Struct ComputedVar 

pub struct ComputedVar {
    pub key: String,
    pub dependencies: Vec<String>,
    pub compute: Arc<dyn Fn(&State) -> Option<Value> + Send + Sync>,
}

A computed state variable: a pure function of other state keys.

The compute closure receives the full State and returns an optional Value. When it returns Some(value), the result is written to derived:{key} in state. When it returns None, the key is skipped (no write, no change detection).

Fields

key: String

The state key this computed variable writes to (prefixed with derived:).

dependencies: Vec<String>

State keys this variable depends on.

compute: Arc<dyn Fn(&State) -> Option<Value> + Send + Sync>

Closure that computes the derived value from current state.