1.4.2 RC 1 - Parallel optimistic

• Optimistic updates are now unlocked and can be executed in parallel
• Optimistic updates are applied again when data is mutated while an optimistic block is pending
• Optimistic updates must now be deterministic / pure / idempotent : they should give the same result when called multiple times with the same state
• New syntax for optimistic updates:

BEFORE

document.update(async function* (previous) {
  yield { data: "hello world" } 
  yield { data: "it works" } 
})

NOW

document.update(async function* () {
  yield (previous) => ({ data: "hello world" })
  yield (previous) => ({ data: "it works" })
})

Basically, XSWR store those functions and apply them again when necessary