@traversable/derive-codec

ᯓ𝘁𝗿𝗮𝘃𝗲𝗿𝘀𝗮𝗯𝗹𝗲/𝗱𝗲𝗿𝗶𝘃𝗲-𝗰𝗼𝗱𝗲𝗰

Re-use your schema to derive a bi-directional codec (with compiled codecs coming soon!)

       

     

TypeScript Playground   •   npm

Overview

• Instructions: to install the .codec method on all schemas, all you need to do is import @traversable/derive-codec.
  • To create a covariant codec (similar to zod's .transform), use .codec.pipe
  • To create a contravariant codec (similar to zod's .preprocess), use .codec.extend (WIP)

Example

Play with this example in the TypeScript playground.

import { t } from '@traversable/schema'
import '@traversable/derive-codec'
//      ^^ this installs the `.pipe` and `.extend` methods on all schemas

let User = t
  .object({ name: t.optional(t.string), createdAt: t.string }).codec   // <-- notice we're pulling off the `.codec` property
  .pipe((user) => ({ ...user, createdAt: new Date(user.createdAt) }))
  .unpipe((user) => ({ ...user, createdAt: user.createdAt.toISOString() }))

let fromAPI = User.parse({ name: 'Bill Murray', createdAt: new Date().toISOString() })
//   ^?  let fromAPI: Error | { name?: string, createdAt: Date}

if (fromAPI instanceof Error) throw fromAPI
fromAPI
// ^? { name?: string, createdAt: Date }

let toAPI = User.encode(fromAPI)
//  ^? let toAPI: { name?: string, createdAt: string }