Minor refactoring

diff --git a/compiler/typecheck/TcGadt.lhs b/compiler/typecheck/TcGadt.lhs
index 45debe9..5bad13e 100644 (file)
--- a/compiler/typecheck/TcGadt.lhs
+++ b/compiler/typecheck/TcGadt.lhs
@@ -47,6 +47,8 @@ import UniqFM
 
 \begin{code}
 data Refinement = Reft InScopeSet InternalReft 
+
+type InternalReft = TyVarEnv (Coercion, Type)
 -- INVARIANT:   a->(co,ty)   then   co :: (a:=:ty)
 -- Not necessarily idemopotent
 
@@ -139,7 +141,7 @@ gadtRefine (Reft in_scope env1)
           ex_tvs co_vars
 -- Precondition: fvs( co_vars ) # env1
 -- That is, the kinds of the co_vars are a
--- fixed point of the  incoming refinement
+-- fixed point of the incoming refinement
 
   = ASSERT2( not $ any (`elemVarEnv` env1) (varSetElems $ tyVarsOfTypes $ map tyVarKind co_vars),
             ppr env1 $$ ppr co_vars $$ ppr (map tyVarKind co_vars) )
@@ -157,9 +159,11 @@ gadtRefine (Reft in_scope env1)
   where
     tv_set = mkVarSet ex_tvs
     in_scope' = foldr extend in_scope co_vars
+
+       -- For each co_var, add it *and* the tyvars it mentions, to in_scope
     extend co_var in_scope
-       = extendInScopeSetSet (extendInScopeSet in_scope co_var)
-                             (tyVarsOfType (tyVarKind co_var))
+       = extendInScopeSetSet in_scope $
+         extendVarSet (tyVarsOfType (tyVarKind co_var)) co_var
        
     do_one reft co_var = unify reft (TyVarTy co_var) ty1 ty2
        where
@@ -252,11 +256,6 @@ tryToBind tv_set tv | tv `elemVarSet` tv_set = BindMe
 %************************************************************************
 
 \begin{code}
-type InternalReft = TyVarEnv (Coercion, Type)
-
--- INVARIANT:   a->(co,ty)   then   co :: (a:=:ty)
--- Not necessarily idemopotent
-
 #ifdef DEBUG
 badReftElts :: InternalReft -> [(Unique, (Coercion,Type))]
 -- Return the BAD elements of the refinement