feat: initial commit

src/react/useAtomState.luau

@@ -0,0 +1,35 @@
+local React = require(script.Parent.Parent.modules.React)
+
+local atom = require(script.Parent.Parent.atom)
+type Atom<T> = atom.Atom<T>
+
+type UseAtomState =
+	(<State>(atom: Atom<State>) -> State)
+	& (<State, Result>(atom: Atom<State>, ((State) -> Result)?) -> State | Result)
+	& <State, Result>(atom: Atom<State>, selector: (State) -> Result) -> Result
+
+local function useAtomState<State>(atom: Atom<State>, selector: ((State) -> State)?): State
+	local state, setState = React.useState(function()
+		return atom:get(selector :: (State) -> State)
+	end)
+
+	local latestSelector = React.useRef(selector)
+	latestSelector.current = selector
+
+	React.useEffect(function()
+		local function listener(state: State)
+			local selector = latestSelector.current
+			setState(if selector then selector(state) else state)
+		end
+
+		atom.listeners[listener] = true
+
+		return function()
+			atom.listeners[listener] = nil
+		end
+	end, { atom })
+
+	return state
+end
+
+return useAtomState :: UseAtomState