From 555ca3989a32c65df393efe7202561074d702802 Mon Sep 17 00:00:00 2001
From: Hal Blackburn <hwtb2@cam.ac.uk>
Date: Sun, 2 Feb 2025 09:26:56 +0000
Subject: [PATCH 1/2] feat: define all the types we use in
 denokv._pycompat.typing

This allows us to import all type annotations/types/functions from here,
rather than typing or typing_extensions, which lets us handle the
differences between them in one place, without needing if TYPE_CHECKING
everywhere.
---
 pyproject.toml                      |   1 +
 src/denokv/_pycompat/dataclasses.py |  17 ++-
 src/denokv/_pycompat/typing.py      | 178 +++++++++++++++++++++++++++-
 3 files changed, 194 insertions(+), 2 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index dc4f043..ac52135 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -123,4 +123,5 @@ omit = [
 exclude_also = [
   "if TYPE_CHECKING:",
   "^\\s*def .+: [.]{3}$", # def foo(): ... (... instead of pass)
+  "^\\s*assert_never\\(.*\\)$", # unreachable assertion, expected to not execute
 ]
diff --git a/src/denokv/_pycompat/dataclasses.py b/src/denokv/_pycompat/dataclasses.py
index c9482d9..3767436 100644
--- a/src/denokv/_pycompat/dataclasses.py
+++ b/src/denokv/_pycompat/dataclasses.py
@@ -5,7 +5,7 @@
 from dataclasses import dataclass
 from dataclasses import fields as dataclass_fields
 from typing import Literal
-from typing import TypedDict
+from typing import TypedDict  # avoid circular reference with _pycompat.typing
 
 
 class NoArg(TypedDict):
@@ -27,6 +27,21 @@ def slots_if310() -> SlotsTrue:
         return SlotsTrue(slots=True)
 
 
+class KwOnly(TypedDict):
+    kw_only: Literal[True]
+
+
+if sys.version_info < (3, 10):
+
+    def kw_only_if310() -> NoArg:
+        return NoArg()
+
+else:
+
+    def kw_only_if310() -> KwOnly:
+        return KwOnly(kw_only=True)
+
+
 @dataclass
 class FrozenAfterInitDataclass:
     """A mixin for dataclasses that disallows changing fields after init.
diff --git a/src/denokv/_pycompat/typing.py b/src/denokv/_pycompat/typing.py
index e80a179..c2f2e47 100644
--- a/src/denokv/_pycompat/typing.py
+++ b/src/denokv/_pycompat/typing.py
@@ -1,4 +1,167 @@
-from typing import TYPE_CHECKING
+"""
+Runtime comparability for typing things that come from typing_extensions.
+
+We import all type annotations/types/functions from here, rather than typing or
+typing_extensions in order to handle the differences between them in one place,
+without needing if TYPE_CHECKING everywhere.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from dataclasses import field
+from typing import IO as IO
+from typing import TYPE_CHECKING as TYPE_CHECKING
+
+# Everything that exist in typing >=py39 except:
+# - ByteString (deprecated)
+# - overload (ruff does not recognise it when re-exported)
+# - Literal (ruff does not recognise it when re-exported)
+# - Handled below due to runtime differences:
+#   - TypeVar
+from typing import AbstractSet as AbstractSet
+from typing import Annotated as Annotated
+from typing import Any as Any
+from typing import AnyStr as AnyStr
+from typing import AsyncContextManager as AsyncContextManager
+from typing import AsyncGenerator as AsyncGenerator
+from typing import AsyncIterable as AsyncIterable
+from typing import AsyncIterator as AsyncIterator
+from typing import Awaitable as Awaitable
+from typing import BinaryIO as BinaryIO
+from typing import Callable as Callable
+from typing import ChainMap as ChainMap
+from typing import ClassVar as ClassVar
+from typing import Collection as Collection
+from typing import Container as Container
+from typing import ContextManager as ContextManager
+from typing import Coroutine as Coroutine
+from typing import Counter as Counter
+from typing import DefaultDict as DefaultDict
+from typing import Deque as Deque
+from typing import Dict as Dict
+from typing import Final as Final
+from typing import ForwardRef as ForwardRef
+from typing import FrozenSet as FrozenSet
+from typing import Generator as Generator
+from typing import Generic as Generic
+from typing import Hashable as Hashable
+from typing import ItemsView as ItemsView
+from typing import Iterable as Iterable
+from typing import Iterator as Iterator
+from typing import KeysView as KeysView
+from typing import List as List
+from typing import Mapping as Mapping
+from typing import MappingView as MappingView
+from typing import Match as Match
+from typing import MutableMapping as MutableMapping
+from typing import MutableSequence as MutableSequence
+from typing import MutableSet as MutableSet
+from typing import NamedTuple as NamedTuple
+from typing import NewType as NewType
+from typing import NoReturn as NoReturn
+from typing import Optional as Optional
+from typing import OrderedDict as OrderedDict
+from typing import Pattern as Pattern
+from typing import Protocol as Protocol
+from typing import Reversible as Reversible
+from typing import Sequence as Sequence
+from typing import Set as Set
+from typing import Sized as Sized
+from typing import SupportsAbs as SupportsAbs
+from typing import SupportsBytes as SupportsBytes
+from typing import SupportsComplex as SupportsComplex
+from typing import SupportsFloat as SupportsFloat
+from typing import SupportsIndex as SupportsIndex
+from typing import SupportsInt as SupportsInt
+from typing import SupportsRound as SupportsRound
+from typing import Text as Text
+from typing import TextIO as TextIO
+from typing import Tuple as Tuple
+from typing import Type as Type
+from typing import TypedDict as TypedDict
+from typing import Union as Union
+from typing import ValuesView as ValuesView
+from typing import cast as cast
+from typing import final as final
+from typing import get_args as get_args
+from typing import get_origin as get_origin
+from typing import get_type_hints as get_type_hints
+from typing import no_type_check as no_type_check
+from typing import no_type_check_decorator as no_type_check_decorator
+from typing import runtime_checkable as runtime_checkable
+
+if TYPE_CHECKING:
+    from typing_extensions import Never as Never
+    from typing_extensions import Self as Self
+    from typing_extensions import TypeAlias as TypeAlias
+    from typing_extensions import TypeGuard as TypeGuard
+    from typing_extensions import TypeIs as TypeIs
+    from typing_extensions import TypeVarTuple as TypeVarTuple
+    from typing_extensions import Unpack as Unpack
+else:
+    Never = "Never"
+    ParamSpec = "ParamSpec"
+    Self = "Self"
+    TypeAlias = "TypeAlias"
+    TypeGuard = "TypeGuard"
+    TypeIs = "TypeIs"
+    # TypeVarTuple = "TypeVarTuple"
+    # Unpack = "Unpack"
+
+if TYPE_CHECKING:
+    from typing_extensions import TypeVar as TypeVar
+else:
+    from typing import TypeVar as _TypeVar
+
+    def TypeVar(
+        name: str,
+        *constraints: Any,
+        bound: Any | None = None,
+        covariant: bool = False,
+        contravariant: bool = False,
+        default: Any = ...,
+        infer_variance: bool = False,
+    ) -> TypeVar:
+        return _TypeVar(
+            name, *constraints, covariant=covariant, contravariant=contravariant
+        )
+
+
+_T = TypeVar("_T")
+
+if TYPE_CHECKING:
+    from typing_extensions import TypeVarTuple as TypeVarTuple
+else:
+
+    @dataclass
+    class TypeVarTuple:
+        name: str
+        default: Any = field(default=None)
+
+
+if TYPE_CHECKING:
+    from typing_extensions import ParamSpec as ParamSpec
+else:
+    from denokv._pycompat.dataclasses import kw_only_if310
+
+    @dataclass
+    class ParamSpec:
+        name: str
+        bound: type[Any] | str | None = field(default=None, **kw_only_if310())
+        contravariant: bool = field(default=False, **kw_only_if310())
+        covariant: bool = field(default=False, **kw_only_if310())
+        default: Any = field(default=None, **kw_only_if310())
+
+
+if TYPE_CHECKING:
+    from typing_extensions import Unpack as Unpack
+else:
+
+    @dataclass
+    class Unpack(Generic[_T]):
+        pass
+
 
 if TYPE_CHECKING:
     from typing_extensions import override as override
@@ -6,3 +169,16 @@
 
     def override(method, /):
         return method
+
+
+def assert_never(value: Never, /) -> Never:
+    """Assert to the type checker that a line of code is unreachable."""
+    raise AssertionError(f"Expected code to be unreachable, but got: {value!r}")
+
+
+if TYPE_CHECKING:
+    from typing_extensions import assert_type as assert_type
+else:
+
+    def assert_type(val: _T, typ: Any, /) -> _T:
+        pass

From 89f6ad55c49b809341f23de6a7d59c00c3cc137d Mon Sep 17 00:00:00 2001
From: Hal Blackburn <hwtb2@cam.ac.uk>
Date: Sun, 2 Feb 2025 10:24:50 +0000
Subject: [PATCH 2/2] refactor: use denokv._pycompat.typing everywhere

---
 src/denokv/_pycompat/enum.py     |  6 +--
 src/denokv/_rfc3339.py           |  6 +--
 src/denokv/auth.py               |  6 +--
 src/denokv/backoff.py            | 10 ++--
 src/denokv/datapath.py           | 92 ++++++++++++--------------------
 src/denokv/errors.py             |  3 +-
 src/denokv/kv.py                 | 53 ++++++++----------
 src/denokv/kv_keys.py            | 67 +++++++++--------------
 src/denokv/result.py             | 42 +++++++--------
 test/advance_time.py             |  7 +--
 test/denokv_testing.py           | 14 ++---
 test/pycompat/test_protobuf.py   |  3 +-
 test/test_auth.py                | 12 ++---
 test/test_datapath.py            | 12 ++---
 test/test_kv.py                  | 18 +++----
 test/test_kv_keys__kvkey.py      |  6 +--
 test/test_kv_keys__kvkeyrange.py |  2 +-
 test/test_result.py              | 14 ++---
 18 files changed, 157 insertions(+), 216 deletions(-)

diff --git a/src/denokv/_pycompat/enum.py b/src/denokv/_pycompat/enum.py
index fe84abe..36b38ff 100644
--- a/src/denokv/_pycompat/enum.py
+++ b/src/denokv/_pycompat/enum.py
@@ -4,11 +4,9 @@
 from enum import EnumMeta
 from enum import Flag
 from enum import IntFlag
-from typing import TYPE_CHECKING
-from typing import Iterator
 
-if TYPE_CHECKING:
-    from typing_extensions import Self
+from denokv._pycompat.typing import Iterator
+from denokv._pycompat.typing import Self
 
 
 class ContainsValueEnumMeta(EnumMeta):
diff --git a/src/denokv/_rfc3339.py b/src/denokv/_rfc3339.py
index 46f8edc..7e08f32 100644
--- a/src/denokv/_rfc3339.py
+++ b/src/denokv/_rfc3339.py
@@ -4,10 +4,10 @@
 from datetime import datetime
 from datetime import timedelta
 from datetime import timezone
-from typing import Final
-from typing import TypedDict
-from typing import cast
 
+from denokv._pycompat.typing import Final
+from denokv._pycompat.typing import TypedDict
+from denokv._pycompat.typing import cast
 from denokv.result import Err
 from denokv.result import Ok
 from denokv.result import Result
diff --git a/src/denokv/auth.py b/src/denokv/auth.py
index 5dadf21..a18219e 100644
--- a/src/denokv/auth.py
+++ b/src/denokv/auth.py
@@ -2,9 +2,6 @@
 
 from dataclasses import dataclass
 from datetime import datetime
-from typing import Mapping
-from typing import Sequence
-from typing import cast
 from uuid import UUID
 
 import aiohttp
@@ -13,6 +10,9 @@
 
 from denokv._pycompat.dataclasses import slots_if310
 from denokv._pycompat.enum import StrEnum
+from denokv._pycompat.typing import Mapping
+from denokv._pycompat.typing import Sequence
+from denokv._pycompat.typing import cast
 from denokv._rfc3339 import parse_rfc3339_datetime
 from denokv.errors import DenoKvError
 from denokv.errors import DenoKvValidationError
diff --git a/src/denokv/backoff.py b/src/denokv/backoff.py
index 1c6270c..61380f8 100644
--- a/src/denokv/backoff.py
+++ b/src/denokv/backoff.py
@@ -6,14 +6,12 @@
 from dataclasses import dataclass
 from enum import IntEnum
 from itertools import count
-from typing import TYPE_CHECKING
-from typing import Callable
-from typing import Iterable
-from typing import Iterator
 from typing import Literal
 
-if TYPE_CHECKING:
-    from typing_extensions import TypeAlias
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import Iterable
+from denokv._pycompat.typing import Iterator
+from denokv._pycompat.typing import TypeAlias
 
 Backoff: TypeAlias = Iterable[float]
 """
diff --git a/src/denokv/datapath.py b/src/denokv/datapath.py
index 94ba7ab..fd8372a 100644
--- a/src/denokv/datapath.py
+++ b/src/denokv/datapath.py
@@ -9,17 +9,7 @@
 from dataclasses import dataclass
 from enum import Enum
 from enum import auto
-from typing import TYPE_CHECKING
-from typing import Awaitable
-from typing import Callable
-from typing import Container
-from typing import Final
-from typing import Protocol
-from typing import Type
-from typing import TypedDict
-from typing import Union
 from typing import overload
-from typing import runtime_checkable
 
 import aiohttp
 import aiohttp.client_exceptions
@@ -34,6 +24,19 @@
 from denokv._datapath_pb2 import SnapshotReadOutput
 from denokv._datapath_pb2 import SnapshotReadStatus
 from denokv._datapath_pb2 import ValueEncoding
+from denokv._pycompat.typing import Awaitable
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import Container
+from denokv._pycompat.typing import Final
+from denokv._pycompat.typing import Protocol
+from denokv._pycompat.typing import Type
+from denokv._pycompat.typing import TypeAlias
+from denokv._pycompat.typing import TypedDict
+from denokv._pycompat.typing import TypeGuard
+from denokv._pycompat.typing import TypeVar
+from denokv._pycompat.typing import Union
+from denokv._pycompat.typing import Unpack
+from denokv._pycompat.typing import runtime_checkable
 from denokv.auth import ConsistencyLevel
 from denokv.auth import DatabaseMetadata
 from denokv.auth import EndpointInfo
@@ -45,55 +48,30 @@
 KV_KEY_PIECE_TYPES: Final = (str, bytes, int, float, bool)
 
 
-if TYPE_CHECKING:
-    from typing_extensions import TypeAlias
-    from typing_extensions import TypeGuard
-    from typing_extensions import TypeVar
-    from typing_extensions import Unpack
+KvKeyPiece: TypeAlias = Union[str, bytes, int, float, bool]
+KvKeyPieceT = TypeVar("KvKeyPieceT", bound=KvKeyPiece, default=KvKeyPiece)
 
-    KvKeyPiece: TypeAlias = Union[str, bytes, int, float, bool]
-    KvKeyPieceT = TypeVar("KvKeyPieceT", bound=KvKeyPiece, default=KvKeyPiece)
-
-    KvKeyTuple: TypeAlias = tuple[KvKeyPieceT, ...]
-    KvKeyTupleT = TypeVar("KvKeyTupleT", bound=KvKeyTuple, default=KvKeyTuple)
-    KvKeyTupleT_co = TypeVar(
-        "KvKeyTupleT_co", bound=KvKeyTuple, default=KvKeyTuple, covariant=True
-    )
-
-    @runtime_checkable
-    class KvKeyEncodable(Protocol):
-        __slots__ = ()
-
-        def kv_key_bytes(self) -> bytes: ...
+KvKeyTuple: TypeAlias = tuple[KvKeyPieceT, ...]
+KvKeyTupleT = TypeVar("KvKeyTupleT", bound=KvKeyTuple, default=KvKeyTuple)
+KvKeyTupleT_co = TypeVar(
+    "KvKeyTupleT_co", bound=KvKeyTuple, default=KvKeyTuple, covariant=True
+)
 
-    KvKeyEncodableT = TypeVar("KvKeyEncodableT", bound=KvKeyEncodable)
-    AnyKvKey: TypeAlias = "KvKeyEncodable | KvKeyTuple"
-    AnyKvKeyT = TypeVar("AnyKvKeyT", bound=AnyKvKey, default=AnyKvKey)
-    AnyKvKeyT_co = TypeVar(
-        "AnyKvKeyT_co", bound=AnyKvKey, default=AnyKvKey, covariant=True
-    )
-    AnyKvKeyT_con = TypeVar(
-        "AnyKvKeyT_con", bound=AnyKvKey, default=AnyKvKey, contravariant=True
-    )
-else:
-    from typing import TypeVar
 
-    KvKeyPiece: TypeAlias = "str | bytes | int | float | bool"
-    KvKeyPieceT = TypeVar("KvKeyPieceT", bound=KvKeyPiece)
+@runtime_checkable
+class KvKeyEncodable(Protocol):
+    __slots__ = ()
 
-    KvKeyTuple: TypeAlias = tuple[KvKeyPieceT, ...]
-    KvKeyTupleT = TypeVar("KvKeyTupleT", bound=KvKeyTuple)
-    KvKeyTupleT_co = TypeVar("KvKeyTupleT_co", bound=KvKeyTuple, covariant=True)
+    def kv_key_bytes(self) -> bytes: ...
 
-    @runtime_checkable
-    class KvKeyEncodable(Protocol):
-        def kv_key_bytes(self) -> bytes: ...
 
-    KvKeyEncodableT = TypeVar("KvKeyEncodableT", bound=KvKeyEncodable)
-    AnyKvKey: TypeAlias = "KvKeyEncodable | KvKeyTuple"
-    AnyKvKeyT = TypeVar("AnyKvKeyT", bound=AnyKvKey)
-    AnyKvKeyT_co = TypeVar("AnyKvKeyT", bound=AnyKvKey, covariant=True)
-    AnyKvKeyT_con = TypeVar("AnyKvKeyT_con", bound=AnyKvKey, contravariant=True)
+KvKeyEncodableT = TypeVar("KvKeyEncodableT", bound=KvKeyEncodable)
+AnyKvKey: TypeAlias = Union[KvKeyEncodable, KvKeyTuple]
+AnyKvKeyT = TypeVar("AnyKvKeyT", bound=AnyKvKey, default=AnyKvKey)
+AnyKvKeyT_co = TypeVar("AnyKvKeyT_co", bound=AnyKvKey, default=AnyKvKey, covariant=True)
+AnyKvKeyT_con = TypeVar(
+    "AnyKvKeyT_con", bound=AnyKvKey, default=AnyKvKey, contravariant=True
+)
 
 _T = TypeVar("_T")
 
@@ -196,9 +174,9 @@ class RequestUnsuccessful(DataPathDenoKvError):
     pass
 
 
-DataPathError: TypeAlias = (
-    "EndpointNotUsable | RequestUnsuccessful | ResponseUnsuccessful | ProtocolViolation"
-)
+DataPathError: TypeAlias = Union[
+    EndpointNotUsable, RequestUnsuccessful, ResponseUnsuccessful, ProtocolViolation
+]
 
 
 class _DataPathRequestKind(Enum):
@@ -300,7 +278,7 @@ async def _response_body_bytes(response: aiohttp.ClientResponse) -> Ok[bytes]:
         return Ok(await response.read())
 
 
-SnapshotReadResult: TypeAlias = "Result[SnapshotReadOutput, DataPathError]"
+SnapshotReadResult: TypeAlias = Result[SnapshotReadOutput, DataPathError]
 
 
 async def snapshot_read(
diff --git a/src/denokv/errors.py b/src/denokv/errors.py
index 199be0f..83734a0 100644
--- a/src/denokv/errors.py
+++ b/src/denokv/errors.py
@@ -1,5 +1,6 @@
 from dataclasses import dataclass
-from typing import cast
+
+from denokv._pycompat.typing import cast
 
 
 @dataclass(init=False)
diff --git a/src/denokv/kv.py b/src/denokv/kv.py
index ce53323..cde6e88 100644
--- a/src/denokv/kv.py
+++ b/src/denokv/kv.py
@@ -12,18 +12,7 @@
 from enum import auto
 from os import environ
 from types import TracebackType
-from typing import TYPE_CHECKING
-from typing import AsyncIterator
-from typing import Awaitable
-from typing import Callable
-from typing import ClassVar
-from typing import Final
-from typing import Generic
-from typing import Iterable
 from typing import Literal
-from typing import Protocol
-from typing import Sequence
-from typing import TypedDict
 from typing import overload
 
 import aiohttp
@@ -36,6 +25,21 @@
 from denokv._datapath_pb2 import SnapshotRead
 from denokv._datapath_pb2 import SnapshotReadOutput
 from denokv._pycompat.dataclasses import slots_if310
+from denokv._pycompat.typing import AsyncIterator
+from denokv._pycompat.typing import Awaitable
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import ClassVar
+from denokv._pycompat.typing import Final
+from denokv._pycompat.typing import Generic
+from denokv._pycompat.typing import Iterable
+from denokv._pycompat.typing import Protocol
+from denokv._pycompat.typing import Self
+from denokv._pycompat.typing import Sequence
+from denokv._pycompat.typing import TypeAlias
+from denokv._pycompat.typing import TypedDict
+from denokv._pycompat.typing import TypeVar
+from denokv._pycompat.typing import TypeVarTuple
+from denokv._pycompat.typing import Unpack
 from denokv._pycompat.typing import override
 from denokv.asyncio import loop_time
 from denokv.auth import ConsistencyLevel
@@ -66,23 +70,10 @@
 from denokv.result import Ok
 from denokv.result import Result
 
-if TYPE_CHECKING:
-    from typing_extensions import Self
-    from typing_extensions import TypeAlias
-    from typing_extensions import TypeVar
-    from typing_extensions import TypeVarTuple
-    from typing_extensions import Unpack
-
-    T = TypeVar("T", default=object)
-    # Note that the default arg doesn't seem to work with MyPy yet. The
-    # DefaultKvKey alias is what this should behave as when defaulted.
-    Pieces = TypeVarTuple("Pieces", default=Unpack[tuple[KvKeyPiece, ...]])
-else:
-    from typing import TypeVar
-
-    T = TypeVar("T")
-    Unpack = tuple  # hack to support py39 at runtime w/o typing_extensions
-    Pieces = TypeVar("Pieces")  # hack to support py39 at runtime w/o typing_extensions
+T = TypeVar("T", default=object)
+# Note that the default arg doesn't seem to work with MyPy yet. The
+# DefaultKvKey alias is what this should behave as when defaulted.
+Pieces = TypeVarTuple("Pieces", default=Unpack[tuple[KvKeyPiece, ...]])
 
 SAFE_FLOAT_INT_RANGE: Final = range(-(2**53 - 1), 2**53)  # 2**53 - 1 is max safe
 
@@ -860,9 +851,9 @@ async def _snapshot_read(
         return Ok((result.value, endpoint))
 
 
-_KvSnapshotReadResult: TypeAlias = (
-    "Result[tuple[SnapshotReadOutput, EndpointInfo], DataPathError]"
-)
+_KvSnapshotReadResult: TypeAlias = Result[
+    tuple[SnapshotReadOutput, EndpointInfo], DataPathError
+]
 
 
 @dataclass(frozen=True)
diff --git a/src/denokv/kv_keys.py b/src/denokv/kv_keys.py
index cba2dad..0221c5d 100644
--- a/src/denokv/kv_keys.py
+++ b/src/denokv/kv_keys.py
@@ -4,20 +4,26 @@
 import sys
 from dataclasses import dataclass
 from dataclasses import field
-from typing import TYPE_CHECKING
-from typing import Any
-from typing import Final
-from typing import Generic
-from typing import Iterator
-from typing import Sequence
-from typing import Union
-from typing import cast
 from typing import overload
 
 from fdb.tuple import pack
 from fdb.tuple import unpack
 
 from denokv._pycompat.dataclasses import slots_if310
+from denokv._pycompat.typing import TYPE_CHECKING
+from denokv._pycompat.typing import Any
+from denokv._pycompat.typing import Final
+from denokv._pycompat.typing import Generic
+from denokv._pycompat.typing import Iterator
+from denokv._pycompat.typing import Self
+from denokv._pycompat.typing import Sequence
+from denokv._pycompat.typing import SupportsIndex
+from denokv._pycompat.typing import TypeAlias
+from denokv._pycompat.typing import TypeVar
+from denokv._pycompat.typing import TypeVarTuple
+from denokv._pycompat.typing import Union
+from denokv._pycompat.typing import Unpack
+from denokv._pycompat.typing import cast
 from denokv._pycompat.typing import override
 from denokv.datapath import KV_KEY_PIECE_TYPES
 from denokv.datapath import AnyKvKey
@@ -36,24 +42,10 @@
 from denokv.result import Nothing
 from denokv.result import Some
 
-if TYPE_CHECKING:
-    from typing_extensions import Self
-    from typing_extensions import SupportsIndex
-    from typing_extensions import TypeAlias
-    from typing_extensions import TypeVar
-    from typing_extensions import TypeVarTuple
-    from typing_extensions import Unpack
-
-    T = TypeVar("T", default=object)
-    # Note that the default arg doesn't seem to work with MyPy yet. The
-    # DefaultKvKey alias is what this should behave as when defaulted.
-    Pieces = TypeVarTuple("Pieces", default=Unpack[tuple[KvKeyPiece, ...]])
-else:
-    from typing import TypeVar
-
-    T = TypeVar("T")
-    Unpack = tuple  # hack to support py39 at runtime w/o typing_extensions
-    Pieces = TypeVar("Pieces")  # hack to support py39 at runtime w/o typing_extensions
+T = TypeVar("T", default=object)
+# Note that the default arg doesn't seem to work with MyPy yet. The
+# DefaultKvKey alias is what this should behave as when defaulted.
+Pieces = TypeVarTuple("Pieces", default=Unpack[tuple[KvKeyPiece, ...]])
 
 _T_co = TypeVar("_T_co", covariant=True)
 
@@ -447,23 +439,12 @@ def range(cls) -> KvKeyRange[IncludeAll, IncludeAll]:
 StopBoundary: TypeAlias = Union[
     IncludeAll, Include[AnyKvKeyT], IncludePrefix[AnyKvKeyT], Exclude[AnyKvKeyT]
 ]
-
-if TYPE_CHECKING:
-    StartT = TypeVar(
-        "StartT", bound=StartBoundary, default=StartBoundary, covariant=False
-    )
-    StartT_co = TypeVar(
-        "StartT_co", bound=StartBoundary, default=StartBoundary, covariant=True
-    )
-    StopT = TypeVar("StopT", bound=StopBoundary, default=StopBoundary, covariant=False)
-    StopT_co = TypeVar(
-        "StopT_co", bound=StopBoundary, default=StopBoundary, covariant=True
-    )
-else:
-    StartT = TypeVar("StartT", bound=StartBoundary, covariant=False)
-    StopT = TypeVar("StopT", bound=StopBoundary, covariant=False)
-    StartT_co = TypeVar("StartT_co", bound=StartBoundary, covariant=True)
-    StopT_co = TypeVar("StopT_co", bound=StopBoundary, covariant=True)
+StartT = TypeVar("StartT", bound=StartBoundary, default=StartBoundary, covariant=False)
+StartT_co = TypeVar(
+    "StartT_co", bound=StartBoundary, default=StartBoundary, covariant=True
+)
+StopT = TypeVar("StopT", bound=StopBoundary, default=StopBoundary, covariant=False)
+StopT_co = TypeVar("StopT_co", bound=StopBoundary, default=StopBoundary, covariant=True)
 
 
 @functools.total_ordering
diff --git a/src/denokv/result.py b/src/denokv/result.py
index 36201c0..68ba208 100644
--- a/src/denokv/result.py
+++ b/src/denokv/result.py
@@ -2,31 +2,29 @@
 
 from abc import ABCMeta
 from dataclasses import dataclass
-from typing import TYPE_CHECKING
-from typing import Any
-from typing import Callable
-from typing import Final
-from typing import Generic
-from typing import Iterable
-from typing import Iterator
-from typing import Protocol
-from typing import TypeVar
-from typing import Union
-from typing import cast
 from typing import overload
-from typing import runtime_checkable
 
 from denokv._pycompat.dataclasses import slots_if310
-
-if TYPE_CHECKING:
-    from typing_extensions import Never
-    from typing_extensions import ParamSpec
-    from typing_extensions import Self
-    from typing_extensions import TypeAlias
-    from typing_extensions import TypeGuard
-    from typing_extensions import TypeIs
-
-    P = ParamSpec("P")
+from denokv._pycompat.typing import TYPE_CHECKING
+from denokv._pycompat.typing import Any
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import Final
+from denokv._pycompat.typing import Generic
+from denokv._pycompat.typing import Iterable
+from denokv._pycompat.typing import Iterator
+from denokv._pycompat.typing import Never
+from denokv._pycompat.typing import ParamSpec
+from denokv._pycompat.typing import Protocol
+from denokv._pycompat.typing import Self
+from denokv._pycompat.typing import TypeAlias
+from denokv._pycompat.typing import TypeGuard
+from denokv._pycompat.typing import TypeIs
+from denokv._pycompat.typing import TypeVar
+from denokv._pycompat.typing import Union
+from denokv._pycompat.typing import cast
+from denokv._pycompat.typing import runtime_checkable
+
+P = ParamSpec("P")
 
 
 @runtime_checkable
diff --git a/test/advance_time.py b/test/advance_time.py
index d166867..f5dcff7 100644
--- a/test/advance_time.py
+++ b/test/advance_time.py
@@ -4,13 +4,14 @@
 import time
 from dataclasses import dataclass
 from dataclasses import field
-from typing import Callable
-from typing import Final
-from typing import Generator
 from unittest.mock import patch
 
 import pytest
 
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import Final
+from denokv._pycompat.typing import Generator
+
 
 @pytest.fixture
 def advance_time_time() -> Generator[None]:
diff --git a/test/denokv_testing.py b/test/denokv_testing.py
index 88256f9..e257ca2 100644
--- a/test/denokv_testing.py
+++ b/test/denokv_testing.py
@@ -8,13 +8,6 @@
 from datetime import datetime
 from datetime import timedelta
 from itertools import groupby
-from typing import Any
-from typing import ClassVar
-from typing import Iterable
-from typing import Mapping
-from typing import NamedTuple
-from typing import Sequence
-from typing import TypeVar
 from typing import overload
 from uuid import UUID
 
@@ -26,6 +19,13 @@
 from denokv._datapath_pb2 import ReadRange
 from denokv._datapath_pb2 import ReadRangeOutput
 from denokv._datapath_pb2 import ValueEncoding
+from denokv._pycompat.typing import Any
+from denokv._pycompat.typing import ClassVar
+from denokv._pycompat.typing import Iterable
+from denokv._pycompat.typing import Mapping
+from denokv._pycompat.typing import NamedTuple
+from denokv._pycompat.typing import Sequence
+from denokv._pycompat.typing import TypeVar
 from denokv.auth import DatabaseMetadata
 from denokv.auth import EndpointInfo
 from denokv.datapath import AnyKvKey
diff --git a/test/pycompat/test_protobuf.py b/test/pycompat/test_protobuf.py
index ef42013..b7bce07 100644
--- a/test/pycompat/test_protobuf.py
+++ b/test/pycompat/test_protobuf.py
@@ -1,11 +1,10 @@
-from typing import cast
-
 import pytest
 
 from denokv._datapath_pb2 import AtomicWriteStatus
 from denokv._datapath_pb2 import MutationType
 from denokv._datapath_pb2 import ValueEncoding
 from denokv._pycompat.protobuf import enum_name
+from denokv._pycompat.typing import cast
 
 
 def test_enum_name() -> None:
diff --git a/test/test_auth.py b/test/test_auth.py
index 7557240..00de3a9 100644
--- a/test/test_auth.py
+++ b/test/test_auth.py
@@ -2,11 +2,6 @@
 
 import json
 from copy import deepcopy
-from typing import Any
-from typing import Awaitable
-from typing import Callable
-from typing import Sequence
-from typing import cast
 from uuid import UUID
 
 import aiohttp
@@ -14,9 +9,14 @@
 import pytest_asyncio
 from aiohttp import web
 from aiohttp.test_utils import TestClient as _TestClient
-from typing_extensions import TypeAlias
 from yarl import URL
 
+from denokv._pycompat.typing import Any
+from denokv._pycompat.typing import Awaitable
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import Sequence
+from denokv._pycompat.typing import TypeAlias
+from denokv._pycompat.typing import cast
 from denokv._rfc3339 import parse_rfc3339_datetime
 from denokv.auth import ConsistencyLevel
 from denokv.auth import DatabaseMetadata
diff --git a/test/test_datapath.py b/test/test_datapath.py
index f73d53a..8ab2248 100644
--- a/test/test_datapath.py
+++ b/test/test_datapath.py
@@ -5,12 +5,7 @@
 import struct
 from datetime import datetime
 from datetime import timedelta
-from typing import Awaitable
-from typing import Callable
-from typing import Final
 from typing import Literal
-from typing import Mapping
-from typing import cast
 from uuid import UUID
 
 import pytest
@@ -23,7 +18,6 @@
 from hypothesis import example
 from hypothesis import given
 from hypothesis import strategies as st
-from typing_extensions import TypeAlias
 from v8serialize import Decoder
 from yarl import URL
 
@@ -35,6 +29,12 @@
 from denokv._datapath_pb2 import SnapshotReadOutput
 from denokv._datapath_pb2 import SnapshotReadStatus
 from denokv._datapath_pb2 import ValueEncoding
+from denokv._pycompat.typing import Awaitable
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import Final
+from denokv._pycompat.typing import Mapping
+from denokv._pycompat.typing import TypeAlias
+from denokv._pycompat.typing import cast
 from denokv.auth import ConsistencyLevel
 from denokv.auth import DatabaseMetadata
 from denokv.auth import EndpointInfo
diff --git a/test/test_kv.py b/test/test_kv.py
index 83d9a0f..2389c43 100644
--- a/test/test_kv.py
+++ b/test/test_kv.py
@@ -9,12 +9,6 @@
 from datetime import timedelta
 from functools import partial
 from itertools import repeat
-from typing import TYPE_CHECKING
-from typing import Any
-from typing import AsyncGenerator
-from typing import Callable
-from typing import Mapping
-from typing import cast
 from unittest.mock import AsyncMock
 from unittest.mock import Mock
 from unittest.mock import patch
@@ -40,6 +34,13 @@
 from denokv._datapath_pb2 import SnapshotReadStatus
 from denokv._datapath_pb2 import ValueEncoding
 from denokv._pycompat.enum import StrEnum
+from denokv._pycompat.typing import Any
+from denokv._pycompat.typing import AsyncGenerator
+from denokv._pycompat.typing import Callable
+from denokv._pycompat.typing import Generator
+from denokv._pycompat.typing import Mapping
+from denokv._pycompat.typing import TypeAlias
+from denokv._pycompat.typing import cast
 from denokv.asyncio import loop_time
 from denokv.auth import ConsistencyLevel
 from denokv.auth import DatabaseMetadata
@@ -84,11 +85,6 @@
 from test.denokv_testing import mk_db_meta
 from test.denokv_testing import unsafe_parse_protobuf_kv_entry
 
-if TYPE_CHECKING:
-    from typing import Generator
-
-    from typing_extensions import TypeAlias
-
 pytest_mark_asyncio = pytest.mark.asyncio()
 
 
diff --git a/test/test_kv_keys__kvkey.py b/test/test_kv_keys__kvkey.py
index 67bf47e..b75dd9a 100644
--- a/test/test_kv_keys__kvkey.py
+++ b/test/test_kv_keys__kvkey.py
@@ -3,13 +3,13 @@
 import re
 import weakref
 from typing import Literal
-from typing import Sequence
-from typing import cast
 
 import pytest
 from fdb.tuple import pack
-from typing_extensions import Unpack
 
+from denokv._pycompat.typing import Sequence
+from denokv._pycompat.typing import Unpack
+from denokv._pycompat.typing import cast
 from denokv.datapath import AnyKvKey
 from denokv.datapath import KvKeyEncodable
 from denokv.datapath import KvKeyPiece
diff --git a/test/test_kv_keys__kvkeyrange.py b/test/test_kv_keys__kvkeyrange.py
index 68ce3b2..d8de0d6 100644
--- a/test/test_kv_keys__kvkeyrange.py
+++ b/test/test_kv_keys__kvkeyrange.py
@@ -1,8 +1,8 @@
 from typing import Literal
-from typing import cast
 
 import pytest
 
+from denokv._pycompat.typing import cast
 from denokv.kv_keys import Exclude
 from denokv.kv_keys import Include
 from denokv.kv_keys import IncludeAll
diff --git a/test/test_result.py b/test/test_result.py
index 846550e..4e9394c 100644
--- a/test/test_result.py
+++ b/test/test_result.py
@@ -1,18 +1,18 @@
 from __future__ import annotations
 
 import sys
-from typing import TYPE_CHECKING
-from typing import Any
-from typing import Iterable
 from typing import Literal
-from typing import Sequence
-from typing import cast
 from unittest.mock import Mock
 
 import pytest
-from typing_extensions import Never
-from typing_extensions import TypeIs
 
+from denokv._pycompat.typing import TYPE_CHECKING
+from denokv._pycompat.typing import Any
+from denokv._pycompat.typing import Iterable
+from denokv._pycompat.typing import Never
+from denokv._pycompat.typing import Sequence
+from denokv._pycompat.typing import TypeIs
+from denokv._pycompat.typing import cast
 from denokv.result import AnyFailure
 from denokv.result import AnySuccess
 from denokv.result import Err