\begin{code}
module TcHsSyn (
- TcDictBinds,
mkHsTyApp, mkHsDictApp, mkHsConApp,
mkHsTyLam, mkHsDictLam, mkHsLet, mkHsApp,
hsLitType, hsPatType, mkHsAppTy, mkSimpleHsAlt,
idCoercion, isIdCoercion,
-- re-exported from TcMonad
- TcId, TcIdSet,
+ TcId, TcIdSet, TcDictBinds,
zonkTopDecls, zonkTopExpr, zonkTopLExpr,
zonkId, zonkTopBndrs
import TcRnMonad
import Type ( Type )
-import TcType ( TcType, TcTyVar, mkTyVarTy, tcGetTyVar, mkTyConApp )
+import TcType ( TcType, TcTyVar, mkTyVarTy, mkTyConApp, isImmutableTyVar, tcGetTyVar )
import Kind ( isLiftedTypeKind, liftedTypeKind, isSubKind )
import qualified Type
-import TcMType ( zonkTcTyVarToTyVar, zonkType, zonkTcType, zonkTcTyVars,
- putTcTyVar )
+import TcMType ( zonkQuantifiedTyVar, zonkType, zonkTcType, zonkTcTyVars, putMetaTyVar )
import TysPrim ( charPrimTy, intPrimTy, floatPrimTy,
doublePrimTy, addrPrimTy
)
import TysWiredIn ( charTy, stringTy, intTy,
mkListTy, mkPArrTy, mkTupleTy, unitTy,
voidTy, listTyCon, tupleTyCon )
-import TyCon ( mkPrimTyCon, tyConKind )
+import TyCon ( mkPrimTyCon, tyConKind, PrimRep(..) )
import Kind ( splitKindFunTys )
-import PrimRep ( PrimRep(VoidRep) )
import Name ( getOccName, mkInternalName, mkDerivedTyConOcc )
import Var ( Var, isId, isLocalVar, tyVarKind )
import VarSet
\end{code}
-\begin{code}
-type TcDictBinds = LHsBinds TcId -- Bag of dictionary bindings
-\end{code}
-
-
%************************************************************************
%* *
\subsection[mkFailurePair]{Code for pattern-matching and other failures}
hsPatType :: OutPat Id -> Type
hsPatType pat = pat_type (unLoc pat)
-pat_type (ParPat pat) = hsPatType pat
-pat_type (WildPat ty) = ty
-pat_type (VarPat var) = idType var
-pat_type (LazyPat pat) = hsPatType pat
-pat_type (LitPat lit) = hsLitType lit
-pat_type (AsPat var pat) = idType (unLoc var)
-pat_type (ListPat _ ty) = mkListTy ty
-pat_type (PArrPat _ ty) = mkPArrTy ty
-pat_type (TuplePat pats box) = mkTupleTy box (length pats) (map hsPatType pats)
-pat_type (ConPatOut _ _ ty _ _) = ty
-pat_type (SigPatOut _ ty _) = ty
-pat_type (NPatOut lit ty _) = ty
-pat_type (NPlusKPatOut id _ _ _) = idType (unLoc id)
-pat_type (DictPat ds ms) = case (ds ++ ms) of
+pat_type (ParPat pat) = hsPatType pat
+pat_type (WildPat ty) = ty
+pat_type (VarPat var) = idType var
+pat_type (VarPatOut var _) = idType var
+pat_type (LazyPat pat) = hsPatType pat
+pat_type (LitPat lit) = hsLitType lit
+pat_type (AsPat var pat) = idType (unLoc var)
+pat_type (ListPat _ ty) = mkListTy ty
+pat_type (PArrPat _ ty) = mkPArrTy ty
+pat_type (TuplePat pats box) = mkTupleTy box (length pats) (map hsPatType pats)
+pat_type (ConPatOut _ _ _ _ _ ty) = ty
+pat_type (SigPatOut pat ty) = ty
+pat_type (NPatOut lit ty _) = ty
+pat_type (NPlusKPatOut id _ _ _) = idType (unLoc id)
+pat_type (DictPat ds ms) = case (ds ++ ms) of
[] -> unitTy
[d] -> idType d
ds -> mkTupleTy Boxed (length ds) (map idType ds)
extendZonkEnv (ZonkEnv zonk_ty env) ids
= ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
+extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
+extendZonkEnv1 (ZonkEnv zonk_ty env) id
+ = ZonkEnv zonk_ty (extendVarEnv env id id)
+
setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
-mkZonkEnv :: [Id] -> ZonkEnv
-mkZonkEnv ids = extendZonkEnv emptyZonkEnv ids
+zonkEnvIds :: ZonkEnv -> [Id]
+zonkEnvIds (ZonkEnv _ env) = varEnvElts env
zonkIdOcc :: ZonkEnv -> TcId -> Id
-- Ids defined in this module should be in the envt;
zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
zonkTopLExpr e = zonkLExpr emptyZonkEnv e
-zonkTopDecls :: Bag (LHsBind TcId) -> [LRuleDecl TcId] -> [LForeignDecl TcId]
+zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
-> TcM ([Id],
Bag (LHsBind Id),
[LForeignDecl Id],
[LRuleDecl Id])
-zonkTopDecls binds rules fords -- Top level is implicitly recursive
- = fixM (\ ~(new_ids, _, _, _) ->
- let
- zonk_env = mkZonkEnv new_ids
- in
- zonkMonoBinds zonk_env binds `thenM` \ binds' ->
- zonkRules zonk_env rules `thenM` \ rules' ->
- zonkForeignExports zonk_env fords `thenM` \ fords' ->
-
- returnM (collectHsBindBinders binds', binds', fords', rules')
- )
+zonkTopDecls binds rules fords
+ = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
+ -- Top level is implicitly recursive
+ ; rules' <- zonkRules env rules
+ ; fords' <- zonkForeignExports env fords
+ ; return (zonkEnvIds env, binds', fords', rules') }
---------------------------------------------
zonkGroup :: ZonkEnv -> HsBindGroup TcId -> TcM (ZonkEnv, HsBindGroup Id)
zonkGroup env (HsBindGroup bs sigs is_rec)
= ASSERT( null sigs )
- do { (env1, bs') <- fixM (\ ~(_, new_binds) -> do
- { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
- ; bs' <- zonkMonoBinds env1 bs
- ; return (env1, bs') })
- ; return (env1, HsBindGroup bs' [] is_rec) }
+ do { (env1, bs') <- zonkRecMonoBinds env bs
+ ; return (env1, HsBindGroup bs' [] is_rec) }
-
zonkGroup env (HsIPBinds binds)
= mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
let
; return (env2, b':bs') }
---------------------------------------------
-zonkMonoBinds :: ZonkEnv -> Bag (LHsBind TcId) -> TcM (Bag (LHsBind Id))
+zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
+zonkRecMonoBinds env binds
+ = fixM (\ ~(_, new_binds) -> do
+ { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
+ ; binds' <- zonkMonoBinds env1 binds
+ ; return (env1, binds') })
+
+zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
-zonk_bind env (PatBind pat grhss)
- = zonkPat env pat `thenM` \ (new_pat, _) ->
- zonkGRHSs env grhss `thenM` \ new_grhss ->
- returnM (PatBind new_pat new_grhss)
+zonk_bind env (PatBind pat grhss ty)
+ = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
+ ; new_grhss <- zonkGRHSs env grhss
+ ; new_ty <- zonkTcTypeToType env ty
+ ; return (PatBind new_pat new_grhss new_ty) }
zonk_bind env (VarBind var expr)
= zonkIdBndr env var `thenM` \ new_var ->
zonk_bind env (FunBind var inf ms)
= wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
- mappM (zonkMatch env) ms `thenM` \ new_ms ->
+ zonkMatchGroup env ms `thenM` \ new_ms ->
returnM (FunBind new_var inf new_ms)
zonk_bind env (AbsBinds tyvars dicts exports inlines val_binds)
- = mappM zonkTcTyVarToTyVar tyvars `thenM` \ new_tyvars ->
- -- No need to extend tyvar env: the effects are
- -- propagated through binding the tyvars themselves
-
+ = ASSERT( all isImmutableTyVar tyvars )
zonkIdBndrs env dicts `thenM` \ new_dicts ->
fixM (\ ~(new_val_binds, _) ->
let
- env1 = extendZonkEnv (extendZonkEnv env new_dicts)
+ env1 = extendZonkEnv (extendZonkEnv env new_dicts)
(collectHsBindBinders new_val_binds)
in
zonkMonoBinds env1 val_binds `thenM` \ new_val_binds ->
mappM (zonkExport env1) exports `thenM` \ new_exports ->
returnM (new_val_binds, new_exports)
) `thenM` \ (new_val_bind, new_exports) ->
- returnM (AbsBinds new_tyvars new_dicts new_exports inlines new_val_bind)
+ returnM (AbsBinds tyvars new_dicts new_exports inlines new_val_bind)
where
zonkExport env (tyvars, global, local)
= zonkTcTyVars tyvars `thenM` \ tys ->
%************************************************************************
\begin{code}
-zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
+zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
+zonkMatchGroup env (MatchGroup ms ty)
+ = do { ms' <- mapM (zonkMatch env) ms
+ ; ty' <- zonkTcTypeToType env ty
+ ; return (MatchGroup ms' ty') }
+zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
zonkMatch env (L loc (Match pats _ grhss))
- = zonkPats env pats `thenM` \ (new_pats, new_ids) ->
- zonkGRHSs (extendZonkEnv env (bagToList new_ids)) grhss `thenM` \ new_grhss ->
- returnM (L loc (Match new_pats Nothing new_grhss))
+ = do { (env1, new_pats) <- zonkPats env pats
+ ; new_grhss <- zonkGRHSs env1 grhss
+ ; return (L loc (Match new_pats Nothing new_grhss)) }
-------------------------------------------------------------------------
zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
-zonkGRHSs env (GRHSs grhss binds ty)
+zonkGRHSs env (GRHSs grhss binds)
= zonkNestedBinds env binds `thenM` \ (new_env, new_binds) ->
let
zonk_grhs (GRHS guarded)
returnM (GRHS new_guarded)
in
mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
- zonkTcTypeToType env ty `thenM` \ new_ty ->
- returnM (GRHSs new_grhss new_binds new_ty)
+ returnM (GRHSs new_grhss new_binds)
\end{code}
%************************************************************************
zonkExpr env (HsLit lit)
= returnM (HsLit lit)
-
-- HsOverLit doesn't appear in typechecker output
-zonkExpr env (HsLam match)
- = zonkMatch env match `thenM` \ new_match ->
- returnM (HsLam new_match)
+zonkExpr env (HsLam matches)
+ = zonkMatchGroup env matches `thenM` \ new_matches ->
+ returnM (HsLam new_matches)
zonkExpr env (HsApp e1 e2)
= zonkLExpr env e1 `thenM` \ new_e1 ->
zonkLExpr env expr `thenM` \ new_expr ->
returnM (SectionR new_op new_expr)
+-- gaw 2004
zonkExpr env (HsCase expr ms)
= zonkLExpr env expr `thenM` \ new_expr ->
- mappM (zonkMatch env) ms `thenM` \ new_ms ->
+ zonkMatchGroup env ms `thenM` \ new_ms ->
returnM (HsCase new_expr new_ms)
zonkExpr env (HsIf e1 e2 e3)
zonkRbinds env rbinds `thenM` \ new_rbinds ->
returnM (RecordUpdOut new_expr new_in_ty new_out_ty new_rbinds)
+zonkExpr env (ExprWithTySigOut e ty)
+ = do { e' <- zonkLExpr env e
+ ; return (ExprWithTySigOut e' ty) }
+
zonkExpr env (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
zonkExpr env (ArithSeqIn _) = panic "zonkExpr env:ArithSeqIn"
zonkExpr env (PArrSeqIn _) = panic "zonkExpr env:PArrSeqIn"
returnM (HsCoreAnn lbl new_expr)
zonkExpr env (TyLam tyvars expr)
- = mappM zonkTcTyVarToTyVar tyvars `thenM` \ new_tyvars ->
- -- No need to extend tyvar env; see AbsBinds
-
+ = ASSERT( all isImmutableTyVar tyvars )
zonkLExpr env expr `thenM` \ new_expr ->
- returnM (TyLam new_tyvars new_expr)
+ returnM (TyLam tyvars new_expr)
zonkExpr env (TyApp expr tys)
= zonkLExpr env expr `thenM` \ new_expr ->
-- arrow notation extensions
zonkExpr env (HsProc pat body)
- = zonkPat env pat `thenM` \ (new_pat, new_ids) ->
- let
- env1 = extendZonkEnv env (bagToList new_ids)
- in
- zonkCmdTop env1 body `thenM` \ new_body ->
- returnM (HsProc new_pat new_body)
+ = do { (env1, new_pat) <- zonkPat env pat
+ ; new_body <- zonkCmdTop env1 body
+ ; return (HsProc new_pat new_body) }
zonkExpr env (HsArrApp e1 e2 ty ho rl)
= zonkLExpr env e1 `thenM` \ new_e1 ->
zonkReboundNames env prs
= mapM zonk prs
where
- zonk (n, e) = zonkLExpr env e `thenM` \ new_e ->
+ zonk (n, e) = zonkExpr env e `thenM` \ new_e ->
returnM (n, new_e)
returnM (env1, LetStmt new_binds)
zonkStmt env (BindStmt pat expr)
- = zonkLExpr env expr `thenM` \ new_expr ->
- zonkPat env pat `thenM` \ (new_pat, new_ids) ->
- let
- env1 = extendZonkEnv env (bagToList new_ids)
- in
- returnM (env1, BindStmt new_pat new_expr)
-
+ = do { new_expr <- zonkLExpr env expr
+ ; (env1, new_pat) <- zonkPat env pat
+ ; return (env1, BindStmt new_pat new_expr) }
-------------------------------------------------------------------------
%************************************************************************
\begin{code}
-zonkPat :: ZonkEnv -> OutPat TcId -> TcM (OutPat Id, Bag Id)
-zonkPat env pat = wrapLocFstM (zonk_pat env) pat
+zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
+-- Extend the environment as we go, because it's possible for one
+-- pattern to bind something that is used in another (inside or
+-- to the right)
+zonkPat env pat = wrapLocSndM (zonk_pat env) pat
zonk_pat env (ParPat p)
- = zonkPat env p `thenM` \ (new_p, ids) ->
- returnM (ParPat new_p, ids)
+ = do { (env', p') <- zonkPat env p
+ ; return (env', ParPat p') }
zonk_pat env (WildPat ty)
- = zonkTcTypeToType env ty `thenM` \ new_ty ->
- returnM (WildPat new_ty, emptyBag)
+ = do { ty' <- zonkTcTypeToType env ty
+ ; return (env, WildPat ty') }
zonk_pat env (VarPat v)
- = zonkIdBndr env v `thenM` \ new_v ->
- returnM (VarPat new_v, unitBag new_v)
+ = do { v' <- zonkIdBndr env v
+ ; return (extendZonkEnv1 env v', VarPat v') }
+
+zonk_pat env (VarPatOut v binds)
+ = do { v' <- zonkIdBndr env v
+ ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
+ ; returnM (env', VarPatOut v' binds') }
zonk_pat env (LazyPat pat)
- = zonkPat env pat `thenM` \ (new_pat, ids) ->
- returnM (LazyPat new_pat, ids)
+ = do { (env', pat') <- zonkPat env pat
+ ; return (env', LazyPat pat') }
-zonk_pat env (AsPat n pat)
- = wrapLocM (zonkIdBndr env) n `thenM` \ new_n ->
- zonkPat env pat `thenM` \ (new_pat, ids) ->
- returnM (AsPat new_n new_pat, unLoc new_n `consBag` ids)
+zonk_pat env (AsPat (L loc v) pat)
+ = do { v' <- zonkIdBndr env v
+ ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
+ ; return (env', AsPat (L loc v') pat') }
zonk_pat env (ListPat pats ty)
- = zonkTcTypeToType env ty `thenM` \ new_ty ->
- zonkPats env pats `thenM` \ (new_pats, ids) ->
- returnM (ListPat new_pats new_ty, ids)
+ = do { ty' <- zonkTcTypeToType env ty
+ ; (env', pats') <- zonkPats env pats
+ ; return (env', ListPat pats' ty') }
zonk_pat env (PArrPat pats ty)
- = zonkTcTypeToType env ty `thenM` \ new_ty ->
- zonkPats env pats `thenM` \ (new_pats, ids) ->
- returnM (PArrPat new_pats new_ty, ids)
+ = do { ty' <- zonkTcTypeToType env ty
+ ; (env', pats') <- zonkPats env pats
+ ; return (env', PArrPat pats' ty') }
zonk_pat env (TuplePat pats boxed)
- = zonkPats env pats `thenM` \ (new_pats, ids) ->
- returnM (TuplePat new_pats boxed, ids)
+ = do { (env', pats') <- zonkPats env pats
+ ; return (env', TuplePat pats' boxed) }
-zonk_pat env (ConPatOut n stuff ty tvs dicts)
- = zonkTcTypeToType env ty `thenM` \ new_ty ->
- mappM zonkTcTyVarToTyVar tvs `thenM` \ new_tvs ->
- zonkIdBndrs env dicts `thenM` \ new_dicts ->
- let
- env1 = extendZonkEnv env new_dicts
- in
- zonkConStuff env1 stuff `thenM` \ (new_stuff, ids) ->
- returnM (ConPatOut n new_stuff new_ty new_tvs new_dicts,
- listToBag new_dicts `unionBags` ids)
+zonk_pat env (ConPatOut n tvs dicts binds stuff ty)
+ = ASSERT( all isImmutableTyVar tvs )
+ do { new_ty <- zonkTcTypeToType env ty
+ ; new_dicts <- zonkIdBndrs env dicts
+ ; let env1 = extendZonkEnv env new_dicts
+ ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
+ ; (env', new_stuff) <- zonkConStuff env2 stuff
+ ; returnM (env', ConPatOut n tvs new_dicts new_binds new_stuff new_ty) }
-zonk_pat env (LitPat lit) = returnM (LitPat lit, emptyBag)
+zonk_pat env (LitPat lit) = return (env, LitPat lit)
-zonk_pat env (SigPatOut pat ty expr)
- = zonkPat env pat `thenM` \ (new_pat, ids) ->
- zonkTcTypeToType env ty `thenM` \ new_ty ->
- zonkExpr env expr `thenM` \ new_expr ->
- returnM (SigPatOut new_pat new_ty new_expr, ids)
+zonk_pat env (SigPatOut pat ty)
+ = do { ty' <- zonkTcTypeToType env ty
+ ; (env', pat') <- zonkPat env pat
+ ; return (env', SigPatOut pat' ty') }
zonk_pat env (NPatOut lit ty expr)
- = zonkTcTypeToType env ty `thenM` \ new_ty ->
- zonkExpr env expr `thenM` \ new_expr ->
- returnM (NPatOut lit new_ty new_expr, emptyBag)
+ = do { ty' <- zonkTcTypeToType env ty
+ ; expr' <- zonkExpr env expr
+ ; return (env, NPatOut lit ty' expr') }
-zonk_pat env (NPlusKPatOut n k e1 e2)
- = wrapLocM (zonkIdBndr env) n `thenM` \ new_n ->
- zonkExpr env e1 `thenM` \ new_e1 ->
- zonkExpr env e2 `thenM` \ new_e2 ->
- returnM (NPlusKPatOut new_n k new_e1 new_e2, unitBag (unLoc new_n))
+zonk_pat env (NPlusKPatOut (L loc n) k e1 e2)
+ = do { n' <- zonkIdBndr env n
+ ; e1' <- zonkExpr env e1
+ ; e2' <- zonkExpr env e2
+ ; return (extendZonkEnv1 env n', NPlusKPatOut (L loc n') k e1' e2') }
zonk_pat env (DictPat ds ms)
- = zonkIdBndrs env ds `thenM` \ new_ds ->
- zonkIdBndrs env ms `thenM` \ new_ms ->
- returnM (DictPat new_ds new_ms,
- listToBag new_ds `unionBags` listToBag new_ms)
+ = do { ds' <- zonkIdBndrs env ds
+ ; ms' <- zonkIdBndrs env ms
+ ; return (extendZonkEnv env (ds' ++ ms'), DictPat ds' ms') }
---------------------------
zonkConStuff env (PrefixCon pats)
- = zonkPats env pats `thenM` \ (new_pats, ids) ->
- returnM (PrefixCon new_pats, ids)
+ = do { (env', pats') <- zonkPats env pats
+ ; return (env', PrefixCon pats') }
zonkConStuff env (InfixCon p1 p2)
- = zonkPat env p1 `thenM` \ (new_p1, ids1) ->
- zonkPat env p2 `thenM` \ (new_p2, ids2) ->
- returnM (InfixCon new_p1 new_p2, ids1 `unionBags` ids2)
+ = do { (env1, p1') <- zonkPat env p1
+ ; (env', p2') <- zonkPat env1 p2
+ ; return (env', InfixCon p1' p2') }
zonkConStuff env (RecCon rpats)
- = mapAndUnzipM zonk_rpat rpats `thenM` \ (new_rpats, ids_s) ->
- returnM (RecCon new_rpats, unionManyBags ids_s)
+ = do { (env', pats') <- zonkPats env pats
+ ; returnM (env', RecCon (fields `zip` pats')) }
where
- zonk_rpat (f, pat)
- = zonkPat env pat `thenM` \ (new_pat, ids) ->
- returnM ((f, new_pat), ids)
+ (fields, pats) = unzip rpats
---------------------------
-zonkPats env []
- = returnM ([], emptyBag)
-
-zonkPats env (pat:pats)
- = zonkPat env pat `thenM` \ (pat', ids1) ->
- zonkPats env pats `thenM` \ (pats', ids2) ->
- returnM (pat':pats', ids1 `unionBags` ids2)
+zonkPats env [] = return (env, [])
+zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
+ ; (env', pats') <- zonkPats env1 pats
+ ; return (env', pat':pats') }
\end{code}
%************************************************************************
where
zonk_bndr (RuleBndr v)
| isId (unLoc v) = wrapLocM (zonkIdBndr env) v
- | otherwise = wrapLocM zonkTcTyVarToTyVar v
+ | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
+ return v
\end{code}
zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
-- This variant collects unbound type variables in a mutable variable
zonkTypeCollecting unbound_tv_set
- = zonkType zonk_unbound_tyvar
+ = zonkType zonk_unbound_tyvar True
where
zonk_unbound_tyvar tv
- = zonkTcTyVarToTyVar tv `thenM` \ tv' ->
+ = zonkQuantifiedTyVar tv `thenM` \ tv' ->
readMutVar unbound_tv_set `thenM` \ tv_set ->
writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
return (mkTyVarTy tv')
-- This variant is used for everything except the LHS of rules
-- It zaps unbound type variables to (), or some other arbitrary type
zonkTypeZapping ty
- = zonkType zonk_unbound_tyvar ty
+ = zonkType zonk_unbound_tyvar True ty
where
-- Zonk a mutable but unbound type variable to an arbitrary type
-- We know it's unbound even though we don't carry an environment,
-- mutable tyvar to a fresh immutable one. So the mutable store
-- plays the role of an environment. If we come across a mutable
-- type variable that isn't so bound, it must be completely free.
- zonk_unbound_tyvar tv = putTcTyVar tv (mkArbitraryType tv)
+ zonk_unbound_tyvar tv = do { putMetaTyVar tv ty; return ty }
+ where
+ ty = mkArbitraryType tv
-- When the type checker finds a type variable with no binding,
projects / ghc-hetmet.git / blobdiff