cljrs-builtins

Built-in functions for clojurust (the clojure.core-equivalent runtime implemented in Rust, registered into a name → fn dispatch table).

Map entries

Map entries are a dedicated type, not plain 2-element vectors: seq'ing a map, find, and the map-entry constructor produce vectors tagged as entries (PersistentVector::map_entry in cljrs-value).

• (map-entry k v) / (map-entry coll) — build an entry from a key and value, or from any seqable of exactly two elements.
• (map-entry? x) — true only for real entries; (map-entry? [:a 1]) is false.
• key / val (bootstrap) — accept only real map entries and throw otherwise.

Entries otherwise behave exactly like 2-element vectors (equality, hashing, printing, nth, destructuring), and, as in Clojure, any vector derived from an entry (conj, assoc, pop, subvec, ...) is a plain vector again.

Unchecked arithmetic

Includes the unchecked-* integer arithmetic family — unchecked-add, unchecked-subtract, unchecked-multiply, unchecked-inc, unchecked-dec, unchecked-negate (and their -int aliases) — which wrap on overflow, in contrast to the checked +/-/* (which throw on overflow at the IR/compiled tiers and promote to BigInt in the tree-walk tier).

Phase B3 — shared-atom (cross-isolate, two-tier atom ADR)

shared-atom is the cross-isolate tier of the two-tier atom design in docs/async-worker-pool-plan.md. Unlike atom (isolate-local, GC-backed), its contents are promoted to a Send + Sync SharedValue (cljrs_value::shared) behind a lock-free ArcSwap, so the reference can cross the isolate boundary and be mutated concurrently:

• (shared-atom x) — construct, promoting x (non-promotable values such as closures and native resources are rejected here).
• (shared-atom? x) — predicate.
• deref / reset! / swap! / compare-and-set! — dispatch on Value::SharedAtom alongside the local atom path; writes promote, reads demote, and swap!/compare-and-set! use a single lock-free CAS with retry.