Hyukjin Kwon

Hm, the general idea might be fine but I think the implementation is the problem. For example, the current design is that the user defined `function` always takes one group...

cc @itholic @xinrong-meng @zhengruifeng FYI

cc @sarutak and @gengliangwang FYI

@maryannxue FYI

@Transurgeon is this still WIP? If there are too many to fix, feel free to split into multiple PRs.

I think you can reuse the same JIRA, and make a followup.

We should make the tests passed before merging it in (https://github.com/Transurgeon/spark/runs/7981691501). cc @dcoliversun @khalidmammadov FYI if you guys find some time to review, and work on the rest of API.

Im gonna take this over if the PR author gets inactive few more days - this is the last task left for the umbrella task.

Hey, let's co-author this change. I will create another PR on the top of this PR to speed this up.

cc @BryanCutler @ueshin FYI