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Merged
hellerve merged 1 commit into from
May 31, 2026
Merged

Add merge and merge-with for hash-map and ord-map #2

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56 changes: 56 additions & 0 deletions persistent.carp
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Original file line number Diff line number Diff line change
Expand Up @@ -1788,6 +1788,34 @@ This generates:
(defn values [map-ref]
(reduce &(fn [acc p] (Array.push-back acc @(Pair.b &p))) [] map-ref))

(doc merge
"Merge two maps. On key collision the second (right) map wins.")
(sig merge (Fn [(Ref %name a) (Ref %name b)] %name))
(defn merge [a-ref b-ref]
(reduce
&(fn [acc p] (insert @(Pair.a &p) @(Pair.b &p) &acc))
@a-ref
b-ref))

(doc merge-with
"Merge two maps with a conflict resolver. For keys in both maps, call the resolver with both values.")
(sig merge-with
(Fn
[(Ref (Fn [%value-type %value-type] %value-type) q)
(Ref %name a)
(Ref %name b)]
%name))
(defn merge-with [f a-ref b-ref]
(reduce
&(fn [acc p]
(let [k @(Pair.a &p)
bv @(Pair.b &p)]
(match (get @&k &acc)
(Maybe.Nothing) (insert k bv &acc)
(Maybe.Just av) (insert k (~f av bv) &acc))))
@a-ref
b-ref))

(doc =
"Structural equality: same size and pairwise equal entries in ascending key order.")
(sig = (Fn [(Ref %name q) (Ref %name q)] Bool))
Expand Down Expand Up @@ -2404,6 +2432,34 @@ Example:
(defn values [map-ref]
(reduce &(fn [acc p] (Array.push-back acc @(Pair.b &p))) [] map-ref))

(doc merge
"Merge two maps. On key collision the second (right) map wins.")
(sig merge (Fn [(Ref %name a) (Ref %name b)] %name))
(defn merge [a-ref b-ref]
(reduce
&(fn [acc p] (insert @(Pair.a &p) @(Pair.b &p) &acc))
@a-ref
b-ref))

(doc merge-with
"Merge two maps with a conflict resolver. For keys in both maps, call the resolver with both values.")
(sig merge-with
(Fn
[(Ref (Fn [%value-type %value-type] %value-type) q)
(Ref %name a)
(Ref %name b)]
%name))
(defn merge-with [f a-ref b-ref]
(reduce
&(fn [acc p]
(let [k @(Pair.a &p)
bv @(Pair.b &p)]
(match (get &k &acc)
(Maybe.Nothing) (insert k bv &acc)
(Maybe.Just av) (insert k (~f av bv) &acc))))
@a-ref
b-ref))

(doc =
"Structural equality: same size and same set of `(key, value)` entries.")
(sig = (Fn [(Ref %name q) (Ref %name q)] Bool))
Expand Down
73 changes: 73 additions & 0 deletions test/persistent_hash_map.carp
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Expand Up @@ -188,6 +188,79 @@
(and (= &a &b) (not (= &a &c))))
"= is structural regardless of insertion order")

(assert-equal test
true
(let [a (IntIntMap.insert 1 10 &(IntIntMap.insert 2 20 &(IntIntMap.empty)))
b (IntIntMap.insert 3 30 &(IntIntMap.insert 4 40 &(IntIntMap.empty)))
m (IntIntMap.merge &a &b)]
(and (= (IntIntMap.length &m) 4l)
(let [k1 1
k3 3]
(and
(match (IntIntMap.get &k1 &m)
(Maybe.Just v) (= v 10)
(Maybe.Nothing) false)
(match (IntIntMap.get &k3 &m)
(Maybe.Just v) (= v 30)
(Maybe.Nothing) false)))))
"merge of disjoint maps contains all entries")

(assert-equal test
true
(let [a (IntIntMap.insert 1 10 &(IntIntMap.insert 2 20 &(IntIntMap.empty)))
b (IntIntMap.insert 2 99 &(IntIntMap.insert 3 30 &(IntIntMap.empty)))
m (IntIntMap.merge &a &b)
k 2]
(and (= (IntIntMap.length &m) 3l)
(match (IntIntMap.get &k &m)
(Maybe.Just v) (= v 99)
(Maybe.Nothing) false)))
"merge right wins on key collision")

(assert-equal test
true
(let [a (IntIntMap.insert 1 10 &(IntIntMap.insert 2 20 &(IntIntMap.empty)))
e (IntIntMap.empty)
m1 (IntIntMap.merge &a &e)
m2 (IntIntMap.merge &e &a)]
(and (= &m1 &a) (= &m2 &a)))
"merge with empty is identity")

(assert-equal test
true
(let [a (IntIntMap.insert 1 10 &(IntIntMap.insert 2 20 &(IntIntMap.empty)))
b (IntIntMap.insert 2 3 &(IntIntMap.insert 3 30 &(IntIntMap.empty)))
m (IntIntMap.merge-with &(fn [x y] (+ x y)) &a &b)
k1 1
k2 2
k3 3]
(and (= (IntIntMap.length &m) 3l)
(match (IntIntMap.get &k1 &m)
(Maybe.Just v) (= v 10)
(Maybe.Nothing) false)
(match (IntIntMap.get &k2 &m)
(Maybe.Just v) (= v 23)
(Maybe.Nothing) false)
(match (IntIntMap.get &k3 &m)
(Maybe.Just v) (= v 30)
(Maybe.Nothing) false)))
"merge-with addition combiner on overlapping keys")

(assert-equal test
true
(let [a (IntIntMap.insert 1 10 &(IntIntMap.empty))
b (IntIntMap.insert 2 20 &(IntIntMap.empty))
m (IntIntMap.merge-with &(fn [x y] (+ x y)) &a &b)
k1 1
k2 2]
(and (= (IntIntMap.length &m) 2l)
(match (IntIntMap.get &k1 &m)
(Maybe.Just v) (= v 10)
(Maybe.Nothing) false)
(match (IntIntMap.get &k2 &m)
(Maybe.Just v) (= v 20)
(Maybe.Nothing) false)))
"merge-with on disjoint maps just takes values")
(assert-memory-balance test
map-branch-lifecycle
0l
Expand Down
77 changes: 77 additions & 0 deletions test/persistent_ord_map.carp
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Original file line number Diff line number Diff line change
Expand Up @@ -204,6 +204,83 @@
(= &filtered &m2))
"filter with always-true preserves all entries")

(assert-equal test
true
(let [a (IntIntOMap.insert 1
10
&(IntIntOMap.insert 2 20 &(IntIntOMap.empty)))
b (IntIntOMap.insert 3
30
&(IntIntOMap.insert 4 40 &(IntIntOMap.empty)))
m (IntIntOMap.merge &a &b)]
(and (= (IntIntOMap.length &m) 4l)
(match (IntIntOMap.get 1 &m)
(Maybe.Just v) (= v 10)
(Maybe.Nothing) false)
(match (IntIntOMap.get 3 &m)
(Maybe.Just v) (= v 30)
(Maybe.Nothing) false)))
"merge of disjoint maps contains all entries")

(assert-equal test
true
(let [a (IntIntOMap.insert 1
10
&(IntIntOMap.insert 2 20 &(IntIntOMap.empty)))
b (IntIntOMap.insert 2
99
&(IntIntOMap.insert 3 30 &(IntIntOMap.empty)))
m (IntIntOMap.merge &a &b)]
(and (= (IntIntOMap.length &m) 3l)
(match (IntIntOMap.get 2 &m)
(Maybe.Just v) (= v 99)
(Maybe.Nothing) false)))
"merge right wins on key collision")

(assert-equal test
true
(let [a (IntIntOMap.insert 1
10
&(IntIntOMap.insert 2 20 &(IntIntOMap.empty)))
e (IntIntOMap.empty)
m1 (IntIntOMap.merge &a &e)
m2 (IntIntOMap.merge &e &a)]
(and (= &m1 &a) (= &m2 &a)))
"merge with empty is identity")

(assert-equal test
true
(let [a (IntIntOMap.insert 1
10
&(IntIntOMap.insert 2 20 &(IntIntOMap.empty)))
b (IntIntOMap.insert 2 3 &(IntIntOMap.insert 3 30 &(IntIntOMap.empty)))
m (IntIntOMap.merge-with &(fn [x y] (+ x y)) &a &b)]
(and (= (IntIntOMap.length &m) 3l)
(match (IntIntOMap.get 1 &m)
(Maybe.Just v) (= v 10)
(Maybe.Nothing) false)
(match (IntIntOMap.get 2 &m)
(Maybe.Just v) (= v 23)
(Maybe.Nothing) false)
(match (IntIntOMap.get 3 &m)
(Maybe.Just v) (= v 30)
(Maybe.Nothing) false)))
"merge-with addition combiner on overlapping keys")

(assert-equal test
true
(let [a (IntIntOMap.insert 1 10 &(IntIntOMap.empty))
b (IntIntOMap.insert 2 20 &(IntIntOMap.empty))
m (IntIntOMap.merge-with &(fn [x y] (+ x y)) &a &b)]
(and (= (IntIntOMap.length &m) 2l)
(match (IntIntOMap.get 1 &m)
(Maybe.Just v) (= v 10)
(Maybe.Nothing) false)
(match (IntIntOMap.get 2 &m)
(Maybe.Just v) (= v 20)
(Maybe.Nothing) false)))
"merge-with on disjoint maps just takes values")

(assert-memory-balance test
map-branch-lifecycle
0l
Expand Down
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