Support python310 pipe unions.

cyclopts/_convert.py

@@ -27,6 +27,13 @@
 else:
     from typing import Annotated  # pragma: no cover
 
+_union_types = set()
+_union_types.add(Union)
+if sys.version_info >= (3, 10):
+    from types import UnionType
+
+    _union_types.add(UnionType)
+
 from cyclopts.exceptions import CoercionError
 
 if TYPE_CHECKING:
@@ -93,7 +100,7 @@ def _convert(type_, element, converter=None):
     if origin_type is collections.abc.Iterable:
         assert len(inner_types) == 1
         return pconvert(List[inner_types[0]], element)  # pyright: ignore[reportGeneralTypeIssues]
-    elif origin_type is Union:
+    elif origin_type in _union_types:
         for t in inner_types:
             if t is NoneType:
                 continue
@@ -174,7 +181,7 @@ def resolve_optional(type_: Type) -> Type:
     # Python will automatically flatten out nested unions when possible.
     # So we don't need to loop over resolution.
 
-    if get_origin(type_) is not Union:
+    if get_origin(type_) not in _union_types:
         return type_
 
     non_none_types = [t for t in get_args(type_) if t is not NoneType]

tests/test_bind_basic.py

@@ -112,6 +112,36 @@ def foo(a: Optional[int] = None):
     assert_parse_args(foo, cmd_str, 1)
 
 
+@pytest.mark.skipif(sys.version_info < (3, 10), reason="Pipe Typing Syntax")
+@pytest.mark.parametrize(
+    "cmd_str",
+    [
+        "foo 1",
+        "foo --a=1",
+        "foo --a 1",
+    ],
+)
+@pytest.mark.parametrize("annotated", [False, True])
+def test_optional_nonrequired_implicit_coercion_python310_syntax(app, cmd_str, annotated, assert_parse_args):
+    """
+    For a union without an explicit coercion, the first non-None type annotation
+    should be used. In this case, it's ``int``.
+    """
+    if annotated:
+
+        @app.command
+        def foo(a: Annotated[int | None, Parameter(help="help for a")] = None):
+            pass
+
+    else:
+
+        @app.command
+        def foo(a: int | None = None):
+            pass
+
+    assert_parse_args(foo, cmd_str, 1)
+
+
 @pytest.mark.parametrize(
     "cmd_str",
     [