From 912de5a2745e5d851816b7df7e8b81f23b8a8c8a Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Fri, 1 May 2026 22:49:38 +0000
Subject: [PATCH] phase-22 APL: runtime.sx vectors/bitwise/sets/reduce/format
MIME-Version: 1.0
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lib/apl/runtime.sx (60 forms):
- Core: apl-iota (1..N), apl-rho (shape), apl-at (1-indexed access).
- Rank-polymorphic apl-dyadic/apl-monadic helpers: scalar×scalar,
  scalar×vector, vector×vector all supported uniformly.
- Arithmetic: add/sub/mul/div/mod/pow/max/min, neg/abs/floor/ceil/sqrt.
- Comparison: eq/neq/lt/le/gt/ge → 0/1 result vectors.
- Boolean: and/or/not on 0/1 values, element-wise.
- Bitwise: bitand/bitor/bitxor/bitnot/lshift/rshift — element-wise.
- Reduction: reduce-add/mul/max/min/and/or; scan-add/mul.
- Vector ops: reverse, cat (scalar/vector catenate), take (±N), drop (±N),
  rotate, compress (boolean mask), index (multi-index).
- Set ops: member (∊, → 0/1), nub (∪, unique preserve-order),
  union, intersect (∩), without (~). All use SX make-set internally.
- Format (⍕): vector → space-separated string, scalar → str.

lib/apl/tests/runtime.sx + lib/apl/test.sh: 73/73 pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 lib/apl/runtime.sx                       | 289 ++++++++++++++++++++
 lib/apl/test.sh                          |  51 ++++
 lib/apl/tests/runtime.sx                 | 327 +++++++++++++++++++++++
 plans/agent-briefings/primitives-loop.md |   4 +-
 4 files changed, 670 insertions(+), 1 deletion(-)
 create mode 100644 lib/apl/runtime.sx
 create mode 100755 lib/apl/test.sh
 create mode 100644 lib/apl/tests/runtime.sx

diff --git a/lib/apl/runtime.sx b/lib/apl/runtime.sx
new file mode 100644
index 00000000..76c48ed7
--- /dev/null
+++ b/lib/apl/runtime.sx
@@ -0,0 +1,289 @@
+;; lib/apl/runtime.sx — APL primitives on SX
+;;
+;; APL vectors are represented as SX lists (functional, immutable results).
+;; Operations are rank-polymorphic: scalar/vector arguments both accepted.
+;; Index origin: 1 (traditional APL).
+;;
+;; Primitives used:
+;;   map (multi-arg, Phase 1)
+;;   bitwise-and/or/xor/not/arithmetic-shift (Phase 7)
+;;   make-set/set-member?/set-add!/set->list (Phase 18)
+
+;; ---------------------------------------------------------------------------
+;; 1. Core vector constructors
+;; ---------------------------------------------------------------------------
+
+;; ⍳N — iota: generate integer vector 1, 2, ..., N
+(define
+  (apl-iota n)
+  (letrec
+    ((go (fn (i acc) (if (< i 1) acc (go (- i 1) (cons i acc))))))
+    (go n (list))))
+
+;; ⍴A — shape (length of a vector)
+(define (apl-rho v) (if (list? v) (len v) 1))
+
+;; A[I] — 1-indexed access
+(define (apl-at v i) (nth v (- i 1)))
+
+;; Scalar predicate
+(define (apl-scalar? v) (not (list? v)))
+
+;; ---------------------------------------------------------------------------
+;; 2. Rank-polymorphic helpers
+;;    dyadic: scalar/vector × scalar/vector → scalar/vector
+;;    monadic: scalar/vector → scalar/vector
+;; ---------------------------------------------------------------------------
+
+(define
+  (apl-dyadic op a b)
+  (cond
+    ((and (list? a) (list? b)) (map op a b))
+    ((list? a) (map (fn (x) (op x b)) a))
+    ((list? b) (map (fn (y) (op a y)) b))
+    (else (op a b))))
+
+(define (apl-monadic op a) (if (list? a) (map op a) (op a)))
+
+;; ---------------------------------------------------------------------------
+;; 3. Arithmetic (element-wise, rank-polymorphic)
+;; ---------------------------------------------------------------------------
+
+(define (apl-add a b) (apl-dyadic + a b))
+(define (apl-sub a b) (apl-dyadic - a b))
+(define (apl-mul a b) (apl-dyadic * a b))
+(define (apl-div a b) (apl-dyadic / a b))
+(define (apl-mod a b) (apl-dyadic modulo a b))
+(define (apl-pow a b) (apl-dyadic pow a b))
+(define (apl-max a b) (apl-dyadic (fn (x y) (if (> x y) x y)) a b))
+(define (apl-min a b) (apl-dyadic (fn (x y) (if (< x y) x y)) a b))
+
+(define (apl-neg a) (apl-monadic (fn (x) (- 0 x)) a))
+(define (apl-abs a) (apl-monadic abs a))
+(define (apl-floor a) (apl-monadic floor a))
+(define (apl-ceil a) (apl-monadic ceil a))
+(define (apl-sqrt a) (apl-monadic sqrt a))
+(define (apl-exp a) (apl-monadic exp a))
+(define (apl-log a) (apl-monadic log a))
+
+;; ---------------------------------------------------------------------------
+;; 4. Comparison (element-wise, returns 0/1 booleans)
+;; ---------------------------------------------------------------------------
+
+(define (apl-bool v) (if v 1 0))
+
+(define (apl-eq a b) (apl-dyadic (fn (x y) (apl-bool (= x y))) a b))
+(define
+  (apl-neq a b)
+  (apl-dyadic (fn (x y) (apl-bool (not (= x y)))) a b))
+(define (apl-lt a b) (apl-dyadic (fn (x y) (apl-bool (< x y))) a b))
+(define (apl-le a b) (apl-dyadic (fn (x y) (apl-bool (<= x y))) a b))
+(define (apl-gt a b) (apl-dyadic (fn (x y) (apl-bool (> x y))) a b))
+(define (apl-ge a b) (apl-dyadic (fn (x y) (apl-bool (>= x y))) a b))
+
+;; Boolean logic (0/1 vectors)
+(define
+  (apl-and a b)
+  (apl-dyadic
+    (fn
+      (x y)
+      (if
+        (and (not (= x 0)) (not (= y 0)))
+        1
+        0))
+    a
+    b))
+(define
+  (apl-or a b)
+  (apl-dyadic
+    (fn
+      (x y)
+      (if
+        (or (not (= x 0)) (not (= y 0)))
+        1
+        0))
+    a
+    b))
+(define
+  (apl-not a)
+  (apl-monadic (fn (x) (if (= x 0) 1 0)) a))
+
+;; ---------------------------------------------------------------------------
+;; 5. Bitwise operations (element-wise)
+;; ---------------------------------------------------------------------------
+
+(define (apl-bitand a b) (apl-dyadic bitwise-and a b))
+(define (apl-bitor a b) (apl-dyadic bitwise-or a b))
+(define (apl-bitxor a b) (apl-dyadic bitwise-xor a b))
+(define (apl-bitnot a) (apl-monadic bitwise-not a))
+(define
+  (apl-lshift a b)
+  (apl-dyadic (fn (x n) (arithmetic-shift x n)) a b))
+(define
+  (apl-rshift a b)
+  (apl-dyadic (fn (x n) (arithmetic-shift x (- 0 n))) a b))
+
+;; ---------------------------------------------------------------------------
+;; 6. Reduction (fold) and scan
+;; ---------------------------------------------------------------------------
+
+(define (apl-reduce-add v) (reduce + 0 v))
+(define (apl-reduce-mul v) (reduce * 1 v))
+(define
+  (apl-reduce-max v)
+  (reduce (fn (acc x) (if (> acc x) acc x)) (first v) (rest v)))
+(define
+  (apl-reduce-min v)
+  (reduce (fn (acc x) (if (< acc x) acc x)) (first v) (rest v)))
+(define
+  (apl-reduce-and v)
+  (reduce
+    (fn
+      (acc x)
+      (if
+        (and (not (= acc 0)) (not (= x 0)))
+        1
+        0))
+    1
+    v))
+(define
+  (apl-reduce-or v)
+  (reduce
+    (fn
+      (acc x)
+      (if
+        (or (not (= acc 0)) (not (= x 0)))
+        1
+        0))
+    0
+    v))
+
+;; Scan: prefix reduction (yields a vector of running totals)
+(define
+  (apl-scan op v)
+  (if
+    (= (len v) 0)
+    (list)
+    (letrec
+      ((go (fn (xs acc result) (if (= (len xs) 0) (reverse result) (let ((next (op acc (first xs)))) (go (rest xs) next (cons next result)))))))
+      (go (rest v) (first v) (list (first v))))))
+
+(define (apl-scan-add v) (apl-scan + v))
+(define (apl-scan-mul v) (apl-scan * v))
+
+;; ---------------------------------------------------------------------------
+;; 7. Vector manipulation
+;; ---------------------------------------------------------------------------
+
+;; ⌽A — reverse
+(define (apl-reverse v) (reverse v))
+
+;; A,B — catenate
+(define
+  (apl-cat a b)
+  (cond
+    ((and (list? a) (list? b)) (append a b))
+    ((list? a) (append a (list b)))
+    ((list? b) (cons a b))
+    (else (list a b))))
+
+;; ↑N A — take first N elements (negative: take last N)
+(define
+  (apl-take n v)
+  (if
+    (>= n 0)
+    (letrec
+      ((go (fn (xs i) (if (or (= i 0) (= (len xs) 0)) (list) (cons (first xs) (go (rest xs) (- i 1)))))))
+      (go v n))
+    (apl-reverse (apl-take (- 0 n) (apl-reverse v)))))
+
+;; ↓N A — drop first N elements
+(define
+  (apl-drop n v)
+  (if
+    (>= n 0)
+    (letrec
+      ((go (fn (xs i) (if (or (= i 0) (= (len xs) 0)) xs (go (rest xs) (- i 1))))))
+      (go v n))
+    (apl-reverse (apl-drop (- 0 n) (apl-reverse v)))))
+
+;; Rotate left by n positions
+(define
+  (apl-rotate n v)
+  (let ((m (modulo n (len v)))) (append (apl-drop m v) (apl-take m v))))
+
+;; Compression: A/B — select elements of B where A is 1
+(define
+  (apl-compress mask v)
+  (if
+    (= (len mask) 0)
+    (list)
+    (let
+      ((rest-result (apl-compress (rest mask) (rest v))))
+      (if
+        (not (= (first mask) 0))
+        (cons (first v) rest-result)
+        rest-result))))
+
+;; Indexing: A[B] — select elements at indices B (1-indexed)
+(define (apl-index v indices) (map (fn (i) (apl-at v i)) indices))
+
+;; Grade up: indices that would sort the vector ascending
+(define
+  (apl-grade-up v)
+  (let
+    ((indexed (map (fn (x i) (list x i)) v (apl-iota (len v)))))
+    (map (fn (p) (nth p 1)) (sort indexed))))
+
+;; ---------------------------------------------------------------------------
+;; 8. Set operations (∊ ∪ ∩ ~)
+;; ---------------------------------------------------------------------------
+
+;; Membership ∊: for each element in A, is it in B? → 0/1 vector
+(define
+  (apl-member a b)
+  (let
+    ((bset (let ((s (make-set))) (for-each (fn (x) (set-add! s x)) b) s)))
+    (if
+      (list? a)
+      (map (fn (x) (apl-bool (set-member? bset x))) a)
+      (apl-bool (set-member? bset a)))))
+
+;; Nub ∪A — unique elements, preserving order
+(define
+  (apl-nub v)
+  (let
+    ((seen (make-set)))
+    (letrec
+      ((go (fn (xs acc) (if (= (len xs) 0) (reverse acc) (if (set-member? seen (first xs)) (go (rest xs) acc) (begin (set-add! seen (first xs)) (go (rest xs) (cons (first xs) acc))))))))
+      (go v (list)))))
+
+;; Union A∪B — nub of concatenation
+(define (apl-union a b) (apl-nub (apl-cat a b)))
+
+;; Intersection A∩B
+(define
+  (apl-intersect a b)
+  (let
+    ((bset (let ((s (make-set))) (for-each (fn (x) (set-add! s x)) b) s)))
+    (filter (fn (x) (set-member? bset x)) a)))
+
+;; Without A~B
+(define
+  (apl-without a b)
+  (let
+    ((bset (let ((s (make-set))) (for-each (fn (x) (set-add! s x)) b) s)))
+    (filter (fn (x) (not (set-member? bset x))) a)))
+
+;; ---------------------------------------------------------------------------
+;; 9. Format (⍕) — APL-style display
+;; ---------------------------------------------------------------------------
+
+(define
+  (apl-format v)
+  (if
+    (list? v)
+    (letrec
+      ((go (fn (xs acc) (if (= (len xs) 0) acc (go (rest xs) (str acc (if (= acc "") "" " ") (str (first xs))))))))
+      (go v ""))
+    (str v)))
diff --git a/lib/apl/test.sh b/lib/apl/test.sh
new file mode 100755
index 00000000..a8a967c0
--- /dev/null
+++ b/lib/apl/test.sh
@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+# lib/apl/test.sh — smoke-test the APL runtime layer.
+
+set -uo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="${SX_SERVER:-hosts/ocaml/_build/default/bin/sx_server.exe}"
+if [ ! -x "$SX_SERVER" ]; then
+  SX_SERVER="/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe"
+fi
+if [ ! -x "$SX_SERVER" ]; then
+  echo "ERROR: sx_server.exe not found."
+  exit 1
+fi
+
+TMPFILE=$(mktemp); trap "rm -f $TMPFILE" EXIT
+
+cat > "$TMPFILE" << 'EPOCHS'
+(epoch 1)
+(load "spec/stdlib.sx")
+(load "lib/apl/runtime.sx")
+(epoch 2)
+(load "lib/apl/tests/runtime.sx")
+(epoch 3)
+(eval "(list apl-test-pass apl-test-fail)")
+EPOCHS
+
+OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
+
+LINE=$(echo "$OUTPUT" | awk '/^\(ok-len 3 / {getline; print; exit}')
+if [ -z "$LINE" ]; then
+  LINE=$(echo "$OUTPUT" | grep -E '^\(ok 3 \([0-9]+ [0-9]+\)\)' | tail -1 \
+          | sed -E 's/^\(ok 3 //; s/\)$//')
+fi
+if [ -z "$LINE" ]; then
+  echo "ERROR: could not extract summary"
+  echo "$OUTPUT" | tail -10
+  exit 1
+fi
+
+P=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\1/')
+F=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\2/')
+TOTAL=$((P + F))
+
+if [ "$F" -eq 0 ]; then
+  echo "ok $P/$TOTAL lib/apl tests passed"
+else
+  echo "FAIL $P/$TOTAL passed, $F failed"
+fi
+
+[ "$F" -eq 0 ]
diff --git a/lib/apl/tests/runtime.sx b/lib/apl/tests/runtime.sx
new file mode 100644
index 00000000..8087872d
--- /dev/null
+++ b/lib/apl/tests/runtime.sx
@@ -0,0 +1,327 @@
+;; lib/apl/tests/runtime.sx — Tests for lib/apl/runtime.sx
+
+;; --- Test framework ---
+(define apl-test-pass 0)
+(define apl-test-fail 0)
+(define apl-test-fails (list))
+
+(define
+  (apl-test name got expected)
+  (if
+    (= got expected)
+    (set! apl-test-pass (+ apl-test-pass 1))
+    (begin
+      (set! apl-test-fail (+ apl-test-fail 1))
+      (set! apl-test-fails (append apl-test-fails (list {:got got :expected expected :name name}))))))
+
+;; ---------------------------------------------------------------------------
+;; 1. Core vector constructors
+;; ---------------------------------------------------------------------------
+
+(apl-test
+  "iota 5"
+  (apl-iota 5)
+  (list 1 2 3 4 5))
+(apl-test "iota 1" (apl-iota 1) (list 1))
+(apl-test "iota 0" (apl-iota 0) (list))
+(apl-test
+  "rho list"
+  (apl-rho (list 1 2 3))
+  3)
+(apl-test "rho scalar" (apl-rho 42) 1)
+(apl-test
+  "at 1"
+  (apl-at (list 10 20 30) 1)
+  10)
+(apl-test
+  "at 3"
+  (apl-at (list 10 20 30) 3)
+  30)
+
+;; ---------------------------------------------------------------------------
+;; 2. Arithmetic — element-wise and rank-polymorphic
+;; ---------------------------------------------------------------------------
+
+(apl-test
+  "add v+v"
+  (apl-add
+    (list 1 2 3)
+    (list 10 20 30))
+  (list 11 22 33))
+(apl-test
+  "add s+v"
+  (apl-add 10 (list 1 2 3))
+  (list 11 12 13))
+(apl-test
+  "add v+s"
+  (apl-add (list 1 2 3) 100)
+  (list 101 102 103))
+(apl-test "add s+s" (apl-add 3 4) 7)
+(apl-test
+  "sub v-v"
+  (apl-sub
+    (list 5 4 3)
+    (list 1 2 3))
+  (list 4 2 0))
+(apl-test
+  "mul v*s"
+  (apl-mul (list 1 2 3) 3)
+  (list 3 6 9))
+(apl-test
+  "neg -v"
+  (apl-neg (list 1 -2 3))
+  (list -1 2 -3))
+(apl-test
+  "abs v"
+  (apl-abs (list -1 2 -3))
+  (list 1 2 3))
+(apl-test
+  "floor v"
+  (apl-floor (list 1.7 2.2 3.9))
+  (list 1 2 3))
+(apl-test
+  "ceil v"
+  (apl-ceil (list 1.1 2.5 3))
+  (list 2 3 3))
+(apl-test
+  "max v v"
+  (apl-max
+    (list 1 5 3)
+    (list 4 2 6))
+  (list 4 5 6))
+(apl-test
+  "min v v"
+  (apl-min
+    (list 1 5 3)
+    (list 4 2 6))
+  (list 1 2 3))
+
+;; ---------------------------------------------------------------------------
+;; 3. Comparison (returns 0/1)
+;; ---------------------------------------------------------------------------
+
+(apl-test "eq 3 3" (apl-eq 3 3) 1)
+(apl-test "eq 3 4" (apl-eq 3 4) 0)
+(apl-test
+  "gt v>s"
+  (apl-gt (list 1 5 3 7) 4)
+  (list 0 1 0 1))
+(apl-test
+  "lt v<v"
+  (apl-lt
+    (list 1 2 3)
+    (list 3 2 1))
+  (list 1 0 0))
+(apl-test
+  "le v<=s"
+  (apl-le (list 3 4 5) 4)
+  (list 1 1 0))
+(apl-test
+  "ge v>=s"
+  (apl-ge (list 3 4 5) 4)
+  (list 0 1 1))
+(apl-test
+  "neq v!=s"
+  (apl-neq (list 1 2 3) 2)
+  (list 1 0 1))
+
+;; ---------------------------------------------------------------------------
+;; 4. Boolean logic (0/1 values)
+;; ---------------------------------------------------------------------------
+
+(apl-test "and 1 1" (apl-and 1 1) 1)
+(apl-test "and 1 0" (apl-and 1 0) 0)
+(apl-test "or 0 1" (apl-or 0 1) 1)
+(apl-test "or 0 0" (apl-or 0 0) 0)
+(apl-test "not 0" (apl-not 0) 1)
+(apl-test "not 1" (apl-not 1) 0)
+(apl-test
+  "not vec"
+  (apl-not (list 1 0 1 0))
+  (list 0 1 0 1))
+
+;; ---------------------------------------------------------------------------
+;; 5. Bitwise operations
+;; ---------------------------------------------------------------------------
+
+(apl-test "bitand s" (apl-bitand 5 3) 1)
+(apl-test "bitor s" (apl-bitor 5 3) 7)
+(apl-test "bitxor s" (apl-bitxor 5 3) 6)
+(apl-test "bitnot 0" (apl-bitnot 0) -1)
+(apl-test "lshift 1 4" (apl-lshift 1 4) 16)
+(apl-test "rshift 16 2" (apl-rshift 16 2) 4)
+(apl-test
+  "bitand vec"
+  (apl-bitand (list 5 6) (list 3 7))
+  (list 1 6))
+(apl-test
+  "bitor vec"
+  (apl-bitor (list 5 6) (list 3 7))
+  (list 7 7))
+
+;; ---------------------------------------------------------------------------
+;; 6. Reduction and scan
+;; ---------------------------------------------------------------------------
+
+(apl-test
+  "reduce-add"
+  (apl-reduce-add
+    (list 1 2 3 4 5))
+  15)
+(apl-test
+  "reduce-mul"
+  (apl-reduce-mul (list 1 2 3 4))
+  24)
+(apl-test
+  "reduce-max"
+  (apl-reduce-max
+    (list 3 1 4 1 5))
+  5)
+(apl-test
+  "reduce-min"
+  (apl-reduce-min
+    (list 3 1 4 1 5))
+  1)
+(apl-test
+  "reduce-and"
+  (apl-reduce-and (list 1 1 1))
+  1)
+(apl-test
+  "reduce-and0"
+  (apl-reduce-and (list 1 0 1))
+  0)
+(apl-test
+  "reduce-or"
+  (apl-reduce-or (list 0 1 0))
+  1)
+(apl-test
+  "scan-add"
+  (apl-scan-add (list 1 2 3 4))
+  (list 1 3 6 10))
+(apl-test
+  "scan-mul"
+  (apl-scan-mul (list 1 2 3 4))
+  (list 1 2 6 24))
+
+;; ---------------------------------------------------------------------------
+;; 7. Vector manipulation
+;; ---------------------------------------------------------------------------
+
+(apl-test
+  "reverse"
+  (apl-reverse (list 1 2 3 4))
+  (list 4 3 2 1))
+(apl-test
+  "cat v v"
+  (apl-cat (list 1 2) (list 3 4))
+  (list 1 2 3 4))
+(apl-test
+  "cat v s"
+  (apl-cat (list 1 2) 3)
+  (list 1 2 3))
+(apl-test
+  "cat s v"
+  (apl-cat 1 (list 2 3))
+  (list 1 2 3))
+(apl-test
+  "cat s s"
+  (apl-cat 1 2)
+  (list 1 2))
+(apl-test
+  "take 3"
+  (apl-take
+    3
+    (list 10 20 30 40 50))
+  (list 10 20 30))
+(apl-test
+  "take 0"
+  (apl-take 0 (list 1 2 3))
+  (list))
+(apl-test
+  "take neg"
+  (apl-take -2 (list 10 20 30))
+  (list 20 30))
+(apl-test
+  "drop 2"
+  (apl-drop 2 (list 10 20 30 40))
+  (list 30 40))
+(apl-test
+  "drop neg"
+  (apl-drop -1 (list 10 20 30))
+  (list 10 20))
+(apl-test
+  "rotate 2"
+  (apl-rotate
+    2
+    (list 1 2 3 4 5))
+  (list 3 4 5 1 2))
+(apl-test
+  "compress"
+  (apl-compress
+    (list 1 0 1 0)
+    (list 10 20 30 40))
+  (list 10 30))
+(apl-test
+  "index"
+  (apl-index
+    (list 10 20 30 40)
+    (list 2 4))
+  (list 20 40))
+
+;; ---------------------------------------------------------------------------
+;; 8. Set operations
+;; ---------------------------------------------------------------------------
+
+(apl-test
+  "member yes"
+  (apl-member
+    (list 1 2 5)
+    (list 2 4 6))
+  (list 0 1 0))
+(apl-test
+  "member s"
+  (apl-member 2 (list 1 2 3))
+  1)
+(apl-test
+  "member no"
+  (apl-member 9 (list 1 2 3))
+  0)
+(apl-test
+  "nub"
+  (apl-nub (list 1 2 1 3 2))
+  (list 1 2 3))
+(apl-test
+  "union"
+  (apl-union
+    (list 1 2 3)
+    (list 2 3 4))
+  (list 1 2 3 4))
+(apl-test
+  "intersect"
+  (apl-intersect
+    (list 1 2 3 4)
+    (list 2 4 6))
+  (list 2 4))
+(apl-test
+  "without"
+  (apl-without
+    (list 1 2 3 4)
+    (list 2 4))
+  (list 1 3))
+
+;; ---------------------------------------------------------------------------
+;; 9. Format
+;; ---------------------------------------------------------------------------
+
+(apl-test
+  "format vec"
+  (apl-format (list 1 2 3))
+  "1 2 3")
+(apl-test "format scalar" (apl-format 42) "42")
+(apl-test "format empty" (apl-format (list)) "")
+
+;; ---------------------------------------------------------------------------
+;; Summary
+;; ---------------------------------------------------------------------------
+
+(list apl-test-pass apl-test-fail)
diff --git a/plans/agent-briefings/primitives-loop.md b/plans/agent-briefings/primitives-loop.md
index a608a46f..a568dacf 100644
--- a/plans/agent-briefings/primitives-loop.md
+++ b/plans/agent-briefings/primitives-loop.md
@@ -698,8 +698,9 @@ Brief each language's loop agent (or do inline) after rebasing their branch onto
       `Set new`; char type for `Character`; string ports + `read`/`write` for `printString`.
       lib/smalltalk/runtime.sx (72 forms) + tests/runtime.sx (86/86 pass). COMMIT.
 
-- [ ] APL: vectors as core array type; bitwise ops for array masks; sets for APL set ops;
+- [x] APL: vectors as core array type; bitwise ops for array masks; sets for APL set ops;
       sequence protocol for rank-polymorphic operations; format for APL output formatting.
+      lib/apl/runtime.sx (60 forms) + tests/runtime.sx (73/73 pass). COMMIT.
 
 - [ ] Ruby: coroutines for fibers; hash tables for `Hash`; sets for `Set`; regexp for
       Ruby regex; string ports for `StringIO`; bytevectors for `String` binary encoding.
@@ -726,6 +727,7 @@ Brief each language's loop agent (or do inline) after rebasing their branch onto
 
 _Newest first._
 
+- 2026-05-01: Phase 22 APL done — runtime.sx (60 forms): iota/rho/at, rank-polymorphic dyadic/monadic helpers, arithmetic/comparison/boolean/bitwise element-wise, reduce/scan, take/drop/rotate/compress/index, set ops (member/nub/union/intersect/without), format. 73/73 tests. COMMIT.
 - 2026-05-01: Phase 22 Smalltalk done — runtime.sx (72 forms): numeric helpers, Character (1-indexed Array backed by dict), Dictionary (list-of-pairs any-key map), Set (make-set), WriteStream/ReadStream/printString. set-member? (set item) order. 86/86 tests. COMMIT.
 - 2026-05-01: Phase 22 JS done — stdlib.sx (36 forms): bitwise (truncate not js-num-to-int; set-member? takes (set item) order), Map (dict-backed pairs), Set (SX make-set), RegExp (callable lambda). 25/25 new tests pass; total 492/585. COMMIT.
 - 2026-05-01: Phase 22 Haskell done — runtime.sx (113 forms): numeric tower (hk-div floor semantics), rational (dict GCD-normalised), hk-force (promises), Data.Char, Data.Set, Data.List, Maybe/Either, tuples, string helpers, hk-show. 148/148 tests. c02ffcf3.