windmill/system_prompts/languages/bun.md

TypeScript (Bun)

Bun runtime with full npm ecosystem and fastest execution.

Structure

Export a single async function called main:

export async function main(param1: string, param2: number) {
  // Your code here
  return { result: param1, count: param2 };
}

Do not call the main function. Libraries are installed automatically.

Resource Types

On Windmill, credentials and configuration are stored in resources and passed as parameters to main.

Use the RT namespace for resource types:

export async function main(stripe: RT.Stripe) {
  // stripe contains API key and config from the resource
}

Only use resource types if you need them to satisfy the instructions. Always use the RT namespace.

Imports

import Stripe from "stripe";
import { someFunction } from "some-package";

Windmill Client

Import the windmill client for platform interactions:

import * as wmill from "windmill-client";

See the SDK documentation for available methods.

Preprocessor Scripts

For preprocessor scripts, the function should be named preprocessor and receives an event parameter:

type Event = {
  kind:
    | "webhook"
    | "http"
    | "websocket"
    | "kafka"
    | "email"
    | "nats"
    | "postgres"
    | "sqs"
    | "mqtt"
    | "gcp";
  body: any;
  headers: Record<string, string>;
  query: Record<string, string>;
};

export async function preprocessor(event: Event) {
  return {
    param1: event.body.field1,
    param2: event.query.id,
  };
}

S3 Object Operations

Windmill provides built-in support for S3-compatible storage operations.

S3Object Type

The S3Object type represents a file in S3 storage:

type S3Object = {
  s3: string; // Path within the bucket
};

TypeScript Operations

import * as wmill from "windmill-client";

// Load file content from S3
const content: Uint8Array = await wmill.loadS3File(s3object);

// Load file as stream
const blob: Blob = await wmill.loadS3FileStream(s3object);

// Write file to S3
const result: S3Object = await wmill.writeS3File(
  s3object, // Target path (or undefined to auto-generate)
  fileContent, // string or Blob
  s3ResourcePath // Optional: specific S3 resource to use
);