return empty lists as-is

1 files changed, 3 insertions, 0 deletions

diff --git a/interpreter.py b/interpreter.py
index 576af47..09f298b 100644
--- a/interpreter.py
+++ b/interpreter.py
@@ -101,6 +101,9 @@ def evaluate(expr, env):
     # if it's a literal list, return it
     if expr.data:
         return expr
+    # if it's an empty list, return it
+    elif len(expr.args) == 0:
+        return expr
 
     if not isinstance(expr.args[0], Symbol):
         raise Exception("can't evaluate without a symbol")