a b c. ...
786 -> TcM ([TyVar], -- Universal
787 [TyVar], -- Existential (distinct OccNames from univs)
788 [(TyVar,Type)], -- Equality predicates
789 TyCon) -- TyCon given in the ResTy
790 -- We don't check that the TyCon given in the ResTy is
791 -- the same as the parent tycon, becuase we are in the middle
792 -- of a recursive knot; so it's postponed until checkValidDataCon
794 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
795 = return (tc_tvs, dc_tvs, [], decl_tycon)
796 -- In H98 syntax the dc_tvs are the existential ones
797 -- data T a b c = forall d e. MkT ...
798 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
800 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
801 -- E.g. data T a b c where
802 -- MkT :: forall x y z. T (x,y) z z
804 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
806 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
808 ; let univ_tvs = choose_univs [] tidy_tc_tvs res_tys
809 -- Each univ_tv is either a dc_tv or a tc_tv
810 ex_tvs = dc_tvs `minusList` univ_tvs
811 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
813 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
815 -- choose_univs uses the res_ty itself if it's a type variable
816 -- and hasn't already been used; otherwise it uses one of the tc_tvs
817 choose_univs used tc_tvs []
818 = ASSERT( null tc_tvs ) []
819 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
820 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
821 = tv : choose_univs (tv:used) tc_tvs res_tys
823 = tc_tv : choose_univs used tc_tvs res_tys
825 -- NB: tc_tvs and dc_tvs are distinct, but
826 -- we want them to be *visibly* distinct, both for
827 -- interface files and general confusion. So rename
828 -- the tc_tvs, since they are not used yet (no
829 -- consequential renaming needed)
830 init_occ_env = initTidyOccEnv (map getOccName dc_tvs)
831 (_, tidy_tc_tvs) = mapAccumL tidy_one init_occ_env tc_tvs
832 tidy_one env tv = (env', setTyVarName tv (tidyNameOcc name occ'))
835 (env', occ') = tidyOccName env (getOccName name)
838 argStrictness :: Bool -- True <=> -funbox-strict_fields
840 -> [TcType] -> [StrictnessMark]
841 argStrictness unbox_strict bangs arg_tys
842 = ASSERT( length bangs == length arg_tys )
843 zipWith (chooseBoxingStrategy unbox_strict) arg_tys bangs
845 -- We attempt to unbox/unpack a strict field when either:
846 -- (i) The field is marked '!!', or
847 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
849 -- We have turned off unboxing of newtypes because coercions make unboxing
850 -- and reboxing more complicated
851 chooseBoxingStrategy :: Bool -> TcType -> HsBang -> StrictnessMark
852 chooseBoxingStrategy unbox_strict_fields arg_ty bang
854 HsNoBang -> NotMarkedStrict
855 HsStrict | unbox_strict_fields
856 && can_unbox arg_ty -> MarkedUnboxed
857 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
858 other -> MarkedStrict
860 -- we can unbox if the type is a chain of newtypes with a product tycon
862 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
864 Just (arg_tycon, tycon_args) ->
865 not (isRecursiveTyCon arg_tycon) && -- Note [Recusive unboxing]
866 isProductTyCon arg_tycon &&
867 (if isNewTyCon arg_tycon then
868 can_unbox (newTyConInstRhs arg_tycon tycon_args)
872 Note [Recursive unboxing]
873 ~~~~~~~~~~~~~~~~~~~~~~~~~
874 Be careful not to try to unbox this!
876 But it's the *argument* type that matters. This is fine:
878 because Int is non-recursive.
880 %************************************************************************
882 \subsection{Dependency analysis}
884 %************************************************************************
886 Validity checking is done once the mutually-recursive knot has been
887 tied, so we can look at things freely.
890 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
891 checkCycleErrs tyclss
895 = do { mappM_ recClsErr cls_cycles
896 ; failM } -- Give up now, because later checkValidTyCl
897 -- will loop if the synonym is recursive
899 cls_cycles = calcClassCycles tyclss
901 checkValidTyCl :: TyClDecl Name -> TcM ()
902 -- We do the validity check over declarations, rather than TyThings
903 -- only so that we can add a nice context with tcAddDeclCtxt
905 = tcAddDeclCtxt decl $
906 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
907 ; traceTc (text "Validity of" <+> ppr thing)
909 ATyCon tc -> checkValidTyCon tc
910 AClass cl -> checkValidClass cl
911 ; traceTc (text "Done validity of" <+> ppr thing)
914 -------------------------
915 -- For data types declared with record syntax, we require
916 -- that each constructor that has a field 'f'
917 -- (a) has the same result type
918 -- (b) has the same type for 'f'
919 -- module alpha conversion of the quantified type variables
920 -- of the constructor.
922 checkValidTyCon :: TyCon -> TcM ()
925 = case synTyConRhs tc of
926 OpenSynTyCon _ _ -> return ()
927 SynonymTyCon ty -> checkValidType syn_ctxt ty
929 = -- Check the context on the data decl
930 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
932 -- Check arg types of data constructors
933 mappM_ (checkValidDataCon tc) data_cons `thenM_`
935 -- Check that fields with the same name share a type
936 mappM_ check_fields groups
939 syn_ctxt = TySynCtxt name
941 data_cons = tyConDataCons tc
943 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
944 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
945 get_fields con = dataConFieldLabels con `zip` repeat con
946 -- dataConFieldLabels may return the empty list, which is fine
948 -- See Note [GADT record selectors] in MkId.lhs
949 -- We must check (a) that the named field has the same
950 -- type in each constructor
951 -- (b) that those constructors have the same result type
953 -- However, the constructors may have differently named type variable
954 -- and (worse) we don't know how the correspond to each other. E.g.
955 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
956 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
958 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
959 -- result type against other candidates' types BOTH WAYS ROUND.
960 -- If they magically agrees, take the substitution and
961 -- apply them to the latter ones, and see if they match perfectly.
962 check_fields fields@((label, con1) : other_fields)
963 -- These fields all have the same name, but are from
964 -- different constructors in the data type
965 = recoverM (return ()) $ mapM_ checkOne other_fields
966 -- Check that all the fields in the group have the same type
967 -- NB: this check assumes that all the constructors of a given
968 -- data type use the same type variables
970 (tvs1, _, _, res1) = dataConSig con1
972 fty1 = dataConFieldType con1 label
974 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
975 = do { checkFieldCompat label con1 con2 ts1 res1 res2 fty1 fty2
976 ; checkFieldCompat label con2 con1 ts2 res2 res1 fty2 fty1 }
978 (tvs2, _, _, res2) = dataConSig con2
980 fty2 = dataConFieldType con2 label
982 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
983 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
984 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
986 mb_subst1 = tcMatchTy tvs1 res1 res2
987 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
989 -------------------------------
990 checkValidDataCon :: TyCon -> DataCon -> TcM ()
991 checkValidDataCon tc con
992 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
993 addErrCtxt (dataConCtxt con) $
994 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
995 ; checkValidType ctxt (dataConUserType con)
996 ; ifM (isNewTyCon tc) (checkNewDataCon con)
999 ctxt = ConArgCtxt (dataConName con)
1001 -------------------------------
1002 checkNewDataCon :: DataCon -> TcM ()
1003 -- Checks for the data constructor of a newtype
1005 = do { checkTc (isSingleton arg_tys) (newtypeFieldErr con (length arg_tys))
1007 ; checkTc (null eq_spec) (newtypePredError con)
1008 -- Return type is (T a b c)
1009 ; checkTc (null ex_tvs && null theta) (newtypeExError con)
1011 ; checkTc (not (any isMarkedStrict (dataConStrictMarks con)))
1012 (newtypeStrictError con)
1016 (_univ_tvs, ex_tvs, eq_spec, theta, arg_tys, _res_ty) = dataConFullSig con
1018 -------------------------------
1019 checkValidClass :: Class -> TcM ()
1021 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
1022 gla_exts <- doptM Opt_GlasgowExts
1024 -- Check that the class is unary, unless GlaExs
1025 ; checkTc (notNull tyvars) (nullaryClassErr cls)
1026 ; checkTc (gla_exts || unary) (classArityErr cls)
1028 -- Check the super-classes
1029 ; checkValidTheta (ClassSCCtxt (className cls)) theta
1031 -- Check the class operations
1032 ; mappM_ (check_op gla_exts) op_stuff
1034 -- Check that if the class has generic methods, then the
1035 -- class has only one parameter. We can't do generic
1036 -- multi-parameter type classes!
1037 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
1040 (tyvars, theta, _, op_stuff) = classBigSig cls
1041 unary = isSingleton tyvars
1042 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
1044 check_op gla_exts (sel_id, dm)
1045 = addErrCtxt (classOpCtxt sel_id tau) $ do
1046 { checkValidTheta SigmaCtxt (tail theta)
1047 -- The 'tail' removes the initial (C a) from the
1048 -- class itself, leaving just the method type
1050 ; checkValidType (FunSigCtxt op_name) tau
1052 -- Check that the type mentions at least one of
1053 -- the class type variables...or at least one reachable
1054 -- from one of the class variables. Example: tc223
1055 -- class Error e => Game b mv e | b -> mv e where
1056 -- newBoard :: MonadState b m => m ()
1057 -- Here, MonadState has a fundep m->b, so newBoard is fine
1058 ; let grown_tyvars = grow theta (mkVarSet tyvars)
1059 ; checkTc (tyVarsOfType tau `intersectsVarSet` grown_tyvars)
1060 (noClassTyVarErr cls sel_id)
1062 -- Check that for a generic method, the type of
1063 -- the method is sufficiently simple
1064 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1065 (badGenericMethodType op_name op_ty)
1068 op_name = idName sel_id
1069 op_ty = idType sel_id
1070 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1071 (_,theta2,tau2) = tcSplitSigmaTy tau1
1072 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1073 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1074 -- Ugh! The function might have a type like
1075 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1076 -- With -fglasgow-exts, we want to allow this, even though the inner
1077 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1078 -- in the context of a for-all must mention at least one quantified
1079 -- type variable. What a mess!
1082 ---------------------------------------------------------------------
1083 resultTypeMisMatch field_name con1 con2
1084 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1085 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1086 nest 2 $ ptext SLIT("but have different result types")]
1087 fieldTypeMisMatch field_name con1 con2
1088 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1089 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1091 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1093 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1094 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1097 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1100 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1101 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1103 noClassTyVarErr clas op
1104 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1105 ptext SLIT("mentions none of the type variables of the class") <+>
1106 ppr clas <+> hsep (map ppr (classTyVars clas))]
1108 genericMultiParamErr clas
1109 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1110 ptext SLIT("cannot have generic methods")
1112 badGenericMethodType op op_ty
1113 = hang (ptext SLIT("Generic method type is too complex"))
1114 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1115 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1118 = setSrcSpan (getLoc (head sorted_decls)) $
1119 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1120 nest 2 (vcat (map ppr_decl sorted_decls))])
1122 sorted_decls = sortLocated syn_decls
1123 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1126 = setSrcSpan (getLoc (head sorted_decls)) $
1127 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1128 nest 2 (vcat (map ppr_decl sorted_decls))])
1130 sorted_decls = sortLocated cls_decls
1131 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1133 sortLocated :: [Located a] -> [Located a]
1134 sortLocated things = sortLe le things
1136 le (L l1 _) (L l2 _) = l1 <= l2
1138 badDataConTyCon data_con
1139 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1140 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1141 2 (ptext SLIT("instead of its parent type"))
1144 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1145 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
1147 badStupidTheta tc_name
1148 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1150 newtypeConError tycon n
1151 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1152 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1155 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1156 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1158 newtypeStrictError con
1159 = sep [ptext SLIT("A newtype constructor cannot have a strictness annotation,"),
1160 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1162 newtypePredError con
1163 = sep [ptext SLIT("A newtype constructor must have a return type of form T a1 ... an"),
1164 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does not")]
1166 newtypeFieldErr con_name n_flds
1167 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1168 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1170 badSigTyDecl tc_name
1171 = vcat [ ptext SLIT("Illegal kind signature") <+>
1172 quotes (ppr tc_name)
1173 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow kind signatures")) ]
1175 badFamInstDecl tc_name
1176 = vcat [ ptext SLIT("Illegal family instance for") <+>
1177 quotes (ppr tc_name)
1178 , nest 2 (parens $ ptext SLIT("Use -ftype-families to allow indexed type families")) ]
1180 badGadtIdxTyDecl tc_name
1181 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1182 quotes (ppr tc_name)
1183 , nest 2 (parens $ ptext SLIT("Family instances can not yet use GADT declarations")) ]
1185 tooManyParmsErr tc_name
1186 = ptext SLIT("Family instance has too many parameters:") <+>
1187 quotes (ppr tc_name)
1189 tooFewParmsErr tc_name
1190 = ptext SLIT("Family instance has too few parameters:") <+>
1191 quotes (ppr tc_name)
1193 badBootFamInstDeclErr =
1194 ptext SLIT("Illegal family instance in hs-boot file")
1196 wrongKindOfFamily family =
1197 ptext SLIT("Wrong category of family instance; declaration was for a") <+>
1200 kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
1201 | isAlgTyCon family = ptext SLIT("data type")
1202 | otherwise = pprPanic "wrongKindOfFamily" (ppr family)
1204 emptyConDeclsErr tycon
1205 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1206 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]