Struct NanBox 

pub struct NanBox(/* private fields */);

A NaN-boxed value: 8 bytes encoding any VM value type.

Floats are stored as-is (their bit pattern). Non-float values are encoded in the NaN payload space.

Implementations

impl NanBox

pub const fn null() -> Self

Create a null value.

pub const fn bool(b: bool) -> Self

Create a boolean value.

pub fn int(n: i64) -> Self

Create an integer value preserving the full i64 range.

Values that fit in 48 bits (sign-extended) take the inline fast path — one tagged NaN, no allocation. Values outside that range are boxed as HeapObject::BigInt so the full i64 round-trips without precision loss.

This is the load-bearing contract for CppNix compatibility: i64::MAX - 1 must round-trip exactly, otherwise any flake containing large integer literals (timestamps, byte counts, builtins.bitAnd over wide masks) would diverge.

pub fn float(f: f64) -> Self

Create a float value.

pub fn heap(obj: HeapObject) -> Self

Create a pointer to a heap-allocated object.

pub fn string(s: String) -> Self

Create a string value (heap-allocated).

pub fn path(s: String) -> Self

Create a path value (heap-allocated).

pub fn list(items: Vec<NanBox>) -> Self

Create a list value (heap-allocated).

pub fn attrs(map: BTreeMap<Symbol, NanBox>) -> Self

Create an attrs value (heap-allocated).

pub fn closure(c: VMClosure) -> Self

Create a closure value (heap-allocated).

pub fn builtin(b: VMBuiltin) -> Self

Create a builtin function value (heap-allocated).

pub fn thunk(t: VMThunk) -> Self

Create a thunk value (heap-allocated).

pub fn higher_order_builtin(h: HigherOrderBuiltin) -> Self

Create a higher-order builtin value (heap-allocated).

pub fn is_float(&self) -> bool

Check if this value is a float (not a tagged NaN).

pub fn is_null(&self) -> bool

pub fn is_bool(&self) -> bool

pub fn is_int(&self) -> bool

pub fn is_ptr(&self) -> bool

pub fn as_bool(&self) -> Option<bool>

Extract a boolean. Returns None if not a bool.

pub fn as_int(&self) -> Option<i64>

Extract an integer. Returns None if not an int.

Handles both the inline 48-bit fast path AND the heap-boxed BigInt fallback so the full i64 range round-trips.

pub fn as_float(&self) -> Option<f64>

Extract a float. Returns None if this is a tagged value.

pub fn as_heap(&self) -> Option<&HeapObject>

Extract the heap object. Returns None if not a pointer.

pub fn type_name(&self) -> &'static str

Return the Nix type name for this value (mirrors VMValue::type_name).

pub fn is_truthy(&self) -> Result<bool, VMError>

Check if this value is truthy (for conditionals). Only booleans are valid; everything else is a type error.

pub fn is_string(&self) -> bool

Check if this is a string.

pub fn is_path(&self) -> bool

Check if this is a path.

pub fn is_list(&self) -> bool

Check if this is a list.

pub fn is_attrs(&self) -> bool

Check if this is an attrset.

pub fn is_closure(&self) -> bool

Check if this is a closure.

pub fn is_builtin(&self) -> bool

Check if this is a builtin.

pub fn is_thunk(&self) -> bool

Check if this is a thunk.

pub fn is_higher_order_builtin(&self) -> bool

Check if this is a higher-order builtin.

pub fn as_string(&self) -> Option<&str>

Extract a string reference. Returns None if not a string.

pub fn as_path(&self) -> Option<&str>

Extract a path reference. Returns None if not a path.

pub fn as_list(&self) -> Option<&[NanBox]>

Extract a list reference. Returns None if not a list.

pub fn as_attrs(&self) -> Option<&BTreeMap<Symbol, NanBox>>

Extract an attrs reference. Returns None if not an attrset.

pub fn as_closure(&self) -> Option<&VMClosure>

Extract a closure reference. Returns None if not a closure.

pub fn as_builtin(&self) -> Option<&VMBuiltin>

Extract a builtin reference. Returns None if not a builtin.

pub fn as_thunk(&self) -> Option<&VMThunk>

Extract a thunk reference. Returns None if not a thunk.

pub fn as_higher_order_builtin(&self) -> Option<&HigherOrderBuiltin>

Extract a higher-order builtin reference.

pub fn from_vmvalue(val: &VMValue) -> Self

Convert a VMValue to a NanBox.

pub fn to_vmvalue(&self) -> VMValue

Convert a NanBox back to a VMValue.

Trait Implementations

impl Clone for NanBox

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for NanBox

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

Formats the value using the given formatter.

impl Drop for NanBox

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl Eq for NanBox

impl PartialEq for NanBox

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

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.