Module value 

Nix value types, environments, thunks, and error types. Nix value types and environments.

The evaluator is single-threaded: Env and NixAttrs contain Rc<UnsafeCell<ThunkRepr>> thunks. All shared pointers use Rc (not Arc) because the values are never sent across threads.

Modules

census

Env-gated LIVE-OBJECT CENSUS.

Structs

BuiltinFn

A builtin function.

Closure

A closure — lambda + captured environment.

Env

Evaluation environment — flattened binding map with structural sharing.

NixAttrs

A Nix attribute set with lazy overlay support.

NixList

Census wrapper around a list’s backing Vec<Value>.

NixString

A Nix string value with associated context (store-path references).

Rc

A single-threaded reference-counting pointer. ‘Rc’ stands for ‘Reference Counted’.

SmolStr

A SmolStr is a string type that has the following properties:

StringContext

The context attached to a Nix string: a set of store-path references that the string depends on. Plain string literals have an empty context.

Thunk

A lazy value with memoization and blackhole detection.

Enums

Concrete

A demanded Nix value. Guaranteed NOT a Thunk at the TYPE level.

ContextElement

An element of a Nix string’s context set.

EvalError

Evaluation errors produced by the Nix evaluator.

ThunkRepr

Internal representation of a thunk’s state machine.

Value

A Nix value — potentially lazy (may be a Thunk).

Functions

clear_ident_cache

Clear the identifier symbol cache.

concat_lists

Concatenate two Nix lists: left ++ right_elems.

in_promise_eval

true if the evaluator is currently inside the body of a ThunkRepr::Promise (used by eval_select to relax AttrNotFound errors during fix-point construction).

intern

Intern a string key, returning a Symbol handle. Used for NixAttrs keys and Env binding names.

intern_cached

Intern a string with caching by source ID and AST text offset.

intern_cached_with

Cache an interned Symbol by (source_id, text_offset), computing it lazily via cold only on a cache miss.

next_source_id

Allocate a new source ID for a freshly parsed AST tree.

promotion_occurred

true if any overlay-fixpoint promotion has fired in this eval.

resolve

Resolve a Symbol back to its string content. Allocates a fresh String. For hot paths prefer resolve_rc or with_resolved — Rc::clone is ~20x cheaper than String::from for identifier- sized inputs.

resolve_rc

Resolve a Symbol to a shared Rc<str>. Zero-copy.

with_resolved

Borrow the resolved string inside a closure without allocating.

Type Aliases

AttrsMap

Compact attrset map — a real hashbrown (std) HashMap with FxBuildHasher.

BuiltinFunc

The function signature stored inside a BuiltinFn.

FxHashMap

Type alias for the persistent hash map used by NixAttrs and Env.