Enum FnResult 

pub enum FnResult {
    Data {
        handle: HandleId,
        tracked: Option<Vec<usize>>,
    },
    Noop {
        tracked: Option<Vec<usize>>,
    },
    Batch {
        emissions: SmallVec<[FnEmission; 2]>,
        tracked: Option<Vec<usize>>,
    },
}

What the binding side returns when the Core invokes a fn via BindingBoundary::invoke_fn.

Models the three emission modes from the canonical spec:

• FnResult::Data — single DATA, equals substitution applies (R1.3.2). Maps to actions.emit(v) in sugar constructors.
• FnResult::Batch — multi-message wave, no equals substitution (R1.3.2.d / R1.3.3.c). Maps to actions.down(msgs).
• FnResult::Noop — no emission. RESOLVED if node was DIRTY.

Per R2.4.5, the fn return value in the canonical spec is cleanup hooks only — all emission is explicit via actions. The Rust Core folds the emission into FnResult as a pragmatic simplification; the binding layer maps between the two representations.

Variants

Data

fn produced a single value. The Core treats this as outgoing DATA — equals-substitution against the cache may rewrite it to RESOLVED on the wire (R1.3.2).

Fields

handle: HandleId

tracked: Option<Vec<usize>>

For dynamic nodes only: the dep indices fn actually read this run. Static derived nodes pass None. See dynamic-node semantics in the canonical spec §2.8 / Lock 2.B.

Noop

fn ran but produced no emission this wave. The Core sends RESOLVED to subscribers if the node was already DIRTY this wave; otherwise no outgoing message.

Fields

tracked: Option<Vec<usize>>

Same as Data::tracked — dynamic nodes only.

Batch

Multi-message wave — models actions.down(msgs). Emissions are processed in sequence within the same wave. No equals substitution on any Data emission (R1.3.2.d: substitution only on single-DATA waves; R1.3.3.c: multi-DATA passes verbatim). DIRTY auto-prefix only on first Data per R1.3.1.a.

Fields

emissions: SmallVec<[FnEmission; 2]>

tracked: Option<Vec<usize>>

Same as Data::tracked — dynamic nodes only.

Trait Implementations

impl Clone for FnResult

fn clone(&self) -> FnResult

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FnResult

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.