match

Minified1.00 KBMinzipped305 B

Zero-runtime exhaustive pattern matching, inspired by ts-pattern and pattycake.

This library is a lightweight alternative to ts-pattern, with an optional Babel plugin that compiles match expressions to fast, plain JavaScript.

Features

• Very small size
• Up to 60x faster than ts-pattern
• 600+ tests
• Type-safe exhaustiveness checks
• Match against literals, primitives, and shallow objects
• Eager (case(pattern, result)) and lazy (case(pattern, () => result)) matching
• Fallback methods: or, orElse, orThrow

Examples

import { match } from "@monstermann/match"

// Match primitives:
match(value)
    .case(1, 2)
    .case(2, 3)
    .orElse(v => v + 1)

// Match object shapes:
match({ value: foo })
    .shape({ value: 1 }, 2)
    .shape({ value: 2 }, 3)
    .or(0)

// Match with conditions:
match({ value: foo })
    .cond(v => v.value > 0, "positive")
    .cond(v => v.value < 0, "negative")
    .or("zero")

Babel plugin

The Babel plugin can optimize your code to be as fast as hand-written if/else statements.

🐢

import { match } from "@monstermann/match"

match(value)
    .case(1, 2)
    .case(2, 3)
    .orElse(v => v + 1)

🚀

  value === 1 ? 2 
: value === 2 ? 3 
: value + 1

🐢

import { match } from "@monstermann/match"

match({ value: foo })
    .shape({ value: 1 }, 2)
    .shape({ value: 2 }, 3)
    .or(0)

🚀

  foo === 1 ? 2
: foo === 2 ? 3
: 0

🐢

import { match } from "@monstermann/match"

match({ value: foo })
    .cond(v => v.value > 0, "positive")
    .cond(v => v.value < 0, "negative")
    .or("zero")

🚀

  foo > 0 ? "positive" 
: foo < 0 ? "negative" 
: "zero"

🐢

import { match } from "@monstermann/match"

match(expensive())
    .shape({ value: undefined }, "undefined")
    .cond((v) => isString(v.value), "string")
    .cond((v) => isNumber(v.value), "number")
    .or("unknown")

🚀

((_v) =>
    _v && typeof _v === "object" && _v.value === undefined ? "undefined"
    : isString(_v.value) ? "string"
    : isNumber(_v.value) ? "number"
    : "unknown"
)(expensive())

Benchmarks

• Runtime: Node v24.0.1
• System: Apple M1 Max

case	summary	ops/sec	time/op	margin	samples
@monstermann/babel-plugin-match	🥇	36M	21ns	±0.09%	47M
@monstermann/match	-29%	25M	33ns	±0.05%	30M
ts-pattern	-88%	4M	279ns	±5.25%	4M

shape (object expression)	summary	ops/sec	time/op	margin	samples
@monstermann/babel-plugin-match	🥇	37M	21ns	±0.05%	49M
@monstermann/match	-72%	10M	103ns	±0.56%	10M
ts-pattern	-98%	597K	2µs	±5.92%	557K

shape (identifier)	summary	ops/sec	time/op	margin	samples
@monstermann/babel-plugin-match	🥇	37M	20ns	±0.08%	49M
@monstermann/match	-69%	12M	92ns	±1.13%	11M
ts-pattern	-98%	591K	2µs	±1.18%	562K

cond	summary	ops/sec	time/op	margin	samples
@monstermann/babel-plugin-match	🥇	34M	22ns	±0.04%	45M
@monstermann/match	-27%	24M	36ns	±0.05%	28M
ts-pattern	-73%	9M	134ns	±6.87%	7M

Installation

npm

npm install @monstermann/match
npm install -D @monstermann/babel-plugin-match

pnpm

pnpm add @monstermann/match
pnpm add -D @monstermann/babel-plugin-match

yarn

yarn add @monstermann/match
yarn add -D @monstermann/babel-plugin-match

bun

bun add @monstermann/match
bun add -D @monstermann/babel-plugin-match

Please consult your bundler of choice on how to enable Babel plugins, some examples:

vite + @vitejs/plugin-react

vite

import { defineConfig } from "vite";
import react from "@vitejs/plugin-react";

export default defineConfig(() => ({
    plugins: [
        react({
            babel: {
                plugins: [["@monstermann/babel-plugin-match"]],
            },
        }),
    ],
}));

vite + vite-plugin-babel

vite

import { defineConfig } from "vite";
import babel from "vite-plugin-babel";

export default defineConfig({
    plugins: [babel()],
});

.babelrc.json

{
    "plugins": [["@monstermann/babel-plugin-match"]]
}