diff --git a/onnxscript/function_libs/torch_aten/typing.py b/onnxscript/function_libs/torch_aten/typing.py
new file mode 100644
index 0000000000..2e6395faba
--- /dev/null
+++ b/onnxscript/function_libs/torch_aten/typing.py
@@ -0,0 +1,18 @@
+# --------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+# --------------------------------------------------------------------------
+
+"""Typings for function definitions."""
+
+from __future__ import annotations
+
+from typing import TypeVar, Union
+
+from onnxscript import DOUBLE, FLOAT, FLOAT16, INT8, INT16, INT32, INT64
+
+FloatType = Union[FLOAT16, FLOAT, DOUBLE]
+IntType = Union[INT8, INT16, INT32, INT64]
+
+TFloat = TypeVar("TFloat", bound=FloatType)
+TInt = TypeVar("TInt", bound=IntType)