prelude.ls is a functionally oriented utility library. It is powerful and flexible. Almost all of its functions are curried. It is written in, and is the recommended base library for, LiveScript.

Rich errors

Type utilties for creating nominal/branded types in TypeScript

Angular9+ form validator, make error tips easy and automatic. don't need to manually write error tips templates.

Make presentable errors

Returns an object with on-event callback props curried with provided args.

express.js middleware for winstonjs/winston

Convert an argument into a valid iterator. Based on the `.makeIterator()` implementation in mout https://github.com/mout/mout.

Check whether a request can be retried based on the `error.code`

Symbol.observable ponyfill

Unicode CLDR pluralization rules as JavaScript functions

Make a synchronous function asynchronous by running it in a worker

Easy error subclassing and stack customization

Error comparison and information related utility for node and the browser

A window.fetch polyfill.

`Start a promise chain

Wrap zod validation errors in user-friendly readable messages

Create an error from multiple errors

Provides functions for detecting if the host environment supports the WebCrypto API

React hook for using error boundaries