Enum Upvalue 

pub enum Upvalue {
    Immutable(ValueWord),
    Mutable(Arc<RwLock<ValueWord>>),
}

Upvalue - a captured variable that can be shared between closures and their enclosing scope.

Most captures are immutable (the compiler never emits StoreClosure), so the Immutable variant stores the ValueWord directly — no Arc, no RwLock, just an 8-byte clone. The Mutable variant preserves the old Arc<RwLock<ValueWord>> path for the rare case where a capture is written to.

Variants

Immutable(ValueWord)

Direct value — no lock, no Arc overhead. Clone is 8 bytes (or Arc bump for heap values).

Mutable(Arc<RwLock<ValueWord>>)

Shared mutable capture — used if StoreClosure is ever emitted.

Implementations

impl Upvalue

pub fn new(value: ValueWord) -> Self

Create a new immutable upvalue (fast path — default for all captures).

pub fn new_mutable(value: ValueWord) -> Self

Create a new mutable upvalue (slow path — only when writes are needed).

pub fn get(&self) -> ValueWord

Get a clone of the contained ValueWord value.

pub fn set(&mut self, value: ValueWord)

Set the contained value.

If the upvalue is Immutable, it is upgraded to Mutable on the first write. This requires &mut self.

Trait Implementations

impl Clone for Upvalue

fn clone(&self) -> Upvalue

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Upvalue

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

Formats the value using the given formatter.