[project @ 2001-01-25 17:54:24 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcRules.lhs

diff --git a/ghc/compiler/typecheck/TcRules.lhs b/ghc/compiler/typecheck/TcRules.lhs
index 7550e73..ca6dab6 100644 (file)
--- a/ghc/compiler/typecheck/TcRules.lhs
+++ b/ghc/compiler/typecheck/TcRules.lhs
@@ -14,19 +14,18 @@ import RnHsSyn              ( RenamedRuleDecl )
 import HscTypes                ( PackageRuleBase )
 import TcHsSyn         ( TypecheckedRuleDecl, mkHsLet )
 import TcMonad
-import TcSimplify      ( tcSimplifyToDicts, tcSimplifyAndCheck )
-import TcType          ( zonkTcTypes, zonkTcTyVarToTyVar, newTyVarTy )
+import TcSimplify      ( tcSimplifyToDicts, tcSimplifyInferCheck )
+import TcType          ( zonkTcTyVarToTyVar, newTyVarTy )
 import TcIfaceSig      ( tcCoreExpr, tcCoreLamBndrs, tcVar )
 import TcMonoType      ( kcHsSigType, tcHsSigType, tcTyVars, checkSigTyVars )
 import TcExpr          ( tcExpr )
-import TcEnv           ( tcExtendLocalValEnv, tcExtendTyVarEnv, tcGetGlobalTyVars, isLocalThing )
+import TcEnv           ( tcExtendLocalValEnv, tcExtendTyVarEnv, isLocalThing )
 import Rules           ( extendRuleBase )
 import Inst            ( LIE, plusLIEs, instToId )
-import Id              ( idType, idName, mkVanillaId )
+import Id              ( idName, mkVanillaId )
 import Module          ( Module )
 import VarSet
-import Type            ( tyVarsOfTypes, openTypeKind )
-import Bag             ( bagToList )
+import Type            ( tyVarsOfType, openTypeKind )
 import List            ( partition )
 import Outputable
 \end{code}
@@ -87,12 +86,12 @@ tcSourceRule (HsRule name sig_tvs vars lhs rhs src_loc)
     )                                          `thenTc` \ (sig_tyvars, ids, lhs', rhs', lhs_lie, rhs_lie) ->
 
                -- Check that LHS has no overloading at all
-    tcSimplifyToDicts lhs_lie                          `thenTc` \ (lhs_dicts, lhs_binds) ->
-    checkSigTyVars sig_tyvars emptyVarSet              `thenTc_`
+    tcSimplifyToDicts lhs_lie                  `thenTc` \ (lhs_dicts, lhs_binds) ->
+    checkSigTyVars sig_tyvars emptyVarSet      `thenTc_`
 
        -- Gather the template variables and tyvars
     let
-       tpl_ids = map instToId (bagToList lhs_dicts) ++ ids
+       tpl_ids = map instToId lhs_dicts ++ ids
 
        -- IMPORTANT!  We *quantify* over any dicts that appear in the LHS
        -- Reason: 
@@ -106,22 +105,13 @@ tcSourceRule (HsRule name sig_tvs vars lhs rhs src_loc)
        --         See the 'lhs_dicts' in tcSimplifyAndCheck for the RHS
     in
 
-       -- Gather type variables to quantify over
-       -- and turn them into real TyVars (just as in TcBinds.tcBindWithSigs)
-    zonkTcTypes (rule_ty : map idType tpl_ids) `thenNF_Tc` \ zonked_tys ->
-    tcGetGlobalTyVars                          `thenNF_Tc` \ free_tyvars ->
-    let
-       poly_tyvars = tyVarsOfTypes zonked_tys `minusVarSet` free_tyvars
-       -- There can be tyvars free in the environment, if there are
-       -- monomorphic overloaded top-level bindings.  Sigh.
-    in
-    mapTc zonkTcTyVarToTyVar (varSetElems poly_tyvars) `thenTc` \ tvs ->
-
        -- RHS can be a bit more lenient.  In particular,
        -- we let constant dictionaries etc float outwards
-    tcSimplifyAndCheck (text "tcRule") (mkVarSet tvs)
-                      lhs_dicts rhs_lie                `thenTc` \ (lie', rhs_binds) ->
+    tcSimplifyInferCheck (text "tcRule")
+                        (varSetElems (tyVarsOfType rule_ty))
+                        lhs_dicts rhs_lie      `thenTc` \ (forall_tvs', lie', rhs_binds) ->
 
+    mapTc zonkTcTyVarToTyVar forall_tvs'               `thenTc` \ tvs ->
     returnTc (lie', HsRule     name tvs
                                (map RuleBndr tpl_ids)  -- yuk
                                (mkHsLet lhs_binds lhs')