It seems that right now there isn't a convenient way to pass mutable state outside of the component or hook, i.e. return it, pass it to a function or pass it to children.
The only way to get the setter is by creating a closureval => myState = val. So if I want to pass around mutable state (read and write) I need to get the setter, then I need to pass both the setter and the value around.
This is a little verbose, and also wherever I pass the mutable state to I'll have to deal with two variables again (value and setter) instead of one.
I think that it could be nice if there was a better way to get the setter and pass around mutable state.