I like the idea of having types at runtime for parsing etc and generating validators in various languages. What stopped me from going there so far is that I already have TypeScript types provided for the various libraries I use. How good are the tools for importing TypeScript types into ArkType/Zod and working with types in various representations in parallel?
The way zod and arktype generally handle this is by providing treating the schema as the source of truth, rather than a type. They then provide a way to define the type in terms of the schema:
// zod 3 syntax
import { z } from 'zod'
const RGB = z.schema({
red: z.number(),
green: z.number(),
blue: z.number(),
})
type RGB = z.infer<typeof RGB>
// same thing as:
// type RGB = { red: number; green: number; blue: number };
For the initial migration, there are tools that can automatically convert types into the equivalent schema. A quick search turned up https://transform.tools/typesgcript-to-zodghl, but I've seen others too.
For what it's worth, I have come to prefer this deriving types from parsers approach to the other way around.
With Zod you can build a schema that would match an existing type. Typescript will complain if the schema you build does not match the type you are representing, which is helpful. From memory:
import { z } from ‘zod’
type Message = { body: string; }
const messageSchema: z.Type<Message> = z.object({ body: z.string() })
