API reference › @evolu/common › Function › Thunk

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

Defined in: packages/common/src/Function.ts:241

A function that takes no arguments and returns a value.

Useful for:

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

Example

import { constVoid, type Thunk } from "@evolu/common";

const notify = (onDone: Thunk<void> = constVoid) => onDone();
notify();

let value = 0;
const compute: Thunk<number> = () => ++value;
const jobs: Array<Thunk<void>> = [];
const schedule = (job: Thunk<void>): void => {
  jobs.push(job);
};
schedule(() => {
  value += 10;
});

const computed = compute();
jobs.shift()?.();
expect(computed).toBe(1);
expect(value).toBe(11);
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