Sorted collections were a sorted VECTOR — insert-at = (into (conj (subvec es
0 i) x) (subvec es i)) is O(n) per assoc with a large constant, so building was
O(n^2): 2000 entries took 55.6s.
Replace the rep with a red-black tree (assoc/dissoc/get/contains O(log n)),
ported from the ClojureScript PersistentTreeMap (cljs.core: tree-map-add /
balance-left / balance-right / tree-map-append / balance-*-del). This tier (25)
loads before 30-macros so deftype isn't available; a node is a plain vector
[color k v left right] and cljs's BlackNode/RedNode methods become functions —
the algorithm is unchanged. A sorted-set stores elements as keys with a nil
value; its ops project the key.
The seed read the old :entries vector directly for equality/printing; route
those through a new :entries op that materializes ascending from the tree
(core_types/sorted-entries-arr + main.janet's printer).
2000 sorted-map assocs: 55.6s -> 0.98s (57x); now O(log n) (per-op cost flat
from n=2000 to 10000). Correctness in test/integration/sorted-rbtree-test.janet
(shuffled insert ordering, delete rebalancing, custom comparator, comparator
lookup, subseq, count); sorted specs + full gate green. (key/val on sorted
entries stays a pre-existing gap — entries are pvecs not host tuples; jolt-jk23.)
Co-authored-by: Yogthos <yogthos@gmail.com>
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