2 % (c) The AQUA Project, Glasgow University, 1996
4 \section[TcTyClsDecls]{Typecheck type and class declarations}
7 #include "HsVersions.h"
15 import HsSyn ( HsDecl(..), TyDecl(..), ConDecl(..), ConDetails(..), BangType(..),
16 ClassDecl(..), HsType(..), HsTyVar, DefaultDecl, InstDecl,
17 IfaceSig, Sig(..), MonoBinds, Fake, InPat, HsBinds(..), HsExpr,
18 hsDeclName, NewOrData(..)
20 import RnHsSyn ( RenamedTyDecl(..), RenamedClassDecl(..), SYN_IE(RenamedHsDecl)
22 import TcHsSyn ( SYN_IE(TcHsBinds), TcIdOcc(..) )
25 import Inst ( SYN_IE(InstanceMapper) )
26 import TcClassDcl ( tcClassDecl1 )
27 import TcEnv ( tcExtendTyConEnv, tcExtendClassEnv )
28 import SpecEnv ( SpecEnv )
29 import TcKind ( TcKind, newKindVars )
30 import TcTyDecls ( tcTyDecl, mkDataBinds )
31 import TcMonoType ( tcTyVarScope )
34 import Class ( SYN_IE(Class) )
35 import Digraph ( stronglyConnComp, SCC(..) )
36 import Name ( Name, getSrcLoc, isTvOcc, nameOccName )
40 import Maybes ( mapMaybe )
41 import UniqSet ( SYN_IE(UniqSet), emptyUniqSet,
42 unitUniqSet, unionUniqSets,
43 unionManyUniqSets, uniqSetToList )
44 import SrcLoc ( SrcLoc )
45 import TyCon ( TyCon, SYN_IE(Arity) )
46 import Unique ( Unique )
47 import UniqFM ( Uniquable(..) )
48 import Util ( panic{-, pprTrace-} )
55 tcTyAndClassDecls1 :: InstanceMapper
59 tcTyAndClassDecls1 inst_mapper decls
60 = sortByDependency decls `thenTc` \ groups ->
61 tcGroups inst_mapper groups
63 tcGroups inst_mapper []
64 = tcGetEnv `thenNF_Tc` \ env ->
67 tcGroups inst_mapper (group:groups)
68 = tcGroup inst_mapper group `thenTc` \ new_env ->
70 -- Extend the environment using the new tycons and classes
73 -- Do the remaining groups
74 tcGroups inst_mapper groups
80 tcGroup :: InstanceMapper -> Bag RenamedHsDecl -> TcM s (TcEnv s)
81 tcGroup inst_mapper decls
82 = -- pprTrace "tcGroup: " (hsep (map (fst.fmt_decl) (bagToList decls))) $
85 fixTc ( \ ~(tycons,classes,_) ->
87 -- EXTEND TYPE AND CLASS ENVIRONMENTS
88 -- NB: it's important that the tycons and classes come back in just
89 -- the same order from this fix as from get_binders, so that these
90 -- extend-env things work properly. A bit UGH-ish.
91 tcExtendTyConEnv tycon_names_w_arities tycons $
92 tcExtendClassEnv class_names classes $
94 -- DEAL WITH TYPE VARIABLES
95 tcTyVarScope tyvar_names ( \ tyvars ->
97 -- DEAL WITH THE DEFINITIONS THEMSELVES
98 foldBag combine (tcDecl inst_mapper)
99 (returnTc (emptyBag, emptyBag))
101 ) `thenTc` \ (tycon_bag,class_bag) ->
103 tycons = bagToList tycon_bag
104 classes = bagToList class_bag
107 -- SNAFFLE ENV TO RETURN
108 tcGetEnv `thenNF_Tc` \ final_env ->
110 returnTc (tycons, classes, final_env)
111 ) `thenTc` \ (_, _, final_env) ->
116 (tyvar_names, tycon_names_w_arities, class_names) = get_binders decls
119 = do_a `thenTc` \ (a1,a2) ->
120 do_b `thenTc` \ (b1,b2) ->
121 returnTc (a1 `unionBags` b1, a2 `unionBags` b2)
124 Dealing with one decl
125 ~~~~~~~~~~~~~~~~~~~~~
127 tcDecl :: InstanceMapper
129 -> TcM s (Bag TyCon, Bag Class)
131 tcDecl inst_mapper (TyD decl)
132 = tcTyDecl decl `thenTc` \ tycon ->
133 returnTc (unitBag tycon, emptyBag)
135 tcDecl inst_mapper (ClD decl)
136 = tcClassDecl1 inst_mapper decl `thenTc` \ clas ->
137 returnTc (emptyBag, unitBag clas)
143 sortByDependency :: [RenamedHsDecl] -> TcM s [Bag RenamedHsDecl]
144 sortByDependency decls
145 = let -- CHECK FOR SYNONYM CYCLES
146 syn_sccs = stronglyConnComp (filter is_syn_decl edges)
147 syn_cycles = [ decls | CyclicSCC decls <- syn_sccs]
150 checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_`
152 let -- CHECK FOR CLASS CYCLES
153 cls_sccs = stronglyConnComp (filter is_cls_decl edges)
154 cls_cycles = [ decls | CyclicSCC decls <- cls_sccs]
157 checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_`
159 -- DO THE MAIN DEPENDENCY ANALYSIS
161 decl_sccs = stronglyConnComp (filter is_ty_cls_decl edges)
162 scc_bags = map bag_acyclic decl_sccs
167 edges = mapMaybe mk_edges decls
169 bag_acyclic (AcyclicSCC scc) = unitBag scc
170 bag_acyclic (CyclicSCC sccs) = listToBag sccs
172 is_syn_decl (TyD (TySynonym _ _ _ _), _, _) = True
173 is_syn_decl _ = False
175 is_ty_cls_decl (TyD _, _, _) = True
176 is_ty_cls_decl (ClD _, _, _) = True
177 is_ty_cls_decl other = False
179 is_cls_decl (ClD _, _, _) = True
180 is_cls_decl other = False
183 Edges in Type/Class decls
184 ~~~~~~~~~~~~~~~~~~~~~~~~~
186 mk_edges decl@(TyD (TyData _ ctxt name _ condecls derivs _ _))
187 = Just (decl, uniqueOf name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
188 get_cons condecls `unionUniqSets`
191 mk_edges decl@(TyD (TySynonym name _ rhs _))
192 = Just (decl, uniqueOf name, uniqSetToList (get_ty rhs))
194 mk_edges decl@(ClD (ClassDecl ctxt name _ sigs _ _ _))
195 = Just (decl, uniqueOf name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
198 mk_edges other_decl = Nothing
200 get_ctxt ctxt = unionManyUniqSets (map (set_name.fst) ctxt)
202 get_deriv Nothing = emptyUniqSet
203 get_deriv (Just clss) = unionManyUniqSets (map set_name clss)
205 get_cons cons = unionManyUniqSets (map get_con cons)
207 get_con (ConDecl _ ctxt details _)
208 = get_ctxt ctxt `unionUniqSets` get_con_details details
210 get_con_details (VanillaCon btys) = unionManyUniqSets (map get_bty btys)
211 get_con_details (InfixCon bty1 bty2) = unionUniqSets (get_bty bty1) (get_bty bty2)
212 get_con_details (NewCon ty) = get_ty ty
213 get_con_details (RecCon nbtys) = unionManyUniqSets (map (get_bty.snd) nbtys)
215 get_bty (Banged ty) = get_ty ty
216 get_bty (Unbanged ty) = get_ty ty
218 get_ty (MonoTyVar name)
219 = if isTvOcc (nameOccName name) then emptyUniqSet else set_name name
220 get_ty (MonoTyApp ty1 ty2)
221 = unionUniqSets (get_ty ty1) (get_ty ty2)
222 get_ty (MonoFunTy ty1 ty2)
223 = unionUniqSets (get_ty ty1) (get_ty ty2)
224 get_ty (MonoListTy tc ty)
225 = set_name tc `unionUniqSets` get_ty ty
226 get_ty (MonoTupleTy tc tys)
227 = set_name tc `unionUniqSets` get_tys tys
228 get_ty (HsForAllTy _ ctxt mty)
229 = get_ctxt ctxt `unionUniqSets` get_ty mty
230 get_ty other = panic "TcTyClsDecls:get_ty"
233 = unionManyUniqSets (map get_ty tys)
236 = unionManyUniqSets (map get_sig sigs)
238 get_sig (ClassOpSig _ _ ty _) = get_ty ty
239 get_sig other = panic "TcTyClsDecls:get_sig"
241 set_name name = unitUniqSet (uniqueOf name)
243 set_to_bag set = listToBag (uniqSetToList set)
249 Extract *binding* names from type and class decls. Type variables are
250 bound in type, data, newtype and class declarations and the polytypes
251 in the class op sigs.
253 Why do we need to grab all these type variables at once, including
254 those locally-quantified type variables in class op signatures?
255 Because we can only commit to the final kind of a type variable when
256 we've completed the mutually recursive group. For example:
259 op :: D b => a -> b -> b
262 bop :: (Monad c) => ...
264 Here, the kind of the locally-polymorphic type variable "b"
265 depends on *all the uses of class D*. For example, the use of
266 Monad c in bop's type signature means that D must have kind Type->Type.
270 get_binders :: Bag RenamedHsDecl
271 -> ([HsTyVar Name], -- TyVars; no dups
272 [(Name, Maybe Arity)], -- Tycons; no dups; arities for synonyms
273 [Name]) -- Classes; no dups
275 get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes)
277 (tyvars, tycons, classes) = foldBag union3 get_binders1
278 (emptyBag,emptyBag,emptyBag)
281 union3 (a1,a2,a3) (b1,b2,b3)
282 = (a1 `unionBags` b1, a2 `unionBags` b2, a3 `unionBags` b3)
284 get_binders1 (TyD (TyData _ _ name tyvars _ _ _ _))
285 = (listToBag tyvars, unitBag (name,Nothing), emptyBag)
286 get_binders1 (TyD (TySynonym name tyvars _ _))
287 = (listToBag tyvars, unitBag (name, Just (length tyvars)), emptyBag)
288 get_binders1 (ClD (ClassDecl _ name tyvar sigs _ _ _))
289 = (unitBag tyvar `unionBags` sigs_tvs sigs,
290 emptyBag, unitBag name)
292 sigs_tvs sigs = unionManyBags (map sig_tvs sigs)
294 sig_tvs (ClassOpSig _ _ ty _) = pty_tvs ty
295 pty_tvs (HsForAllTy tvs _ _) = listToBag tvs -- tvs doesn't include the class tyvar
296 pty_tvs other = emptyBag
301 typeCycleErr syn_cycles sty
302 = vcat (map (pp_cycle sty "Cycle in type declarations ...") syn_cycles)
304 classCycleErr cls_cycles sty
305 = vcat (map (pp_cycle sty "Cycle in class declarations ...") cls_cycles)
307 pp_cycle sty str decls
309 4 (vcat (map pp_decl decls))
312 = hsep [ppr sty name, ppr sty (getSrcLoc name)]
314 name = hsDeclName decl