From be9919478aafcfa21957256d4f549059bc5ebc25 Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <petermikkelsen10@gmail.com>
Date: Fri, 28 Jan 2022 18:59:37 +0000
Subject: =?UTF-8?q?Implement=20where=20(=E2=8D=B8),=20unique=20mask=20(?=
 =?UTF-8?q?=E2=89=A0)=20and=20unique=20(=E2=88=AA)?=
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---
 apl9.h      |  3 +++
 functions.c | 24 +++++++++++++++++++++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/apl9.h b/apl9.h
index 2846861..2a7565f 100644
--- a/apl9.h
+++ b/apl9.h
@@ -294,6 +294,7 @@ Array *fnMagnitude(Array *);
 Array *fnCeiling(Array *);
 Array *fnFloor(Array *);
 Array *fnSame(Array *);
+Array *fnUniqueMask(Array *);
 Array *fnDepth(Array *);
 Array *fnTally(Array *);
 Array *fnMix(Array *);
@@ -304,7 +305,9 @@ Array *fnNest(Array *);
 Array *fnGradeUp(Array *);
 Array *fnGradeDown(Array *);
 Array *fnIndexGenerator(Array *);
+Array *fnWhere(Array *);
 Array *fnEnlist(Array *);
+Array *fnUnique(Array *);
 Array *fnNot(Array *);
 Array *fnRavel(Array *);
 Array *fnTable(Array *);
diff --git a/functions.c b/functions.c
index ad87c11..3b32cca 100644
--- a/functions.c
+++ b/functions.c
@@ -25,7 +25,7 @@ fnmonad monadfunctiondefs[] = {
 	fnSame, /* ⊣ */
 	fnSame, /* ⊢ */
 	0, /* = */
-	0, /* ≠ */
+	fnUniqueMask, /* ≠ */
 	0, /* ≤ */
 	0, /* < */
 	0, /* > */
@@ -45,10 +45,10 @@ fnmonad monadfunctiondefs[] = {
 	fnGradeUp, /* ⍋ */
 	fnGradeDown, /* ⍒ */
 	fnIndexGenerator, /* ⍳ */
-	0, /* ⍸ */
+	fnWhere, /* ⍸ */
 	fnEnlist, /* ∊ */
 	0, /* ⍷ */
-	0, /* ∪ */
+	fnUnique, /* ∪ */
 	0, /* ∩ */
 	fnNot, /* ~ */
 	fnRavel, /* , */
@@ -366,6 +366,12 @@ fnSame(Array *right)
 	return right;
 }
 
+Array *
+fnUniqueMask(Array *right)
+{
+	return rundfn(L"(⍳≢⍵)≤⊃∘⍸¨↓≡⌾⍨⌷∘⍵¨⍳≢⍵", nil, nil, nil, right);
+}
+
 Array *
 fnDepth(Array *right)
 {
@@ -575,6 +581,12 @@ fnIndexGenerator(Array *right)
 	return res;
 }
 
+Array *
+fnWhere(Array *right)
+{
+	return rundfn(L"(,⍵)⌿,⍳⍴⍵", nil, nil, nil, right);
+}
+
 Array *
 fnEnlist(Array *right)
 {
@@ -595,6 +607,12 @@ fnEnlist(Array *right)
 	}
 }
 
+Array *
+fnUnique(Array *right)
+{
+	return rundfn(L"(≠⍵)⌿⍵", nil, nil, nil, right);
+}
+
 Array *
 fnNot(Array *right)
 {
-- 
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