Enum Shape 

pub enum Shape<N = ()> {
    Base,
    Optional(N, Box<Shape<N>>),
    Iterable(Box<Shape<N>>),
}

A base leaf wrapped in zero or more Optional / Iterable layers, from the inside out. N is the payload each Optional layer carries.

Variants

Base

The leaf — no wrapping layers.

Optional(N, Box<Shape<N>>)

Option<…> layer over inner. meta is this layer’s payload.

Iterable(Box<Shape<N>>)

Vec<…> / List<…> layer over inner.

Implementations

impl<N> Shape<N>

pub fn optional(meta: N, inner: Shape<N>) -> Self

Optional(meta, inner) without the explicit Box.

pub fn iterable(inner: Shape<N>) -> Self

Iterable(inner) without the explicit Box.

pub fn has_iterable_layer(&self) -> bool

True when any layer of the stack is Iterable. This is the fold-delivery discriminator: a fold surface (accumulator + per-element callback) is selected whether or not Optional layers wrap the iterable, and an iterable-shaped value has no single return.

Trait Implementations

impl<N: Clone> Clone for Shape<N>

fn clone(&self) -> Shape<N>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<N: Debug> Debug for Shape<N>

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

Formats the value using the given formatter.