Welcome to type-a – a tiny but powerful schema & validation library for TypeScript. This guide shows how to install the package and run your first schema.
With pnpm (recommended):
pnpm add @rybosome/type-a vitest -D # vitest is used in all docs samples
or with npm:
npm install @rybosome/type-a vitest --save-dev
The snippet below defines a minimal User schema, instantiates it with data, and
runs a validation.
import { describe, it, expect } from "vitest";
import { Schema, one, constraints as c, typed as t } from "@rybosome/type-a";
describe("Hello type-a", () => {
it("creates and validates a User", () => {
class User extends Schema.from({
id: one(t.string, { is: c.nonEmpty }),
name: one(t.string),
createdAt: one(t.serdes(Date, t.string), {
serdes: [(d: Date) => d.toISOString(), (iso: string) => new Date(iso)],
}),
}) {}
const u = new User({
id: "550e8400-e29b-41d4-a716-446655440000",
name: "Alice",
createdAt: "2025-01-01T00:00:00Z",
});
expect(u.validate()).toEqual([]); // no errors
});
});
Next up: explore the rest of the API reference to learn how to model maps, tuples, nested schemas, and more.