From 714160c76463d462162121cb5a823e52a9672506 Mon Sep 17 00:00:00 2001
From: An Phan <me@phanan.net>
Date: Sat, 21 Mar 2026 19:55:58 +0100
Subject: [PATCH] Add `juxt`, inspired by Clojure's `juxt`

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 composer.json                 |  1 +
 docs/functional-php.md        | 17 +++++++++
 src/Functional/Functional.php |  5 +++
 src/Functional/Juxt.php       | 32 +++++++++++++++++
 tests/Functional/JuxtTest.php | 68 +++++++++++++++++++++++++++++++++++
 5 files changed, 123 insertions(+)
 create mode 100644 src/Functional/Juxt.php
 create mode 100644 tests/Functional/JuxtTest.php

diff --git a/composer.json b/composer.json
index 905624ab..b84ab0da 100644
--- a/composer.json
+++ b/composer.json
@@ -74,6 +74,7 @@
             "src/Functional/InvokeIf.php",
             "src/Functional/InvokeLast.php",
             "src/Functional/Invoker.php",
+            "src/Functional/Juxt.php",
             "src/Functional/Last.php",
             "src/Functional/LastIndexOf.php",
             "src/Functional/LessThan.php",
diff --git a/docs/functional-php.md b/docs/functional-php.md
index 62134233..4cf3fafa 100644
--- a/docs/functional-php.md
+++ b/docs/functional-php.md
@@ -329,6 +329,23 @@ use function Functional\partial_method;
 $registeredUsers = select($users, partial_method('isRegistered'));
 ```
 
+## juxt()
+Takes a list of functions and returns a new function that applies each function to the given arguments and returns an array of the results. Inspired by Clojure's `juxt`.
+
+``callable Functional\juxt(callable ...$functions)``
+
+```php
+use function Functional\juxt;
+
+$getStats = juxt('min', 'max');
+$getStats(3, 1, 5, 2); // [1, 5]
+
+$transform = juxt('strtoupper', 'strtolower', 'strrev');
+$transform('Hello'); // ['HELLO', 'hello', 'olleH']
+```
+
+_See also `converge()`, which additionally passes the results through a converging function._
+
 ## converge()
 
 ``callable Functional\converge(callable $convergingFunction, callable[] branchingFunctions)``
diff --git a/src/Functional/Functional.php b/src/Functional/Functional.php
index 58784708..b57edf9f 100644
--- a/src/Functional/Functional.php
+++ b/src/Functional/Functional.php
@@ -237,6 +237,11 @@ final class Functional
      */
     const invoker = '\Functional\invoker';
 
+    /**
+     * @see \Functional\juxt
+     */
+    const juxt = '\Functional\juxt';
+
     /**
      * @see \Functional\last
      */
diff --git a/src/Functional/Juxt.php b/src/Functional/Juxt.php
new file mode 100644
index 00000000..8a36b0aa
--- /dev/null
+++ b/src/Functional/Juxt.php
@@ -0,0 +1,32 @@
+<?php
+
+/**
+ * @package   Functional-php
+ * @author    Lars Strojny <lstrojny@php.net>
+ * @copyright 2011-2021 Lars Strojny
+ * @license   https://opensource.org/licenses/MIT MIT
+ * @link      https://github.com/lstrojny/functional-php
+ */
+
+namespace Functional;
+
+/**
+ * Takes a list of functions and returns a new function that applies each
+ * function to the given arguments and returns an array of the results.
+ *
+ * @param callable ...$functions
+ * @return callable
+ * @no-named-arguments
+ */
+function juxt(callable ...$functions)
+{
+    return function (...$values) use ($functions) {
+        $result = [];
+
+        foreach ($functions as $function) {
+            $result[] = $function(...$values);
+        }
+
+        return $result;
+    };
+}
diff --git a/tests/Functional/JuxtTest.php b/tests/Functional/JuxtTest.php
new file mode 100644
index 00000000..82e9d250
--- /dev/null
+++ b/tests/Functional/JuxtTest.php
@@ -0,0 +1,68 @@
+<?php
+
+/**
+ * @package   Functional-php
+ * @author    Lars Strojny <lstrojny@php.net>
+ * @copyright 2011-2021 Lars Strojny
+ * @license   https://opensource.org/licenses/MIT MIT
+ * @link      https://github.com/lstrojny/functional-php
+ */
+
+namespace Functional\Tests;
+
+use function Functional\juxt;
+
+class JuxtTest extends AbstractTestCase
+{
+    public function test(): void
+    {
+        $juxted = juxt('strtoupper', 'strtolower', 'strrev');
+
+        self::assertSame(['HELLO', 'hello', 'olleH'], $juxted('Hello'));
+    }
+
+    public function testWithMultipleArguments(): void
+    {
+        $minMax = juxt('min', 'max');
+
+        self::assertSame([1, 5], $minMax(3, 1, 5, 2));
+    }
+
+    public function testWithArrayFunctions(): void
+    {
+        $stats = juxt('array_sum', 'count');
+
+        self::assertSame([15, 5], $stats([1, 2, 3, 4, 5]));
+    }
+
+    public function testWithClosures(): void
+    {
+        $double = static function ($x) {
+            return $x * 2;
+        };
+        $square = static function ($x) {
+            return $x * $x;
+        };
+        $negate = static function ($x) {
+            return -$x;
+        };
+
+        $juxted = juxt($double, $square, $negate);
+
+        self::assertSame([10, 25, -5], $juxted(5));
+    }
+
+    public function testWithNoFunctions(): void
+    {
+        $juxted = juxt();
+
+        self::assertSame([], $juxted('anything'));
+    }
+
+    public function testWithSingleFunction(): void
+    {
+        $juxted = juxt('strlen');
+
+        self::assertSame([5], $juxted('hello'));
+    }
+}