🔥 matchbook

pattern matching in typescript & javascript made easy

matchbook is a lightweight & easy to use pattern matching library, for TypeScript and JavaScript.

If you want to know more about matchbook, check out the docs or read on!

If you want to start using matchbook, install it like any other npm package:

npm i @matchbook/ts

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table of contents

• what matchbook does for you

• what you can do for matchbook

• pattern matching explained

• matchbook at a glance

• matchbook at a slightly longer glance (examples)

  • switching on part of an object
  • switching on an enum
  • acting on the type of an Event
  • matching if a value is an instanceof a constructor

what matchbook does for you

(list is in no particular order)

• expressive - pattern matching helps you write less code that's more expressive than if/else trees
• simple - API is just 5 functions, 1 error class, and some stylistic aliases for the core functions
• powerful - type inference backed by Typescript
• well documented - check out the docs here!
• low cost - no runtime dependencies, & small package size
• reliable - 100% unit test coverage, with all pushes verified via Travis CI

what you can do for matchbook

use it!

The project is very minimal, with the intent of starting with a very simple & focused API that grows with its needs.

ask questions!

If you have any questions, any feedback, or just want to shoot the shirt, open an issue of type question, and we'll do our best to answer quickly!

pattern matching explained

Pattern matching is a modern language feature that is similar to a switch / case statement.

With pattern matching, you can switch on the type of the incoming value, meaning you can reduce a lot of extra-verbose if-else branches just by replacing them with pattern matching statements.

You might consider using pattern matching if you find you're switching on types or states frequently, and want to handle the different cases in a concise and expressive way.

This project takes heavy inspiration from Rust's pattern matching idiom.

matchbook at a glance

want to know more? read the docs!

matchbook at a slightly longer glance

want to know more? read the docs!

switching on part of an object

switching on an enum

acting on the type of an Event

Type guards

matching if a value is an instanceof a constructor