extra-lazy

extra-lazy

Yet another lazy evaluation library.

Install

npm install --save extra-lazy
# or
yarn add extra-lazy

Usage

import { lazy } from 'extra-lazy'

const getValue = lazy(() => {
  // ...
  return value
})
const value = getValue()

API

lazy

function lazy<T>(getter: () => T): () => T

Create a value lazily.

which implicitly has memoization, because the evaluation will only be performed once.

lazyFunction

function lazyFunction<Result, Args extends any[]>(
  getter: () => (...args: Args) => Result
): (...args: Args) => Result

Create a function lazily.

lazyAsyncFunction

function lazyAsyncFunction<Result, Args extends any[]>(
  getter: () => PromiseLike<(...args: Args) => Result>
): (...args: Args) => Promise<Result>

Create a async function lazily.

lazyStatic

function lazyStatic<T>(
  getter: () => T
, deps?: unknown[] = []
): T

/**
 * @param fn
 * The function must satisfy the following conditions, it's like React hooks very much:
 * - The function should not be an async function,
 *   it is impossible to ensure that `lazyStatic` works correctly in asynchronous flows.
 * - `lazyStatic` calls should not be in loops or branches.
 */
function withLazyStatic<Result, Args extends any[]>(
  fn: (...args: Args) => Result
): (...args: Args) => Result

const fn = withLazyStatic((text: string) => lazyStatic(() => text))

fn('hello') // 'hello'
fn('world') // 'hello'