Apache Arrow doesn’t have any data-frame operations, currently.
It’s just a in-memory columnar storage library.
When you try to make daru to support Apache Arrow, there are two options:
(1) Write Apache Arrow storage wrapper, and implement operations in daru side
(2) Contribute to Apache Arrow so that it has data-frame operations that can be used in production, and then make daru as a wrapper over Apache Arrow
I asked @ktou, Apache Arrow PMC and Red Data Tools organizer, about the above, and he said that only (2) is recommenadble and (1) is worst. If daru team will contribute to Apache Arrow, people may rethink Rubyists' attitude to data science.
My opinion is same as @ktou.