Type Alias Predicate 

pub type Predicate = Arc<dyn Fn() -> bool + Send + Sync>;

A predicate closure that gates a binding.

When the predicate returns false the binding is treated as if it does not exist: lookup skips it and has_prefix still reports deeper children so the chord can extend. The closure is stored in an Arc so that Binding<A>: Clone even when the closure is not Clone.

Aliased Type

pub struct Predicate { /* private fields */ }