Struct Machine 

pub struct Machine {
    pub mode: Mode,
    pub kont: Vec<Cont>,
}

The CK machine’s execution state.

Owns the Mode (current eval/apply step) and the kont stack. EvalCtx is passed alongside via reference because it represents long-lived staging context (fresh, block, fun, level, io) rather than per-evaluation loop state.

A Machine is constructed at the top of an evalms call, run to completion (or error), and then consumed. Machine::run drives the loop and returns the final Val.

Fields

mode: Mode

The current step: evaluate an expression or apply a value to the kont.

kont: Vec<Cont>

The continuation stack; empty means the next Apply is final.

Implementations

impl Machine

pub fn new(env: Env, exp: RcExp) -> Self

Create a fresh machine that will start by evaluating exp under env. The kont stack is empty; the loop terminates when an Apply finds the stack empty.

pub fn run(self, ctx: &mut EvalCtx) -> Result<Val, NarjuError>

Drive the machine to completion.

Every Exp variant is handled natively; there is no recursive baseline. The loop alternates Mode::Eval → step_eval and Mode::Apply → pop-cont → step_apply, with unwind_to_catch handling Catch error boundaries.