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 Debug for Order

fn fmt(&self, __arg_0: &mut Formatter) -> Result

Formats the value using the given formatter.

impl PartialEq for Order

fn eq(&self, __arg_0: &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 !=.

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 Copy for Order

impl Display for Order

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

Formats the value using the given formatter.