Enum Verdict 

pub enum Verdict {
    Incremental,
    Trivial,
    Recompute {
        because: String,
    },
    Effectful {
        effects: Vec<Effect>,
    },
}

What a view engine could do with one vertex.

Variants

Incremental

Every operation has a delta rule: this vertex could be maintained rather than recomputed.

Trivial

Pure, and it applies no collection operation at all — a vertex that rebuilds a value from its inputs, as map2(combine, board, here) does when combine is a record constructor.

Neither of the two interesting answers: there is nothing to maintain by delta and nothing that would cost a recount. It is its own verdict because saying “incremental” about it produced a row with an empty explanation, which is what incremental.rs’s “none of them is a mystery” gate exists to catch — and did, the first time a program in the corpus applied nothing (docs/96 §96.5).

Recompute

Pure, but something in it has no delta rule. The reason names the first blocker found, in source order, because the first is the one to fix.

Fields

because: String

Effectful

The row is not empty, so §3.8’s precondition fails before the shape is even looked at.

Fields

effects: Vec<Effect>

Implementations

impl Verdict

pub fn name(&self) -> &'static str

Trait Implementations

impl Clone for Verdict

fn clone(&self) -> Verdict

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Verdict

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

Formats the value using the given formatter.

impl PartialEq for Verdict

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Verdict

impl StructuralPartialEq for Verdict