Actions

Reads are derived: change an input and an async memo asks again. A write is different. It changes the data on the server, so something has to ask the server again afterwards.

Wrap a write in action. Its body is a generator: yield each promise, and the action resumes when it settles.

const like = action(function* () {
  affects(likes);
  yield api.like();
  refresh(likes);
});

refresh(likes) re-runs the memo so it reads the server's new count. affects(likes) marks likes as about to change while the action runs, so isPending(likes) can show that a save is in progress.

Try it: clicking Like saves to the server, but the count never changes. Turn like into an action that marks likes as affected, yields the API call, and then refreshes likes. The button should read "Saving..." while the action runs.