Enum PairElement 

pub enum PairElement {
    I32,
    Bool,
    Ratio,
    Commodity,
    StringRef,
    Entity(EntityKind),
    AnyRef,
}

Element type of a homogeneous $pair chain. Tracked at compile time so CAR/CDR emit the right downcast and CONS refuses heterogeneous mixing with a structured type error. Kept as a Copy enum so WasmType stays Copy — and so adding a new element type stays a one-line variant addition. Nesting (pairs-of-pairs) waits for a follow-up sub-slice once flat lists are stable across the consumers.

Variants

I32

Bool

Truth-value cell: shares I32’s i31-boxed car representation (CAR/CDR emit the same i31 downcast), but distinct so a bool extracted from a list serializes as Nil / Bool, not Number — the list-element analogue of WasmType::Bool vs I32.

Ratio

Commodity

StringRef

Entity(EntityKind)

AnyRef

Heterogeneous escape hatch (ADR-0025). Cars stay as raw anyref; CAR returns WasmType::AnyRef and the script must downcast at the use site (or consume via type-test natives like ok? / err-code). CONS widens to this variant when the two arms disagree on element type, and host fns that produce fundamentally heterogeneous lists (e.g. =catch-each= result cells) construct directly into PairRef(AnyRef).

Implementations

impl PairElement

pub fn as_wasm_type(self) -> WasmType

The matching WasmType for a pair’s car when extracted.

pub fn from_wasm_type(ty: WasmType) -> Option<Self>

Inverse of as_wasm_type: returns None if the given type can’t ride a $pair’s anyref car. WasmType::AnyRef round-trips to PairElement::AnyRef; nested pairs and closures still need their own follow-up lattice extension.

pub fn widen(self, other: Self) -> Self

Widen self against other to the most-specific common element. Identical types stay; everything else widens to AnyRef so heterogeneous CONS no longer errors. Symmetric.

Trait Implementations

impl Clone for PairElement

fn clone(&self) -> PairElement

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PairElement

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

Formats the value using the given formatter.

impl Display for PairElement

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

Formats the value using the given formatter.

impl Hash for PairElement

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 PairElement

fn eq(&self, other: &PairElement) -> 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 Copy for PairElement

impl Eq for PairElement

impl StructuralPartialEq for PairElement