From ce72070d2ac874213e3410ed92862628232333b5 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Wed, 6 May 2026 19:24:46 +0000
Subject: [PATCH] =?UTF-8?q?apl:=20membership=20=E2=88=8A,=20dyadic=20?=
 =?UTF-8?q?=E2=8D=B3,=20without=20~=20(dyadic);=2094/94=20tests?=
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Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 lib/apl/runtime.sx          | 42 +++++++++++++++++
 lib/apl/tests/structural.sx | 93 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 134 insertions(+), 1 deletion(-)

diff --git a/lib/apl/runtime.sx b/lib/apl/runtime.sx
index ca6fa2c7..ec3e5e1e 100644
--- a/lib/apl/runtime.sx
+++ b/lib/apl/runtime.sx
@@ -753,3 +753,45 @@
             ((inner-shape (rest shape))
               (inner-size (reduce * 1 (rest shape))))
             (make-array inner-shape (take ravel inner-size))))))))
+
+(define
+  apl-member
+  (fn
+    (a b)
+    (let
+      ((a-ravel (if (scalar? a) (list (disclose a)) (get a :ravel)))
+        (b-ravel (if (scalar? b) (list (disclose b)) (get b :ravel)))
+        (a-shape (get a :shape)))
+      (make-array
+        a-shape
+        (map (fn (x) (if (index-of b-ravel x) 1 0)) a-ravel)))))
+
+(define
+  apl-index-of
+  (fn
+    (v w)
+    (let
+      ((v-ravel (if (scalar? v) (list (disclose v)) (get v :ravel)))
+        (w-ravel (if (scalar? w) (list (disclose w)) (get w :ravel)))
+        (w-shape (get w :shape))
+        (n (len (if (scalar? v) (list (disclose v)) (get v :ravel)))))
+      (make-array
+        w-shape
+        (map
+          (fn
+            (x)
+            (let
+              ((i (index-of v-ravel x)))
+              (if i (+ i apl-io) (+ n apl-io))))
+          w-ravel)))))
+
+(define
+  apl-without
+  (fn
+    (a b)
+    (let
+      ((a-ravel (if (scalar? a) (list (disclose a)) (get a :ravel)))
+        (b-ravel (if (scalar? b) (list (disclose b)) (get b :ravel))))
+      (let
+        ((result (filter (fn (x) (not (index-of b-ravel x))) a-ravel)))
+        (make-array (list (len result)) result)))))
diff --git a/lib/apl/tests/structural.sx b/lib/apl/tests/structural.sx
index cfdf16cf..03c28a53 100644
--- a/lib/apl/tests/structural.sx
+++ b/lib/apl/tests/structural.sx
@@ -514,4 +514,95 @@
 (apl-test
   "disclose matrix returns first row"
   (rv (apl-disclose (make-array (list 2 3) (list 1 2 3 4 5 6))))
-  (list 1 2 3))
\ No newline at end of file
+  (list 1 2 3))
+
+(apl-test
+  "member basic"
+  (rv
+    (apl-member
+      (make-array (list 3) (list 1 2 3))
+      (make-array (list 2) (list 2 3))))
+  (list 0 1 1))
+
+(apl-test
+  "member all absent"
+  (rv
+    (apl-member
+      (make-array (list 3) (list 4 5 6))
+      (make-array (list 3) (list 1 2 3))))
+  (list 0 0 0))
+
+(apl-test
+  "member scalar"
+  (rv (apl-member (apl-scalar 5) (make-array (list 3) (list 1 5 9))))
+  (list 1))
+
+(apl-test
+  "member shape preserved"
+  (sh
+    (apl-member
+      (make-array (list 2 3) (list 1 2 3 4 5 6))
+      (make-array (list 3) (list 1 3 5))))
+  (list 2 3))
+
+(apl-test
+  "member matrix ravel"
+  (rv
+    (apl-member
+      (make-array (list 2 3) (list 1 2 3 4 5 6))
+      (make-array (list 3) (list 1 3 5))))
+  (list 1 0 1 0 1 0))
+
+(apl-test
+  "index-of basic"
+  (rv
+    (apl-index-of
+      (make-array (list 4) (list 10 20 30 40))
+      (make-array (list 3) (list 20 40 10))))
+  (list 2 4 1))
+
+(apl-test
+  "index-of not-found"
+  (rv
+    (apl-index-of
+      (make-array (list 3) (list 1 2 3))
+      (make-array (list 2) (list 5 2))))
+  (list 4 2))
+
+(apl-test
+  "index-of scalar right"
+  (rv
+    (apl-index-of (make-array (list 3) (list 10 20 30)) (apl-scalar 20)))
+  (list 2))
+
+(apl-test
+  "without basic"
+  (rv
+    (apl-without
+      (make-array (list 5) (list 1 2 3 4 5))
+      (make-array (list 2) (list 2 4))))
+  (list 1 3 5))
+
+(apl-test
+  "without shape"
+  (sh
+    (apl-without
+      (make-array (list 5) (list 1 2 3 4 5))
+      (make-array (list 2) (list 2 4))))
+  (list 3))
+
+(apl-test
+  "without nothing removed"
+  (rv
+    (apl-without
+      (make-array (list 3) (list 1 2 3))
+      (make-array (list 3) (list 4 5 6))))
+  (list 1 2 3))
+
+(apl-test
+  "without all removed"
+  (rv
+    (apl-without
+      (make-array (list 3) (list 1 2 3))
+      (make-array (list 3) (list 1 2 3))))
+  (list))
\ No newline at end of file