diff --git a/src/hooks.ts b/src/hooks.ts
index a1b2f50..cd2398e 100644
--- a/src/hooks.ts
+++ b/src/hooks.ts
@@ -1,4 +1,4 @@
-import type { Atom, Selector } from './types.js';
+import type { Atom, AtomSelector } from './types.js';
 
 import * as React from 'react';
 
@@ -19,7 +19,7 @@ import * as React from 'react';
  *
  * @noinline
  */
-export const useAtomSelector = /*#__INLINE__*/<T, S>(atom: Readonly<Atom<T>>, selector: Selector<T, S>) => {
+export const useAtomSelector = <T, S>(atom: Atom<T>, selector: AtomSelector<T, S>) => {
   const reselect = React.useRef(() => selector(atom.get())).current;
 
   return React.useSyncExternalStore(
@@ -42,7 +42,7 @@ export const useAtomSelector = /*#__INLINE__*/<T, S>(atom: Readonly<Atom<T>>, se
  *
  * @nosideeffects
  */
-export const useAtomValue = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
+export const useAtomValue = <T>(atom: Atom<T>) => {
   return React.useSyncExternalStore(
     atom.sub,
     atom.get,
@@ -63,7 +63,7 @@ export const useAtomValue = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
  *
  * @nosideeffects
  */
-export const useSetAtomState = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
+export const useSetAtomState = <T>(atom: Atom<T>) => {
   return React.useRef(atom.set).current;
 };
 
@@ -81,7 +81,7 @@ export const useSetAtomState = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
  *
  * @nosideeffects
  */
-export const useAtomState = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
+export const useAtomState = <T>(atom: Atom<T>) => {
   const state = useAtomValue(atom);
   const update = useSetAtomState(atom);
 
@@ -100,7 +100,7 @@ export const useAtomState = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
  *
  * @nosideeffects
  */
-export const useResetAtomState = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
+export const useResetAtomState = <T>(atom: Atom<T>) => {
   return React.useRef(() => atom.set(atom.def)).current;
 };
 
@@ -117,8 +117,8 @@ export const useResetAtomState = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) =>
  *
  * @nosideeffects
  */
-export const useAtomConst = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
-  return React.useState(atom.get)[0];
+export const useAtomConst = <T>(atom: Atom<T>) => {
+  return React.useMemo(atom.get, []);
 };
 
 /**
@@ -134,6 +134,6 @@ export const useAtomConst = /*#__INLINE__*/<T>(atom: Readonly<Atom<T>>) => {
  *
  * @nosideeffects
  */
-export const useAtomSelectorConst = /*#__INLINE__*/<T, S>(atom: Readonly<Atom<T>>, selector: Selector<T, S>) => {
-  return React.useState(() => selector(atom.get()))[0];
+export const useAtomSelectorConst = <T, S>(atom: Atom<T>, selector: AtomSelector<T, S>) => {
+  return React.useMemo(() => selector(atom.get()), []);
 };
diff --git a/src/ssr.ts b/src/ssr.ts
index acd78e6..a45a9d1 100644
--- a/src/ssr.ts
+++ b/src/ssr.ts
@@ -1,24 +1,24 @@
 import type { Atom } from './types.js';
 
-import { store } from './store.js';
+import { unsafe_store } from './store.js';
 
 /**
  * Sets the state of the passed atom.
  */
-export const hydrateAtom = <T>(atom: Readonly<Atom<T>>, value: Readonly<T>) => {
-  store.set(atom.key, value);
+export const hydrateAtom = <T>(atom: Atom<T>, value: T) => {
+  unsafe_store.set(atom.key, value);
 };
 
 /**
  * Resets a state of passed atom.
  */
-export const resetAtom = <T>(atom: Readonly<Atom<T>>) => {
-  store.set(atom.key, atom.def);
+export const resetAtom = <T>(atom: Atom<T>) => {
+  unsafe_store.set(atom.key, atom.def);
 };
 
 /**
  * Resets states of passed atoms.
  */
-export const resetAtoms = (atoms: ReadonlyArray<Readonly<Atom<any>>>) => {
-  atoms.forEach(resetAtom);
+export const resetAtoms = (atoms: ReadonlyArray<Atom<any>>) => {
+  atoms.some(resetAtom);
 };
diff --git a/src/types.ts b/src/types.ts
index 8703627..9d851a6 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,18 +1,32 @@
-export type Store = Map<string, unknown>;
+export type AtomKey = string | number | symbol;
 
-export type AtomUpdater<T> = (state: T) => T;
-export type AtomValOrUpdater<T> = T | AtomUpdater<T>;
+export type AtomStore = Map<AtomKey, any>;
+export type AtomStoreUpdate = Record<AtomKey, any>;
 
-export type Selector<T, S> = (partial: T) => S;
+export type AtomUpdater<Value, Update = Value> = (value: Value) => Update;
+export type AtomValueUpdate<Value, Update = Value> = Update | AtomUpdater<Value, Update>;
 
-export type AtomGetter<T> = () => T;
-export type AtomSetter<T> = (value: AtomValOrUpdater<T>) => T;
-export type AtomSubscribe<T> = (set: (value: T) => void) => () => void;
+export type AtomSelector<Value, Selected> = (value: Value) => Selected;
 
-export type Atom<T> = {
-  key: string;
-  def: T;
-  get: AtomGetter<T>;
-  set: AtomSetter<T>;
-  sub: AtomSubscribe<T>;
+export type AtomGetter<Value> = () => Value;
+export type AtomSetter<Value, Update = Value> = (update: AtomValueUpdate<Value, Update>) => Value;
+
+export type AtomSubscribe<Value> = (next: (value: Value) => void) => () => void;
+
+export type Atom<Value, Update = Value> = {
+  readonly key: AtomKey;
+  readonly def: Value;
+
+  get: AtomGetter<Value>;
+  set: AtomSetter<Value, Update>;
+  sub: AtomSubscribe<Value>;
 };
+
+export type DynamicAtomGetter = <Value, Update = Value>(
+  atom: Atom<Value, Update>
+) => Value;
+
+export type DynamicAtomSetter = <Value, Update = Value>(
+  atom: Atom<Value, Update>,
+  update: AtomValueUpdate<Value, Update>
+) => Value;