4 files changed, 82 insertions, 0 deletions
diff --git a/numpy/typing/__init__.py b/numpy/typing/__init__.py
new file mode 100644
index 000000000..94f76a91f
--- /dev/null
+++ b/numpy/typing/__init__.py
@@ -0,0 +1,3 @@
+from ._array_like import _SupportsArray, ArrayLike
+from ._shape import _Shape, _ShapeLike
+from ._dtype_like import DtypeLike
diff --git a/numpy/typing/_array_like.py b/numpy/typing/_array_like.py
new file mode 100644
index 000000000..54a612fb4
--- /dev/null
+++ b/numpy/typing/_array_like.py
@@ -0,0 +1,27 @@
+import sys
+from typing import Any, overload, Sequence, Tuple, Union
+
+from numpy import ndarray
+from ._dtype_like import DtypeLike
+
+if sys.version_info >= (3, 8):
+    from typing import Protocol
+    HAVE_PROTOCOL = True
+else:
+    try:
+        from typing_extensions import Protocol
+    except ImportError:
+        HAVE_PROTOCOL = False
+    else:
+        HAVE_PROTOCOL = True
+
+if HAVE_PROTOCOL:
+    class _SupportsArray(Protocol):
+        @overload
+        def __array__(self, __dtype: DtypeLike = ...) -> ndarray: ...
+        @overload
+        def __array__(self, dtype: DtypeLike = ...) -> ndarray: ...
+else:
+    _SupportsArray = Any
+
+ArrayLike = Union[bool, int, float, complex, _SupportsArray, Sequence]
diff --git a/numpy/typing/_dtype_like.py b/numpy/typing/_dtype_like.py
new file mode 100644
index 000000000..b9df0af04
--- /dev/null
+++ b/numpy/typing/_dtype_like.py
@@ -0,0 +1,46 @@
+from typing import Any, Dict, List, Sequence, Tuple, Union
+
+from numpy import dtype
+from ._shape import _ShapeLike
+
+_DtypeLikeNested = Any  # TODO: wait for support for recursive types
+
+# Anything that can be coerced into numpy.dtype.
+# Reference: https://docs.scipy.org/doc/numpy/reference/arrays.dtypes.html
+DtypeLike = Union[
+    dtype,
+    # default data type (float64)
+    None,
+    # array-scalar types and generic types
+    type,  # TODO: enumerate these when we add type hints for numpy scalars
+    # TODO: add a protocol for anything with a dtype attribute
+    # character codes, type strings or comma-separated fields, e.g., 'float64'
+    str,
+    # (flexible_dtype, itemsize)
+    Tuple[_DtypeLikeNested, int],
+    # (fixed_dtype, shape)
+    Tuple[_DtypeLikeNested, _ShapeLike],
+    # [(field_name, field_dtype, field_shape), ...]
+    #
+    # The type here is quite broad because NumPy accepts quite a wide
+    # range of inputs inside the list; see the tests for some
+    # examples.
+    List[Any],
+    # {'names': ..., 'formats': ..., 'offsets': ..., 'titles': ...,
+    #  'itemsize': ...}
+    # TODO: use TypedDict when/if it's officially supported
+    Dict[
+        str,
+        Union[
+            Sequence[str],  # names
+            Sequence[_DtypeLikeNested],  # formats
+            Sequence[int],  # offsets
+            Sequence[Union[bytes, str, None]],  # titles
+            int,  # itemsize
+        ],
+    ],
+    # {'field1': ..., 'field2': ..., ...}
+    Dict[str, Tuple[_DtypeLikeNested, int]],
+    # (base_dtype, new_dtype)
+    Tuple[_DtypeLikeNested, _DtypeLikeNested],
+]
diff --git a/numpy/typing/_shape.py b/numpy/typing/_shape.py
new file mode 100644
index 000000000..4629046ea
--- /dev/null
+++ b/numpy/typing/_shape.py
@@ -0,0 +1,6 @@
+from typing import Sequence, Tuple, Union
+
+_Shape = Tuple[int, ...]
+
+# Anything that can be coerced to a shape tuple
+_ShapeLike = Union[int, Sequence[int]]