Enum Purity 

pub enum Purity {
    Pure,
    SideChannel {
        sink: SideChannelSink,
    },
    Nondeterministic {
        reason: &'static str,
    },
}

Per-node purity classification per runtime_model.md’s D2 axiom and composition_substrate.md’s T1+T2 axioms.

Every node declares its purity status via PolydatNode::purity. The default is Purity::Pure; nodes with observable side channels (logging, file I/O, network) or eval-call-spanning state override to declare Purity::SideChannel or Purity::Nondeterministic.

D1 (Typed Return Determinism) holds for every purity class. The slot contract carries only typed return values; impure nodes still produce typed-deterministic returns. What varies between purity classes is the observable side channels (D2): pure nodes have none; SideChannel nodes have declared side channels; Stateful nodes additionally have internal eval-call-spanning state that affects future evaluations.

Variants

Pure

Pure function — eval(inputs) is a function of inputs, no observable side effects, byte-identical determinism across calls with identical inputs.

SideChannel

Has an observable side channel (logging, file I/O, network, etc.) but the typed return value is still a function of inputs. Hosts that care about side-channel observability examine the sink to know what observable surface this node writes to.

Fields

sink: SideChannelSink

The observable surface the node writes to.

Nondeterministic

The typed return value is not a function of declared inputs alone — it depends on external sources (system clock, entropy, thread identity, environment) or on eval-call-spanning internal state mutated by prior calls. In either case, the runtime’s node_clean caching model must opt the node out of within-cycle memoization suppression; the lifecycle classifier marks the node as nondeterministic per kernel/engines.rs::nondeterministic_nodes. The reason string documents the source of non-determinism (e.g., “reads system clock”, “monotonic counter incremented per call”, “accumulates signal buffer across calls”).

This is the intrinsic-volatility marker referenced by runtime_model.md R1.v: certain library nodes declare themselves volatile via this variant; no user opt-in is required, and the workload author cannot remove the marker. User-opt-in volatility via the volatile modifier is a separate surface that produces the same runtime effect (see R1.v).

Fields

reason: &'static str

The source of the non-determinism, for diagnostics.

Trait Implementations

impl Clone for Purity

fn clone(&self) -> Purity

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Purity

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

Formats the value using the given formatter.

impl Eq for Purity

impl Hash for Purity

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Purity

fn eq(&self, other: &Purity) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Purity