1 files changed, 3 insertions, 0 deletions
diff --git a/AStack.dcl b/AStack.dcl
index 799892f..423b81c 100644
--- a/AStack.dcl
+++ b/AStack.dcl
@@ -1,11 +1,14 @@
 definition module ABC.AStack
 
+from StdOverloaded import class toString
 from ABC.Def import ::NodeId, ::NrArgs
 
 :: ASrc    :== Int
 :: ADst    :== Int
 :: AStack (:== [NodeId])
 
+instance toString AStack
+
 as_get    :: ASrc AStack -> NodeId
 as_init   :: AStack
 as_popn   :: NrArgs AStack -> AStack