apl: ⊆ partition — mask-driven split (+8)

- apl-partition: new partition where M[i]>M[i-1] (init prev=0);
  continue where M[i]≤prev∧M[i]≠0; drop cells where M[i]=0
- Returns apl-vector of apl-vector parts
- pipeline 140/140

lib/apl/runtime.sx

@@ -913,6 +913,20 @@
           ((result (reduce (fn (acc-and-n i) (let ((acc (first acc-and-n)) (rem (nth acc-and-n 1))) (let ((b (nth b-ravel (- (- b-len 1) i)))) (if (= b 0) (list (cons rem acc) 0) (list (cons (modulo rem b) acc) (floor (/ rem b))))))) (list (list) n) (range 0 b-len))))
           (apl-vector (first result)))))))
 
+(define
+  apl-partition
+  (fn
+    (mask val)
+    (let
+      ((m-ravel (if (scalar? mask) (list (disclose mask)) (get mask :ravel)))
+        (v-ravel
+          (if (scalar? val) (list (disclose val)) (get val :ravel))))
+      (let
+        ((n (len m-ravel)))
+        (let
+          ((built (reduce (fn (acc-and-prev i) (let ((acc (first acc-and-prev)) (prev (nth acc-and-prev 1))) (let ((mi (nth m-ravel i)) (vi (nth v-ravel i))) (cond ((= mi 0) (list acc 0)) ((> mi prev) (list (append acc (list (list vi))) mi)) (else (let ((idx (- (len acc) 1))) (list (append (slice acc 0 idx) (list (append (nth acc idx) (list vi)))) mi))))))) (list (list) 0) (range 0 n))))
+          (apl-vector (map (fn (part) (apl-vector part)) (first built))))))))
+
 (define
   apl-primes
   (fn

lib/apl/tests/pipeline.sx

@@ -590,3 +590,40 @@
     "⊥ decode: round-trip B⊤(B⊥V) = V"
     (mkrv (apl-run "2 2 2 ⊤ 2 2 2 ⊥ 1 0 1"))
     (list 1 0 1)))
+
+(begin
+  (define
+    mk-parts
+    (fn (s) (map (fn (p) (get p :ravel)) (get (apl-run s) :ravel))))
+  (apl-test
+    "⊆ partition: 1 1 0 1 1 ⊆ 'abcde' → ('ab' 'de')"
+    (mk-parts "1 1 0 1 1 ⊆ 'abcde'")
+    (list (list "a" "b") (list "d" "e")))
+  (apl-test
+    "⊆ partition: 1 0 0 1 1 ⊆ ⍳5 → ((1) (4 5))"
+    (mk-parts "1 0 0 1 1 ⊆ ⍳5")
+    (list (list 1) (list 4 5)))
+  (apl-test
+    "⊆ partition: all-zero mask → empty"
+    (len (get (apl-run "0 0 0 ⊆ 1 2 3") :ravel))
+    0)
+  (apl-test
+    "⊆ partition: all-one mask → single partition"
+    (mk-parts "1 1 1 ⊆ 7 8 9")
+    (list (list 7 8 9)))
+  (apl-test
+    "⊆ partition: strict increase 1 2 starts new"
+    (mk-parts "1 2 ⊆ 10 20")
+    (list (list 10) (list 20)))
+  (apl-test
+    "⊆ partition: same level continues 2 2 → one partition"
+    (mk-parts "2 2 ⊆ 10 20")
+    (list (list 10 20)))
+  (apl-test
+    "⊆ partition: 0 separates"
+    (mk-parts "1 1 0 0 1 ⊆ 1 2 3 4 5")
+    (list (list 1 2) (list 5)))
+  (apl-test
+    "⊆ partition: outer length matches partition count"
+    (len (get (apl-run "1 0 1 0 1 ⊆ ⍳5") :ravel))
+    3))

lib/apl/transpile.sx

@@ -97,6 +97,7 @@
       ((= g "∩") apl-intersect)
       ((= g "⊥") apl-decode)
       ((= g "⊤") apl-encode)
+      ((= g "⊆") apl-partition)
       (else (error "no dyadic fn for glyph")))))
 
 (define