2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcTyClsDecls]{Typecheck type and class declarations}
11 #include "HsVersions.h"
13 import HsSyn ( HsDecl(..), TyClDecl(..),
14 HsType(..), HsTyVarBndr,
15 ConDecl(..), ConDetails(..), BangType(..),
16 Sig(..), HsPred(..), HsTupCon(..),
17 tyClDeclName, isClassDecl, isSynDecl
19 import RnHsSyn ( RenamedHsDecl, RenamedTyClDecl, listTyCon_name )
20 import BasicTypes ( RecFlag(..), NewOrData(..), Arity )
23 import Inst ( InstanceMapper )
24 import TcClassDcl ( kcClassDecl, tcClassDecl1 )
25 import TcEnv ( ValueEnv, TcTyThing(..),
26 tcExtendTypeEnv, getEnvAllTyCons
28 import TcTyDecls ( tcTyDecl, kcTyDecl )
29 import TcMonoType ( kcHsTyVar )
30 import TcType ( TcKind, newKindVar, newKindVars, kindToTcKind, zonkTcKindToKind )
32 import Type ( mkArrowKind, boxedTypeKind )
34 import Class ( Class )
35 import Var ( TyVar, tyVarKind )
39 import Digraph ( stronglyConnComp, SCC(..) )
40 import Name ( Name, NamedThing(..), getSrcLoc, isTvOcc, nameOccName )
42 import Maybes ( mapMaybe, catMaybes, expectJust )
43 import UniqSet ( UniqSet, emptyUniqSet,
44 unitUniqSet, unionUniqSets,
45 unionManyUniqSets, uniqSetToList )
46 import ErrUtils ( Message )
47 import SrcLoc ( SrcLoc )
48 import TyCon ( TyCon, ArgVrcs )
49 import Variance ( calcTyConArgVrcs )
50 import Unique ( Unique, Uniquable(..) )
51 import UniqFM ( listToUFM, lookupUFM )
57 tcTyAndClassDecls :: ValueEnv -> InstanceMapper -- Knot tying stuff
61 tcTyAndClassDecls unf_env inst_mapper decls
62 = sortByDependency decls `thenTc` \ groups ->
63 tcGroups unf_env inst_mapper groups
65 tcGroups unf_env inst_mapper []
66 = tcGetEnv `thenNF_Tc` \ env ->
69 tcGroups unf_env inst_mapper (group:groups)
70 = tcGroup unf_env inst_mapper group `thenTc` \ env ->
72 tcGroups unf_env inst_mapper groups
78 The knot-tying parameters: @rec_tyclss@ is an alist mapping @Name@s to
79 @TcTyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s.
82 tcGroup :: ValueEnv -> InstanceMapper -> SCC RenamedTyClDecl -> TcM s TcEnv
83 tcGroup unf_env inst_mapper scc
85 mapNF_Tc getTyBinding1 decls `thenNF_Tc` \ ty_env_stuff1 ->
86 tcExtendTypeEnv ty_env_stuff1 (mapTc kcDecl decls) `thenTc_`
89 -- traceTc (ppr (map fst ty_env_stuff1)) `thenTc_`
90 fixTc ( \ ~(rec_tyclss, _) ->
92 rec_env = listToUFM rec_tyclss
93 rec_tycons = getEnvAllTyCons rec_tyclss
94 rec_vrcs = calcTyConArgVrcs rec_tycons
98 mapNF_Tc (getTyBinding2 rec_env) ty_env_stuff1 `thenNF_Tc` \ ty_env_stuff2 ->
99 tcExtendTypeEnv ty_env_stuff2 $
100 mapTc (tcDecl is_rec_group unf_env inst_mapper rec_vrcs) decls
103 tcGetEnv `thenTc` \ env ->
104 returnTc (tyclss, env)
105 ) `thenTc` \ (_, env) ->
106 -- traceTc (text "done" <+> ppr (map fst ty_env_stuff1)) `thenTc_`
109 is_rec_group = case scc of
110 AcyclicSCC _ -> NonRecursive
111 CyclicSCC _ -> Recursive
114 AcyclicSCC decl -> [decl]
115 CyclicSCC decls -> decls
118 Dealing with one decl
119 ~~~~~~~~~~~~~~~~~~~~~
122 = tcAddDeclCtxt decl $
123 if isClassDecl decl then
128 tcDecl :: RecFlag -- True => recursive group
129 -> ValueEnv -> InstanceMapper -> FiniteMap Name ArgVrcs
130 -> RenamedTyClDecl -> TcM s (Name, TcTyThing)
132 tcDecl is_rec_group unf_env inst_mapper vrcs_env decl
133 = tcAddDeclCtxt decl $
134 if isClassDecl decl then
135 tcClassDecl1 unf_env inst_mapper vrcs_env decl
137 tcTyDecl is_rec_group vrcs_env decl
140 tcAddDeclCtxt decl thing_inside
147 (ClassDecl _ name _ _ _ _ _ _ _ _ _ loc) -> (name, loc, "class")
148 (TySynonym name _ _ loc) -> (name, loc, "type synonym")
149 (TyData NewType _ name _ _ _ _ _ loc) -> (name, loc, "data type")
150 (TyData DataType _ name _ _ _ _ _ loc) -> (name, loc, "newtype")
152 ctxt = hsep [ptext SLIT("In the"), text thing,
153 ptext SLIT("declaration for"), quotes (ppr name)]
159 Extract *binding* names from type and class decls. Type variables are
160 bound in type, data, newtype and class declarations,
161 *and* the polytypes in the class op sigs.
162 *and* the existentially quantified contexts in datacon decls
164 Why do we need to grab all these type variables at once, including
165 those locally-quantified type variables in class op signatures?
167 [Incidentally, this only works because the names are all unique by now.]
169 Because we can only commit to the final kind of a type variable when
170 we've completed the mutually recursive group. For example:
173 op :: D b => a -> b -> b
176 bop :: (Monad c) => ...
178 Here, the kind of the locally-polymorphic type variable "b"
179 depends on *all the uses of class D*. For example, the use of
180 Monad c in bop's type signature means that D must have kind Type->Type.
182 [April 00: looks as if we've dropped this subtlety; I'm not sure when]
185 getTyBinding1 :: RenamedTyClDecl -> NF_TcM s (Name, (TcKind, TcTyThing))
186 getTyBinding1 (TySynonym name tyvars _ _)
187 = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds ->
188 newKindVar `thenNF_Tc` \ result_kind ->
189 returnNF_Tc (name, (foldr mkArrowKind result_kind arg_kinds,
190 ASynTyCon (pprPanic "ATyCon: syn" (ppr name)) (length tyvars)))
192 getTyBinding1 (TyData _ _ name tyvars _ _ _ _ _)
193 = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds ->
194 returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds,
195 ADataTyCon (error "ATyCon: data")))
197 getTyBinding1 (ClassDecl _ name tyvars _ _ _ _ _ _ _ _ _)
198 = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds ->
199 returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds,
200 AClass (pprPanic "AClass" (ppr name)) (length tyvars)))
202 -- Zonk the kind to its final form, and lookup the
203 -- recursive tycon/class
204 getTyBinding2 rec_env (name, (tc_kind, thing))
205 = zonkTcKindToKind tc_kind `thenNF_Tc` \ kind ->
206 returnNF_Tc (name, (kind, mk_thing thing (lookupUFM rec_env name)))
208 mk_thing (ADataTyCon _) ~(Just (ADataTyCon tc)) = ADataTyCon tc
209 mk_thing (ASynTyCon _ arity) ~(Just (ASynTyCon tc _)) = ASynTyCon tc arity
210 mk_thing (AClass _ arity) ~(Just (AClass cls _)) = AClass cls arity
214 %************************************************************************
216 \subsection{Dependency analysis}
218 %************************************************************************
223 sortByDependency :: [RenamedHsDecl] -> TcM s [SCC RenamedTyClDecl]
224 sortByDependency decls
225 = let -- CHECK FOR CLASS CYCLES
226 cls_sccs = stronglyConnComp (mapMaybe mk_cls_edges tycl_decls)
227 cls_cycles = [ decls | CyclicSCC decls <- cls_sccs]
229 checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_`
231 let -- CHECK FOR SYNONYM CYCLES
232 syn_sccs = stronglyConnComp (filter is_syn_decl edges)
233 syn_cycles = [ decls | CyclicSCC decls <- syn_sccs]
236 checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_`
238 -- DO THE MAIN DEPENDENCY ANALYSIS
240 decl_sccs = stronglyConnComp edges
244 tycl_decls = [d | TyClD d <- decls]
245 edges = map mk_edges tycl_decls
247 is_syn_decl (d, _, _) = isSynDecl d
250 Edges in Type/Class decls
251 ~~~~~~~~~~~~~~~~~~~~~~~~~
254 ----------------------------------------------------
255 -- mk_cls_edges looks only at the context of class decls
256 -- Its used when we are figuring out if there's a cycle in the
257 -- superclass hierarchy
259 mk_cls_edges :: RenamedTyClDecl -> Maybe (RenamedTyClDecl, Unique, [Unique])
261 mk_cls_edges decl@(ClassDecl ctxt name _ _ _ _ _ _ _ _ _ _)
262 = Just (decl, getUnique name, map getUnique (catMaybes (map get_clas ctxt)))
263 mk_cls_edges other_decl
266 ----------------------------------------------------
267 mk_edges :: RenamedTyClDecl -> (RenamedTyClDecl, Unique, [Unique])
269 mk_edges decl@(TyData _ ctxt name _ condecls _ derivs _ _)
270 = (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
271 get_cons condecls `unionUniqSets`
274 mk_edges decl@(TySynonym name _ rhs _)
275 = (decl, getUnique name, uniqSetToList (get_ty rhs))
277 mk_edges decl@(ClassDecl ctxt name _ _ sigs _ _ _ _ _ _ _)
278 = (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
282 ----------------------------------------------------
283 get_ctxt ctxt = unionManyUniqSets (map set_name (catMaybes (map get_clas ctxt)))
284 get_clas (HsPClass clas _) = Just clas
287 ----------------------------------------------------
288 get_deriv Nothing = emptyUniqSet
289 get_deriv (Just clss) = unionManyUniqSets (map set_name clss)
291 ----------------------------------------------------
292 get_cons cons = unionManyUniqSets (map get_con cons)
294 ----------------------------------------------------
295 get_con (ConDecl _ _ _ ctxt details _)
296 = get_ctxt ctxt `unionUniqSets` get_con_details details
298 ----------------------------------------------------
299 get_con_details (VanillaCon btys) = unionManyUniqSets (map get_bty btys)
300 get_con_details (InfixCon bty1 bty2) = unionUniqSets (get_bty bty1) (get_bty bty2)
301 get_con_details (NewCon ty _) = get_ty ty
302 get_con_details (RecCon nbtys) = unionManyUniqSets (map (get_bty.snd) nbtys)
304 ----------------------------------------------------
305 get_bty (Banged ty) = get_ty ty
306 get_bty (Unbanged ty) = get_ty ty
307 get_bty (Unpacked ty) = get_ty ty
309 ----------------------------------------------------
310 get_ty (HsTyVar name) | isTvOcc (nameOccName name) = emptyUniqSet
311 | otherwise = set_name name
312 get_ty (HsAppTy ty1 ty2) = unionUniqSets (get_ty ty1) (get_ty ty2)
313 get_ty (HsFunTy ty1 ty2) = unionUniqSets (get_ty ty1) (get_ty ty2)
314 get_ty (HsListTy ty) = set_name listTyCon_name `unionUniqSets` get_ty ty
315 get_ty (HsTupleTy (HsTupCon n _) tys) = set_name n `unionUniqSets` get_tys tys
316 get_ty (HsUsgTy _ ty) = get_ty ty
317 get_ty (HsUsgForAllTy _ ty) = get_ty ty
318 get_ty (HsForAllTy _ ctxt mty) = get_ctxt ctxt `unionUniqSets` get_ty mty
319 get_ty (HsPredTy (HsPClass name _)) = set_name name
320 get_ty (HsPredTy (HsPIParam _ _)) = emptyUniqSet -- I think
322 ----------------------------------------------------
323 get_tys tys = unionManyUniqSets (map get_ty tys)
325 ----------------------------------------------------
327 = unionManyUniqSets (map get_sig sigs)
329 get_sig (ClassOpSig _ _ _ ty _) = get_ty ty
330 get_sig (FixSig _) = emptyUniqSet
331 get_sig other = panic "TcTyClsDecls:get_sig"
333 ----------------------------------------------------
334 set_name name = unitUniqSet (getUnique name)
335 set_to_bag set = listToBag (uniqSetToList set)
340 typeCycleErr, classCycleErr :: [[RenamedTyClDecl]] -> Message
342 typeCycleErr syn_cycles
343 = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles)
345 classCycleErr cls_cycles
346 = vcat (map (pp_cycle "Cycle in class declarations:") cls_cycles)
350 4 (vcat (map pp_decl decls))
353 = hsep [quotes (ppr name), ptext SLIT("at"), ppr (getSrcLoc name)]
355 name = tyClDeclName decl