ts-pattern

<h1 align="center">TS-Pattern</h1>

<p align="center">
The exhaustive Pattern Matching library for <a href="https://github.com/microsoft/TypeScript">TypeScript</a>
with smart type inference.
</p>

<p align="center">
  <a href="https://www.npmjs.com/package/ts-pattern">
    <img src="https://img.shields.io/npm/dm/ts-pattern.svg" alt="downloads" height="18">
  </a>
  <a href="https://www.npmjs.com/package/ts-pattern">
    <img src="https://img.shields.io/npm/v/ts-pattern.svg" alt="npm version" height="18">
  </a>
  <a href="https://github.com/gvergnaud/ts-pattern">
    <img src="https://img.shields.io/npm/l/ts-pattern.svg" alt="MIT license" height="18">
  </a>
</p>

```tsx
import { match, P } from 'ts-pattern';

type Data =
  | { type: 'text'; content: string }
  | { type: 'img'; src: string };

type Result =
  | { type: 'ok'; data: Data }
  | { type: 'error'; error: Error };

const result: Result = ...;

const html = match(result)
  .with({ type: 'error' }, () => <p>Oups! An error occured</p>)
  .with({ type: 'ok', data: { type: 'text' } }, (res) => <p>{res.data.content}</p>)
  .with({ type: 'ok', data: { type: 'img', src: P.select() } }, (src) => <img src={src} />)
  .exhaustive();
```

## About

Write **better** and **safer conditions**. Pattern matching lets you express complex conditions in a single, compact expression. Your code becomes **shorter** and **more readable**. Exhaustiveness checking ensures you haven’t forgotten **any possible case**.

![ts-pattern](https://user-images.githubusercontent.com/9265418/231688650-7cd957a9-8edc-4db8-a5fe-61e1c2179d91.gif)

<p align="center"><i>Animation by <a target="_blank" href="https://twitter.com/nicoespeon/status/1644342570389061634?s=20">@nicoespeon</a></i></p>

## Features

- Pattern-match on **any data structure**: nested [Objects](#objects), [Arrays](#tuples-arrays), [Tuples](#tuples-arrays), [Sets](#pset-patterns), [Maps](#pmap-patterns) and all primitive types.
- **Typesafe**, with helpful [type inference](#type-inference).
- **Exhaustiveness checking** support, enforcing that you are matching every possible case with [`.exhaustive()`](#exhaustive).
- Use [patterns](#patterns) to **validate** the shape of your data with [`isMatching`](#ismatching).
- **Expressive API**, with catch-all and type specific **wildcards**: [`P._`](#p_-wildcard), [`P.string`](#pstring-wildcard), [`P.number`](#pnumber-wildcard), etc.
- Supports [**predicates**](#pwhen-patterns), [**unions**](#punion-patterns), [**intersections**](#pintersection-patterns) and [**exclusion**](#pnot-patterns) patterns for non-trivial cases.
- Supports properties selection, via the [`P.select(name?)`](#pselect-patterns) function.
- Tiny bundle footprint ([**only ~2kB**](https://bundlephobia.com/package/ts-pattern)).

## What is Pattern Matching?

[Pattern Matching](https://en.wikipedia.org/wiki/Pattern_matching) is a code-branching technique coming from functional programming languages that's more powerful and often less verbose than imp