src/cpl_query/base/queryable_abc.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Optional, Callable, Union, Iterable, Self
+from typing import Optional, Callable, Union, Iterable, Self, Any
 from typing import TYPE_CHECKING
 
 from cpl_query._helper import is_number
@@ -378,7 +378,10 @@ class QueryableABC(Sequence):
         if _func is None:
             _func = _default_lambda
 
-        return type(self)(object, [_func(_o) for _o in self])
+        _l = [_func(_o) for _o in self]
+        _t = type(_l[0]) if len(_l) > 0 else Any
+
+        return type(self)(_t, _l)
 
     def select_many(self, _func: Callable) -> Self:
         r"""Flattens resulting lists to one

src/cpl_query/base/sequence.py

@@ -25,7 +25,7 @@ class Sequence(ABC):
         return self.to_list().__len__()
 
     @classmethod
-    def __class_getitem__(cls, _t: type):
+    def __class_getitem__(cls, _t: type) -> type:
         return _t
 
     def __repr__(self):

unittests/unittests_query/iterable_query_test_case.py

@@ -270,6 +270,12 @@ class IterableQueryTestCase(unittest.TestCase):
         self.assertEqual(res.to_list(), l_res)
 
     def test_select(self):
+        def test(_l: List) -> List[int]:
+            return _l.select(lambda user: user.address.nr)
+
+        self.assertEqual(List[User], self._tests.type)
+        self.assertEqual(List[int], test(self._tests).type)
+
         range_list = List(int, range(0, 100))
         selected_range = range_list.select(lambda x: x + 1)