Enum lambda_calculus::reduction::Order

pub enum Order {
    NOR,
    CBN,
    HSP,
    HNO,
    APP,
    CBV,
    HAP,
}

The evaluation order of β-reductions.

• the NOR, HNO, APP and HAP orders reduce expressions to their normal form
• the APP order will fail to fully reduce expressions containing terms without a normal form, e.g. the Y combinator (they will expand forever)
• the CBN order reduces to weak head normal form
• the CBV order reduces to weak normal form
• the HSP order reduces to head normal form

Variants

NOR

normal - leftmost outermost; the most popular reduction strategy

CBN

call-by-name - leftmost outermost, no reductions inside abstractions

HSP

head spine - leftmost outermost, abstractions reduced only in head position

HNO

hybrid normal - a mix between HSP (head spine) and NOR (normal) strategies

APP

applicative - leftmost innermost; the most eager strategy; unfit for recursion combinators

CBV

call-by-value - leftmost innermost, no reductions inside abstractions

HAP

hybrid applicative - a mix between CBV (call-by-value) and APP (applicative) strategies; usually the fastest-reducing normalizing strategy

Trait Implementations

impl Clone for Order

fn clone(&self) -> Order

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Order

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

Formats the value using the given formatter.

impl Display for Order

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

Formats the value using the given formatter.

impl PartialEq<Order> for Order

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

This method tests for self and other values to be equal, and is used by ==.

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

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

impl Copy for Order

impl Eq for Order

impl StructuralEq for Order

impl StructuralPartialEq for Order