Internal documentation — Work in progress

This page has not been confirmed as accurate or approved for publication. Current documentation version: 0.1.0-internal.1.

Classes and interfaces

Settled design: Sagan favors small, composable interfaces over inheritance hierarchies. face introduces an interface and class introduces a class. is and has are intended as interchangeable conformance words.

face Renderable {
  fun render()
}

face Spacecraft is Renderable, Movable {
  fun trajectory(): Vector
}

class ExplorerShip has Spacecraft {
  let name: String = "Explorer"

  fun render() {
    self.renderer.draw(self)
  }

  fun .calculate_internal_state(): Vector {
    return self.position + self.velocity
  }
}

enum GuidanceStatus {
  waiting
  ready
  failed
}

Implemented in the parser: a face contains method signatures or block-bodied default methods. A class contains let fields and block-bodied methods. is and has introduce interchangeable comma-separated composition lists on faces and classes. self parses as the current-object expression, and a leading dot marks a private class method in the AST. Simple enums contain identifier members separated by newlines or commas.

The parser records these distinctions but does not yet enforce interface conformance, privacy, dispatch, or field and method types.

Open questions: structural versus explicit conformance, default-method conflict resolution, constructor rules, enum payloads and explicit values, value versus reference behavior, visibility enforcement, and whether limited implementation inheritance will exist.