Tiny Zod implementation.

Zod is a dense library, and its module structure (or lack thereof) makes it difficult for bundlers to tree-shake unused modules.

Additionally, using Zod in vals requires the await import syntax which means having to wrap every schema in a Promise and awaiting it. This is extremely annoying.

So this is a lil-tiny-smol Zod meant for use in vals. A noteworthy use-case is using minizod to generate tyep-safe API calls to run vals outside of Val Town (such as client-side).

We can use minizod to create type safe HTTP handlers and generate the corresponding code to call them using Val Town's API, all in a type-safe manner.

First, create a schema for a function. The following example defines a schema for a function that takes a { name: string } parameter and returns a Promise<{ text: string }>.

const minizodExampleSchema = () =>
  @zackoverflow.minizod().chain((z) =>
    z
      .func()
      .args(z.tuple().item(z.object({ name: z.string() })))
      .ret(z.promise().return(z.object({ text: z.string() })))
  );

With a function schema, you can then create an implementation and export it as a val:

const minizodExample = @me.minizodExampleSchema().impl(async (
  { name },
) => ({ text: `Hello, ${name}!` })).json()

In the above example, we call .impl() on a function schema and pass in a closure which implements the actual body of the function. Here, we simply return a greeting to the name passed in.

We can call this val, and it will automatically parse and validate the args we give it:

// Errors at compile time and runtime for us!
const response = @me.minizodExample({ name: 420 })

Alternatively, we can use the .json() function to use it as a JSON HTTP handler:

const minizodExample = @me.minizodExampleSchema().impl(async (
  { name },
) => ({ text: `Hello, ${name}!` })).json() // <-- this part

We can now call minizodExample through Val Town's API. Since we defined a schema for it, we know exactly the types of its arguments and return, which means we can generate type-safe code to call the API:

let generatedApiCode =
  @zackoverflow.minizodFunctionGenerateTypescript(
    // put your username here
    "zackoverflow",
    "minizodExample",
    // put your auth token here
    "my auth token",
    @me.minizodExampleSchema(),
  );

This generates the following the code:

export const fetchMinizodExample = async (
  ...args: [{ name: string }]
): Promise<Awaited<Promise<{ text: string }>>> =>
  await fetch(`https://api.val.town/v1/run/zackoverflow.minizodExample`, {
    method: "POST",
    body: JSON.stringify({
      args: [...args],
    }),
    headers: {
      Authorization: "Bearer ksafajslfkjal;kjf;laksjl;fajsdf",
    },
  }).then((res) => res.json());