@axhxrx/lazy

Type-safe lazy evaluation for TypeScript.

(Migrated from axhxrx-mmxxv/libs/ts/core/src/lib/resolve/ on 2025-12-31.)

Usage

The Lazy<T> type allows values to be either direct values or functions that return values:

import { Lazy, lazy } from "@axhxrx/lazy";

// Configuration with mixed static and dynamic values
const config: {
  apiKey: Lazy<string>;
  timestamp: Lazy<number>;
  debug: Lazy<boolean>;
} = {
  apiKey: "static-key-123", // static value
  timestamp: () => Date.now(), // computed each time
  debug: () => Deno.env.get("DEBUG") === "true", // context-dependent
};

// Resolve values when needed
const apiKey = lazyval(config.apiKey); // 'static-key-123'
const timestamp = lazyval(config.timestamp); // current timestamp
const debug = lazyval(config.debug); // boolean from env

Why?

TypeScript doesn't support T | (() => T) naturally because it can't narrow typeof value === 'function' to prove the function returns T. This library provides a workaround with proper type safety.

See the TypeScript issue #37663 for more details.

License

MIT

---

🎅 2025-12-31: publish 0.1.1 to jsr.io 🤖 2025-12-31: repo initialized by Bottie McBotface bot@axhxrx.com