#Getting started

Install fault and write your first Result.

#Install

Install the dependency for each import path you use.

npm add @thourum/fault
npm add zod@^4
npm add drizzle-orm pg

The core package has no runtime dependencies; zod >=4.0.0 is only needed for @thourum/fault/zod, drizzle-orm and pg for @thourum/fault/drizzle, and pg for @thourum/fault/pg.

#Your first Result

import { ok, err, type Result, Fault } from '@thourum/fault'

function parsePort(raw: string): Result<number, Fault> {
  const n = Number(raw)
  if (!Number.isInteger(n) || n < 1 || n > 65535) {
    return err(new Fault(`invalid port: ${raw}`).withTag('VALIDATION_ERROR'))
  }
  return ok(n)
}

parsePort(process.env.PORT ?? '').match(
  (port) => listen(port),
  (fault) => fault.capture(),
)

A function that can fail returns Result<T, Fault> instead of throwing.

#Mental model

• Result is synchronous; ResultAsync is a thenable whose awaited value is a Result.
• and* methods run on Ok; or* methods run on Err.
• Fault is the only error type you should ever put in E.