treyhoover/zod-pattern

README

Zod Pattern

Pattern matching utility powered by Zod schemas

Overview

zod-pattern provides a simple, typesafe and flexible pattern matching utility based on Zod schemas. With this library, you can validate and transform data using the power of Zod, and easily handle various cases based on the shape and value of the input.

Features

⚡ Clear Syntax: Concise and expressive syntax to make your patterns clear and readable.
🌟 Full Type Inference: Achieve strong typing for matched data and results with the power of Zod's infer.
🚀 Optional Transforms: Either provide static outcomes or utilize dynamic transform functions for matched results.

Installation

npm install zod-pattern

Usage

Basic Matching

Define patterns using Zod schemas and corresponding results:

import { pattern } from "zod-pattern";
import { z } from "zod";

type Strength = "strong" | "medium" | "weak";

const predictionMatcher = pattern()
  .returnType<Strength>()
  .case(z.number().gte(0.8), "strong")
  .case(z.number().gte(0.5), "medium")
  .default("weak");

const result = predictionMatcher.match(0.97); // "strong"

Matching with Transform Functions

Transform matched data on-the-fly:

const predictionMatcher = pattern()
  .case(z.number().gte(0.8), (value) => `strong (${value * 100}%)`)
  .case(z.number().gte(0.5), (value) => `medium (${value * 100}%)`)
  .default((value) => `weak (${value * 100}%)`);

const result = predictionMatcher.match(0.97); // "strong (97%)"

Matching Partial Objects

Match based on partial object shapes:

const partialMatcher = pattern()
  .case(z.object({ key: z.string() }), ({ key }) => `Matched via key: "${key}"`)
  .default("not matched");

const result = partialMatcher.match({ key: "magic", unused: "value" }); // `Matched via key: "magic"`

Routing Events

Process and route various messages/events:

const messageMatcher = pattern()
  .case(textMessageSchema, handleTextMessage)
  .case(userUpdateSchema, handleUserUpdate)
  .case(connectionSchema, handleConnection)
  .case(errorSchema, handleError)
  .default((err) => new Error(`Unknown message: ${err}`));

License

zod-pattern is MIT licensed.