Merge pull request #495 from numpy/fix-ndarray.__add__

Author: jorenham

src/_numtype/@test/test_nep50.pyi

@@ -75,7 +75,7 @@ i1_from_c16: CanCast0D[np.int8] = c16  # type: ignore[assignment]  # pyright: ig
 i1_from_cld: CanCast0D[np.int8] = cld  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 
 i1_to_b1: CanCast0D[Any, np.int8] = b1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-i1_to_i1: CanCast0D[Any, np.int8] = i1
+i1_to_i1: CanCast0D[Any, np.int8] = i1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i1_to_u1: CanCast0D[Any, np.int8] = u1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i1_to_i2: CanCast0D[Any, np.int8] = i2
 i1_to_u2: CanCast0D[Any, np.int8] = u2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
@@ -110,7 +110,7 @@ u1_from_cld: CanCast0D[np.uint8] = cld  # type: ignore[assignment]  # pyright: i
 
 u1_to_b1: CanCast0D[Any, np.uint8] = b1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u1_to_i1: CanCast0D[Any, np.uint8] = i1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-u1_to_u1: CanCast0D[Any, np.uint8] = u1
+u1_to_u1: CanCast0D[Any, np.uint8] = u1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u1_to_i2: CanCast0D[Any, np.uint8] = i2
 u1_to_u2: CanCast0D[Any, np.uint8] = u2
 u1_to_i4: CanCast0D[Any, np.uint8] = i4
@@ -145,7 +145,7 @@ i2_from_cld: CanCast0D[np.int16] = cld  # type: ignore[assignment]  # pyright: i
 i2_to_b1: CanCast0D[Any, np.int16] = b1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i2_to_i1: CanCast0D[Any, np.int16] = i1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i2_to_u1: CanCast0D[Any, np.int16] = u1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-i2_to_i2: CanCast0D[Any, np.int16] = i2
+i2_to_i2: CanCast0D[Any, np.int16] = i2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i2_to_u2: CanCast0D[Any, np.int16] = u2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i2_to_i4: CanCast0D[Any, np.int16] = i4
 i2_to_u4: CanCast0D[Any, np.int16] = u4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
@@ -180,7 +180,7 @@ u2_to_b1: CanCast0D[Any, np.uint16] = b1  # type: ignore[assignment]  # pyright:
 u2_to_i1: CanCast0D[Any, np.uint16] = i1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u2_to_u1: CanCast0D[Any, np.uint16] = u1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u2_to_i2: CanCast0D[Any, np.uint16] = i2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-u2_to_u2: CanCast0D[Any, np.uint16] = u2
+u2_to_u2: CanCast0D[Any, np.uint16] = u2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u2_to_i4: CanCast0D[Any, np.uint16] = i4
 u2_to_u4: CanCast0D[Any, np.uint16] = u4
 u2_to_i8: CanCast0D[Any, np.uint16] = i8
@@ -215,7 +215,7 @@ i4_to_i1: CanCast0D[Any, np.int32] = i1  # type: ignore[assignment]  # pyright:
 i4_to_u1: CanCast0D[Any, np.int32] = u1  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i4_to_i2: CanCast0D[Any, np.int32] = i2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i4_to_u2: CanCast0D[Any, np.int32] = u2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-i4_to_i4: CanCast0D[Any, np.int32] = i4
+i4_to_i4: CanCast0D[Any, np.int32] = i4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i4_to_u4: CanCast0D[Any, np.int32] = u4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i4_to_i8: CanCast0D[Any, np.int32] = i8
 i4_to_u8: CanCast0D[Any, np.int32] = u8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
@@ -250,7 +250,7 @@ u4_to_u1: CanCast0D[Any, np.uint32] = u1  # type: ignore[assignment]  # pyright:
 u4_to_i2: CanCast0D[Any, np.uint32] = i2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u4_to_u2: CanCast0D[Any, np.uint32] = u2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u4_to_i4: CanCast0D[Any, np.uint32] = i4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-u4_to_u4: CanCast0D[Any, np.uint32] = u4
+u4_to_u4: CanCast0D[Any, np.uint32] = u4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u4_to_i8: CanCast0D[Any, np.uint32] = i8
 u4_to_u8: CanCast0D[Any, np.uint32] = u8
 u4_to_f2: CanCast0D[Any, np.uint32] = f2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
@@ -285,7 +285,7 @@ i8_to_i2: CanCast0D[Any, np.int64] = i2  # type: ignore[assignment]  # pyright:
 i8_to_u2: CanCast0D[Any, np.int64] = u2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i8_to_i4: CanCast0D[Any, np.int64] = i4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i8_to_u4: CanCast0D[Any, np.int64] = u4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-i8_to_i8: CanCast0D[Any, np.int64] = i8
+i8_to_i8: CanCast0D[Any, np.int64] = i8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i8_to_u8: CanCast0D[Any, np.int64] = u8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i8_to_f2: CanCast0D[Any, np.int64] = f2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 i8_to_f4: CanCast0D[Any, np.int64] = f4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
@@ -320,7 +320,7 @@ u8_to_u2: CanCast0D[Any, np.uint64] = u2  # type: ignore[assignment]  # pyright:
 u8_to_i4: CanCast0D[Any, np.uint64] = i4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u8_to_u4: CanCast0D[Any, np.uint64] = u4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u8_to_i8: CanCast0D[Any, np.uint64] = i8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-u8_to_u8: CanCast0D[Any, np.uint64] = u8
+u8_to_u8: CanCast0D[Any, np.uint64] = u8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u8_to_f2: CanCast0D[Any, np.uint64] = f2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u8_to_f4: CanCast0D[Any, np.uint64] = f4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 u8_to_f8: CanCast0D[Any, np.uint64] = f8
@@ -355,7 +355,7 @@ f2_to_i4: CanCast0D[Any, np.float16] = i4  # type: ignore[assignment]  # pyright
 f2_to_u4: CanCast0D[Any, np.float16] = u4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f2_to_i8: CanCast0D[Any, np.float16] = i8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f2_to_u8: CanCast0D[Any, np.float16] = u8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-f2_to_f2: CanCast0D[Any, np.float16] = f2
+f2_to_f2: CanCast0D[Any, np.float16] = f2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f2_to_f4: CanCast0D[Any, np.float16] = f4
 f2_to_f8: CanCast0D[Any, np.float16] = f8
 f2_to_ld: CanCast0D[Any, np.float16] = ld
@@ -390,7 +390,7 @@ f4_to_u4: CanCast0D[Any, np.float32] = u4  # type: ignore[assignment]  # pyright
 f4_to_i8: CanCast0D[Any, np.float32] = i8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f4_to_u8: CanCast0D[Any, np.float32] = u8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f4_to_f2: CanCast0D[Any, np.float32] = f2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-f4_to_f4: CanCast0D[Any, np.float32] = f4
+f4_to_f4: CanCast0D[Any, np.float32] = f4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f4_to_f8: CanCast0D[Any, np.float32] = f8
 f4_to_ld: CanCast0D[Any, np.float32] = ld
 f4_to_c8: CanCast0D[Any, np.float32] = c8
@@ -425,7 +425,7 @@ f8_to_i8: CanCast0D[Any, np.float64] = i8  # type: ignore[assignment]  # pyright
 f8_to_u8: CanCast0D[Any, np.float64] = u8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f8_to_f2: CanCast0D[Any, np.float64] = f2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f8_to_f4: CanCast0D[Any, np.float64] = f4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-f8_to_f8: CanCast0D[Any, np.float64] = f8
+f8_to_f8: CanCast0D[Any, np.float64] = f8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f8_to_ld: CanCast0D[Any, np.float64] = ld
 f8_to_c8: CanCast0D[Any, np.float64] = c8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 f8_to_c16: CanCast0D[Any, np.float64] = c16
@@ -460,7 +460,7 @@ ld_to_u8: CanCast0D[Any, np.longdouble] = u8  # type: ignore[assignment]  # pyri
 ld_to_f2: CanCast0D[Any, np.longdouble] = f2  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 ld_to_f4: CanCast0D[Any, np.longdouble] = f4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 ld_to_f8: CanCast0D[Any, np.longdouble] = f8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-ld_to_ld: CanCast0D[Any, np.longdouble] = ld
+ld_to_ld: CanCast0D[Any, np.longdouble] = ld  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 ld_to_c8: CanCast0D[Any, np.longdouble] = c8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 ld_to_c16: CanCast0D[Any, np.longdouble] = c16  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 ld_to_cld: CanCast0D[Any, np.longdouble] = cld
@@ -495,7 +495,7 @@ c8_to_f2: CanCast0D[Any, np.complex64] = f2  # type: ignore[assignment]  # pyrig
 c8_to_f4: CanCast0D[Any, np.complex64] = f4  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 c8_to_f8: CanCast0D[Any, np.complex64] = f8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 c8_to_ld: CanCast0D[Any, np.complex64] = ld  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-c8_to_c8: CanCast0D[Any, np.complex64] = c8
+c8_to_c8: CanCast0D[Any, np.complex64] = c8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 c8_to_c16: CanCast0D[Any, np.complex64] = c16
 c8_to_cld: CanCast0D[Any, np.complex64] = cld
 
@@ -530,7 +530,7 @@ c16_to_f4: CanCast0D[Any, np.complex128] = f4  # type: ignore[assignment]  # pyr
 c16_to_f8: CanCast0D[Any, np.complex128] = f8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 c16_to_ld: CanCast0D[Any, np.complex128] = ld  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 c16_to_c8: CanCast0D[Any, np.complex128] = c8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-c16_to_c16: CanCast0D[Any, np.complex128] = c16
+c16_to_c16: CanCast0D[Any, np.complex128] = c16  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 c16_to_cld: CanCast0D[Any, np.complex128] = cld
 
 cld_from_b1: CanCast0D[np.clongdouble] = b1
@@ -565,4 +565,4 @@ cld_to_f8: CanCast0D[Any, np.clongdouble] = f8  # type: ignore[assignment]  # py
 cld_to_ld: CanCast0D[Any, np.clongdouble] = ld  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 cld_to_c8: CanCast0D[Any, np.clongdouble] = c8  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
 cld_to_c16: CanCast0D[Any, np.clongdouble] = c16  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]
-cld_to_cld: CanCast0D[Any, np.clongdouble] = cld
+cld_to_cld: CanCast0D[Any, np.clongdouble] = cld  # type: ignore[assignment]  # pyright: ignore[reportAssignmentType]

src/_numtype/__init__.pyi

@@ -6,7 +6,7 @@ import decimal
 import fractions
 from collections.abc import Sequence
 from typing import Any, TypeAlias, type_check_only
-from typing_extensions import Protocol, TypeAliasType, TypeVar, Unpack
+from typing_extensions import Never, Protocol, TypeAliasType, TypeVar, Unpack
 
 import numpy as np
 from numpy._typing import _NestedSequence
@@ -48,9 +48,11 @@ from ._just import (
     JustStr as JustStr,
 )
 from ._nep50 import (
-    CanCast as CanCast,
     CanCast0D as CanCast0D,
     CanCastND as CanCastND,
+    CanNEP50 as CanNEP50,
+    MatchND as MatchND,
+    PromoteWith as PromoteWith,
 )
 from ._scalar import (
     inexact32 as inexact32,
@@ -97,17 +99,16 @@ from ._scalar_co import (
 # Type parameters
 
 _T = TypeVar("_T")
+_ShapeT = TypeVar("_ShapeT", bound=tuple[int, ...], default=tuple[int, ...])
 _ShapeT_co = TypeVar("_ShapeT_co", bound=tuple[int, ...], covariant=True)
 _ScalarT = TypeVar("_ScalarT", bound=np.generic)
 _ScalarT_co = TypeVar("_ScalarT_co", bound=np.generic, covariant=True)
 _ScalarT0 = TypeVar("_ScalarT0", bound=np.generic, default=Any)
+_NaT = TypeVar("_NaT", default=Never)
+_NaT0 = TypeVar("_NaT0", default=Any)
+_NaT_co = TypeVar("_NaT_co", covariant=True)
 _ToT = TypeVar("_ToT")
 
-###
-# Type constraints (bijective type mappings)
-
-_ShapeT = TypeVar("_ShapeT", bound=tuple[int, ...], default=tuple[int, ...])
-
 ###
 # Protocols
 
@@ -141,6 +142,10 @@ class CanLenArray(Protocol[_ScalarT_co, _ShapeT_co]):
     def __len__(self, /) -> int: ...
     def __array__(self, /) -> np.ndarray[_ShapeT_co, np.dtype[_ScalarT_co]]: ...
 
+@type_check_only
+class _CanStringArray(Protocol[_ShapeT_co, _NaT_co]):
+    def __array__(self, /) -> np.ndarray[_ShapeT_co, np.dtypes.StringDType[_NaT_co]]: ...
+
 ###
 # Shape aliases
 
@@ -158,6 +163,7 @@ Sequence2D: TypeAlias = Sequence[Sequence[_T]]
 Sequence3D: TypeAlias = Sequence[Sequence[Sequence[_T]]]
 
 # nested sequences with at least k dims, e.g. `2nd` denotes a dimensionality in the interval [2, n]
+SequenceND: TypeAlias = _T | _NestedSequence[_T]
 Sequence1ND: TypeAlias = _NestedSequence[_T]
 Sequence2ND: TypeAlias = Sequence[_NestedSequence[_T]]
 Sequence3ND: TypeAlias = Sequence[Sequence[_NestedSequence[_T]]]
@@ -180,6 +186,37 @@ MArray3D = TypeAliasType("MArray3D", np.ma.MaskedArray[tuple[int, int, int], np.
 
 Matrix = TypeAliasType("Matrix", np.matrix[tuple[int, int], np.dtype[_ScalarT0]], type_params=(_ScalarT0,))
 
+StringArray = TypeAliasType(
+    "StringArray",
+    np.ndarray[_ShapeT, np.dtypes.StringDType[_NaT]],
+    type_params=(_ShapeT, _NaT),
+)
+StringArray0D = TypeAliasType(
+    "StringArray0D",
+    np.ndarray[tuple[()], np.dtypes.StringDType[_NaT]],
+    type_params=(_NaT,),
+)
+StringArray1D = TypeAliasType(
+    "StringArray1D",
+    np.ndarray[tuple[int], np.dtypes.StringDType[_NaT]],
+    type_params=(_NaT,),
+)
+StringArray2D = TypeAliasType(
+    "StringArray2D",
+    np.ndarray[tuple[int, int], np.dtypes.StringDType[_NaT]],
+    type_params=(_NaT,),
+)
+StringArray3D = TypeAliasType(
+    "StringArray3D",
+    np.ndarray[tuple[int, int, int], np.dtypes.StringDType[_NaT]],
+    type_params=(_NaT,),
+)
+StringArrayND = TypeAliasType(
+    "StringArrayND",
+    np.ndarray[tuple[int, ...], np.dtypes.StringDType[_NaT]],
+    type_params=(_NaT,),
+)
+
 ###
 # helper aliases
 
@@ -192,8 +229,8 @@ _PyObject: TypeAlias = decimal.Decimal | fractions.Fraction
 _PyScalar: TypeAlias = complex | _PyCharacter | _PyObject
 
 _ToArray2_0d: TypeAlias = CanArray0D[_ScalarT] | _ToT
-_ToArray_nd: TypeAlias = CanArrayND[_ScalarT] | Sequence1ND[CanArrayND[_ScalarT]]
-_ToArray2_nd: TypeAlias = CanArrayND[_ScalarT] | _ToT | Sequence1ND[_ToT | CanArrayND[_ScalarT]]
+_ToArray_nd: TypeAlias = SequenceND[CanArrayND[_ScalarT]]
+_ToArray2_nd: TypeAlias = SequenceND[CanArrayND[_ScalarT] | _ToT]
 
 # don't require matching shape-types by default
 _ToArray_1d: TypeAlias = CanLenArrayND[_ScalarT] | Sequence[CanArray0D[_ScalarT]]
@@ -636,6 +673,15 @@ ToObject_1nd = TypeAliasType("ToObject_1nd", _ToArray2_1nd[np.object_, _PyObject
 ToObject_2nd = TypeAliasType("ToObject_2nd", _ToArray2_2nd[np.object_, _PyObject])
 ToObject_3nd = TypeAliasType("ToObject_3nd", _ToArray2_3nd[np.object_, _PyObject])
 
+# StringDType
+ToString_nd = TypeAliasType("ToString_nd", _CanStringArray[AtLeast0D, _NaT0], type_params=(_NaT0,))
+ToString_1ds = TypeAliasType("ToString_1ds", _CanStringArray[tuple[int], _NaT0], type_params=(_NaT0,))
+ToString_2ds = TypeAliasType("ToString_2ds", _CanStringArray[tuple[int, int], _NaT0], type_params=(_NaT0,))
+ToString_3ds = TypeAliasType("ToString_3ds", _CanStringArray[tuple[int, int, int], _NaT0], type_params=(_NaT0,))
+ToString_1nd = TypeAliasType("ToString_1nd", _CanStringArray[AtLeast1D, _NaT0], type_params=(_NaT0,))
+ToString_2nd = TypeAliasType("ToString_2nd", _CanStringArray[AtLeast2D, _NaT0], type_params=(_NaT0,))
+ToString_3nd = TypeAliasType("ToString_3nd", _CanStringArray[AtLeast3D, _NaT0], type_params=(_NaT0,))
+
 # any scalar
 ToGeneric_nd = TypeAliasType("ToGeneric_nd", _ToArray2_nd[np.generic, _PyScalar])
 ToGeneric_0d = TypeAliasType("ToGeneric_0d", _ToArray2_0d[np.generic, _PyScalar])

src/_numtype/_nep50.pyi

@@ -3,37 +3,70 @@
 # https://numpy.org/neps/nep-0050-scalar-promotion.html
 
 from typing import Any, Protocol, type_check_only
-from typing_extensions import TypeVar
+from typing_extensions import TypeAliasType, TypeVar
 
 import numpy as np
 
-__all__ = ["CanCast", "CanCast0D", "CanCastND"]
+__all__ = ["CanCast0D", "CanCastND", "CanNEP50", "MatchND", "PromoteWith"]
 
 _T_co = TypeVar("_T_co", covariant=True)
+_BelowT_contra = TypeVar("_BelowT_contra", bound=np.generic, contravariant=True)
+_AboveT_contra = TypeVar("_AboveT_contra", bound=np.generic, contravariant=True, default=Any)
+_OtherT_contra = TypeVar("_OtherT_contra", contravariant=True)
+_MatchT_co = TypeVar("_MatchT_co", bound=np.generic, covariant=True, default=Any)
 _ShapeT_co = TypeVar("_ShapeT_co", bound=tuple[int, ...], covariant=True)
-_ToScalarT_contra = TypeVar("_ToScalarT_contra", bound=np.generic, contravariant=True)
-_FromScalarT_contra = TypeVar("_FromScalarT_contra", bound=np.generic, contravariant=True, default=Any)
-_SelfScalarT_co = TypeVar("_SelfScalarT_co", bound=np.generic, covariant=True, default=Any)
+
+@type_check_only
+class CanNEP50(Protocol[_BelowT_contra, _AboveT_contra, _MatchT_co]):
+    def __nep50__(self, below: _BelowT_contra, above: _AboveT_contra, /) -> _MatchT_co: ...
+
+@type_check_only
+class _CanNEP50Int(Protocol[_OtherT_contra, _T_co]):
+    def __nep50_int__(self, other: _OtherT_contra, /) -> _T_co: ...
+
+@type_check_only
+class _CanNEP50Float(Protocol[_OtherT_contra, _T_co]):
+    def __nep50_float__(self, other: _OtherT_contra, /) -> _T_co: ...
+
+@type_check_only
+class _CanNEP50Complex(Protocol[_OtherT_contra, _T_co]):
+    def __nep50_complex__(self, other: _OtherT_contra, /) -> _T_co: ...
+
+_WithT = TypeVar("_WithT")
+_OutT = TypeVar("_OutT", bound=np.generic)
+
+PromoteWith = TypeAliasType(
+    "PromoteWith",
+    _CanNEP50Int[_WithT, _OutT] | _CanNEP50Float[_WithT, _OutT] | _CanNEP50Complex[_WithT, _OutT],
+    type_params=(_WithT, _OutT),
+)
+
+###
 
 @type_check_only
 class _HasType(Protocol[_T_co]):
     @property
     def type(self, /) -> type[_T_co]: ...
 
 @type_check_only
-class CanCast(Protocol[_ToScalarT_contra, _FromScalarT_contra, _SelfScalarT_co]):
-    def __nep50__(self, to: _ToScalarT_contra, from_: _FromScalarT_contra, /) -> _SelfScalarT_co: ...
+class MatchND(Protocol[_ShapeT_co, _T_co]):
+    @property
+    def shape(self, /) -> _ShapeT_co: ...
+    @property
+    def dtype(self, /) -> _HasType[_T_co]: ...
+
+# TODO(jorenham): Rename these
 
 @type_check_only
-class CanCast0D(Protocol[_ToScalarT_contra, _FromScalarT_contra, _SelfScalarT_co]):
+class CanCast0D(Protocol[_BelowT_contra, _AboveT_contra, _MatchT_co]):
     @property
     def shape(self, /) -> tuple[()]: ...
     @property
-    def dtype(self, /) -> _HasType[CanCast[_ToScalarT_contra, _FromScalarT_contra, _SelfScalarT_co]]: ...
+    def dtype(self, /) -> _HasType[CanNEP50[_BelowT_contra, _AboveT_contra, _MatchT_co]]: ...
 
 @type_check_only
-class CanCastND(Protocol[_ShapeT_co, _ToScalarT_contra, _FromScalarT_contra, _SelfScalarT_co]):
+class CanCastND(Protocol[_ShapeT_co, _BelowT_contra, _AboveT_contra, _MatchT_co]):
     @property
     def shape(self, /) -> _ShapeT_co: ...
     @property
-    def dtype(self, /) -> _HasType[CanCast[_ToScalarT_contra, _FromScalarT_contra, _SelfScalarT_co]]: ...
+    def dtype(self, /) -> _HasType[CanNEP50[_BelowT_contra, _AboveT_contra, _MatchT_co]]: ...