@vytches/ddd-utils

Foundation utilities: Result pattern, safeRun, LibUtils, and middleware pipeline

Installation

pnpm add @vytches/ddd-utils

What's included

| Export | Kind | Description | | ------------------------------ | --------- | --------------------------------------------------------------------- | | Result<T, E> | class | Functional error handling — Result.ok(value) / Result.fail(error) | | safeRun(fn) | function | Executes fn and returns [error, result] tuple; never throws | | LibUtils | class | Static helpers: LibUtils.getUUID(), isEmpty checks, type guards | | MiddlewarePipelineExecutor | class | Composes and executes an ordered middleware chain | | IMiddleware<TIn, TOut> | interface | Middleware contract for the pipeline | | MiddlewareHandler<TIn, TOut> | type | Handler function type | | SimpleHandler<T> | type | Single-argument handler shorthand |

Result pattern

Result<T, E> is a re-export from @vytches/ddd-contracts for backwards compatibility. New code may import directly from @vytches/ddd-contracts.

import { Result } from '@vytches/ddd-utils';

function divide(a: number, b: number): Result<number, Error> {
  if (b === 0) return Result.fail(new Error('Division by zero'));
  return Result.ok(a / b);
}

const result = divide(10, 2);
if (result.isSuccess) {
  console.log(result.value); // 5
} else {
  console.error(result.error.message);
}

safeRun

Converts a throwing function into an [error, result] tuple. Works with both sync and async functions.

import { safeRun } from '@vytches/ddd-utils';

// async
const [err, user] = await safeRun(() => userRepository.findById('123'));
if (err) {
  console.error('Not found:', err.message);
  return;
}
console.log(user.name);

// sync
const [parseErr, json] = safeRun(() => JSON.parse(rawInput));

LibUtils

import { LibUtils } from '@vytches/ddd-utils';

const id = LibUtils.getUUID(); // UUID v4 string

Middleware pipeline

import { MiddlewarePipelineExecutor } from '@vytches/ddd-utils';
import type { IMiddleware } from '@vytches/ddd-utils';

class LoggingMiddleware implements IMiddleware<Request, Response> {
  async handle(req: Request, next: () => Promise<Response>): Promise<Response> {
    console.log('Request:', req.url);
    const res = await next();
    console.log('Response:', res.status);
    return res;
  }
}

const pipeline = new MiddlewarePipelineExecutor([new LoggingMiddleware()]);
const response = await pipeline.execute(request, () => handler(request));

Package boundaries

@vytches/ddd-utils depends on:

• @vytches/ddd-contracts — Result (re-exported from there)
• uuid — for LibUtils.getUUID()

License

MIT