Enum Exp 

pub enum Exp {
    Lit(i64),
    Flo(f64),
    Sym(SmolStr),
    Atom(Atom),
    Nil,
    Var(usize),
    Lam(u16, RcExp),
    App(RcExp, Box<[RcExp]>),
    Apply(RcExp, RcExp),
    Let(RcExp, RcExp),
    If(RcExp, RcExp, RcExp),
    Prim1(Prim1, RcExp),
    Prim2(Prim2, RcExp, RcExp),
    Op(u16, Vec<RcExp>),
    Lift(RcExp),
    LiftFun(RcExp, RcExp),
    LiftRef(RcExp, RcExp),
    Proc(RcVal),
    Run(RcExp, RcExp),
    IsCode(RcExp, RcExp),
    Evalms(RcExp, RcExp),
    Catch(RcExp),
    Throw(RcExp),
}

Variants

Lit(i64)

Flo(f64)

In the core rather than behind host because boxing a register-sized scalar is not a constant factor. Costs one match arm.

Sym(SmolStr)

Atom(Atom)

Nil

Var(usize)

De Bruijn index, counted from the outermost binding

Lam(u16, RcExp)

Binds its own name and then arity parameters, so the body sees arity + 1 bindings. A closure carries this node rather than just the body, which is how the arity reaches the call.

App(RcExp, Box<[RcExp]>)

Apply(RcExp, RcExp)

Application at an arity not known until the call: the operands arrive as a list value rather than as syntax, which is what an n-ary interpreter has, and Exp::App fixes its arity when it is read.

Let(RcExp, RcExp)

If(RcExp, RcExp, RcExp)

Prim1(Prim1, RcExp)

Prim2(Prim2, RcExp, RcExp)

Op(u16, Vec<RcExp>)

A call into the host op table, resolved to an index by the reader

Lift(RcExp)

LiftFun(RcExp, RcExp)

Eta-expand at a stated arity, since an interpreter compiling an object function has no floor closure to take one from. Variables as a list, self first.

LiftRef(RcExp, RcExp)

Cross-stage persistence: carry a value into the next stage by reference rather than by structure

Proc(RcVal)

A persisted value, the residue of Exp::LiftRef. Syntax that is not syntax: it holds a value the next stage may only pass along.

Run(RcExp, RcExp)

IsCode(RcExp, RcExp)

Evalms(RcExp, RcExp)

The one way to animate code compiled against a scope other than the current one, which is what loading a module amounts to.

Catch(RcExp)

Throw(RcExp)

Implementations

impl Exp

pub fn iter_children(&self) -> impl Iterator<Item = &RcExp>

Trait Implementations

impl Clone for Exp

fn clone(&self) -> Exp

Returns a duplicate of the value.

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

Floor source as read, except the three things with no syntax: a de Bruijn variable, a persisted value, a host atom. Iterative for Drop’s reason.

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

Formats the value using the given formatter.

impl Drop for Exp

Deep trees are ordinary in staged output, so recursive drop glue would overflow on residuals the specializer routinely produces.

fn drop(&mut self)

Executes the destructor for this type.

impl PartialEq for Exp

fn eq(&self, other: &Exp) -> 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 StructuralPartialEq for Exp