Warning

This package is no longer maintained. It moved into @monstermann/fn.

match

Zero-runtime exhaustive pattern matching.

Documentation

Features

• Very small size
• Up to 60x faster than ts-pattern
• 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
    .shape({ value: foo })
    .case({ value: 1 }, 2)
    .case({ value: 2 }, 3)
    .or(0)

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

Unplugin

The unplugin can optimize your code to be as fast as hand-written if/else statements, with the help of the Oxidation Compiler, for example:

import { match } from "@monstermann/match"

match(value)
    .case(1, 2)
    .case(2, 3)
    .or(4)

  value === 1 ? 2 
: value === 2 ? 3 
: 4

Benchmarks

Bun

• Runtime: Bun v1.2.19
• CPU: AMD Ryzen 9 7900 12-Core

case	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	41M	26ns	±0.07%	39M
@monstermann/match	-15%	35M	32ns	±0.45%	32M
ts-pattern	-95%	2M	762ns	±0.33%	1M

shape (object expression)	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	41M	27ns	±0.21%	38M
@monstermann/match	-64%	15M	85ns	±0.65%	12M
ts-pattern	-97%	1M	980ns	±0.28%	1M

shape (identifier)	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	41M	25ns	±0.06%	39M
@monstermann/match	-63%	15M	79ns	±0.58%	13M
ts-pattern	-97%	1M	975ns	±0.31%	1M

cond	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	41M	26ns	±0.13%	38M
@monstermann/match	-51%	20M	59ns	±0.65%	17M
ts-pattern	-76%	10M	138ns	±0.29%	7M

Node

• Runtime: Node v25.1.0
• CPU: AMD Ryzen 9 7900 12-Core

case	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	42M	25ns	±0.09%	40M
@monstermann/match	-7.7%	39M	28ns	±0.63%	35M
ts-pattern	-87%	5M	219ns	±3.38%	5M

shape (object expression)	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	42M	25ns	±0.04%	40M
@monstermann/match	-65%	15M	70ns	±0.15%	14M
ts-pattern	-98%	657K	2µs	±7.02%	608K

shape (identifier)	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	42M	25ns	±0.11%	40M
@monstermann/match	-66%	14M	72ns	±0.08%	14M
ts-pattern	-98%	658K	2µs	±5.66%	618K

cond	summary	ops/sec	time/op	margin	samples
@monstermann/unplugin-match	🥇	42M	25ns	±0.07%	40M
@monstermann/match	-12%	37M	29ns	±0.55%	34M
ts-pattern	-68%	14M	84ns	±0.60%	12M

Installation

npm install @monstermann/match
npm install -D @monstermann/unplugin-match

pnpm add @monstermann/match
pnpm add -D @monstermann/unplugin-match

yarn add @monstermann/match
yarn add -D @monstermann/unplugin-match

bun add @monstermann/match
bun add -D @monstermann/unplugin-match

Setup

// vite.config.ts
import match from "@monstermann/unplugin-match/vite";

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

// rollup.config.js
import match from "@monstermann/unplugin-match/rollup";

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

// rolldown.config.js
import match from "@monstermann/unplugin-match/rolldown";

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

// webpack.config.js
module.exports = {
    plugins: [require("@monstermann/unplugin-match/webpack")()],
};

// rspack.config.js
module.exports = {
    plugins: [require("@monstermann/unplugin-match/rspack")()],
};

// esbuild.config.js
import { build } from "esbuild";
import match from "@monstermann/unplugin-match/esbuild";

build({
    plugins: [match()],
});

Usage

import { match } from "@monstermann/match";

// Match a literal or primitive:
match(value);

// Or match an object:
match.shape(value);

// Optionally set a strict return type:
.returnType<Type>()

// Match against a pattern:
.case(value, result)
.onCase(value, (match) => result)

// Or match against a predicate:
.cond((unmatched) => boolean, result)
.onCond((unmatched) => boolean, (match) => result)

// Handle result:
.or(fallback)
.orElse((unmatched) => fallback)
.orThrow()