Enum knube::exp::Exp

pub enum Exp {
    Cst(&'static str),
    Var(&'static str),
    App(ExpBox, ExpBox),
}

A simple expression, as described in the module documentation.

This recursive form is what we study in class. Other implementations might be completely different.

Variants

Cst(&'static str)

Var(&'static str)

App(ExpBox, ExpBox)

Implementations

impl Exp

pub fn size(&self) -> usize

Computes the size of the given expression.

The size of an expression is equal to the number of constants it contains added to the number of variables it contains.

Trait Implementations

impl Clone for Exp

fn clone(&self) -> Exp

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Exp

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

Formats the value using the given formatter.

impl Display for Exp

Formats the expressions using the Rust style of expressions.

The expressions are formatted as follows:

• Variables and constants are replaced by their name. For example Cst("a") becomes a and Cst("x") becomes x.
• Applications are replaced by a function call. For example App(Cst("f"), Var("x")) becomes f(x).

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

Formats the value using the given formatter.

impl Eq for Exp

impl PartialEq<Exp> for Exp

The comparison is done as follows:

• Cst(a) == Cst(b) iff a == b, where a and b are strings.
• Var(a) == Var(b) iff a == b, where a and b are strings.
• App(a, b) == App(c, d) iff (a == c) && (b == d), where a, b, c, and d are expressions.

This definition of the equality operator matches the behavior of OCaml’s sum type comparison.

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

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

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl StructuralEq for Exp