[Python] Improve ergonomics of compute functions

[asfimport]

Introspection of exported compute functions currently yield suboptimal output:

>>> from pyarrow import compute as pc                                                                                                                                 
>>> pc.list_flatten                                                                                                                                                   
<function pyarrow.compute._simple_unary_function.<locals>.func(arg)>
>>> ?pc.list_flatten                                                                                                                                                  
Signature: pc.list_flatten(arg)
Docstring: <no docstring>
File:      ~/arrow/dev/python/pyarrow/compute.py
Type:      function
>>> help(pc.list_flatten)                                                                                                                                             
Help on function func in module pyarrow.compute:

func(arg)

The function should ideally have:

• the right global name
• an appropriate signature
• a docstring

Reporter: Antoine Pitrou / @pitrou
Assignee: Antoine Pitrou / @pitrou

Related issues:

• [Python] Expose more compute kernels (fixes)
• [C++] Provide APIs for adding "docstrings" to arrow::compute::Function classes that can be accessed by bindings (is related to)

PRs and other links:

• GitHub Pull Request #8163

_{Note: This issue was originally created as ARROW-9465. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 8163
#8163