Appendix · The Lexicon

This is the contract between xrune’s medieval vocabulary and ordinary compiler/CS terms. Every chapter reaches back here when the metaphor risks drifting from the engineering meaning.

Naming compact

xrune term	Plain meaning
sigil	A derive macro (`xrune-sigil`). The `DsRef` derive mints `{Name}Ref` newtypes around `Rc<RefCell<Name>>`.
nexus	The core crate (`xrune-nexus`) — AST node types, the `DsRune` trait, and the `decipher` walker. The hub everything else binds to.
incant	The proc-macro crate (`xrune-incant`) that exposes `ui! { … }`. The act of invoking the DSL.
rune	A backend implementation of the `DsRune` trait — turns the parsed tree into emitted code. The DSL is one casting; runes are many translations.
decipher	The free function `xrune::ds_rune::decipher::decipher(tree, &mut rune)` that walks a `DsTree` and dispatches one inscribe call per node.
inscribe	One method on `DsRune` — `inscribe_root` / `inscribe_widget` / `inscribe_if` / `inscribe_iter` / `inscribe_niche` / `inscribe_match`. Each receives a node and accumulates output into the rune.
seal	The trait method `seal(self) -> TokenStream`. Consumes the rune at the end of decipher to produce the final emitted code. Not Rust’s “sealed trait” pattern — same name, unrelated meaning.
enchant	A bracketed expression list `[expr, expr, …]` attached to a widget. Arbitrary data the rune can attach to a node — typically ECS components or attached state.
niche	A `@name { … }` node. An anchor / slot / named region routed by the host rune (e.g. portals, named ports).
walk … with …	Iteration. `walk iterable with var { … }` is xrune’s `for` loop.
on	An event handler clause attached to a widget — `on EventKind { … }` (body form) or `on EventKind(cb)` (callback form).
scribe	The formatter binary `xrune-fmt` — re-renders DSL inside `ui! { … }` blocks.
grimoire	This documentation site.
codex	The version history (CHANGELOG).

DSL casting compact

Form	Reads as
`:( ... :)` (each attr on its own line)	Context area. `parent` is required; other keys are rune-defined (`world`, `theme`, …).
`Widget (k: v) { … }`	A widget node with named attrs and children.
`Widget (Text("hi"))`	A widget with a positional attr. No body required.
`Widget (k: v) [Comp{…}, Tag] { … }`	Same, with enchants between attrs and body.
`if expr { … }`	Conditional render.
`walk it with x { … }`	Iteration.
`@slot { … }`	Niche (named anchor).
`match e { Pat => { … } … }`	Pattern match across sub-trees.
`Widget () {} on Tap { fire() }`	Form B: `on` after the body, attaches to the preceding sibling.
`Widget () on Tap { … } { … }`	Form C: `on` between attrs and body, attaches to this widget.
`on Tap(cb)`	Callback form. `cb` is the trailing arg; rune decides what it means.

Public API index

The shape every reader needs once:

Crate	Public surface
`xrune-sigil`	`#[derive(DsRef)]`
`xrune-nexus`	`ds_node::` (the `Ds` AST types) · `ds_rune::DsRune` trait · `ds_rune::decipher::decipher` · `pub use xrune_sigil::DsRef`
`xrune-incant`	`#[proc_macro] pub fn ui`
`xrune`	`pub mod default_rune;` · `pub use xrune_incant::ui;` · `pub use xrune_nexus::*;`
`xrune-fmt`	`xrune-fmt <file.rs> [--check]` (binary)