facebookexperimental/Recoil

Implement native map and bind functions for RecoilState

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#317 opened on Jun 12, 2020

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 (13 comments) (2 reactions) (1 assignee)JavaScript (19,428 stars) (1,151 forks)batch import
enhancementhelp wanted

Description

Having a correctly implemented map and bind for a type allows for very powerful abstractions and data transformations.

I have an implementation that given a recoil value it creates a selectorFamily that accepts a lifted function (via constSelector), which then fetches the dependencies, and then returns the new value.

Bind we somewhat get for free as recoil automatically flattens recoil values, so it's the same logic as map.

I'm not terribly confident that this can't somehow cause name conflicts at some point, and having a native implementation of these functions would be great.

I think this also ties in a bit with #314 as ideally the mapped value wouldn't cause a re-render when the parent changes if the resulting output didn't change (such as a simple number atom that had something like this applied: myAtom.map(x => x * 0)

Contributor guide

Tech stack
javascriptreact
Domain
frontend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Recoil state managementReact hooksselectorFamily usage
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Review the existing implementation described in the issue body, which uses constSelector and selectorFamily. Examine the linked issue #314 about memoization to understand potential optimizations. Look at the Recoil source code for Atom and Selector classes to understand how native map and bind could be integrated. Check comments for any additional design considerations.