2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcTyClsDecls]{Typecheck type and class declarations}
8 tcTyAndClassDecls, tcIdxTyInstDecl
11 #include "HsVersions.h"
13 import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
14 ConDecl(..), HsRecField(..), Sig(..), NewOrData(..), ResType(..),
15 tyClDeclTyVars, isSynDecl, isIdxTyDecl,
16 isKindSigDecl, hsConArgs, LTyClDecl, tcdName,
17 hsTyVarName, LHsTyVarBndr, LHsType
19 import HsTypes ( HsBang(..), getBangStrictness, hsLTyVarNames )
20 import BasicTypes ( RecFlag(..), StrictnessMark(..) )
21 import HscTypes ( implicitTyThings, ModDetails )
22 import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon,
23 mkDataTyConRhs, mkNewTyConRhs )
25 import TcEnv ( TyThing(..),
26 tcLookupLocated, tcLookupLocatedGlobal,
27 tcExtendGlobalEnv, tcExtendKindEnv,
28 tcExtendKindEnvTvs, newFamInstTyConName,
29 tcExtendRecEnv, tcLookupTyVar, tcLookupLocatedTyCon )
30 import TcTyDecls ( calcRecFlags, calcClassCycles, calcSynCycles )
31 import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
32 import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
33 kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
34 kcHsSigType, tcHsBangType, tcLHsConResTy,
35 tcDataKindSig, kcCheckHsType )
36 import TcMType ( newKindVar, checkValidTheta, checkValidType,
38 UserTypeCtxt(..), SourceTyCtxt(..) )
39 import TcType ( TcKind, TcType, Type, tyVarsOfType, mkPhiTy,
40 mkArrowKind, liftedTypeKind,
41 tcSplitSigmaTy, tcGetTyVar_maybe )
42 import Type ( splitTyConApp_maybe,
43 newTyConInstRhs, isLiftedTypeKind, Kind,
44 splitKindFunTys, mkArrowKinds
45 -- pprParendType, pprThetaArrow
47 import Generics ( validGenericMethodType, canDoGenerics )
48 import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars )
49 import TyCon ( TyCon, AlgTyConRhs( AbstractTyCon, OpenDataTyCon,
51 SynTyConRhs( OpenSynTyCon, SynonymTyCon ),
52 tyConDataCons, mkForeignTyCon, isProductTyCon,
54 tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName,
55 isNewTyCon, isDataTyCon, tyConKind,
57 import DataCon ( DataCon, dataConUserType, dataConName,
58 dataConFieldLabels, dataConTyCon, dataConAllTyVars,
59 dataConFieldType, dataConResTys )
60 import Var ( TyVar, idType, idName, tyVarName, setTyVarName )
61 import VarSet ( elemVarSet, mkVarSet )
62 import Name ( Name, getSrcLoc, tidyNameOcc, getOccName )
63 import OccName ( initTidyOccEnv, tidyOccName )
65 import Maybe ( isJust, fromJust, isNothing, catMaybes )
66 import Maybes ( expectJust )
67 import Monad ( unless )
68 import Unify ( tcMatchTys, tcMatchTyX )
69 import Util ( zipLazy, isSingleton, notNull, sortLe, mapAccumL )
70 import List ( partition, elemIndex )
71 import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan,
73 import ListSetOps ( equivClasses, minusList )
74 import Digraph ( SCC(..) )
75 import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
76 Opt_UnboxStrictFields, Opt_IndexedTypes ) )
80 %************************************************************************
82 \subsection{Type checking for type and class declarations}
84 %************************************************************************
88 Consider a mutually-recursive group, binding
89 a type constructor T and a class C.
91 Step 1: getInitialKind
92 Construct a KindEnv by binding T and C to a kind variable
95 In that environment, do a kind check
97 Step 3: Zonk the kinds
99 Step 4: buildTyConOrClass
100 Construct an environment binding T to a TyCon and C to a Class.
101 a) Their kinds comes from zonking the relevant kind variable
102 b) Their arity (for synonyms) comes direct from the decl
103 c) The funcional dependencies come from the decl
104 d) The rest comes a knot-tied binding of T and C, returned from Step 4
105 e) The variances of the tycons in the group is calculated from
109 In this environment, walk over the decls, constructing the TyCons and Classes.
110 This uses in a strict way items (a)-(c) above, which is why they must
111 be constructed in Step 4. Feed the results back to Step 4.
112 For this step, pass the is-recursive flag as the wimp-out flag
116 Step 6: Extend environment
117 We extend the type environment with bindings not only for the TyCons and Classes,
118 but also for their "implicit Ids" like data constructors and class selectors
120 Step 7: checkValidTyCl
121 For a recursive group only, check all the decls again, just
122 to check all the side conditions on validity. We could not
123 do this before because we were in a mutually recursive knot.
125 Identification of recursive TyCons
126 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
127 The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
130 Identifying a TyCon as recursive serves two purposes
132 1. Avoid infinite types. Non-recursive newtypes are treated as
133 "transparent", like type synonyms, after the type checker. If we did
134 this for all newtypes, we'd get infinite types. So we figure out for
135 each newtype whether it is "recursive", and add a coercion if so. In
136 effect, we are trying to "cut the loops" by identifying a loop-breaker.
138 2. Avoid infinite unboxing. This is nothing to do with newtypes.
142 Well, this function diverges, but we don't want the strictness analyser
143 to diverge. But the strictness analyser will diverge because it looks
144 deeper and deeper into the structure of T. (I believe there are
145 examples where the function does something sane, and the strictness
146 analyser still diverges, but I can't see one now.)
148 Now, concerning (1), the FC2 branch currently adds a coercion for ALL
149 newtypes. I did this as an experiment, to try to expose cases in which
150 the coercions got in the way of optimisations. If it turns out that we
151 can indeed always use a coercion, then we don't risk recursive types,
152 and don't need to figure out what the loop breakers are.
154 For newtype *families* though, we will always have a coercion, so they
155 are always loop breakers! So you can easily adjust the current
156 algorithm by simply treating all newtype families as loop breakers (and
157 indeed type families). I think.
160 tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
161 -> TcM TcGblEnv -- Input env extended by types and classes
162 -- and their implicit Ids,DataCons
163 tcTyAndClassDecls boot_details allDecls
164 = do { -- Omit instances of indexed types; they are handled together
165 -- with the *heads* of class instances
166 ; let decls = filter (not . isIdxTyDecl . unLoc) allDecls
168 -- First check for cyclic type synonysm or classes
169 -- See notes with checkCycleErrs
170 ; checkCycleErrs decls
172 ; traceTc (text "tcTyAndCl" <+> ppr mod)
173 ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
174 do { let { -- Seperate ordinary synonyms from all other type and
175 -- class declarations and add all associated type
176 -- declarations from type classes. The latter is
177 -- required so that the temporary environment for the
178 -- knot includes all associated family declarations.
179 ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc)
181 ; alg_at_decls = concatMap addATs alg_decls
183 -- Extend the global env with the knot-tied results
184 -- for data types and classes
186 -- We must populate the environment with the loop-tied
187 -- T's right away, because the kind checker may "fault
188 -- in" some type constructors that recursively
190 ; let gbl_things = mkGlobalThings alg_at_decls rec_alg_tyclss
191 ; tcExtendRecEnv gbl_things $ do
193 -- Kind-check the declarations
194 { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
196 ; let { -- Calculate rec-flag
197 ; calc_rec = calcRecFlags boot_details rec_alg_tyclss
198 ; tc_decl = addLocM (tcTyClDecl calc_rec) }
199 -- Type-check the type synonyms, and extend the envt
200 ; syn_tycons <- tcSynDecls kc_syn_decls
201 ; tcExtendGlobalEnv syn_tycons $ do
203 -- Type-check the data types and classes
204 { alg_tyclss <- mappM tc_decl kc_alg_decls
205 ; return (syn_tycons, concat alg_tyclss)
207 -- Finished with knot-tying now
208 -- Extend the environment with the finished things
209 ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
211 -- Perform the validity check
212 { traceTc (text "ready for validity check")
213 ; mappM_ (addLocM checkValidTyCl) decls
214 ; traceTc (text "done")
216 -- Add the implicit things;
217 -- we want them in the environment because
218 -- they may be mentioned in interface files
219 -- NB: All associated types and their implicit things will be added a
220 -- second time here. This doesn't matter as the definitions are
222 ; let { implicit_things = concatMap implicitTyThings alg_tyclss }
223 ; traceTc ((text "Adding" <+> ppr alg_tyclss)
224 $$ (text "and" <+> ppr implicit_things))
225 ; tcExtendGlobalEnv implicit_things getGblEnv
228 -- Pull associated types out of class declarations, to tie them into the
230 -- NB: We put them in the same place in the list as `tcTyClDecl' will
231 -- eventually put the matching `TyThing's. That's crucial; otherwise,
232 -- the two argument lists of `mkGlobalThings' don't match up.
233 addATs decl@(L _ (ClassDecl {tcdATs = ats})) = decl : ats
236 mkGlobalThings :: [LTyClDecl Name] -- The decls
237 -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
239 -- Driven by the Decls, and treating the TyThings lazily
240 -- make a TypeEnv for the new things
241 mkGlobalThings decls things
242 = map mk_thing (decls `zipLazy` things)
244 mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
246 mk_thing (L _ decl, ~(ATyCon tc))
247 = (tcdName decl, ATyCon tc)
251 %************************************************************************
253 \subsection{Type checking instances of indexed types}
255 %************************************************************************
257 Instances of indexed types are somewhat of a hybrid. They are processed
258 together with class instance heads, but can contain data constructors and hence
259 they share a lot of kinding and type checking code with ordinary algebraic
260 data types (and GADTs).
263 tcIdxTyInstDecl :: LTyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
264 tcIdxTyInstDecl (L loc decl)
265 = -- Prime error recovery, set source location
266 recoverM (returnM Nothing) $
269 do { -- indexed data types require -findexed-types and can't be in an
271 ; gla_exts <- doptM Opt_IndexedTypes
272 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
273 ; checkTc gla_exts $ badIdxTyDecl (tcdLName decl)
274 ; checkTc (not is_boot) $ badBootTyIdxDeclErr
276 -- perform kind and type checking
277 ; tcIdxTyInstDecl1 decl
280 tcIdxTyInstDecl1 :: TyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
282 tcIdxTyInstDecl1 (decl@TySynonym {})
283 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
284 do { -- check that the family declaration is for a synonym
285 unless (isSynTyCon family) $
286 addErr (wrongKindOfFamily family)
288 ; -- (1) kind check the right hand side of the type equation
289 ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
291 -- (2) type check type equation
292 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
293 ; t_typats <- mappM tcHsKindedType k_typats
294 ; t_rhs <- tcHsKindedType k_rhs
296 -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
297 ; return Nothing -- !!!TODO: need TyThing for indexed synonym
300 tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
302 = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
303 do { -- check that the family declaration is for the right kind
304 unless (new_or_data == NewType && isNewTyCon family ||
305 new_or_data == DataType && isDataTyCon family) $
306 addErr (wrongKindOfFamily family)
308 ; -- (1) kind check the data declaration as usual
309 ; k_decl <- kcDataDecl decl k_tvs
310 ; let k_ctxt = tcdCtxt k_decl
311 k_cons = tcdCons k_decl
313 -- result kind must be '*' (otherwise, we have too few patterns)
314 ; checkTc (isLiftedTypeKind resKind) $ tooFewParmsErr tc_name
316 -- (2) type check indexed data type declaration
317 ; tcTyVarBndrs k_tvs $ \t_tvs -> do { -- turn kinded into proper tyvars
318 ; unbox_strict <- doptM Opt_UnboxStrictFields
320 -- Check that we don't use GADT syntax for indexed types
321 ; checkTc h98_syntax (badGadtIdxTyDecl tc_name)
323 -- Check that a newtype has exactly one constructor
324 ; checkTc (new_or_data == DataType || isSingleton k_cons) $
325 newtypeConError tc_name (length k_cons)
327 ; t_typats <- mappM tcHsKindedType k_typats
328 ; stupid_theta <- tcHsKindedContext k_ctxt
330 ; rep_tc_name <- newFamInstTyConName tc_name (srcSpanStart loc)
331 ; tycon <- fixM (\ tycon -> do
332 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
337 DataType -> return (mkDataTyConRhs data_cons)
338 NewType -> ASSERT( isSingleton data_cons )
339 mkNewTyConRhs tc_name tycon (head data_cons)
340 ; buildAlgTyCon rep_tc_name t_tvs stupid_theta tc_rhs Recursive
341 False h98_syntax (Just (family, t_typats))
342 -- We always assume that indexed types are recursive. Why?
343 -- (1) Due to their open nature, we can never be sure that a
344 -- further instance might not introduce a new recursive
345 -- dependency. (2) They are always valid loop breakers as
346 -- they involve a coercion.
350 ; return $ Just (ATyCon tycon)
353 h98_syntax = case cons of -- All constructors have same shape
354 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
357 -- Kind checking of indexed types
360 -- Kind check type patterns and kind annotate the embedded type variables.
362 -- * Here we check that a type instance matches its kind signature, but we do
363 -- not check whether there is a pattern for each type index; the latter
364 -- check is only required for type functions.
366 kcIdxTyPats :: TyClDecl Name
367 -> ([LHsTyVarBndr Name] -> [LHsType Name] -> Kind -> TyCon -> TcM a)
368 -- ^^kinded tvs ^^kinded ty pats ^^res kind
370 kcIdxTyPats decl thing_inside
371 = kcHsTyVars (tcdTyVars decl) $ \tvs ->
372 do { family <- tcLookupLocatedTyCon (tcdLName decl)
373 ; let { (kinds, resKind) = splitKindFunTys (tyConKind family)
374 ; hs_typats = fromJust $ tcdTyPats decl }
376 -- we may not have more parameters than the kind indicates
377 ; checkTc (length kinds >= length hs_typats) $
378 tooManyParmsErr (tcdLName decl)
380 -- type functions can have a higher-kinded result
381 ; let resultKind = mkArrowKinds (drop (length hs_typats) kinds) resKind
382 ; typats <- zipWithM kcCheckHsType hs_typats kinds
383 ; thing_inside tvs typats resultKind family
389 %************************************************************************
393 %************************************************************************
395 We need to kind check all types in the mutually recursive group
396 before we know the kind of the type variables. For example:
399 op :: D b => a -> b -> b
402 bop :: (Monad c) => ...
404 Here, the kind of the locally-polymorphic type variable "b"
405 depends on *all the uses of class D*. For example, the use of
406 Monad c in bop's type signature means that D must have kind Type->Type.
408 However type synonyms work differently. They can have kinds which don't
409 just involve (->) and *:
410 type R = Int# -- Kind #
411 type S a = Array# a -- Kind * -> #
412 type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
413 So we must infer their kinds from their right-hand sides *first* and then
414 use them, whereas for the mutually recursive data types D we bring into
415 scope kind bindings D -> k, where k is a kind variable, and do inference.
419 This treatment of type synonyms only applies to Haskell 98-style synonyms.
420 General type functions can be recursive, and hence, appear in `alg_decls'.
422 The kind of an indexed type is solely determinded by its kind signature;
423 hence, only kind signatures participate in the construction of the initial
424 kind environment (as constructed by `getInitialKind'). In fact, we ignore
425 instances of indexed types altogether in the following. However, we need to
426 include the kind signatures of associated types into the construction of the
427 initial kind environment. (This is handled by `allDecls').
430 kcTyClDecls syn_decls alg_decls
431 = do { -- First extend the kind env with each data type, class, and
432 -- indexed type, mapping them to a type variable
433 let initialKindDecls = concat [allDecls decl | L _ decl <- alg_decls]
434 ; alg_kinds <- mappM getInitialKind initialKindDecls
435 ; tcExtendKindEnv alg_kinds $ do
437 -- Now kind-check the type synonyms, in dependency order
438 -- We do these differently to data type and classes,
439 -- because a type synonym can be an unboxed type
441 -- and a kind variable can't unify with UnboxedTypeKind
442 -- So we infer their kinds in dependency order
443 { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
444 ; tcExtendKindEnv syn_kinds $ do
446 -- Now kind-check the data type, class, and kind signatures,
447 -- returning kind-annotated decls; we don't kind-check
448 -- instances of indexed types yet, but leave this to
450 { kc_alg_decls <- mappM (wrapLocM kcTyClDecl)
451 (filter (not . isIdxTyDecl . unLoc) alg_decls)
453 ; return (kc_syn_decls, kc_alg_decls) }}}
455 -- get all declarations relevant for determining the initial kind
457 allDecls (decl@ClassDecl {tcdATs = ats}) = decl : [ at
460 allDecls decl | isIdxTyDecl decl = []
463 ------------------------------------------------------------------------
464 getInitialKind :: TyClDecl Name -> TcM (Name, TcKind)
465 -- Only for data type, class, and indexed type declarations
466 -- Get as much info as possible from the data, class, or indexed type decl,
467 -- so as to maximise usefulness of error messages
469 = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
470 ; res_kind <- mk_res_kind decl
471 ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
473 mk_arg_kind (UserTyVar _) = newKindVar
474 mk_arg_kind (KindedTyVar _ kind) = return kind
476 mk_res_kind (TyFunction { tcdKind = kind }) = return kind
477 mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
478 -- On GADT-style and data signature declarations we allow a kind
480 -- data T :: *->* where { ... }
481 mk_res_kind other = return liftedTypeKind
485 kcSynDecls :: [SCC (LTyClDecl Name)]
486 -> TcM ([LTyClDecl Name], -- Kind-annotated decls
487 [(Name,TcKind)]) -- Kind bindings
490 kcSynDecls (group : groups)
491 = do { (decl, nk) <- kcSynDecl group
492 ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
493 ; return (decl:decls, nk:nks) }
496 kcSynDecl :: SCC (LTyClDecl Name)
497 -> TcM (LTyClDecl Name, -- Kind-annotated decls
498 (Name,TcKind)) -- Kind bindings
499 kcSynDecl (AcyclicSCC ldecl@(L loc decl))
500 = tcAddDeclCtxt decl $
501 kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
502 do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
503 <+> brackets (ppr k_tvs))
504 ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
505 ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
506 ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
507 ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
508 (unLoc (tcdLName decl), tc_kind)) })
510 kcSynDecl (CyclicSCC decls)
511 = do { recSynErr decls; failM } -- Fail here to avoid error cascade
512 -- of out-of-scope tycons
514 kindedTyVarKind (L _ (KindedTyVar _ k)) = k
516 ------------------------------------------------------------------------
517 kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
518 -- Not used for type synonyms (see kcSynDecl)
520 kcTyClDecl decl@(TyData {})
521 = ASSERT( not . isJust $ tcdTyPats decl ) -- must not be instance of idx ty
522 kcTyClDeclBody decl $
525 kcTyClDecl decl@(TyFunction {})
526 = kcTyClDeclBody decl $ \ tvs' ->
527 return (decl {tcdTyVars = tvs'})
529 kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs, tcdATs = ats})
530 = kcTyClDeclBody decl $ \ tvs' ->
531 do { is_boot <- tcIsHsBoot
532 ; ctxt' <- kcHsContext ctxt
533 ; ats' <- mappM (wrapLocM kcTyClDecl) ats
534 ; sigs' <- mappM (wrapLocM kc_sig ) sigs
535 ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs',
538 kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
539 ; return (TypeSig nm op_ty') }
540 kc_sig other_sig = return other_sig
542 kcTyClDecl decl@(ForeignType {})
545 kcTyClDeclBody :: TyClDecl Name
546 -> ([LHsTyVarBndr Name] -> TcM a)
548 -- getInitialKind has made a suitably-shaped kind for the type or class
549 -- Unpack it, and attribute those kinds to the type variables
550 -- Extend the env with bindings for the tyvars, taken from
551 -- the kind of the tycon/class. Give it to the thing inside, and
552 -- check the result kind matches
553 kcTyClDeclBody decl thing_inside
554 = tcAddDeclCtxt decl $
555 do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
556 ; let tc_kind = case tc_ty_thing of { AThing k -> k }
557 (kinds, _) = splitKindFunTys tc_kind
558 hs_tvs = tcdTyVars decl
559 kinded_tvs = ASSERT( length kinds >= length hs_tvs )
560 [ L loc (KindedTyVar (hsTyVarName tv) k)
561 | (L loc tv, k) <- zip hs_tvs kinds]
562 ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
564 -- Kind check a data declaration, assuming that we already extended the
565 -- kind environment with the type variables of the left-hand side (these
566 -- kinded type variables are also passed as the second parameter).
568 kcDataDecl :: TyClDecl Name -> [LHsTyVarBndr Name] -> TcM (TyClDecl Name)
569 kcDataDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
571 = do { ctxt' <- kcHsContext ctxt
572 ; cons' <- mappM (wrapLocM kc_con_decl) cons
573 ; return (decl {tcdTyVars = tvs, tcdCtxt = ctxt', tcdCons = cons'}) }
575 -- doc comments are typechecked to Nothing here
576 kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res _) = do
577 kcHsTyVars ex_tvs $ \ex_tvs' -> do
578 ex_ctxt' <- kcHsContext ex_ctxt
579 details' <- kc_con_details details
581 ResTyH98 -> return ResTyH98
582 ResTyGADT ty -> do { ty' <- kcHsSigType ty; return (ResTyGADT ty') }
583 return (ConDecl name expl ex_tvs' ex_ctxt' details' res' Nothing)
585 kc_con_details (PrefixCon btys)
586 = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
587 kc_con_details (InfixCon bty1 bty2)
588 = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_ty bty2; return (InfixCon bty1' bty2') }
589 kc_con_details (RecCon fields)
590 = do { fields' <- mappM kc_field fields; return (RecCon fields') }
592 kc_field (HsRecField fld bty d) = do { bty' <- kc_larg_ty bty ; return (HsRecField fld bty' d) }
594 kc_larg_ty bty = case new_or_data of
595 DataType -> kcHsSigType bty
596 NewType -> kcHsLiftedSigType bty
597 -- Can't allow an unlifted type for newtypes, because we're effectively
598 -- going to remove the constructor while coercing it to a lifted type.
599 -- And newtypes can't be bang'd
603 %************************************************************************
605 \subsection{Type checking}
607 %************************************************************************
610 tcSynDecls :: [LTyClDecl Name] -> TcM [TyThing]
611 tcSynDecls [] = return []
612 tcSynDecls (decl : decls)
613 = do { syn_tc <- addLocM tcSynDecl decl
614 ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
615 ; return (syn_tc : syn_tcs) }
618 (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
619 = tcTyVarBndrs tvs $ \ tvs' -> do
620 { traceTc (text "tcd1" <+> ppr tc_name)
621 ; rhs_ty' <- tcHsKindedType rhs_ty
622 ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
625 tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
627 tcTyClDecl calc_isrec decl
628 = tcAddDeclCtxt decl (tcTyClDecl1 calc_isrec decl)
630 -- kind signature for a type function
631 tcTyClDecl1 _calc_isrec
632 (TyFunction {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdKind = kind})
633 = tcTyVarBndrs tvs $ \ tvs' -> do
634 { traceTc (text "type family: " <+> ppr tc_name)
635 ; gla_exts <- doptM Opt_IndexedTypes
637 -- Check that we don't use kind signatures without Glasgow extensions
638 ; checkTc gla_exts $ badSigTyDecl tc_name
640 ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind)]
643 -- kind signature for an indexed data type
644 tcTyClDecl1 _calc_isrec
645 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
646 tcdLName = L _ tc_name, tcdKindSig = Just ksig, tcdCons = []})
647 = tcTyVarBndrs tvs $ \ tvs' -> do
648 { traceTc (text "data/newtype family: " <+> ppr tc_name)
649 ; extra_tvs <- tcDataKindSig (Just ksig)
650 ; let final_tvs = tvs' ++ extra_tvs -- we may not need these
652 ; checkTc (null . unLoc $ ctxt) $ badKindSigCtxt tc_name
653 ; gla_exts <- doptM Opt_IndexedTypes
655 -- Check that we don't use kind signatures without Glasgow extensions
656 ; checkTc gla_exts $ badSigTyDecl tc_name
658 ; tycon <- buildAlgTyCon tc_name final_tvs []
660 DataType -> OpenDataTyCon
661 NewType -> OpenNewTyCon)
662 Recursive False True Nothing
663 ; return [ATyCon tycon]
666 tcTyClDecl1 calc_isrec
667 (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
668 tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
669 = tcTyVarBndrs tvs $ \ tvs' -> do
670 { extra_tvs <- tcDataKindSig mb_ksig
671 ; let final_tvs = tvs' ++ extra_tvs
672 ; stupid_theta <- tcHsKindedContext ctxt
673 ; want_generic <- doptM Opt_Generics
674 ; unbox_strict <- doptM Opt_UnboxStrictFields
675 ; gla_exts <- doptM Opt_GlasgowExts
676 ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
678 -- Check that we don't use GADT syntax in H98 world
679 ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
681 -- Check that we don't use kind signatures without Glasgow extensions
682 ; checkTc (gla_exts || isNothing mb_ksig) (badSigTyDecl tc_name)
684 -- Check that the stupid theta is empty for a GADT-style declaration
685 ; checkTc (null stupid_theta || h98_syntax) (badStupidTheta tc_name)
687 -- Check that there's at least one condecl,
688 -- or else we're reading an hs-boot file, or -fglasgow-exts
689 ; checkTc (not (null cons) || gla_exts || is_boot)
690 (emptyConDeclsErr tc_name)
692 -- Check that a newtype has exactly one constructor
693 ; checkTc (new_or_data == DataType || isSingleton cons)
694 (newtypeConError tc_name (length cons))
696 ; tycon <- fixM (\ tycon -> do
697 { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
701 if null cons && is_boot -- In a hs-boot file, empty cons means
702 then return AbstractTyCon -- "don't know"; hence Abstract
703 else case new_or_data of
704 DataType -> return (mkDataTyConRhs data_cons)
706 ASSERT( isSingleton data_cons )
707 mkNewTyConRhs tc_name tycon (head data_cons)
708 ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs is_rec
709 (want_generic && canDoGenerics data_cons) h98_syntax Nothing
711 ; return [ATyCon tycon]
714 is_rec = calc_isrec tc_name
715 h98_syntax = case cons of -- All constructors have same shape
716 L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
719 tcTyClDecl1 calc_isrec
720 (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
721 tcdCtxt = ctxt, tcdMeths = meths,
722 tcdFDs = fundeps, tcdSigs = sigs, tcdATs = ats} )
723 = tcTyVarBndrs tvs $ \ tvs' -> do
724 { ctxt' <- tcHsKindedContext ctxt
725 ; fds' <- mappM (addLocM tc_fundep) fundeps
726 ; atss <- mappM (addLocM (tcTyClDecl1 (const Recursive))) ats
727 ; let ats' = zipWith setTyThingPoss atss (map (tcdTyVars . unLoc) ats)
728 ; sig_stuff <- tcClassSigs class_name sigs meths
729 ; clas <- fixM (\ clas ->
730 let -- This little knot is just so we can get
731 -- hold of the name of the class TyCon, which we
732 -- need to look up its recursiveness
733 tycon_name = tyConName (classTyCon clas)
734 tc_isrec = calc_isrec tycon_name
736 buildClass class_name tvs' ctxt' fds' ats'
738 ; return (AClass clas : ats')
739 -- NB: Order is important due to the call to `mkGlobalThings' when
740 -- tying the the type and class declaration type checking knot.
743 tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
744 ; tvs2' <- mappM tcLookupTyVar tvs2 ;
745 ; return (tvs1', tvs2') }
747 -- For each AT argument compute the position of the corresponding class
748 -- parameter in the class head. This will later serve as a permutation
749 -- vector when checking the validity of instance declarations.
750 setTyThingPoss [ATyCon tycon] atTyVars =
751 let classTyVars = hsLTyVarNames tvs
753 . map (`elemIndex` classTyVars)
756 -- There will be no Nothing, as we already passed renaming
758 ATyCon (setTyConArgPoss tycon poss)
759 setTyThingPoss _ _ = panic "TcTyClsDecls.setTyThingPoss"
761 tcTyClDecl1 calc_isrec
762 (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
763 = returnM [ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0)]
765 -----------------------------------
766 tcConDecl :: Bool -- True <=> -funbox-strict_fields
772 tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
773 (ConDecl name _ ex_tvs ex_ctxt details ResTyH98 _)
774 = do { let tc_datacon field_lbls arg_ty
775 = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
776 ; buildDataCon (unLoc name) False {- Prefix -}
778 (map unLoc field_lbls)
779 tc_tvs [] -- No existentials
780 [] [] -- No equalities, predicates
784 -- Check that a newtype has no existential stuff
785 ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
788 PrefixCon [arg_ty] -> tc_datacon [] arg_ty
789 RecCon [HsRecField field_lbl arg_ty _] -> tc_datacon [field_lbl] arg_ty
791 failWithTc (newtypeFieldErr name (length (hsConArgs details)))
792 -- Check that the constructor has exactly one field
795 tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
796 (ConDecl name _ tvs ctxt details res_ty _)
797 = tcTyVarBndrs tvs $ \ tvs' -> do
798 { ctxt' <- tcHsKindedContext ctxt
799 ; (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
801 -- Tiresome: tidy the tyvar binders, since tc_tvs and tvs' may have the same OccNames
802 tc_datacon is_infix field_lbls btys
803 = do { let bangs = map getBangStrictness btys
804 ; arg_tys <- mappM tcHsBangType btys
805 ; buildDataCon (unLoc name) is_infix
806 (argStrictness unbox_strict bangs arg_tys)
807 (map unLoc field_lbls)
808 univ_tvs ex_tvs eq_preds ctxt' arg_tys
810 -- NB: we put data_tc, the type constructor gotten from the
811 -- constructor type signature into the data constructor;
812 -- that way checkValidDataCon can complain if it's wrong.
815 PrefixCon btys -> tc_datacon False [] btys
816 InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
817 RecCon fields -> tc_datacon False field_names btys
819 (field_names, btys) = unzip [ (n, t) | HsRecField n t _ <- fields ]
823 tcResultType :: TyCon
824 -> [TyVar] -- data T a b c = ...
825 -> [TyVar] -- where MkT :: forall a b c. ...
827 -> TcM ([TyVar], -- Universal
828 [TyVar], -- Existential (distinct OccNames from univs)
829 [(TyVar,Type)], -- Equality predicates
830 TyCon) -- TyCon given in the ResTy
831 -- We don't check that the TyCon given in the ResTy is
832 -- the same as the parent tycon, becuase we are in the middle
833 -- of a recursive knot; so it's postponed until checkValidDataCon
835 tcResultType decl_tycon tc_tvs dc_tvs ResTyH98
836 = return (tc_tvs, dc_tvs, [], decl_tycon)
837 -- In H98 syntax the dc_tvs are the existential ones
838 -- data T a b c = forall d e. MkT ...
839 -- The {a,b,c} are tc_tvs, and {d,e} are dc_tvs
841 tcResultType _ tc_tvs dc_tvs (ResTyGADT res_ty)
842 -- E.g. data T a b c where
843 -- MkT :: forall x y z. T (x,y) z z
845 -- ([a,z,c], [x,y], [a:=:(x,y), c:=:z], T)
847 = do { (dc_tycon, res_tys) <- tcLHsConResTy res_ty
849 ; let univ_tvs = choose_univs [] tidy_tc_tvs res_tys
850 -- Each univ_tv is either a dc_tv or a tc_tv
851 ex_tvs = dc_tvs `minusList` univ_tvs
852 eq_spec = [ (tv, ty) | (tv,ty) <- univ_tvs `zip` res_tys,
854 ; return (univ_tvs, ex_tvs, eq_spec, dc_tycon) }
856 -- choose_univs uses the res_ty itself if it's a type variable
857 -- and hasn't already been used; otherwise it uses one of the tc_tvs
858 choose_univs used tc_tvs []
859 = ASSERT( null tc_tvs ) []
860 choose_univs used (tc_tv:tc_tvs) (res_ty:res_tys)
861 | Just tv <- tcGetTyVar_maybe res_ty, not (tv `elem` used)
862 = tv : choose_univs (tv:used) tc_tvs res_tys
864 = tc_tv : choose_univs used tc_tvs res_tys
866 -- NB: tc_tvs and dc_tvs are distinct, but
867 -- we want them to be *visibly* distinct, both for
868 -- interface files and general confusion. So rename
869 -- the tc_tvs, since they are not used yet (no
870 -- consequential renaming needed)
871 init_occ_env = initTidyOccEnv (map getOccName dc_tvs)
872 (_, tidy_tc_tvs) = mapAccumL tidy_one init_occ_env tc_tvs
873 tidy_one env tv = (env', setTyVarName tv (tidyNameOcc name occ'))
876 (env', occ') = tidyOccName env (getOccName name)
879 argStrictness :: Bool -- True <=> -funbox-strict_fields
881 -> [TcType] -> [StrictnessMark]
882 argStrictness unbox_strict bangs arg_tys
883 = ASSERT( length bangs == length arg_tys )
884 zipWith (chooseBoxingStrategy unbox_strict) arg_tys bangs
886 -- We attempt to unbox/unpack a strict field when either:
887 -- (i) The field is marked '!!', or
888 -- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
890 -- We have turned off unboxing of newtypes because coercions make unboxing
891 -- and reboxing more complicated
892 chooseBoxingStrategy :: Bool -> TcType -> HsBang -> StrictnessMark
893 chooseBoxingStrategy unbox_strict_fields arg_ty bang
895 HsNoBang -> NotMarkedStrict
896 HsStrict | unbox_strict_fields
897 && can_unbox arg_ty -> MarkedUnboxed
898 HsUnbox | can_unbox arg_ty -> MarkedUnboxed
899 other -> MarkedStrict
901 -- we can unbox if the type is a chain of newtypes with a product tycon
903 can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
905 Just (arg_tycon, tycon_args) ->
906 not (isRecursiveTyCon arg_tycon) && -- Note [Recusive unboxing]
907 isProductTyCon arg_tycon &&
908 (if isNewTyCon arg_tycon then
909 can_unbox (newTyConInstRhs arg_tycon tycon_args)
913 Note [Recursive unboxing]
914 ~~~~~~~~~~~~~~~~~~~~~~~~~
915 Be careful not to try to unbox this!
917 But it's the *argument* type that matters. This is fine:
919 because Int is non-recursive.
921 %************************************************************************
923 \subsection{Dependency analysis}
925 %************************************************************************
927 Validity checking is done once the mutually-recursive knot has been
928 tied, so we can look at things freely.
931 checkCycleErrs :: [LTyClDecl Name] -> TcM ()
932 checkCycleErrs tyclss
936 = do { mappM_ recClsErr cls_cycles
937 ; failM } -- Give up now, because later checkValidTyCl
938 -- will loop if the synonym is recursive
940 cls_cycles = calcClassCycles tyclss
942 checkValidTyCl :: TyClDecl Name -> TcM ()
943 -- We do the validity check over declarations, rather than TyThings
944 -- only so that we can add a nice context with tcAddDeclCtxt
946 = tcAddDeclCtxt decl $
947 do { thing <- tcLookupLocatedGlobal (tcdLName decl)
948 ; traceTc (text "Validity of" <+> ppr thing)
950 ATyCon tc -> checkValidTyCon tc
951 AClass cl -> checkValidClass cl
952 ; traceTc (text "Done validity of" <+> ppr thing)
955 -------------------------
956 -- For data types declared with record syntax, we require
957 -- that each constructor that has a field 'f'
958 -- (a) has the same result type
959 -- (b) has the same type for 'f'
960 -- module alpha conversion of the quantified type variables
961 -- of the constructor.
963 checkValidTyCon :: TyCon -> TcM ()
966 = case synTyConRhs tc of
967 OpenSynTyCon _ -> return ()
968 SynonymTyCon ty -> checkValidType syn_ctxt ty
970 = -- Check the context on the data decl
971 checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
973 -- Check arg types of data constructors
974 mappM_ (checkValidDataCon tc) data_cons `thenM_`
976 -- Check that fields with the same name share a type
977 mappM_ check_fields groups
980 syn_ctxt = TySynCtxt name
982 data_cons = tyConDataCons tc
984 groups = equivClasses cmp_fld (concatMap get_fields data_cons)
985 cmp_fld (f1,_) (f2,_) = f1 `compare` f2
986 get_fields con = dataConFieldLabels con `zip` repeat con
987 -- dataConFieldLabels may return the empty list, which is fine
989 -- See Note [GADT record selectors] in MkId.lhs
990 -- We must check (a) that the named field has the same
991 -- type in each constructor
992 -- (b) that those constructors have the same result type
994 -- However, the constructors may have differently named type variable
995 -- and (worse) we don't know how the correspond to each other. E.g.
996 -- C1 :: forall a b. { f :: a, g :: b } -> T a b
997 -- C2 :: forall d c. { f :: c, g :: c } -> T c d
999 -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
1000 -- result type against other candidates' types BOTH WAYS ROUND.
1001 -- If they magically agrees, take the substitution and
1002 -- apply them to the latter ones, and see if they match perfectly.
1003 check_fields fields@((label, con1) : other_fields)
1004 -- These fields all have the same name, but are from
1005 -- different constructors in the data type
1006 = recoverM (return ()) $ mapM_ checkOne other_fields
1007 -- Check that all the fields in the group have the same type
1008 -- NB: this check assumes that all the constructors of a given
1009 -- data type use the same type variables
1011 tvs1 = mkVarSet (dataConAllTyVars con1)
1012 res1 = dataConResTys con1
1013 fty1 = dataConFieldType con1 label
1015 checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
1016 = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
1017 ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
1019 tvs2 = mkVarSet (dataConAllTyVars con2)
1020 res2 = dataConResTys con2
1021 fty2 = dataConFieldType con2 label
1023 checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
1024 = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
1025 ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
1027 mb_subst1 = tcMatchTys tvs1 res1 res2
1028 mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
1030 -------------------------------
1031 checkValidDataCon :: TyCon -> DataCon -> TcM ()
1032 checkValidDataCon tc con
1033 = setSrcSpan (srcLocSpan (getSrcLoc con)) $
1034 addErrCtxt (dataConCtxt con) $
1035 do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
1036 ; checkValidType ctxt (dataConUserType con) }
1038 ctxt = ConArgCtxt (dataConName con)
1040 -------------------------------
1041 checkValidClass :: Class -> TcM ()
1043 = do { -- CHECK ARITY 1 FOR HASKELL 1.4
1044 gla_exts <- doptM Opt_GlasgowExts
1046 -- Check that the class is unary, unless GlaExs
1047 ; checkTc (notNull tyvars) (nullaryClassErr cls)
1048 ; checkTc (gla_exts || unary) (classArityErr cls)
1050 -- Check the super-classes
1051 ; checkValidTheta (ClassSCCtxt (className cls)) theta
1053 -- Check the class operations
1054 ; mappM_ (check_op gla_exts) op_stuff
1056 -- Check that if the class has generic methods, then the
1057 -- class has only one parameter. We can't do generic
1058 -- multi-parameter type classes!
1059 ; checkTc (unary || no_generics) (genericMultiParamErr cls)
1062 (tyvars, theta, _, op_stuff) = classBigSig cls
1063 unary = isSingleton tyvars
1064 no_generics = null [() | (_, GenDefMeth) <- op_stuff]
1066 check_op gla_exts (sel_id, dm)
1067 = addErrCtxt (classOpCtxt sel_id tau) $ do
1068 { checkValidTheta SigmaCtxt (tail theta)
1069 -- The 'tail' removes the initial (C a) from the
1070 -- class itself, leaving just the method type
1072 ; checkValidType (FunSigCtxt op_name) tau
1074 -- Check that the type mentions at least one of
1075 -- the class type variables
1076 ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
1077 (noClassTyVarErr cls sel_id)
1079 -- Check that for a generic method, the type of
1080 -- the method is sufficiently simple
1081 ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
1082 (badGenericMethodType op_name op_ty)
1085 op_name = idName sel_id
1086 op_ty = idType sel_id
1087 (_,theta1,tau1) = tcSplitSigmaTy op_ty
1088 (_,theta2,tau2) = tcSplitSigmaTy tau1
1089 (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
1090 | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
1091 -- Ugh! The function might have a type like
1092 -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
1093 -- With -fglasgow-exts, we want to allow this, even though the inner
1094 -- forall has an (Eq a) constraint. Whereas in general, each constraint
1095 -- in the context of a for-all must mention at least one quantified
1096 -- type variable. What a mess!
1099 ---------------------------------------------------------------------
1100 resultTypeMisMatch field_name con1 con2
1101 = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1102 ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
1103 nest 2 $ ptext SLIT("but have different result types")]
1104 fieldTypeMisMatch field_name con1 con2
1105 = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
1106 ptext SLIT("give different types for field"), quotes (ppr field_name)]
1108 dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
1110 classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
1111 nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
1114 = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
1117 = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
1118 parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
1120 noClassTyVarErr clas op
1121 = sep [ptext SLIT("The class method") <+> quotes (ppr op),
1122 ptext SLIT("mentions none of the type variables of the class") <+>
1123 ppr clas <+> hsep (map ppr (classTyVars clas))]
1125 genericMultiParamErr clas
1126 = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
1127 ptext SLIT("cannot have generic methods")
1129 badGenericMethodType op op_ty
1130 = hang (ptext SLIT("Generic method type is too complex"))
1131 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
1132 ptext SLIT("You can only use type variables, arrows, lists, and tuples")])
1135 = setSrcSpan (getLoc (head sorted_decls)) $
1136 addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
1137 nest 2 (vcat (map ppr_decl sorted_decls))])
1139 sorted_decls = sortLocated syn_decls
1140 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
1143 = setSrcSpan (getLoc (head sorted_decls)) $
1144 addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
1145 nest 2 (vcat (map ppr_decl sorted_decls))])
1147 sorted_decls = sortLocated cls_decls
1148 ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
1150 sortLocated :: [Located a] -> [Located a]
1151 sortLocated things = sortLe le things
1153 le (L l1 _) (L l2 _) = l1 <= l2
1155 badDataConTyCon data_con
1156 = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
1157 ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
1158 2 (ptext SLIT("instead of its parent type"))
1161 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
1162 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
1164 badStupidTheta tc_name
1165 = ptext SLIT("A data type declared in GADT style cannot have a context:") <+> quotes (ppr tc_name)
1167 newtypeConError tycon n
1168 = sep [ptext SLIT("A newtype must have exactly one constructor,"),
1169 nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
1172 = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
1173 nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
1175 newtypeFieldErr con_name n_flds
1176 = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
1177 nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
1179 badSigTyDecl tc_name
1180 = vcat [ ptext SLIT("Illegal kind signature") <+>
1181 quotes (ppr tc_name)
1182 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1184 badKindSigCtxt tc_name
1185 = vcat [ ptext SLIT("Illegal context in kind signature") <+>
1186 quotes (ppr tc_name)
1187 , nest 2 (parens $ ptext SLIT("Currently, kind signatures cannot have a context")) ]
1189 badIdxTyDecl tc_name
1190 = vcat [ ptext SLIT("Illegal indexed type instance for") <+>
1191 quotes (ppr tc_name)
1192 , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow indexed types")) ]
1194 badGadtIdxTyDecl tc_name
1195 = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+>
1196 quotes (ppr tc_name)
1197 , nest 2 (parens $ ptext SLIT("Indexed types cannot use GADT declarations")) ]
1199 tooManyParmsErr tc_name
1200 = ptext SLIT("Indexed type instance has too many parameters:") <+>
1201 quotes (ppr tc_name)
1203 tooFewParmsErr tc_name
1204 = ptext SLIT("Indexed type instance has too few parameters:") <+>
1205 quotes (ppr tc_name)
1207 badBootTyIdxDeclErr =
1208 ptext SLIT("Illegal indexed type instance in hs-boot file")
1210 wrongKindOfFamily family =
1211 ptext SLIT("Wrong category of type instance; declaration was for a") <+>
1214 kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
1215 | isDataTyCon family = ptext SLIT("data type")
1216 | isNewTyCon family = ptext SLIT("newtype")
1218 emptyConDeclsErr tycon
1219 = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
1220 nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]