Macro rules 

macro_rules! rules {
    ($($name:literal => $handler:expr),+ $(,)?) => { ... };
}

Define the rule half of a worm.

Each rule is a name and a handler. larvae calls a rule only on the nodes that match the filter you declared in worm.toml. Thus undeclared kinds do not cross the boundary.

larvae_worm::rules! {
    "strip_debug" => |node: larvae_worm::Node| {
        if node.kind() == "CallExpr" && node.text().starts_with("dprint") {
            node.remove();
        }
    },
}

Combine this macro with frontend! when a worm holds both roles.