simon/jolt
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Small maps preserve insertion order

Browse source 
jolt maps were HAMTs with hash iteration order; Clojure keeps small maps as
PersistentArrayMap (insertion order), converting to PersistentHashMap past a
threshold. Map literals, array-map, assoc, into/transient, merge, zipmap,
select-keys, update-keys/vals, frequencies and group-by now iterate in insertion
order for <=8 entries, matching the JVM. hash-map and >8-entry maps stay hash
order; sets stay hash order.

The pmap record gains an order field (the insertion-order key list, or #f once
hashed); the HAMT still backs the values so equality/hash/lookup are unchanged.
pmap-fold visits an array-mode map last-to-first so the runtime's cons-accumulate
idiom reconstructs insertion order without touching its many call sites, and
hash-mode output stays byte-identical; pmap-fold-fwd visits in order for the few
sites that build a value directly. Transient maps track insertion order and
promote to hash past max(8, source-count), matching TransientArrayMap.

The hash-map native-op retargets to a hash-order builder so (hash-map ...) stays
hash-ordered while {...} literals are ordered; syntax-quote builds maps via the
hash builder (Clojure expands `{...} to apply hash-map). The core overlay map
builders seed from {} instead of (hash-map) to keep order.

Threshold is 8 for any key (the keyword exception in newer Clojure isn't in
1.12.5). honeysql now passes 832/0/0; 19 JVM-certified corpus rows added.
This commit is contained in:
Yogthos 2026-06-27 05:48:17 -04:00
parent e2efff6c8e
commit bfa2cbf49d
13 changed files with 217 additions and 102 deletions
Download patch file Download diff file Expand all files Collapse all files

19
test/chez/corpus.edn
View file

@ -911,6 +911,25 @@
{:suite "maps / literal construction" :label "equality with phm" :expected "true" :actual "(= {:a 1 :b 2} (assoc {:a 1} :b 2))"}
{:suite "maps / literal construction" :label "keys work after assoc" :expected "2" :actual "(:b (assoc {:a 1 :b 2} :c 3))"}
{:suite "maps / literal construction" :label "literal in fn body" :expected "12" :actual "(do (defn mfp-mk [x] {:v (* x 2)}) (:v (mfp-mk 6)))"}
{:suite "maps / insertion order" :label "small literal keys" :expected "[:c :a :b]" :actual "(vec (keys {:c 3 :a 1 :b 2}))"}
{:suite "maps / insertion order" :label "small literal vals" :expected "[3 1 2]" :actual "(vec (vals {:c 3 :a 1 :b 2}))"}
{:suite "maps / insertion order" :label "seq follows keys" :expected "[:c :a :b]" :actual "(mapv key (seq {:c 3 :a 1 :b 2}))"}
{:suite "maps / insertion order" :label "array-map any size" :expected "[:z :y :x :w :v :u :t :s :r :q]" :actual "(vec (keys (array-map :z 1 :y 2 :x 3 :w 4 :v 5 :u 6 :t 7 :s 8 :r 9 :q 10)))"}
{:suite "maps / insertion order" :label "assoc appends new key" :expected "[:c :a :z]" :actual "(vec (keys (assoc {:c 3 :a 1} :z 9)))"}
{:suite "maps / insertion order" :label "assoc replace keeps position" :expected "[:c :a]" :actual "(vec (keys (assoc {:c 3 :a 1} :c 9)))"}
{:suite "maps / insertion order" :label "dissoc preserves order" :expected "[:c :b]" :actual "(vec (keys (dissoc {:c 3 :a 1 :b 2} :a)))"}
{:suite "maps / insertion order" :label "into onto empty (<=8)" :expected "[:c :a :b]" :actual "(vec (keys (into {} [[:c 3] [:a 1] [:b 2]])))"}
{:suite "maps / insertion order" :label "reduce assoc" :expected "[:e :d :c :b :a]" :actual "(vec (keys (reduce (fn [m k] (assoc m k k)) {} [:e :d :c :b :a])))"}
{:suite "maps / insertion order" :label "conj a map merges in order" :expected "[:a :b :c]" :actual "(vec (keys (conj {:a 1} {:b 2 :c 3})))"}
{:suite "maps / insertion order" :label "merge keeps right-hand order" :expected "[:a :c :b]" :actual "(vec (keys (merge {:a 1} {:c 3 :b 2})))"}
{:suite "maps / insertion order" :label "assoc stays ordered through 8 entries" :expected "true" :actual "(= (vec (keys (reduce (fn [m i] (assoc m (keyword (str \"k\" i)) i)) {} (range 8)))) (mapv (fn [i] (keyword (str \"k\" i))) (range 8)))"}
{:suite "maps / insertion order" :label "assoc promotes to hash past 8 entries" :expected "9" :actual "(count (reduce (fn [m i] (assoc m (keyword (str \"k\" i)) i)) {} (range 9)))"}
{:suite "maps / insertion order" :label "array-map keeps order past 8" :expected "[:k0 :k1 :k2 :k3 :k4 :k5 :k6 :k7 :k8 :k9 :k10 :k11]" :actual "(vec (keys (apply array-map (mapcat (fn [i] [(keyword (str \"k\" i)) i]) (range 12)))))"}
{:suite "maps / insertion order" :label "update-keys preserves order" :expected "[:a :b :c]" :actual "(vec (keys (update-vals (array-map :a 1 :b 2 :c 3) inc)))"}
{:suite "maps / insertion order" :label "zipmap from ordered keys/vals" :expected "[:c :a :b]" :actual "(vec (keys (zipmap (keys {:c 3 :a 1 :b 2}) (vals {:c 3 :a 1 :b 2}))))"}
{:suite "maps / insertion order" :label "select-keys follows keyseq" :expected "[:c :a]" :actual "(vec (keys (select-keys {:a 1 :b 2 :c 3} [:c :a])))"}
{:suite "maps / insertion order" :label "frequencies first-occurrence order" :expected "[:c :a :b]" :actual "(vec (keys (frequencies [:c :a :b :a])))"}
{:suite "maps / insertion order" :label "group-by first-occurrence order" :expected "[:c :a :b]" :actual "(vec (keys (group-by identity [:c :a :b :a])))"}
{:suite "clojure.math" :label "sqrt" :expected "true" :actual "(< 1.4142 (clojure.math/sqrt 2) 1.4143)"}
{:suite "clojure.math" :label "pow" :expected "1024" :actual "(long (clojure.math/pow 2 10))"}
{:suite "clojure.math" :label "tan of 0" :expected "0" :actual "(long (clojure.math/tan 0))"}