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 indexed types; 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 -findexed-types and can't be in an
244 ; gla_exts <- doptM Opt_IndexedTypes
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
255 tcFamInstDecl1 (decl@TySynonym {})
256 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
257 do { -- check that the family declaration is for a synonym
258 unless (isSynTyCon family) $
259 addErr (wrongKindOfFamily family)
261 ; -- (1) kind check the right hand side of the type equation
262 ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
264 -- (2) type check type equation
265 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
266 ; t_typats <- mappM tcHsKindedType k_typats
267 ; t_rhs <- tcHsKindedType k_rhs
269 -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
270 ; return Nothing -- !!!TODO: need TyThing for indexed synonym
273 tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
275 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
276 do { -- check that the family declaration is for the right kind
277 unless (new_or_data == NewType && isNewTyCon family ||
278 new_or_data == DataType && isDataTyCon family) $
279 addErr (wrongKindOfFamily family)
281 ; -- (1) kind check the data declaration as usual
282 ; k_decl <- kcDataDecl decl k_tvs
283 ; let k_ctxt = tcdCtxt k_decl
284 k_cons = tcdCons k_decl
286 -- result kind must be '*' (otherwise, we have too few patterns)
287 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
289 -- (2) type check indexed data type declaration
290 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
291 ; unbox_strict <- doptM Opt_UnboxStrictFields
293 -- Check that we don't use GADT syntax for indexed types
294 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
296 -- Check that a newtype has exactly one constructor
297 ; checkTc (new_or_data == DataType || isSingleton k_cons) $
298 newtypeConError tc_name (length k_cons)
300 ; t_typats <- mappM tcHsKindedType k_typats
301 ; stupid_theta <- tcHsKindedContext k_ctxt
303 ; rep_tc_name <- newFamInstTyConName tc_name (srcSpanStart loc)
304 ; tycon <- fixM (\ tycon -> do
305 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
310 DataType -> return (mkDataTyConRhs data_cons)
311 NewType -> ASSERT( isSingleton data_cons )
312 mkNewTyConRhs tc_name tycon (head data_cons)
313 ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive
314 False h98_syntax (Just (family, t_typats))
315 -- We always assume that indexed types are recursive. Why?
316 -- (1) Due to their open nature, we can never be sure that a
317 -- further instance might not introduce a new recursive
318 -- dependency. (2) They are always valid loop breakers as
319 -- they involve a coercion.
323 ; return $ Just (ATyCon tycon)
326 h98_syntax = case cons of -- All constructors have same shape
327 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
330 -- Kind checking of indexed types
333 -- Kind check type patterns and kind annotate the embedded type variables.
335 -- * Here we check that a type instance matches its kind signature, but we do
336 -- not check whether there is a pattern for each type index; the latter
337 -- check is only required for type functions.
339 kcIdxTyPats :: TyClDecl Name
340 -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
341 -- ^^kinded tvs ^^kinded ty pats ^^res kind
343 kcIdxTyPats decl thing_inside
344 = kcHsTyVars (tcdTyVars decl) $ \tvs ->
345 do { family <- tcLookupLocatedTyCon (tcdLName decl)
346 ; let { (kinds, resKind) = splitKindFunTys (tyConKind family)
347 ; hs_typats = fromJust $ tcdTyPats decl }
349 -- we may not have more parameters than the kind indicates
350 ; checkTc (length kinds >= length hs_typats) $
351 tooManyParmsErr (tcdLName decl)
353 -- type functions can have a higher-kinded result
354 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
355 ; typats <- TcRnMonad.zipWithM kcCheckHsType hs_typats kinds
356 ; thing_inside tvs typats resultKind family
362 %************************************************************************
366 %************************************************************************
368 We need to kind check all types in the mutually recursive group
369 before we know the kind of the type variables. For example:
372 op :: D b => a -> b -> b
375 bop :: (Monad c) => ...
377 Here, the kind of the locally-polymorphic type variable "b"
378 depends on *all the uses of class D*. For example, the use of
379 Monad c in bop's type signature means that D must have kind Type->Type.
381 However type synonyms work differently. They can have kinds which don't
382 just involve (->) and *:
383 type R = Int# -- Kind #
384 type S a = Array# a -- Kind * -> #
385 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
386 So we must infer their kinds from their right-hand sides *first* and then
387 use them, whereas for the mutually recursive data types D we bring into
388 scope kind bindings D -> k, where k is a kind variable, and do inference.
392 This treatment of type synonyms only applies to Haskell 98-style synonyms.
393 General type functions can be recursive, and hence, appear in `alg_decls'.
395 The kind of a type family is solely determinded by its kind signature;
396 hence, only kind signatures participate in the construction of the initial
397 kind environment (as constructed by `getInitialKind'). In fact, we ignore
398 instances of families altogether in the following. However, we need to
399 include the kinds of associated families into the construction of the
400 initial kind environment. (This is handled by `allDecls').
403 kcTyClDecls syn_decls alg_decls
404 = do { -- First extend the kind env with each data type, class, and
405 -- indexed type, mapping them to a type variable
406 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
407 ; alg_kinds <- mappM getInitialKind initialKindDecls
408 ; tcExtendKindEnv alg_kinds $ do
410 -- Now kind-check the type synonyms, in dependency order
411 -- We do these differently to data type and classes,
412 -- because a type synonym can be an unboxed type
414 -- and a kind variable can't unify with UnboxedTypeKind
415 -- So we infer their kinds in dependency order
416 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
417 ; tcExtendKindEnv syn_kinds $ do
419 -- Now kind-check the data type, class, and kind signatures,
420 -- returning kind-annotated decls; we don't kind-check
421 -- instances of indexed types yet, but leave this to
423 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
424 (filter (not . isFamInstDecl . unLoc) alg_decls)
426 ; return (kc_syn_decls, kc_alg_decls) }}}
428 -- get all declarations relevant for determining the initial kind
430 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
433 allDecls decl | isFamInstDecl decl = []
436 ------------------------------------------------------------------------
437 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
438 -- Only for data type, class, and indexed type declarations
439 -- Get as much info as possible from the data, class, or indexed type decl,
440 -- so as to maximise usefulness of error messages
442 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
443 ; res_kind <- mk_res_kind decl
444 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
446 mk_arg_kind (UserTyVar _) = newKindVar
447 mk_arg_kind (KindedTyVar _ kind) = return kind
449 mk_res_kind (TyFamily { tcdKind = Just kind }) = return kind
450 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
451 -- On GADT-style declarations we allow a kind signature
452 -- data T :: *->* where { ... }
453 mk_res_kind other = return liftedTypeKind
457 kcSynDecls :: [SCC (LTyClDecl Name)]
458 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
459 [(Name,TcKind)]) -- Kind bindings
462 kcSynDecls (group : groups)
463 = do { (decl, nk) <- kcSynDecl group
464 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
465 ; return (decl:decls, nk:nks) }
468 kcSynDecl :: SCC (LTyClDecl Name)
469 -> TcM (LTyClDecl Name, -- Kind-annotated decls
470 (Name,TcKind)) -- Kind bindings
471 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
472 = tcAddDeclCtxt decl $
473 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
474 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
475 <+> brackets (ppr k_tvs))
476 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
477 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
478 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
479 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
480 (unLoc (tcdLName decl), tc_kind)) })
482 kcSynDecl (CyclicSCC decls)
483 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
484 -- of out-of-scope tycons
486 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
488 ------------------------------------------------------------------------
489 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
490 -- Not used for type synonyms (see kcSynDecl)
492 kcTyClDecl decl@(TyData {})
493 = ASSERT( not . isFamInstDecl $ decl ) -- must not be a family instance
494 kcTyClDeclBody decl $
497 kcTyClDecl decl@(TyFamily {tcdKind = kind})
498 = kcTyClDeclBody decl $ \ tvs' ->
499 return (decl {tcdTyVars = tvs',
500 tcdKind = kind `mplus` Just liftedTypeKind})
501 -- default result kind is '*'
503 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
504 = kcTyClDeclBody decl $ \ tvs' ->
505 do { is_boot <- tcIsHsBoot
506 ; ctxt' <- kcHsContext ctxt
507 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
508 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
509 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
512 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
513 ; return (TypeSig nm op_ty') }
514 kc_sig other_sig = return other_sig
516 kcTyClDecl decl@(ForeignType {})
519 kcTyClDeclBody :: TyClDecl Name
520 -> ([LHsTyVarBndr Name] -> TcM a)
522 -- getInitialKind has made a suitably-shaped kind for the type or class
523 -- Unpack it, and attribute those kinds to the type variables
524 -- Extend the env with bindings for the tyvars, taken from
525 -- the kind of the tycon/class. Give it to the thing inside, and
526 -- check the result kind matches
527 kcTyClDeclBody decl thing_inside
528 = tcAddDeclCtxt decl $
529 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
530 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
531 (kinds, _) = splitKindFunTys tc_kind
532 hs_tvs = tcdTyVars decl
533 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
534 [ L loc (KindedTyVar (hsTyVarName tv) k)
535 | (L loc tv, k) <- zip hs_tvs kinds]
536 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
538 -- Kind check a data declaration, assuming that we already extended the
539 -- kind environment with the type variables of the left-hand side (these
540 -- kinded type variables are also passed as the second parameter).
542 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
543 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
545 = do { ctxt' <- kcHsContext ctxt
546 ; cons' <- mappM (wrapLocM kc_con_decl) cons
547 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
549 -- doc comments are typechecked to Nothing here
550 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res _) = do
551 kcHsTyVars ex_tvs $ \ex_tvs' -> do
552 ex_ctxt' <- kcHsContext ex_ctxt
553 details' <- kc_con_details details
555 ResTyH98 -> return ResTyH98
556 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
557 return (ConDecl name expl ex_tvs' ex_ctxt' details' res' Nothing)
559 kc_con_details (PrefixCon btys)
560 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
561 kc_con_details (InfixCon bty1 bty2)
562 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
563 kc_con_details (RecCon fields)
564 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
566 kc_field (HsRecField fld bty d) = do { bty' <- kc_larg_ty bty ; return (HsRecField fld bty' d) }
568 kc_larg_ty bty = case new_or_data of
569 DataType -> kcHsSigType bty
570 NewType -> kcHsLiftedSigType bty
571 -- Can't allow an unlifted type for newtypes, because we're effectively
572 -- going to remove the constructor while coercing it to a lifted type.
573 -- And newtypes can't be bang'd
577 %************************************************************************
579 \subsection{Type checking}
581 %************************************************************************
584 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
585 tcSynDecls [] = return []
586 tcSynDecls (decl : decls)
587 = do { syn_tc <- addLocM tcSynDecl decl
588 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
589 ; return (syn_tc : syn_tcs) }
592 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
593 = tcTyVarBndrs tvs $ \ tvs' -> do
594 { traceTc (text "tcd1" <+> ppr tc_name)
595 ; rhs_ty' <- tcHsKindedType rhs_ty
596 ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
599 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
601 tcTyClDecl calc_isrec decl
602 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
604 -- "type family" declarations
605 tcTyClDecl1 _calc_isrec
606 (TyFamily {tcdFlavour = TypeFamily,
607 tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = Just kind})
608 -- NB: kind at latest
611 = tcTyVarBndrs tvs $ \ tvs' -> do
612 { traceTc (text "type family: " <+> ppr tc_name)
613 ; idx_tys <- doptM Opt_IndexedTypes
615 -- Check that we don't use families without -findexed-types
616 ; checkTc idx_tys $ badFamInstDecl tc_name
618 ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)]
621 -- "newtype family" or "data family" declaration
622 tcTyClDecl1 _calc_isrec
623 (TyFamily {tcdFlavour = DataFamily new_or_data,
624 tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = mb_kind})
625 = tcTyVarBndrs tvs $ \ tvs' -> do
626 { traceTc (text "data/newtype family: " <+> ppr tc_name)
627 ; extra_tvs <- tcDataKindSig mb_kind
628 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
630 ; idx_tys <- doptM Opt_IndexedTypes
632 -- Check that we don't use families without -findexed-types
633 ; checkTc idx_tys $ badFamInstDecl tc_name
635 ; tycon <- buildAlgTyCon tc_name final_tvs []
637 DataType -> OpenDataTyCon
638 NewType -> OpenNewTyCon)
639 Recursive False True Nothing
640 ; return [ATyCon tycon]
643 -- "newtype", "data", "newtype instance", "data instance"
644 tcTyClDecl1 calc_isrec
645 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
646 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
647 = tcTyVarBndrs tvs $ \ tvs' -> do
648 { extra_tvs <- tcDataKindSig mb_ksig
649 ; let final_tvs = tvs' ++ extra_tvs
650 ; stupid_theta <- tcHsKindedContext ctxt
651 ; want_generic <- doptM Opt_Generics
652 ; unbox_strict <- doptM Opt_UnboxStrictFields
653 ; gla_exts <- doptM Opt_GlasgowExts
654 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
656 -- Check that we don't use GADT syntax in H98 world
657 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
659 -- Check that we don't use kind signatures without Glasgow extensions
660 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
662 -- Check that the stupid theta is empty for a GADT-style declaration
663 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
665 -- Check that there's at least one condecl,
666 -- or else we're reading an hs-boot file, or -fglasgow-exts
667 ; checkTc (not (null cons) || gla_exts || is_boot)
668 (emptyConDeclsErr tc_name)
670 -- Check that a newtype has exactly one constructor
671 ; checkTc (new_or_data == DataType || isSingleton cons)
672 (newtypeConError tc_name (length cons))
674 ; tycon <- fixM (\ tycon -> do
675 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
679 if null cons && is_boot -- In a hs-boot file, empty cons means
680 then return AbstractTyCon -- "don't know"; hence Abstract
681 else case new_or_data of
682 DataType -> return (mkDataTyConRhs data_cons)
684 ASSERT( isSingleton data_cons )
685 mkNewTyConRhs tc_name tycon (head data_cons)
686 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
687 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
689 ; return [ATyCon tycon]
692 is_rec = calc_isrec tc_name
693 h98_syntax = case cons of -- All constructors have same shape
694 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
697 tcTyClDecl1 calc_isrec
698 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
699 tcdCtxt = ctxt, tcdMeths = meths,
700 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
701 = tcTyVarBndrs tvs $ \ tvs' -> do
702 { ctxt' <- tcHsKindedContext ctxt
703 ; fds' <- mappM (addLocM tc_fundep) fundeps
704 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
705 ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
706 ; sig_stuff <- tcClassSigs class_name sigs meths
707 ; clas <- fixM (\ clas ->
708 let -- This little knot is just so we can get
709 -- hold of the name of the class TyCon, which we
710 -- need to look up its recursiveness
711 tycon_name = tyConName (classTyCon clas)
712 tc_isrec = calc_isrec tycon_name
714 buildClass class_name tvs' ctxt' fds' ats'
716 ; return (AClass clas : ats')
717 -- NB: Order is important due to the call to `mkGlobalThings' when
718 -- tying the the type and class declaration type checking knot.
721 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
722 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
723 ; return (tvs1', tvs2') }
725 -- For each AT argument compute the position of the corresponding class
726 -- parameter in the class head. This will later serve as a permutation
727 -- vector when checking the validity of instance declarations.
728 setTyThingPoss [ATyCon tycon] atTyVars =
729 let classTyVars = hsLTyVarNames tvs
731 . map (`elemIndex` classTyVars)
734 -- There will be no Nothing, as we already passed renaming
736 ATyCon (setTyConArgPoss tycon poss)
737 setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
739 tcTyClDecl1 calc_isrec
740 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
741 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
743 -----------------------------------
744 tcConDecl :: Bool -- True <=> -funbox-strict_fields
750 tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
751 (ConDecl name _ ex_tvs ex_ctxt details ResTyH98 _)
752 = do { let tc_datacon field_lbls arg_ty
753 = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
754 ; buildDataCon (unLoc name) False {- Prefix -}
756 (map unLoc field_lbls)
757 tc_tvs [] -- No existentials
758 [] [] -- No equalities, predicates
762 -- Check that a newtype has no existential stuff
763 ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
766 PrefixCon [arg_ty] -> tc_datacon [] arg_ty
767 RecCon [HsRecField field_lbl arg_ty _] -> tc_datacon [field_lbl] arg_ty
769 failWithTc (newtypeFieldErr name (length (hsConArgs details)))
770 -- Check that the constructor has exactly one field
773 tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
774 (ConDecl name _ tvs ctxt details res_ty _)
775 = tcTyVarBndrs tvs $ \ tvs' -> do
776 { ctxt' <- tcHsKindedContext ctxt
777 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
779 -- Tiresome: tidy the tyvar binders, since tc_tvs and tvs' may have the same OccNames
780 tc_datacon is_infix field_lbls btys
781 = do { let bangs = map getBangStrictness btys
782 ; arg_tys <- mappM tcHsBangType btys
783 ; buildDataCon (unLoc name) is_infix
784 (argStrictness unbox_strict bangs arg_tys)
785 (map unLoc field_lbls)
786 univ_tvs ex_tvs eq_preds ctxt' arg_tys
788 -- NB: we put data_tc, the type constructor gotten from the
789 -- constructor type signature into the data constructor;
790 -- that way checkValidDataCon can complain if it's wrong.
793 PrefixCon btys -> tc_datacon False [] btys
794 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
795 RecCon fields -> tc_datacon False field_names btys
797 (field_names, btys) = unzip [ (n, t) | HsRecField n t _ <- fields ]
801 tcResultType :: TyCon
802 -> [TyVar] -- data T a b c = ...
803 -> [TyVar] -- where MkT :: forall a b c. ...
805 -> TcM ([TyVar], -- Universal
806 [TyVar], -- Existential (distinct OccNames from univs)
807 [(TyVar,Type)], -- Equality predicates
808 TyCon) -- TyCon given in the ResTy
809 -- We don't check that the TyCon given in the ResTy is
810 -- the same as the parent tycon, becuase we are in the middle
811 -- of a recursive knot; so it's postponed until checkValidDataCon
813 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
814 = return (tc_tvs, dc_tvs, [], decl_tycon)
815 -- In H98 syntax the dc_tvs are the existential ones
816 -- data T a b c = forall d e. MkT ...
817 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
819 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
820 -- E.g. data T a b c where
821 -- MkT :: forall x y z. T (x,y) z z
823 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
825 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
827 ; let univ_tvs = choose_univs [] tidy_tc_tvs res_tys
828 -- Each univ_tv is either a dc_tv or a tc_tv
829 ex_tvs = dc_tvs `minusList` univ_tvs
830 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
832 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
834 -- choose_univs uses the res_ty itself if it's a type variable
835 -- and hasn't already been used; otherwise it uses one of the tc_tvs
836 choose_univs used tc_tvs []
837 = ASSERT( null tc_tvs ) []
838 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
839 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
840 = tv : choose_univs (tv:used) tc_tvs res_tys
842 = tc_tv : choose_univs used tc_tvs res_tys
844 -- NB: tc_tvs and dc_tvs are distinct, but
845 -- we want them to be *visibly* distinct, both for
846 -- interface files and general confusion. So rename
847 -- the tc_tvs, since they are not used yet (no
848 -- consequential renaming needed)
849 init_occ_env = initTidyOccEnv (map getOccName dc_tvs)
850 (_, tidy_tc_tvs) = mapAccumL tidy_one init_occ_env tc_tvs
851 tidy_one env tv = (env', setTyVarName tv (tidyNameOcc name occ'))
854 (env', occ') = tidyOccName env (getOccName name)
857 argStrictness :: Bool -- True <=> -funbox-strict_fields
859 -> [TcType] -> [StrictnessMark]
860 argStrictness unbox_strict bangs arg_tys
861 = ASSERT( length bangs == length arg_tys )
862 zipWith (chooseBoxingStrategy unbox_strict) arg_tys bangs
864 -- We attempt to unbox/unpack a strict field when either:
865 -- (i) The field is marked '!!', or
866 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
868 -- We have turned off unboxing of newtypes because coercions make unboxing
869 -- and reboxing more complicated
870 chooseBoxingStrategy :: Bool -> TcType -> HsBang -> StrictnessMark
871 chooseBoxingStrategy unbox_strict_fields arg_ty bang
873 HsNoBang -> NotMarkedStrict
874 HsStrict | unbox_strict_fields
875 && can_unbox arg_ty -> MarkedUnboxed
876 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
877 other -> MarkedStrict
879 -- we can unbox if the type is a chain of newtypes with a product tycon
881 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
883 Just (arg_tycon, tycon_args) ->
884 not (isRecursiveTyCon arg_tycon) && -- Note [Recusive unboxing]
885 isProductTyCon arg_tycon &&
886 (if isNewTyCon arg_tycon then
887 can_unbox (newTyConInstRhs arg_tycon tycon_args)
891 Note [Recursive unboxing]
892 ~~~~~~~~~~~~~~~~~~~~~~~~~
893 Be careful not to try to unbox this!
895 But it's the *argument* type that matters. This is fine:
897 because Int is non-recursive.
899 %************************************************************************
901 \subsection{Dependency analysis}
903 %************************************************************************
905 Validity checking is done once the mutually-recursive knot has been
906 tied, so we can look at things freely.
909 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
910 checkCycleErrs tyclss
914 = do { mappM_ recClsErr cls_cycles
915 ; failM } -- Give up now, because later checkValidTyCl
916 -- will loop if the synonym is recursive
918 cls_cycles = calcClassCycles tyclss
920 checkValidTyCl :: TyClDecl Name -> TcM ()
921 -- We do the validity check over declarations, rather than TyThings
922 -- only so that we can add a nice context with tcAddDeclCtxt
924 = tcAddDeclCtxt decl $
925 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
926 ; traceTc (text "Validity of" <+> ppr thing)
928 ATyCon tc -> checkValidTyCon tc
929 AClass cl -> checkValidClass cl
930 ; traceTc (text "Done validity of" <+> ppr thing)
933 -------------------------
934 -- For data types declared with record syntax, we require
935 -- that each constructor that has a field 'f'
936 -- (a) has the same result type
937 -- (b) has the same type for 'f'
938 -- module alpha conversion of the quantified type variables
939 -- of the constructor.
941 checkValidTyCon :: TyCon -> TcM ()
944 = case synTyConRhs tc of
945 OpenSynTyCon _ -> return ()
946 SynonymTyCon ty -> checkValidType syn_ctxt ty
948 = -- Check the context on the data decl
949 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
951 -- Check arg types of data constructors
952 mappM_ (checkValidDataCon tc) data_cons `thenM_`
954 -- Check that fields with the same name share a type
955 mappM_ check_fields groups
958 syn_ctxt = TySynCtxt name
960 data_cons = tyConDataCons tc
962 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
963 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
964 get_fields con = dataConFieldLabels con `zip` repeat con
965 -- dataConFieldLabels may return the empty list, which is fine
967 -- See Note [GADT record selectors] in MkId.lhs
968 -- We must check (a) that the named field has the same
969 -- type in each constructor
970 -- (b) that those constructors have the same result type
972 -- However, the constructors may have differently named type variable
973 -- and (worse) we don't know how the correspond to each other. E.g.
974 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
975 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
977 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
978 -- result type against other candidates' types BOTH WAYS ROUND.
979 -- If they magically agrees, take the substitution and
980 -- apply them to the latter ones, and see if they match perfectly.
981 check_fields fields@((label, con1) : other_fields)
982 -- These fields all have the same name, but are from
983 -- different constructors in the data type
984 = recoverM (return ()) $ mapM_ checkOne other_fields
985 -- Check that all the fields in the group have the same type
986 -- NB: this check assumes that all the constructors of a given
987 -- data type use the same type variables
989 tvs1 = mkVarSet (dataConAllTyVars con1)
990 res1 = dataConResTys con1
991 fty1 = dataConFieldType con1 label
993 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
994 = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
995 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
997 tvs2 = mkVarSet (dataConAllTyVars con2)
998 res2 = dataConResTys con2
999 fty2 = dataConFieldType con2 label
1001 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
1002 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
1003 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
1005 mb_subst1 = tcMatchTys tvs1 res1 res2
1006 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
1008 -------------------------------
1009 checkValidDataCon :: TyCon -> DataCon -> TcM ()
1010 checkValidDataCon tc con
1011 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
1012 addErrCtxt (dataConCtxt con) $
1013 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
1014 ; checkValidType ctxt (dataConUserType con) }
1016 ctxt = ConArgCtxt (dataConName 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 newtypeFieldErr con_name n_flds
1159 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1160 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1162 badSigTyDecl tc_name
1163 = vcat [ ptext SLIT("Illegal kind signature") <+>
1164 quotes (ppr tc_name)
1165 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow kind signatures")) ]
1167 badFamInstDecl tc_name
1168 = vcat [ ptext SLIT("Illegal family instance for") <+>
1169 quotes (ppr tc_name)
1170 , nest 2 (parens $ ptext SLIT("Use -findexed-types to allow indexed type families")) ]
1172 badGadtIdxTyDecl tc_name
1173 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1174 quotes (ppr tc_name)
1175 , nest 2 (parens $ ptext SLIT("Family instances can not yet use GADT declarations")) ]
1177 tooManyParmsErr tc_name
1178 = ptext SLIT("Family instance has too many parameters:") <+>
1179 quotes (ppr tc_name)
1181 tooFewParmsErr tc_name
1182 = ptext SLIT("Family instance has too few parameters:") <+>
1183 quotes (ppr tc_name)
1185 badBootFamInstDeclErr =
1186 ptext SLIT("Illegal family instance in hs-boot file")
1188 wrongKindOfFamily family =
1189 ptext SLIT("Wrong category of family instance; declaration was for a") <+>
1192 kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
1193 | isDataTyCon family = ptext SLIT("data type")
1194 | isNewTyCon family = ptext SLIT("newtype")
1196 emptyConDeclsErr tycon
1197 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1198 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]