Is there any support for changing multiple atoms at once / batch? This is where reducers shine to me - dispatching a single action from the ui in redux that multiple reducers can listen to and use to update their state. Also is there any support for getting the values of atoms outside of a hook? For example from an async action that is not coupled to the render loop which also wants to know the current value.
If you update multiple atoms within a React batch, they will be updated at the same time, just as with React local state. You don't need to wrap the changes in anything to have them occur together.
In other words, this updates both of the atoms together:
const [a, setA] = useRecoilState(atomA);
const [b, setB] = useRecoilState(atomB);
...
onClick={() => {
setA(a => a + 1);
setB(b => b + 1);
}}
const update = useTransactionalUpdate([atomA, atomB]);
...
onClick={() => {
update(([a, b]) => [a + b, b - a]);
}}