Struct Var 

pub struct Var {
    pub namespace: Arc<str>,
    pub name: Arc<str>,
    pub value: Mutex<Option<Value>>,
    pub shared_root: Arc<ArcSwap<Option<SharedValue>>>,
    pub is_macro: bool,
    pub meta: Mutex<Option<Value>>,
    pub watches: Mutex<Vec<(Value, Value)>>,
}

A Clojure var — a namespace-interned mutable root binding.

Two-tier root (Phase B3, issue #171)

A var’s root binding uses the same two-tier mechanism as shared-atom:

• value — the isolate-local, GC-backed fast path. Every var deref, the IR tier, and the JIT/AOT rt_* ABI read this slot; promotion never touches it, so compiled inline caches and pointer-identity assumptions baked into native code stay valid.
• shared_root — a Send + Sync cross-isolate mirror, Arc<ArcSwap<Option<SharedValue>>>, reusing crate::shared::SharedValue. bind (i.e. def / alter-var-root / set!) promotes-on-write: if the new root value is promotable the cell holds Some(SharedValue), otherwise it is cleared to None (option (b) of the ADR — non-promotable roots, e.g. closures, stay isolate-local).

The shared cell is what crosses the structured-clone boundary: a var def’d in one isolate is observable by value from another, with keyword /symbol identity preserved through the intern table. See crate::clone for the serialize/deserialize seam.

Dynamic binding is unchanged — it is already thread-local / per-isolate and lives on the binding stack, not in the var root.

Fields

namespace: Arc<str>

name: Arc<str>

value: Mutex<Option<Value>>

shared_root: Arc<ArcSwap<Option<SharedValue>>>

Cross-isolate mirror of the root binding (Phase B3). None when the var is unbound or its current root is not promotable.

is_macro: bool

meta: Mutex<Option<Value>>

Metadata map (e.g. {:dynamic true}).

watches: Mutex<Vec<(Value, Value)>>

Implementations

impl Var

pub fn new(namespace: impl Into<Arc<str>>, name: impl Into<Arc<str>>) -> Self

pub fn from_shared_root( namespace: impl Into<Arc<str>>, name: impl Into<Arc<str>>, is_macro: bool, shared_root: Arc<ArcSwap<Option<SharedValue>>>, ) -> Self

Reconstruct a var on the receiving side of an isolate boundary.

The shared_root cell is the same Arc as the sending isolate’s, so both isolates share the cross-isolate root cell. The local value fast-path slot is seeded by demoting the current shared snapshot, so an immediate deref observes the value the var carried at crossing time.

pub fn is_bound(&self) -> bool

pub fn deref(&self) -> Option<Value>

pub fn deref_shared(&self) -> Option<Value>

Read the cross-isolate root by demoting the shared cell, ignoring the isolate-local fast path. Returns None when the shared root is empty (unbound or non-promotable). Used to observe writes another isolate made through the shared cell.

pub fn bind(&self, v: Value)

pub fn get_meta(&self) -> Option<Value>

pub fn set_meta(&self, m: Value)

pub fn full_name(&self) -> String

Trait Implementations

impl Debug for Var

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

Formats the value using the given formatter.

impl Trace for Var

fn trace(&self, visitor: &mut MarkVisitor)

fn gc_size_extra(&self) -> usize