remove unused typevars, make dtype type alias

Author: MarcoGorelli

spec/API_specification/dataframe_api/__init__.py

@@ -3,12 +3,15 @@
 """
 from __future__ import annotations
 
-from typing import Mapping, Sequence, Any
+from typing import Mapping, Sequence, Any, TYPE_CHECKING
 
 from .column_object import *
 from .dataframe_object import DataFrame
 from .groupby_object import *
-from ._types import DType
+from .dtypes import *
+
+if TYPE_CHECKING:
+    from ._types import DType
 
 __all__ = [
     "__dataframe_api_version__",
@@ -63,7 +66,7 @@ def concat(dataframes: Sequence[DataFrame]) -> DataFrame:
     """
     ...
 
-def column_from_sequence(sequence: Sequence[Any], *, dtype: Any, name: str = '', api_version: str | None = None) -> Column[Any]:
+def column_from_sequence(sequence: Sequence[Any], *, dtype: DType, name: str = '', api_version: str | None = None) -> Column:
     """
     Construct Column from sequence of elements.
 
@@ -91,7 +94,7 @@ def column_from_sequence(sequence: Sequence[Any], *, dtype: Any, name: str = '',
     """
     ...
 
-def dataframe_from_dict(data: Mapping[str, Column[Any]], *, api_version: str | None = None) -> DataFrame:
+def dataframe_from_dict(data: Mapping[str, Column], *, api_version: str | None = None) -> DataFrame:
     """
     Construct DataFrame from map of column names to Columns.
 
@@ -123,7 +126,7 @@ def dataframe_from_dict(data: Mapping[str, Column[Any]], *, api_version: str | N
     ...
 
 
-def column_from_1d_array(array: Any, *, dtype: Any, name: str = '', api_version: str | None = None) -> Column[Any]:
+def column_from_1d_array(array: Any, *, dtype: DType, name: str = '', api_version: str | None = None) -> Column:
     """
     Construct Column from 1D array.
 
@@ -232,51 +235,13 @@ def is_null(value: object, /) -> bool:
 
     """
 
-##########
-# Dtypes #
-##########
-
-class Int64:
-    """Integer type with 64 bits of precision."""
-
-class Int32:
-    """Integer type with 32 bits of precision."""
-
-class Int16:
-    """Integer type with 16 bits of precision."""
-
-class Int8:
-    """Integer type with 8 bits of precision."""
-
-class UInt64:
-    """Unsigned integer type with 64 bits of precision."""
-
-class UInt32:
-    """Unsigned integer type with 32 bits of precision."""
-
-class UInt16:
-    """Unsigned integer type with 16 bits of precision."""
-
-class UInt8:
-    """Unsigned integer type with 8 bits of precision."""
-
-class Float64:
-    """Floating point type with 64 bits of precision."""
-
-class Float32:
-    """Floating point type with 32 bits of precision."""
-
-class Bool:
-    """Boolean type with 8 bits of precision."""
-
-
-def is_dtype(dtype: Any, kind: str | tuple[str, ...]) -> bool:
+def is_dtype(dtype: DType, kind: str | tuple[str, ...]) -> bool:
     """
     Returns a boolean indicating whether a provided dtype is of a specified data type “kind”.
 
     Parameters
     ----------
-        dtype: Any
+        dtype: DType
             The input dtype.
         kind: str
             data type kind.

spec/API_specification/dataframe_api/_types.py

@@ -1,8 +1,5 @@
 """
 Types for type annotations used in the dataframe API standard.
-
-The type variables should be replaced with the actual types for a given
-library, e.g., for Pandas TypeVar('DataFrame') would be replaced with pd.DataFrame.
 """
 from __future__ import annotations
 
@@ -14,39 +11,35 @@
     Optional,
     Sequence,
     Tuple,
-    TypeVar,
     Union,
-    Protocol,
+    TYPE_CHECKING,
 )
 from enum import Enum
 
+if TYPE_CHECKING:
+    from .dtypes import (
+        Bool,
+        Float64,
+        Float32,
+        Int64,
+        Int32,
+        Int16,
+        Int8,
+        UInt64,
+        UInt32,
+        UInt16,
+        UInt8,
+    )
+
+    DType = Union[Bool, Float64, Float32, Int64, Int32, Int16, Int8, UInt64, UInt32, UInt16, UInt8]
+
 # Type alias: Mypy needs Any, but for readability we need to make clear this
 # is a Python scalar (i.e., an instance of `bool`, `int`, `float`, `str`, etc.)
 Scalar = Any
 # null is a special object which represents a missing value.
 # It is not valid as a type.
 NullType = Any
 
-array = TypeVar("array")
-device = TypeVar("device")
-DType = TypeVar("DType")
-SupportsDLPack = TypeVar("SupportsDLPack")
-SupportsBufferProtocol = TypeVar("SupportsBufferProtocol")
-PyCapsule = TypeVar("PyCapsule")
-# ellipsis cannot actually be imported from anywhere, so include a dummy here
-# to keep pyflakes happy. https://github.com/python/typeshed/issues/3556
-ellipsis = TypeVar("ellipsis")
-
-_T_co = TypeVar("_T_co", covariant=True)
-
-
-class NestedSequence(Protocol[_T_co]):
-    def __getitem__(self, key: int, /) -> Union[_T_co, NestedSequence[_T_co]]:
-        ...
-
-    def __len__(self, /) -> int:
-        ...
-
 
 __all__ = [
     "Any",