Caching

function cache<A extends ReadonlyArray<any>, T>(fn: (...args: A) => T): (...args: A) => T;

// Request-scoped cache on server
const getUser = cache(async (id) => {
  const res = await fetch(`/api/users/${id}`);
  return res.json();
});

// Multiple components share cached result
function UserProfile({ userId }) {
  const user = use(getUser(userId));  // Uses cache
  return <div>{user.name}</div>;
}

function cacheSignal(): AbortSignal | null;

const fetchUser = cache(async (id) => {
  const signal = cacheSignal();
  return fetch(`/api/users/${id}`, { signal });
});