Crate slung 

Slung Rust SDK

Runtime bindings for Slung — an ontology-driven compute engine that executes rules based on real-time component updates.

Overview

Slung rules watch components for changes and fire when facts become dirty. The Rust SDK provides:

• Descriptor macros (#[source], #[component], #[rule]) — self-describing rule modules
• RuleContext — typed access to entity state and host operations
• Host ABI — low-level access to active memory, clock, and connectors

Quickstart

Add to Cargo.toml:

[dependencies]
slung = "0.2.0"

Example: Sensor Alert Rule

use slung::prelude::*;

#[source(builtin = "ws")]
struct SensorData {
    #[config(value = "sensor-data")]
    path: &'static str,

    temperature: Temperature,
    alert: Alert,
}

#[component]
struct Temperature {
    value: f64,
}

#[component]
struct Alert {
    active: bool,
}

#[rule(watch = [SensorData::temperature], priority = 10)]
fn on_high_temp(ctx: &RuleContext) -> Result<()> {
    let temp = ctx.get::<Temperature>(SensorData::temperature)?;
    ctx.set(SensorData::alert, Alert { active: temp.value > 85.0 })?;
    Ok(())
}

// for the compiler to be happy
fn main() {}

The host:

1. Parses descriptors from Wasm exports
2. Builds the capability graph (what watches what)
3. Loads component values from the LWW store
4. Fires your rule when SensorData::temperature changes
5. Captures writes back to the store and re-triggers dependent rules

Source config is baked into the module descriptor. Use #[config(value = "...")] on source fields and the macro emits those values into the source descriptor JSON for the host to consume at load time.

Host ABI

The host module provides typed bindings organized by category:

• generic — get(), set(), now(), yield_control(), emit(), notify()
• http — get(), post()
• ws — connect(), next(), send()
• tcp_udp — raw socket escape hatch

Most rules only need RuleContext::get() and RuleContext::set().

How It Works

Wasm module
  ├─ #[source] descriptors → host opens connectors, maps incoming data
  ├─ #[component] descriptors → host tracks typed facts
  └─ #[rule] descriptors → host builds watchlist and capability graph

At runtime:
  component changes → dirty signal → graph lookup → rule fire → write back

License

MIT License — see LICENSE.

Modules

host

Host ABI bindings — organized by function category Host ABI Bindings — Slung runtime interface

prelude

Common imports for workflow handlers.

Structs

ComponentKey

Typed component selector used by descriptor-based rules.

RuleContext

Rule execution context for typed descriptor-based handlers.