Struct Ast

pub struct Ast { /* private fields */ }

The abstract syntax tree constructed from the lambda expression.

Implementations

impl Ast

pub fn new(expr: Expr) -> Ast

pub fn expr_ref(&self) -> &Expr

Get an un-mutable reference to the underlying expression.

pub fn beta_reduce_print(self, parser: &Parser) -> Option<Ast>

Applies beta reductions until it’s no longer possible, printing the result after each round of beta reduction.

Uses normal order reduction strategy (leftmost outermost redex first), otherwise certain reductions would loop infintely:

let mut parser = Parser::new();
let redex = parser
    .parse("(lambda x . a) ((lambda y . y y) (lambda y . y y))", None)
    .unwrap()
    .unwrap();
let non_redex = redex.beta_reduce_print(&parser);
assert_eq!(non_redex, Some(Ast::new(Expr::Var{name: "a".to_string(), is_free: true})));

This function does not attempt to predict infinite loops.

pub fn beta_reduce_quiet(self, parser: &Parser) -> Option<Ast>

Identical to beta_reduce_print() but doesn’t print anything.

Trait Implementations

impl Clone for Ast

fn clone(&self) -> Ast

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Ast

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

Formats the value using the given formatter.

impl Display for Ast

If a program will read the output, use the alternate formatter, which does not use ANSI color escapes or non-ASCII unicode characters.

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

Formats the value using the given formatter.

impl PartialEq for Ast

fn eq(&self, other: &Ast) -> 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 Eq for Ast

impl StructuralPartialEq for Ast