StarLang

StarLang is a tiny, statically typed, event-driven language and VM for embedded orchestration. It runs on ESP32 and PC with the same bytecode — no OS, no heap fragmentation, no runaway scripts.

What It Does

StarLang scripts orchestrate hardware and network I/O on microcontrollers. Connect to MQTT brokers, handle WebSocket streams, read sensors on timers, react to events — all in a bounded, garbage-collected VM that the host firmware controls.

package main

import "mqtt"

event MqttConnected { conn: i32 }
event MqttMessage { topic: string, payload: string }

fn main(): void {
    var conn: i32 = mqtt.open("192.168.1.10", 1883, "sensor-01")

    mqtt.on(conn, "connected", MqttConnected)
    mqtt.on(conn, "message", MqttMessage)

    on MqttConnected fn(e: MqttConnected): void {
        mqtt.subscribe(e.conn, "commands/#", 0)
    }

    on MqttMessage fn(e: MqttMessage): void {
        console.log(e.payload)
    }

    runtime.keepAlive()
}

Design Principles

• Event-driven, not polling — on handlers fire when data arrives, zero CPU while idle
• Code can die, VM must not — runtime guards (opcode budget, heap limit, event storm) kill scripts cleanly; firmware stays up
• Host owns the floor — guard limits set by firmware are immutable from script; scripts can tighten, never loosen
• No filesystem, no threads, no dynamic loading — scripts are pure computation + I/O events
• Same bytecode, two targets — compile once, run on PC for development, deploy to ESP32 for production

Architecture

 .star source → Compiler → .starbc bytecode → VM → HAL
                                                ├── PC    (stdio, TCP)
                                                └── ESP32 (UART, WiFi)

Layer	Role
Compiler	Single-pass, static types, emits bytecode + debug info
VM	Stack-based, mark-and-sweep GC, cooperative tasks, event loop
Native modules	C libraries (mqtt, ws, json, crypto, ...) called via OP_NATIVE_CALL
Guards	Opcode budget, heap limit, event storm — enforced in release mode
HAL	Platform abstraction — same script on PC and ESP32

Status

Component	Status
Compiler	Done
VM	Done
Event system	Done
Runtime guards	Done
Concurrency (go/chan/select)	Done
Native modules (mqtt, ws, json, crypto, config, ...)	Done
Language Server (LSP)	Done
DAP Debugger	Done
HAL (ESP32)	In Progress