New type shift helper function

SystemF/SystemFBase.hs

@@ -29,7 +29,14 @@ generateHnatTypeVar n c = (STypeVar (generateHnatTypeVar (n - 1) c))
 
 termshiftHelpplus d c (TmVar var) = if (var >= c) then (TmVar (plus var d)) else (TmVar var)
 
-typeshiftHelpplus d c (TyVar var) = if (var >= c) then (TyVar (plus var d)) else (TyVar var)
+-- typeshiftHelpplus d c (TyVar var) = if (var >= c) then (TyVar (plus d var)) else (TyVar var)
+
+typeshiftHelpplus d c (TyVar var) = TyVar (go c var) where
+  go Z            v             = plus d v
+  go (STypeVar c) Z             = Z
+  go (STermVar c) Z             = Z
+  go (STypeVar c) (STypeVar v)  = STypeVar (go c v)
+  go (STermVar c) (STermVar v)  = STermVar (go c v)
 
 termshiftplus d t = (termmap (termshiftHelpplus d) (typeshiftHelpplus d) (Z) t)