Introduction

Receta is a TypeScript library of recipes built on Remeda. Remeda gives you map and pipe. Receta gives you what real code needs on top of them: errors as values, absence as a type, retries with limits, and validation that reports every problem at once.

The point isn't style. When a failure is in the signature, a person can check code they didn't write by reading it, and that includes code an agent wrote.

A first pipeCopy Anchor Link

This function can fail in two ways, and both are in its return type. Nothing throws behind the reader's back.

import * as R from 'remeda'
import { err, flatMap, map, ok, parseJSON, type Result } from '@ontologyio/receta/result'

type Order = { readonly id: string; readonly items: readonly string[] }

const requireItems = (order: Order): Result<Order, string> =>
  order.items.length > 0 ? ok(order) : err('EMPTY_ORDER')

const countItems = (raw: string) =>
  R.pipe(
    parseJSON<Order>(raw),
    flatMap(requireItems),
    map((order) => order.items.length),
  )

countItems('{"id":"a1","items":["tea"]}') // => Ok(1)
countItems('{"id":"a2","items":[]}') // => Err('EMPTY_ORDER')

Read it top to bottom. Each line is one step, and the happy path is the only path on the page. If parseJSON or requireItems fails, the steps after it don't run and the failure comes out the end as a value.

Where to go nextCopy Anchor Link

Every example here runsCopy Anchor Link

The examples in these docs are compiled against the published package on every change, and each // => value comment is checked against what the code really returns. If an example is wrong, the build fails. A few blocks show deliberately broken code, and those are the only ones left out.