X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=ghc%2Fcompiler%2Ftypecheck%2FTcRules.lhs;h=0688922093d41c0fef6343265c8ba687ddf22604;hb=b2d205e39c0e2cdb054c53c6a3f14c9489f6b9b5;hp=6f9890bafa49a4c3e036e50e6bfcdacf4dcb7cee;hpb=deafae587c0ee3b0fc005e2f5e654649aa27596b;p=ghc-hetmet.git

diff --git a/ghc/compiler/typecheck/TcRules.lhs b/ghc/compiler/typecheck/TcRules.lhs
index 6f9890b..0688922 100644
--- a/ghc/compiler/typecheck/TcRules.lhs
+++ b/ghc/compiler/typecheck/TcRules.lhs
@@ -15,7 +15,7 @@ import TcHsSyn		( TypecheckedRuleDecl, TcExpr, mkHsLet )
 import TcRnMonad
 import TcSimplify	( tcSimplifyToDicts, tcSimplifyInferCheck )
 import TcMType		( newTyVarTy )
-import TcType		( TcTyVarSet, tyVarsOfTypes, openTypeKind )
+import TcType		( TcTyVarSet, tyVarsOfTypes, tyVarsOfType, openTypeKind )
 import TcIfaceSig	( tcCoreExpr, tcCoreLamBndrs, tcVar )
 import TcMonoType	( tcHsSigType, UserTypeCtxt(..), tcAddScopedTyVars )
 import TcExpr		( tcMonoExpr )
@@ -87,12 +87,10 @@ tcRule (HsRule name act vars lhs rhs src_loc)
 	--	RULE:  forall v. fst (ss v) = fst v
 	-- The type of the rhs of the rule is just a, but v::(a,(b,c))
 	--
-	-- We also need to get the free tyvars of the LHS; see notes 
-	-- below with ruleLhsTvs.
+	-- We also need to get the free tyvars of the LHS; but we do that
+	-- during zonking (see TcHsSyn.zonkRule)
 	--
 	forall_tvs = tyVarsOfTypes (rule_ty : map idType tpl_ids)
-			`unionVarSet`
-		     ruleLhsTvs lhs'
     in
 	-- RHS can be a bit more lenient.  In particular,
 	-- we let constant dictionaries etc float outwards
@@ -114,34 +112,6 @@ tcRule (HsRule name act vars lhs rhs src_loc)
     new_id (RuleBndrSig var rn_ty) = tcHsSigType (RuleSigCtxt var) rn_ty	`thenM` \ ty ->
 				     returnM (mkLocalId var ty)
 
-ruleLhsTvs :: TcExpr -> TcTyVarSet
--- We need to gather the type variables mentioned on the LHS so we can 
--- quantify over them.  Example:
---   data T a = C
--- 
---   foo :: T a -> Int
---   foo C = 1
---
---   {-# RULES "myrule"  foo C = 1 #-}
--- 
--- After type checking the LHS becomes (foo a (C a))
--- and we do not want to zap the unbound tyvar 'a' to (), because
--- that limits the applicability of the rule.  Instead, we
--- want to quantify over it!  
---
--- Fortunately the form of the LHS is pretty limited (see RnSource.validRuleLhs)
--- so we don't need to deal with the whole of HsSyn.
---
-ruleLhsTvs (OpApp e1 op _ e2)
-  = ruleLhsTvs e1 `unionVarSet` ruleLhsTvs op `unionVarSet` ruleLhsTvs e2
-ruleLhsTvs (HsApp e1 e2)
-  = ruleLhsTvs e1 `unionVarSet` ruleLhsTvs e2
-ruleLhsTvs (HsVar v) = emptyVarSet	-- I don't think we need the tyvars of the Id
-ruleLhsTvs (TyApp e1 tys)
-  = ruleLhsTvs e1 `unionVarSet` tyVarsOfTypes tys
-ruleLhsTvs e = pprPanic "ruleLhsTvs" (ppr e)
-
-
 ruleCtxt name = ptext SLIT("When checking the transformation rule") <+> 
 		doubleQuotes (ftext name)
 \end{code}