Native modules

Contents

How a Program becomes Swift, in parts. Start with the introduction, then follow each part into the rendered output and the runtime it links against.

• Introduction — what the Swift target is, and how to read the rest of this section.
• Capabilities — which high-level features are possible, built in or through a library.
• Example — a full program using every keyword, and the Swift it renders to.
• Naming considerations — how Program's dotted names are carried into Swift.
• Entry point — starting a program and mounting it as a SwiftUI app.
• Drivers — the native drivers that provide the interface, animation and network.
• Runtime — the Reactive and Context machinery the rendered code links against.
• Native modules — the hand-written Swift behind NATIVE functions.
• Keywords — how each of Program's keywords renders to Swift.
• Project setup — the files and commands to build and run the rendered program.
• Reserved words — the words Swift keeps for itself, and how a colliding name is escaped.

Hand-written Swift behind NATIVE

A function's hand-written swift NATIVE body is dropped in where the function is called, wrapped so its inputs arrive as plain Swift values.

public static func Add(_ a: Any, _ b: Any) -> ReactiveValue<Double> {
  return Reactive.Calculate {
    let a = Reactive.Value(__reactive_a) as! Double
    let b = Reactive.Value(__reactive_b) as! Double
    return a + b               // the swift NATIVE body
  }
}

As on JavaScript, the drivers are native code too — the SwiftUI interface driver, animation and network live in their modules' native Swift — and the runtime (Reactive, Context) is itself a native module the rest builds on.