[Arr] add pure implementations of Iter\map{keys,with_key}

src/Psl/Arr/map.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Arr;
+
+/**
+ * Applies a mapping function to all values of an array.
+ *
+ * The function is passed the current array value and should return a
+ * modified array value.
+ *
+ * The key is left as-is and not passed to the mapping function.
+ *
+ * Examples:
+ *
+ *     Arr\map([1, 2, 3, 4, 5], fn($i) => $i * 2);
+ *     => Arr(2, 4, 6, 8, 10)
+ *
+ * @psalm-template Tk of array-key
+ * @psalm-template Tv
+ * @psalm-template T
+ *
+ * @psalm-param array<Tk, Tv>           $array      Array to be mapped over
+ * @psalm-param (pure-callable(Tv): T)  $function
+ *
+ * @psalm-return array<Tk, T>
+ *
+ * @psalm-pure
+ */
+function map(array $array, callable $function): array
+{
+    $result = [];
+    foreach ($array as $key => $value) {
+        $result[$key] = $function($value);
+    }
+
+    return $result;
+}

src/Psl/Arr/map_keys.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Arr;
+
+/**
+ * Applies a mapping function to all keys of an array.
+ *
+ * The function is passed the current array key and should return a
+ * modified array key.
+ *
+ * The value is left as-is and not passed to the mapping function.
+ *
+ * Examples:
+ *
+ *     Arr\map_keys([0 => 1, 1 => 2, 2 => 3, 3 => 4, 4 => 5], fn($i) => $i * 2);
+ *     => Arr(0 => 1, 2 => 2, 4 => 3, 6 => 4, 8 => 5)
+ *
+ * @psalm-template Tk1 of array-key
+ * @psalm-template Tk2 of array-key
+ * @psalm-template Tv
+ *
+ * @psalm-param array<Tk1, Tv>              $array    Array to be mapped over
+ * @psalm-param (pure-callable(Tk1): Tk2)   $function
+ *
+ * @psalm-return array<Tk2, Tv>
+ *
+ * @psalm-pure
+ */
+function map_keys(array $array, callable $function): array
+{
+    $result = [];
+    foreach ($array as $key => $value) {
+        $result[$function($key)] = $value;
+    }
+
+    return $result;
+}

src/Psl/Arr/map_with_key.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Arr;
+
+/**
+ * Applies a mapping function to all values of an array.
+ *
+ * The function is passed the current array key and value and should return a
+ * modified array value.
+ *
+ * The key is left as-is.
+ *
+ * Examples:
+ *
+ *     Arr\map_with_key([1, 2, 3, 4, 5], fn($k, $v) => $k + $v);
+ *     => Arr(1, 3, 5, 7, 9)
+ *
+ * @psalm-template Tk of array-key
+ * @psalm-template Tv
+ * @psalm-template T
+ *
+ * @psalm-param array<Tk, Tv>               $array    Array to be mapped over
+ * @psalm-param (pure-callable(Tk,Tv): T)   $function
+ *
+ * @psalm-return array<Tk, T>
+ *
+ * @psalm-pure
+ */
+function map_with_key(array $array, callable $function): array
+{
+    $result = [];
+    foreach ($array as $key => $value) {
+        $result[$key] = $function($key, $value);
+    }
+
+    return $result;
+}

src/Psl/Internal/Loader.php

@@ -90,6 +90,9 @@ final class Loader
         'Psl\Arr\filter_keys',
         'Psl\Arr\filter_nulls',
         'Psl\Arr\filter_with_key',
+        'Psl\Arr\map',
+        'Psl\Arr\map_keys',
+        'Psl\Arr\map_with_key',
         'Psl\Asio\wrap',
         'Psl\Internal\boolean',
         'Psl\Internal\type',

tests/Psl/Arr/MapKeysTest.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Arr;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Arr;
+
+class MapKeysTest extends TestCase
+{
+    /**
+     * @dataProvider provideData
+     */
+    public function testMapKeys(array $expected, array $array, callable $function): void
+    {
+        $result = Arr\map_keys($array, $function);
+        
+        self::assertSame($expected, $result);
+    }
+
+    public function provideData(): iterable
+    {
+        yield [[1, 2, 3], [1, 2, 3], fn (int $k): int => $k];
+        yield [[1, 2 => 2, 4 => 3], [1, 2, 3], fn (int $k): int => $k * 2];
+        yield [['0' => 1, '1' => 2, '2' => 3], [1, 2, 3], fn (int $k): string => (string) $k];
+        yield [[], [], fn (int $k): string => (string) $k];
+    }
+}

tests/Psl/Arr/MapTest.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Arr;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Arr;
+
+class MapTest extends TestCase
+{
+    /**
+     * @dataProvider provideData
+     */
+    public function testMap(array $expected, array $array, callable $function): void
+    {
+        $result = Arr\map($array, $function);
+
+        self::assertSame($expected, $result);
+    }
+
+    public function provideData(): iterable
+    {
+        yield [[1, 2, 3], [1, 2, 3], fn (int $v): int => $v];
+        yield [[2, 4, 6], [1, 2, 3], fn (int $v): int => $v * 2];
+        yield [['1', '2', '3'], [1, 2, 3], fn (int $v): string => (string)$v];
+        yield [[], [], fn (int $k): string => (string)$v];
+    }
+}

tests/Psl/Arr/MapWithKeyTest.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Arr;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Arr;
+
+class MapWithKeyTest extends TestCase
+{
+    /**
+     * @dataProvider provideData
+     */
+    public function testMapWithKey(array $expected, array $array, callable $function): void
+    {
+        $result = Arr\map_with_key($array, $function);
+        
+        self::assertSame($expected, $result);
+    }
+
+    public function provideData(): iterable
+    {
+        yield [[1, 3, 5], [1, 2, 3], fn (int $k, int $v): int => $k + $v];
+        yield [[0, 4, 16], [1, 2, 3], fn (int $k, int $v): int => $k * (2 ** $v)];
+        yield [['1', '3', '5'], [1, 2, 3], fn (int $k, int $v): string => (string) ($k + $v)];
+        yield [[], [], fn (int $k, int $v): string => (string) ($k + $v)];
+    }
+}