Struct Env 

pub struct Env { /* private fields */ }

An evaluation environment mapping variable names to values.

Environments are immutable — extending creates a new environment that shadows the parent’s bindings. This is implemented via clone since environments are typically small (lambda parameters, let bindings).

Implementations

impl Env

pub fn new() -> Self

Create an empty environment.

pub fn get(&self, name: &str) -> Option<&Literal>

Look up a variable in the environment.

pub fn extend(&self, name: Arc<str>, value: Literal) -> Self

Extend the environment with a new binding, returning a new environment.

pub fn len(&self) -> usize

Returns the number of bindings.

pub fn is_empty(&self) -> bool

Returns true if the environment has no bindings.

pub fn iter(&self) -> impl Iterator<Item = (&Arc<str>, &Literal)>

Iterate over all bindings in the environment.

Trait Implementations

impl Clone for Env

fn clone(&self) -> Env

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Env

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

Formats the value using the given formatter.

impl Default for Env

fn default() -> Env

Returns the “default value” for a type.

impl FromIterator<(Arc<str>, Literal)> for Env

fn from_iter<T: IntoIterator<Item = (Arc<str>, Literal)>>(iter: T) -> Self

Creates a value from an iterator.