[
https://issues.apache.org/jira/browse/ARROW-17901?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Matteo Santamaria updated ARROW-17901:
--------------------------------------
Description:
I understand that, in general, {{pyarrow}} does not support type hints.
However, I think it is still sensible to add a {{py.typed}} marker file to the
library. Let me demonstrate why,
{code:java}
$ pip install mypy pyarrow {code}
{code:java}
# test.py
import pyarrow as pa
table = pa.Table()
reveal_type(table) {code}
{code:java}
$ mypy test.py
test.py:1: error: Skipping analyzing "pyarrow": module is installed, but
missing library stubs or py.typed marker
test.py:1: note: See
https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
test.py:5: note: Revealed type is "Any"
Found 1 error in 1 file (checked 1 source file) {code}
Note that {{mypy}} identifies {{table}} as being an {{Any}} type, when
obviously it is a {{{}Table{}}}. If we include a {{py.typed}} file, {{mypy}}
will be able to make these trivial inferences. The motivating example is this,
{code:java}
@overload
def from_arrow(a: pa.Table) -> DataFrame:
...
@overload
def from_arrow(a: pa.Array | pa.ChunkedArray) -> Series:
...
def from_arrow(a: pa.Table | pa.Array | pa.ChunkedArray) -> DataFrame | Series:
pass {code}
The problem is that since all of {{{}pa.Table{}}}, {{{}pa.Array{}}}, and
{{pa.ChunkedArray}} are determined to be {{{}Any{}}}, so the overloads
effectively become
{code:java}
@overload
def from_arrow(a: Any) -> DataFrame:
...
@overload
def from_arrow(a: Any) -> Series:
... {code}
and {{mypy}} complains that overload 2 is covered entirely by overload 1.
I tried to test what adding a {{py.typed}} file would do, but I ran into
compilation issues. I was hoping someone with a little more experience here
could quickly test this out for me :)
was:
I understand that, in general, `pyarrow` does not support type hints. However,
I think it is still sensible to add a `py.typed` marker file to the library.
Let me demonstrate why,
```
$ pip install mypy pyarrow
```
```python
# test.py
import pyarrow as pa
table = pa.Table()
reveal_type(table)
```
```
$ mypy test.py
test.py:1: *error:* Skipping analyzing {*}"pyarrow"{*}: module is installed,
but missing library stubs or py.typed marker
test.py:1: note: See
https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
test.py:5: note: Revealed type is *"Any"*
*Found 1 error in 1 file (checked 1 source file)*
```
Note that `mypy` identifies `table` as being an `Any` type, when obviously it
is a `Table`. If we include a `py.typed` file, `mypy` will be able to make
these trivial inferences.
The motivating example is this,
```python
@overload
def from_arrow(a: pa.Table) -> DataFrame:
...
@overload
def from_arrow(a: pa.Array | pa.ChunkedArray) -> Series:
...
def from_arrow(a: pa.Table | pa.Array | pa.ChunkedArray) -> DataFrame | Series:
pass
```
The problem is that all of `pa.Table`, `pa.Array`, and `pa.ChunkedArray` are
determined to be `Any`, so the overloads effectively become
```python
@overload
def from_arrow(a: Any) -> DataFrame:
...
@overload
def from_arrow(a: Any) -> Series:
...
```
and `mypy` complains that overload 2 is covered entirely by overload 1.
I tried to test what adding a `py.typed` file would do, but I ran into
compilation issues. I was hoping someone with a little more experience could
quickly test this out for me :)
> `pyarrow` missing `py.typed` marker
> -----------------------------------
>
> Key: ARROW-17901
> URL: https://issues.apache.org/jira/browse/ARROW-17901
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Reporter: Matteo Santamaria
> Priority: Minor
>
> I understand that, in general, {{pyarrow}} does not support type hints.
> However, I think it is still sensible to add a {{py.typed}} marker file to
> the library. Let me demonstrate why,
>
> {code:java}
> $ pip install mypy pyarrow {code}
>
>
> {code:java}
> # test.py
> import pyarrow as pa
>
> table = pa.Table()
>
> reveal_type(table) {code}
>
>
> {code:java}
> $ mypy test.py
> test.py:1: error: Skipping analyzing "pyarrow": module is installed, but
> missing library stubs or py.typed marker
> test.py:1: note: See
> https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
> test.py:5: note: Revealed type is "Any"
> Found 1 error in 1 file (checked 1 source file) {code}
>
> Note that {{mypy}} identifies {{table}} as being an {{Any}} type, when
> obviously it is a {{{}Table{}}}. If we include a {{py.typed}} file, {{mypy}}
> will be able to make these trivial inferences. The motivating example is this,
>
> {code:java}
> @overload
> def from_arrow(a: pa.Table) -> DataFrame:
> ...
> @overload
> def from_arrow(a: pa.Array | pa.ChunkedArray) -> Series:
> ...
> def from_arrow(a: pa.Table | pa.Array | pa.ChunkedArray) -> DataFrame |
> Series:
> pass {code}
>
> The problem is that since all of {{{}pa.Table{}}}, {{{}pa.Array{}}}, and
> {{pa.ChunkedArray}} are determined to be {{{}Any{}}}, so the overloads
> effectively become
>
> {code:java}
> @overload
> def from_arrow(a: Any) -> DataFrame:
> ...
> @overload
> def from_arrow(a: Any) -> Series:
> ... {code}
>
> and {{mypy}} complains that overload 2 is covered entirely by overload 1.
>
> I tried to test what adding a {{py.typed}} file would do, but I ran into
> compilation issues. I was hoping someone with a little more experience here
> could quickly test this out for me :)
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