evaluate undefined into a closure

diff --git a/Eval.hs b/Eval.hs
index e2c8d45a41a6a32d3ef67d52a46361b72869c956..ec9dc3122295b2f4a35c17faf8a2000cbe419a20 100644 (file)
--- a/Eval.hs
+++ b/Eval.hs
@@ -129,6 +129,7 @@ instance Nominal Val where
 
 eval :: Env -> Ter -> Val
 eval rho v = case v of
+  Undef{}             -> Ter v rho
   U                   -> VU
   App r s             -> app (eval rho r) (eval rho s)
   Var i               -> look i rho