diff --git a/src/kiss/Kiss.hx b/src/kiss/Kiss.hx
index 67f1523..eb33e1d 100644
--- a/src/kiss/Kiss.hx
+++ b/src/kiss/Kiss.hx
@@ -111,7 +111,8 @@ class Kiss {
                 "zipThrow" => Symbol("Prelude.zipThrow"),
                 "joinPath" => Symbol("Prelude.joinPath"),
                 "readDirectory" => Symbol("Prelude.readDirectory"),
-                "substr" => Symbol("Prelude.substr")
+                "substr" => Symbol("Prelude.substr"),
+                "isListExp" => Symbol("Prelude.isListExp")
             ],
             fieldList: [],
             fieldDict: new Map(),
diff --git a/src/kiss/Prelude.hx b/src/kiss/Prelude.hx
index 88682f5..de58227 100644
--- a/src/kiss/Prelude.hx
+++ b/src/kiss/Prelude.hx
@@ -420,7 +420,16 @@ class Prelude {
             case ListExp(exps):
                 exps;
             default: throw 'expected $s to be a list expression';
-        }
+        };
+    }
+    
+    public static function isListExp(s:ReaderExp):Bool {
+        return switch (s.def) {
+            case ListExp(exps):
+                true;
+            default:
+                false;
+        };
     }
 
     #if sys