API reference › @evolu/common › Function › Lazy

type Lazy<T> = () => T;

Defined in: packages/common/src/Function.ts:140

A function that takes no arguments and returns a value of type T. Also known as a thunk.

Useful for:

  • Providing default callbacks (see lazyVoid, lazyTrue, etc.)
  • Delaying expensive operations until actually needed
  • Deferring side effects so the callee controls when they run

Example

// Default callback
const notify = (onDone: Lazy<void> = lazyVoid) => {
  onDone();
};

// Delay computation
const getData: Lazy<Data> = () => compute();
const data = getData();

// Defer side effects
const schedule = (job: Lazy<void>) => {
  queueMicrotask(job);
};
schedule(() => logMetric("loaded"));
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