Normalize sorting options

[billylanchantin]

Closes:

• Ensure all options for sorting functions are available #765

Each of these options are now available on all the sorting functions:

• direction: :asc | :desc
  • This takes the form of keys in the first arg on the DF functions
• nils: :first | :last
• parallel: true | false
  • This isn't available on the lazy functions
• stable: true | false

[philss]

LGTM!

[josevalim]

Beautiful work. The only suggestion I have is about the defaults.

Numpy and Pandas do not use stable sorting by default nor Polars. Polars is also parallel by default, which I believe we should try to be as well. So my suggestion is to make stable default to false and parallel default to true. This way, we can also simplify the explanation of parallel. We could say "Use parallel algorithms when possible. Set it to false to disable it.".

Thoughts?

[billylanchantin]

@josevalim That sounds great. I was keeping the defaults we had, but I hadn't thought about what they ought to be. I can definitely have :stable default to false and :parallel default to true.

This way, we can also simplify the explanation of parallel. We could say "Use parallel algorithms when possible. Set it to false to disable it.".

That's a good tactic: describe the philosophy instead of belaboring the implementation (which may change). I think I'll still add a sentence about parallelism not always being available on lazy operations. That way the reader will have some idea of what we mean by "when possible".