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phm/phs: bulk bottom-up HAMT build for the map/set builders (jolt-5vsp) (#154)

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into {}, frequencies, group-by, set, into #{} and persistent! all built
their result by folding an immutable assoc/conj per element — each call
rebuilt the O(log32 n) trie path and allocated a fresh wrapper. Add a
one-pass bottom-up HAMT builder (phm-from-pairs) and route the builders
through it, the map/set analog of the pvec bulk build in #153.

phm-from-pairs partitions entries by hash and constructs the bin/array/
collision nodes directly, with the same bin<=16 / array-node>=17 promotion
the incremental path uses — so the trie is byte-identical to one built by
phm-assoc (validated across the size and branching boundaries, including
hash collisions, duplicate keys and the nil key). persistent! map/set and
the set constructor bulk-build; into {} keeps the small-scalar-map-stays-a
-struct rule via bulk-map-from-pairs; frequencies/group-by switch to the
canonical transient form and ride the fast persistent!.

50k A/B: into {} 704->270ms, frequencies 582->160, set 615->241,
into #{} 702->240, group-by 1358->919 (bound on persistent vector conj).

Gate: conformance x3, full suite (4718 >= baseline), new maps/sets bulk
boundary specs.

Co-authored-by: Yogthos <yogthos@gmail.com>
This commit is contained in:
Dmitri Sotnikov 2026-06-16 22:24:38 +00:00 • committed by GitHub
parent 43e5426601
commit 1873736045
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7 changed files with 182 additions and 18 deletions
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15
test/spec/sets-spec.janet
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@ -56,3 +56,18 @@
["vector is not" "false" "(set? [1])"]
["coll? still true" "true" "(coll? (sorted-set 1))"]
["ifn? sorted-set" "true" "(ifn? (sorted-set 1))"])
# set / into #{} bulk-build the backing HAMT in one pass (phs-from-seq), instead
# of a phs-conj per element (jolt-5vsp collections). Cross the promotion
# boundary, check dedup, collection members, and conj after a bulk build.
(defspec "set / bulk build boundaries"
["set dedup count" "3" "(count (set [1 1 2 3 3 2]))"]
["set big count" "1000" "(count (set (range 1000)))"]
["into #{} count" "500" "(count (into #{} (range 500)))"]
["into #{} onto base" "3" "(count (into #{:a} [:a :b :c]))"]
["set contains" "true" "(contains? (set (range 1000)) 777)"]
["set missing" "false" "(contains? (set (range 1000)) 5000)"]
["set coll members" "true" "(contains? (set [[1 2] [3 4]]) [1 2])"]
["conj after bulk" "true" "(contains? (conj (set (range 100)) :x) :x)"]
["disj after bulk" "false" "(contains? (disj (set (range 100)) 50) 50)"]
["set = literal" "true" "(= #{0 1 2} (set (range 3)))"])