useSelector: Allow optional compararison function

[josepot]

I would like to add this commit to the PR so that it has this suggestion from @markerikson

Thanks!

Changes:

• useSelector: Allow optional compararison function
• Export shallowEqual function

[perrin4869]

@josepot What do you think about the changes I proposed in the react-redux PR? shallowEqual is exported basically with the single use-case of using it as an argument of useSelect, so I think we might as well provide the actual hook rather than a generic comparison. But of course that's only if you and the react-redux maintaners agree

[josepot]

I don't know. I see pros and cons to both options.

I like the idea of having a hook-selector that's made for returning Objects, but it's also true that would increase the API surface, although exporting shallowEqual does that, too... So... 🤷‍♂️

Having a hook that takes the equality function as a second arg is a more flexible approach that "works for everyone", but I'm not sure how I feel about that amount of "flexibility"... TBH my preference would be towards increasing the API surface in favor of specific and idiomatic hooks. Do one thing and do it well kinda approach.

About the exposure of shallowEqual, I actually think that the right thing to do would be to have a tiny library that everyone imports from which has that function... But since we don't have that library, it could be handy to get it from React-Redux. It's a poor argument, I know 😅

All that being said. I think that what's most important at this point is not to find the "best" solution, but a solution that we all feel comfortable with. So, I'm more than willing to compromise in favor of Mark Erikson's proposal.

[perrin4869]

hm... Let's wait and see what Mark Erikson says on the matter before proceeding then :)

[markerikson]

Awright, let's go ahead and merge this in.

[josepot]

Cmon @perrin4869 merge it, quickly! Before Tim comes back from Disney World... 😄