Override __bool__ of TypedListType

pytensor/typed_list/basic.py

@@ -19,6 +19,11 @@ def __getitem__(self, index):
     def __len__(self):
         return length(self)
 
+    def __bool__(self):
+        # Truthiness of typedLists cannot depend on length,
+        # just like truthiness of TensorVariables does not depend on size or contents
+        return True
+
     def append(self, toAppend):
         return append(self, toAppend)
 
@@ -677,3 +682,18 @@ def perform(self, node, inputs, outputs):
 All PyTensor variables must have the same type.
 
 """
+
+
+class MakeEmptyList(Op):
+    __props__ = ()
+
+    def make_node(self, ttype):
+        tl = TypedListType(ttype)()
+        return Apply(self, [], [tl])
+
+    def perform(self, node, inputs, outputs):
+        (out,) = outputs
+        out[0] = []
+
+
+make_empty_list = MakeEmptyList()

tests/typed_list/test_type.py

@@ -150,3 +150,7 @@ def test_variable_is_Typed_List_variable(self):
         )()
 
         assert isinstance(mySymbolicVariable, TypedListVariable)
+
+    def test_any(self):
+        tlist = TypedListType(TensorType(dtype="int64", shape=(None,)))()
+        assert any([tlist])