Enum WithBottom 

pub enum WithBottom<T> {
    Bottom,
    Value(T),
}

Lifts any type T by adding a single Bottom element below all Value(t).

• Bottom is absorbing for Lattice::meet: meet(Bottom, x) = Bottom.
• Bottom is the identity for Lattice::join: join(Bottom, x) = x.
• Symmetric to WithTop: compose as WithTop<WithBottom<T>> for a closed lattice Bottom < Value(t) < Top.

Use case: represents “no progress yet” or “this data path has not started”. Makes the absence of a value explicit in the type system rather than relying on magic constants.

Example

use antichain::{WithBottom, Lattice};

// Bottom absorbs meet.
let bottom: WithBottom<u64> = WithBottom::Bottom;
let val = WithBottom::Value(42u64);
assert_eq!(bottom.meet(&val), WithBottom::Bottom);
assert_eq!(val.meet(&bottom), WithBottom::Bottom);

// Bottom is the identity for join.
assert_eq!(bottom.join(&val), val);
assert_eq!(val.join(&bottom), val);

Variants

Bottom

The bottom element, below all Value(t).

Value(T)

A wrapped value, above Bottom.

Trait Implementations

impl<T: Clone> Clone for WithBottom<T>

fn clone(&self) -> WithBottom<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for WithBottom<T>

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

Formats the value using the given formatter.

impl<T: Eq> Eq for WithBottom<T>

impl<T: Lattice + Clone> Lattice for WithBottom<T>

fn meet(&self, other: &Self) -> Self

Greatest lower bound: Bottom is absorbing — it forces the result to Bottom.

fn join(&self, other: &Self) -> Self

Least upper bound: Bottom is the identity — it does not constrain the other value.

impl<T: PartialEq> PartialEq for WithBottom<T>

fn eq(&self, other: &WithBottom<T>) -> 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<T: PartialOrd> PartialOrd for WithBottom<T>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: PartialEq> StructuralPartialEq for WithBottom<T>