have builtins return :nil when appropriate

1 files changed, 5 insertions, 0 deletions

diff --git a/neb/structs.py b/neb/structs.py
index 2423a69..db71aa0 100644
--- a/neb/structs.py
+++ b/neb/structs.py
@@ -169,6 +169,11 @@ class List:
     def __str__(self):
         return "(" +  " ".join(f"{arg}" for arg in self.args) + ")"
 
+class Nil(List):
+    def __init__(self):
+        self.args = []
+        self.type_ = ALL_TYPES[":nil"]
+
 # function things
 class Arg: